GRB230307A

This page lists all entries on GRB230307A in GRBweb

Summary Fermi GBM IPN GCN 33405 GCN 33406 GCN 33407 GCN 33410 GCN 33411 GCN 33412 GCN 33413 GCN 33414 GCN 33415 GCN 33416 GCN 33418 GCN 33419 GCN 33424 GCN 33425 GCN 33427 GCN 33428 GCN 33429 GCN 33430 GCN 33431 GCN 33434 GCN 33437 GCN 33438 GCN 33439 GCN 33442 GCN 33443 GCN 33444 GCN 33447 GCN 33448 GCN 33449 GCN 33453 GCN 33459 GCN 33461 GCN 33465 GCN 33466 GCN 33471 GCN 33472 GCN 33475 GCN 33478 GCN 33485 GCN 33551 GCN 33558 GCN 33569 GCN 33577 GCN 33578 GCN 33579 GCN 33580 GCN 33635 GCN 33747

Summary table
Variable Value Source
GRB_name_Fermi GRB230307656
T0 15:44:05.615 UTC GCN_circulars,Konus-Wind Det
ra 60.8208° IPN
decl -75.3833° IPN
pos_error 1.67e-01° IPN
T90 34.561 s Fermi_GBM
T90_error 0.572 s Fermi_GBM
T90_start 15:44:08.527 UTC Fermi_GBM
fluence 3.15e-03 erg/cm² Fermi_GBM
fluence_error 2.57e-07 erg/cm² Fermi_GBM
redshift 0.0650 GCN_circulars,Optical
T100 37.473 s
GBM_located False
mjd 60010.655620543985 GCN_circulars,Konus-Wind Det
Fermi GBM table
GRB_name_Fermi GRB230307656
trigger_name bn230307656
ra 54.0600°
decl -76.6100°
pos_error 2.41e+00°
datum 2023-03-07
t_trigger 15:44:06.671 UTC
T90 34.561 s
T90_error 0.572 s
T90_start 15:44:08.527 UTC
fluence 3.15e-03 erg/cm²
fluence_error 2.57e-07 erg/cm²
flux_1024 7.91e+02 erg/cm²/s
flux_1024_error 3.95e+00 erg/cm²/s
flux_1024_time 5.82e+00 erg/cm²/s
flux_64 9.54e+02 erg/cm²/s
flux_64_error 1.66e+01 erg/cm²/s
IPN table
GRB_name GRB230307A
ra 60.8208°
decl -75.3833°
pos_error 1.67e-01°
GCN 33405 table
GRB_name GRB230307A
GCN_number 33405
Detection_method Fermi GBM final loc
t_trigger 15:44:06 UTC
ra 54.1000°
decl -76.6000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33405 SUBJECT: GRB 230307A: Fermi GBM Final Real-time Localization DATE: 23/03/07 15:54:24 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 15:44:06 UT on 7 Mar 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230307A (trigger 699896651.671248 / 230307656). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 54.1, Dec = -76.6 (J2000 degrees, equivalent to J2000 03h 36m, -76d 35'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 142.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230307656/quicklook/glg_skymap_all_bn230307656.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230307656/quicklook/glg_healpix_all_bn230307656.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230307656/quicklook/glg_lc_medres34_bn230307656.gif
GCN 33406 table
GRB_name GRB230307A
GCN_number 33406
Detection_method Fermi GBM Other
ra 28.0300°
decl -81.5100°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33406 SUBJECT: GRB 230307A: GECAM detection of an extremely bright burst DATE: 23/03/07 16:53:45 GMT FROM: Dong Xu at NAOC/CAS Shaolin Xiong, Chenwei Wang, Yue Huang, report on behalf of the GECAM team: GECAM-B was triggered in-flight by the extremely bright long burst at 2023-03-07T15:44:06.650 UTC (T0), which was also observed by Fermi/GBM (GCN 33405). The GECAM-B ground calculated location (J2000) is: R.A.: 28.03 [deg] Dec.: -81.51 [deg] Error: 1 [deg] (1-sigma, statistical only) The systematic error of this location is estimated to be ~2 degrees. This GECAM location is consistent with the Fermi/GBM one within error. The GECAM-B light curve shows a roughly FRED shape with a possible precursor, with a total duration of ~100 sec. The time-averaged spectrum analysis on the trigger alert data shows this burst has a fluence of about 1E-3 erg/cm2 in 20-1000 keV, which is notably high, and comparable to GRB 130427A. We caution that this analysis is very preliminary. Refined analysis will be reported later. Follow-up observations are encouraged.
GCN 33407 table
GRB_name GRB230307A
GCN_number 33407
Detection_method Fermi GBM Det
t_trigger 15:44:06.670 UTC
ra 54.0600°
decl -76.6100°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33407 SUBJECT: GRB 230307A: Fermi GBM detection of a very bright GRB DATE: 23/03/07 17:10:32 GMT FROM: Sarah Dalessi at UAH S. Dalessi(UAH) report on behalf of the Fermi GBM Team: "At 15:44:06.67 UT on 07 March 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 230307A (trigger 699896651 / 230307656). This event is one of the brightest among the GBM detected GRBs. Follow-up across all wavelengths is encouraged. The on-ground calculated location, using the GBM trigger data, is RA = 54.06, DEC = -76.61 (J2000 degrees, equivalent to J2000 03h 36m, -76d 35'), with a statistical uncertainty of 1 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ). The angle from the Fermi LAT boresight at the GBM trigger time is 142.0 degrees. A full GCN of the Fermi-GBM analysis of this event will follow in a later GCN, once the data has become available. For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN 33410 table
GRB_name GRB230307A
GCN_number 33410
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33410 SUBJECT: Solar Orbiter STIX observation of GRB 230307A DATE: 23/03/07 20:59:04 GMT FROM: Hualin Xiao at FHNW Hualin Xiao, Sm Krucker on behalf of the STIX team report: At 2023-03-07T15:44:09Z UT (Solar Orbiter onboard time), STIX detected GRB 230307A, when Solar Orbiter was 0.53 AU from the earth. The one-way light time between the earth and the Solar Orbiter was 264.46 sec. The gamma-ray burst signal can be clearly seen in the STIX quick-look light curves in the range between 10 - 84 keV. The GRB has a single peak and a duration of about 40 seconds. The STIX light curves for this GRB can be found here: https://datacenter.stix.i4ds.net/view/plot/lightcurves?start=1678203251&span=1200 By using the light time difference information, we also estimated the possible locations of the GRB. The result can be found here: https://datacenter.stix.i4ds.net/pub/GRB/GRB230307A/GRB230307A_loc.png The analysis results presented above are preliminary. The science data will only be down-linked from the instrument in a month or two. Detailed analysis of the event will be started after downloading the science data. The Solar Orbiter (SolO) is a Sun-observing satellite developed by the European Space Agency, it was launched on 10th Feb. 2020. It has a unique elliptical orbit around the sun, with distances varying from 0.3 - 1 AU. The Spectrometer Telescope for Imaging X-rays (STIX) is one of the ten instruments onboard the Solar Orbiter. It measures X-rays emitted during solar flares in the energy range of 4 150 keV and takes X-ray images by using an indirect imaging technique, based on the Moir effect. Its detectors consist of thirty-two pixelated CdTe detectors with a total effective area of 6 cm^2. More information about STIX can be found on the STIX data center website: https://datacenter.stix.i4ds.net/
GCN 33411 table
GRB_name GRB230307A
GCN_number 33411
Detection_method Fermi GBM Det
t_trigger 15:44:06.670 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 33411 SUBJECT: GRB 230307A: Fermi GBM Observation of a very bright burst DATE: 23/03/07 22:31:41 GMT FROM: Sarah Dalessi at UAH S. Dalessi(UAH), O.J. Roberts (USRA), and C. Meegan (UAH) report on behalf of the Fermi GBM Team: "At 15:44:06.67 UT on 07 March 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 230307A (trigger 699896651 / 230307656). This burst was also detected by Solar Orbiter STIX (Xiao et al. 2023, GCN 33410), and GECAM (Xiong et al. 2023, GCN 33406). The Fermi GBM Final Real-time Localization (GBM team 2023, GCN 33405) is consistent with the GECAM position. The angle from the Fermi LAT boresight at the GBM trigger time is 142.0 degrees. The GBM light curve consists of a single burst with a duration (T90) of about 35 s (10-1000 keV). The time-averaged spectrum from T0 to T0+148 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.07 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 936 +/- 3 keV. The event fluence (10-1000 keV) in this time interval is (2.951 +/- 0.004)E-03 erg/cm^2. The 1s peak photon flux measured starting from T0+5.8 s in the 10-1000 keV band is 791 +/- 4 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
GCN 33412 table
GRB_name GRB230307A
GCN_number 33412
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33412 SUBJECT: GRB 230307A: AGILE/MCAL detection DATE: 23/03/07 22:40:47 GMT FROM: Claudio Casentini at INAF-IAPS C. Casentini (INAF/IAPS), M. Tavani (INAF/IAPS, and Uni.Roma Tor Vergata), C. Pittori, F. Lucarelli, F. Verrecchia (SSDC, and INAF/OAR) A. Argan, M. Cardillo, Y. Evangelista, L. Foffano, G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, A. Di Piano, V. Fioretti, G. Panebianco, N. Parmiggiani (INAF/OAS-Bologna), F. Longo (Uni. Trieste, INFN Trieste), M. Romani (INAF/OA-Brera), M. Marisaldi (INAF/OAS-Bologna, Bergen University), M. Pilia, A. Trois (INAF/OA Cagliari), I. Donnarumma, E. Menegoni, A.Ursi (ASI), A. Giuliani (INAF/IASF-Mi) and P. Tempesta (TeleSpazio), report on behalf of the AGILE Team: The AGILE satellite detected the long GRB 230307A at T0 = 2023-03-07 15:44:06 (UTC), reported by Fermi/GBM (GCN #33405 and GCN #33407), GECAM (GCN #33406) and Stix (GCN #33410). The burst is clearly visible in the AGILE scientific ratemeters of the MiniCALorimeter (MCAL; 0.4-100 MeV), and in all the panels of the AntiCoincidence detectors (AC Top, 50-200 keV; AC Lat, 80-200 keV). The event lasted about 30 s and it released a total number of 527069 counts in the MCAL detector (above a background rate of 1154 Hz), and 920952 counts in the AC Top detector (above a background rate of 2959 Hz). The AGILE ratemeters light curves can be found at: http://www.agilescienceapp.it/notices/GRB230307A_AGILE_RM_ND.png . The event also triggered a high-time resolution MCAL data acquisition, from T0 to T0+22 s (UTC), and released 241403 counts in the detector, above a background rate of 510 Hz. The MCAL light curve can be found at: http://www.agilescienceapp.it/notices/GRB230307A_082567_605288646.000000.png . At the T0, the event was 54 deg off-axis. Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html
GCN 33413 table
GRB_name GRB230307A
GCN_number 33413
Detection_method IPN Triangulation
t_trigger 15:44:07 UTC
ra 59.2330°
decl -75.2260°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33413 SUBJECT: IPN triangulation of GRB 230307A (long/very bright) DATE: 23/03/07 23:33:26 GMT FROM: Dmitry Svinkin at Ioffe Institute A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, A. Lysenko, A. Ridnaia on behalf of the IPN, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The very bright, long-duration GRB 230307A (Fermi-GBM detection: the Fermi GBM team, GCN Circ. 33405; Dalessi, GCN Circ. 33407; Dalessi and Roberts, GCN Circ. 33411; GECAM detection: Xiong et al., GCN Circ. 33406; Solar Orbiter STIX detection: Xiao and Krucker, GCN Circ. 33410; AGILE-MCAL detection: Casentini et al., GCN Circ. 33412) has been detected by Fermi(GBM trigger 699896651), GECAM, INTEGRAL (SPI-ACS), Swift (BAT), Solar Orbiter (STIX), AGILE (MCAL), and Mars-Odyssey (HEND), so far, at about 56647 s UT (15:44:07). The burst was outside the coded field of view of the BAT. We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: ------------------------------ RA(2000), deg Dec(2000), deg ------------------------------ Center: 59.233 -75.226 Corners: 70.905 -76.077 38.996 -71.948 38.440 -72.064 73.041 -76.146 -------------------------------- The error box area is 1.948 sq. deg, and its maximum dimension is 9.6 deg (the minimum one is 11.6 arcmin). The Sun distance was 100 deg. This box may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi-GBM final localization (GCN 33407). A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB230307_T56646/IPN
GCN 33414 table
GRB_name GRB230307A
GCN_number 33414
Detection_method IPN Triangulation
Circular_text TITLE: GCN CIRCULAR NUMBER: 33414 SUBJECT: GRB 230307A: possibly the second highest GRB energy fluence ever identified DATE: 23/03/08 05:41:31 GMT FROM: Eric Burns at LSU E. Burns (LSU), A. Goldstein (USRA), S. Lesage (UAH), and S. Dalessi (UAH) report on behalf of the Fermi-GBM Team. The very bright long GRB 230307A has been detected by many prompt GRB monitors (GCN Circ. 33405; Dalessi, GCN Circ. 33407; Dalessi and Roberts, GCN Circ. 33411; GECAM detection: Xiong etal., GCN Circ. 33406; Solar Orbiter STIX detection: Xiao and Krucker, GCN Circ. 33410; AGILE-MCAL detection: Casentini et al., GCN Circ. 33412) at 15:44:07. Fermi-GBM reports a preliminary 10-1000 keV fluence of (2.951 +/- 0.004)E-03 erg/cm^2 (Dalessi and Roberts, GCNCirc. 33411) with a best-fit Comptonized spectrum with Epeak = 936 +/- 3 keV and alpha -1.07 +/- 0.01. Utilizing this spectrum, this corresponds to a bolometric fluence of 4.56E-3 erg/cm^2, with negligible error. For reported GRB energy fluence values, only GRB 221009A is higher. GRB 130427A has a reported fluence of 2.83E-3 erg/cm^2, 840304 of ~2.8E-3 erg/cm^2, and 830801 of >2.0e-3erg/cm^2. Noting that these three values have some uncertainty due to detector issues and that this initial value for GRB 230307A is preliminary, from these base values GRB 230307A has the second highest reported value. Follow-up is thus strongly encouraged. The best current localization is from the IPN, reported in GCN 33413.
GCN 33415 table
GRB_name GRB230307A
GCN_number 33415
Detection_method AstroSat CZTI
Circular_text TITLE: GCN CIRCULAR NUMBER: 33415 SUBJECT: GRB 230307A: AstroSat CZTI detection DATE: 23/03/08 06:17:52 GMT FROM: Gaurav Waratkar at IIT,Bombay P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of the extremely bright long GRB 230307A which was also detected by Fermi-GBM (Fermi GBM team, GCN 33405), GECAM (Xiong et al., GCN 33406), Solar Orbiter STIX (Xiao et al., GCN 33410), AGILE/MCAL (Casentini et al., GCN 33412) and IPN (Kozyrev et al., GCN 33413). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-03-07 15:44:10.0 UTC. The measured peak count rate associated with the burst is 4041 (+33, -37) counts/s above the background in the combined data of all quadrants, with a total of 90900 (+758, -850) counts. The local mean background count rate was 453 (+1, -1) counts/s. Using cumulative rates, we measure a T90 of 33 (+1, -1) s. In the preliminary analysis, we find 5484 Compton events associated with this event. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-03-07 15:44:15.17 UTC. The measured peak count rate is 276156 (+268, -300) counts/s above the background in the combined Veto data of all quadrants, with a total of 5571313 (+4953, -6044) counts. The local mean background count rate was 14750 (+7, -6) counts/s. We measure a T90 of 40 (+0.2, -0.2) s from the cumulative Veto light curve. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN 33416 table
GRB_name GRB230307A
GCN_number 33416
Detection_method IPN Triangulation
Circular_text TITLE: GCN CIRCULAR NUMBER: 33416 SUBJECT: GRB 230307A: BALROG localization (Fermi Trigger 699896651/ GRB 230307656) DATE: 23/03/08 09:20:58 GMT FROM: Jochen Greiner at MPE,Garching B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 699896651 at 15:44:06 on 07 March 2023 were fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position (1 sigma statistical errors) is: RA(2000.0) = 41.8+/-0.4 deg Decl.(2000.0) = -71.5+/-0.1 deg We estimate an additional systematic error of 2 deg. The position is in agreement with the IPN localization (GCN Circ. 33413). We note that the determined localization is close to the Earth horizon, which could be an additional source of systematic errors. Further details are available at: https://grb.mpe.mpg.de/grb/GRB230307656/?data_version=h01 The Healpix map can be downloaded from: https://grb.mpe.mpg.de/media/data/GRB230307656/data_files/230308_090913782213_GRB230307656_healpixSysErr_trigdat_h01.fits The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB230307656/json
GCN 33418 table
GRB_name GRB230307A
GCN_number 33418
Detection_method Fermi GBM Det
t_trigger 15:44:12 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 33418 SUBJECT: GRB 230307A: Detection by GRBAlpha DATE: 23/03/08 11:23:01 GMT FROM: Marianna Dafcikova at Masaryk University <500025@mail.muni.cz> M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration. The extremely bright long-duration GRB 230307A (Fermi/GBM detection: GCN 33405, 33407, 33411, 33414; GECAM-B detection: GCN 33406; Solar Orbiter STIX detection: GCN 33410; AGILE/MCAL detection: GCN 33412; IPN triangulation: GCN 33413; AstroSat detection: GCN 33415; BALROG localization: GCN 33416) was observed by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020). The detection was confirmed at the peak time 2023-03-07 15:44:12 UTC. The T90 duration measured by GRBAlpha is 25 s and the overall significance during T90 reaches 305 sigma. GRBAlpha entered the outer Van Allen radiation belt during the tail part of the burst. The peak count rate detected by GRBAlpha reaches almost 10 000 counts/s, which is nearly half of the peak count rate of 22 000 counts/s measured for GRB221009A. The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230307A_GCN.pdf All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume.
GCN 33419 table
GRB_name GRB230307A
GCN_number 33419
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33419 SUBJECT: GRB 230307A: Tiled Swift observations DATE: 23/03/08 12:57:43 GMT FROM: Phil Evans at U of Leicester P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a series of observations, tiled on the sky, of the Fermi/GBM GRB 230307A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00110 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the Fermi/GBM event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team.
GCN 33424 table
GRB_name GRB230307A
GCN_number 33424
Detection_method Fermi GBM Det
t_trigger 15:44:11 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 33424 SUBJECT: GRB 230307A: VZLUSAT-2 detection DATE: 23/03/08 18:13:06 GMT FROM: Jakub Ripa at Masaryk University <245487@mail.muni.cz> J. Ripa (Masaryk U.), M. Dafcikova, A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), M. Ohno (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU) -- the VZLUSAT-2/GRB payload collaboration. The extremely bright long-duration GRB 230307A (Fermi/GBM detection: GCN 33405, 33407, 33411, 33414; GECAM-B detection: GCN 33406; Solar Orbiter STIX detection: GCN 33410; AGILE/MCAL detection: GCN 33412; IPN triangulation: GCN 33413; AstroSat detection: GCN 33415; BALROG localization: GCN 33416; GRBAlpha detection: GCN 33418) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The data acquisition was performed by GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-03-07 15:44:11 UTC. The T90 duration measured by VZLUSAT-2 is 28 s (34 s) and the significance during T90 reaches 219 sigma (213 sigma) for detector unit no. 0 (no. 1). The light curves obtained by VZLUSAT-2 is available here: https://vzlusat2.konkoly.hu/static/share/GRB230307A_GCN_VZLUSAT2.pdf All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/ The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~40 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.
GCN 33425 table
GRB_name GRB230307A
GCN_number 33425
Detection_method IPN Triangulation
ra 60.8190°
decl -75.3790°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33425 SUBJECT: Improved IPN localization for GRB 230307A DATE: 23/03/08 20:16:29 GMT FROM: Dmitry Svinkin at Ioffe Institute A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: Using the Konus-Wind data we have triangulated GRB 230307A (GCNs 33405, 33406, 33407, 33410, 33411, 33412, 33413, 33414, 33415, 33416, 33418, 33424) to the 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 60.819 (04h 03m 17s) -75.379 (-75d 22' 43") Corners: 61.075 (04h 04m 18s) -75.436 (-75d 26' 10") 61.016 (04h 04m 04s) -75.358 (-75d 21' 29") 60.565 (04h 02m 16s) -75.321 (-75d 19' 14") 60.622 (04h 02m 29s) -75.399 (-75d 23' 56") --------------------------------------------- The error box area is 30 sq. arcmin, and its maximum dimension is 10 arcmin (the minimum one is 4.2 arcmin). The Sun distance was 80 deg. This box may be further improved. The Swift ToO is ongoing. An updated triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB230307_T56646/IPN
GCN 33427 table
GRB_name GRB230307A
GCN_number 33427
Detection_method Konus-Wind Det
t_trigger 15:44:05.615 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 33427 SUBJECT: Konus-Wind detection of GRB 230307A DATE: 23/03/08 21:50:47 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report: The very intense, long-duration GRB 230307A (Fermi-GBM detection: the Fermi GBM team, GCN Circ. 33405; Dalessi, GCN Circ. 33407; Dalessi and Roberts, GCN Circ. 33411; GECAM detection: Xiong et al., GCN Circ. 33406; Solar Orbiter STIX detection: Xiao and Krucker, GCN Circ. 33410; AGILE-MCAL detection: Casentini et al., GCN Circ. 33412; IPN triangulation: Kozyrev et al., GCN Circ. 33413 and 33425; AstroSat CZTI detection: Navaneeth et al., GCN Circ. 33415; GRBAlpha detection: Dafcikova et al., GCN Circ. 33418; VZLUSAT-2 detection: Ripa et al., GCN Circ. 33424) triggered Konus-Wind at T0=56645.615 s UT (15:44:05.615). The burst light curve shows a multipeaked structure which starts at ~T0 and has a total duration of ~196 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB230307_T56645/ As observed by Konus-Wind, the burst had a fluence of 3.58(-0.08,+0.08)x10^-3 erg/cm2, and a 64-ms peak flux, measured from T0+6.224 s, of 6.66(-0.42,+0.46)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+71.424 s) is best fit in the 530 keV - 10 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.60(-0.08,+0.08) and Ep = 1000(-16,+15) keV (chi2 = 41/42 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -5.4 (chi2 = 41/41 dof). The spectrum near the maximum count rate (measured from T0+6.144 to T0+6.400 s) is best fit in the 530 keV - 10 MeV range by a power law with exponential cutoff model: with alpha = -0.13(-0.31,+0.35) and Ep = 1321(-62,+60) keV (chi2 = 19/21 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -4.3 (chi2 = 19/20 dof). The energy fluence of the burst is the second highest (after BOAT GRB 221009A) and the energy peak flux is the 5th highest observed for GRBs for almost 28 years of the KW operation. This supports the results reported in Burns et al., GCN Circ. 33414. All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN 33428 table
GRB_name GRB230307A
GCN_number 33428
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33428 SUBJECT: Fermi GRB 230307A: Global MASTER-Net observations report DATE: 23/03/08 22:20:57 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D.Cheryasov, Ya.Kechin (Lomonosov Moscow State University, SAI, Physics Department), R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico Felix Aguilar OAFA), R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias), D. Buckley (South African Astronomical Observatory), O.A. Gres, N.M. Budnev (Irkutsk State University, API), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational State University) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 230307A ( Fermi GBM team, GCN 33405) errorbox 1 days 7520 sec after notice time and 1 days 7572 sec after trigger time at 2023-03-08 17:50:19 UT, with upper limit up to 19.0 mag. Observations started at twilight. The observations began at zenith distance = 46 deg. The sun altitude is -10.1 deg. The galactic latitude b = -37 deg., longitude l = 292 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2202708 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 94063 | 2023-03-08 17:50:19 | MASTER-SAAO | (04h 06m 50.07s , -74d 51m 54.3s) | C | 180 | 17.4 | 94063 | 2023-03-08 17:50:19 | MASTER-SAAO | (04h 09m 51.53s , -74d 51m 58.1s) | C | 180 | 17.1 | 94274 | 2023-03-08 17:53:51 | MASTER-SAAO | (04h 06m 44.57s , -76d 46m 43.0s) | C | 180 | 17.9 | 94274 | 2023-03-08 17:53:51 | MASTER-SAAO | (04h 10m 11.69s , -76d 46m 46.6s) | C | 180 | 17.7 | 94909 | 2023-03-08 18:04:25 | MASTER-SAAO | (03h 08m 23.27s , -74d 51m 18.2s) | C | 180 | 18.5 | 94909 | 2023-03-08 18:04:25 | MASTER-SAAO | (03h 11m 26.50s , -74d 51m 25.8s) | C | 180 | 18.5 | 95120 | 2023-03-08 18:07:56 | MASTER-SAAO | (04h 06m 35.42s , -76d 44m 20.5s) | C | 180 | 19.0 | 95120 | 2023-03-08 18:07:56 | MASTER-SAAO | (04h 10m 04.25s , -76d 44m 25.9s) | C | 180 | 18.8 | 95754 | 2023-03-08 18:18:31 | MASTER-SAAO | (03h 08m 25.33s , -74d 51m 41.6s) | C | 180 | 18.7 | 95754 | 2023-03-08 18:18:31 | MASTER-SAAO | (03h 11m 30.09s , -74d 51m 50.8s) | C | 180 | 18.7 | 106819 | 2023-03-08 21:23:55 | MASTER-SAAO | (03h 03m 53.63s , -76d 38m 21.4s) | C | 60 | 18.5 | 106819 | 2023-03-08 21:23:55 | MASTER-SAAO | (03h 00m 21.60s , -76d 38m 10.8s) | C | 60 | 18.6 | 107112 | 2023-03-08 21:28:48 | MASTER-SAAO | (03h 38m 39.03s , -76d 38m 02.4s) | C | 60 | 18.5 | 107112 | 2023-03-08 21:28:48 | MASTER-SAAO | (03h 35m 05.28s , -76d 37m 50.0s) | C | 60 | 18.5 | 107204 | 2023-03-08 21:30:20 | MASTER-SAAO | (03h 34m 06.25s , -78d 31m 42.8s) | C | 60 | 18.4 | 107204 | 2023-03-08 21:30:20 | MASTER-SAAO | (03h 29m 57.72s , -78d 31m 30.2s) | C | 60 | 18.4 | 107284 | 2023-03-08 21:31:41 | MASTER-SAAO | (04h 14m 36.07s , -78d 32m 15.3s) | C | 60 | 18.5 | 107284 | 2023-03-08 21:31:41 | MASTER-SAAO | (04h 10m 26.79s , -78d 32m 04.8s) | C | 60 | 18.5 | 107714 | 2023-03-08 21:37:50 | MASTER-SAAO | (03h 39m 18.35s , -76d 34m 01.4s) | C | 180 | 18.9 | 107714 | 2023-03-08 21:37:50 | MASTER-SAAO | (03h 35m 45.53s , -76d 33m 46.1s) | C | 180 | 19.0 | 107926 | 2023-03-08 21:41:22 | MASTER-SAAO | (03h 24m 25.90s , -76d 32m 40.7s) | C | 180 | 18.7 | 107926 | 2023-03-08 21:41:22 | MASTER-SAAO | (03h 20m 53.73s , -76d 32m 24.2s) | C | 180 | 18.9 | 108138 | 2023-03-08 21:44:54 | MASTER-SAAO | (03h 24m 23.20s , -76d 33m 24.5s) | C | 180 | 18.7 | 108138 | 2023-03-08 21:44:54 | MASTER-SAAO | (03h 20m 50.60s , -76d 33m 07.7s) | C | 180 | 18.8 | 108349 | 2023-03-08 21:48:25 | MASTER-SAAO | (03h 39m 21.23s , -76d 32m 07.5s) | C | 180 | 18.7 | 108349 | 2023-03-08 21:48:25 | MASTER-SAAO | (03h 35m 48.38s , -76d 31m 51.0s) | C | 180 | 18.9 | 108559 | 2023-03-08 21:51:55 | MASTER-SAAO | (03h 39m 29.26s , -76d 33m 05.1s) | C | 180 | 18.7 | 108559 | 2023-03-08 21:51:56 | MASTER-SAAO | (03h 35m 56.14s , -76d 32m 48.9s) | C | 180 | 18.9 | 108771 | 2023-03-08 21:55:27 | MASTER-SAAO | (03h 38m 53.42s , -74d 34m 06.9s) | C | 180 | 18.6 | 108771 | 2023-03-08 21:55:27 | MASTER-SAAO | (03h 35m 47.35s , -74d 33m 50.3s) | C | 180 | 18.8 | 108982 | 2023-03-08 21:58:58 | MASTER-SAAO | (03h 35m 55.42s , -74d 33m 24.8s) | C | 180 | 18.6 | 108982 | 2023-03-08 21:58:58 | MASTER-SAAO | (03h 39m 01.23s , -74d 33m 41.8s) | C | 180 | 18.5 | 109194 | 2023-03-08 22:02:30 | MASTER-SAAO | (03h 39m 51.43s , -77d 32m 08.3s) | C | 180 | 18.6 | 109194 | 2023-03-08 22:02:30 | MASTER-SAAO | (03h 36m 01.98s , -77d 31m 51.5s) | C | 180 | 18.8 | 109405 | 2023-03-08 22:06:01 | MASTER-SAAO | (03h 36m 04.38s , -77d 33m 31.5s) | C | 180 | 18.8 | 109405 | 2023-03-08 22:06:01 | MASTER-SAAO | (03h 39m 54.39s , -77d 33m 48.0s) | C | 180 | 18.7 | 109617 | 2023-03-08 22:09:33 | MASTER-SAAO | (03h 49m 04.44s , -77d 31m 38.2s) | C | 180 | 18.7 | 109617 | 2023-03-08 22:09:33 | MASTER-SAAO | (03h 52m 54.28s , -77d 31m 54.1s) | C | 180 | 18.7 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 33429 table
GRB_name GRB230307A
GCN_number 33429
Detection_method Swift-XRT Other
ra 60.8593°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33429 SUBJECT: GRB 230307A: Swift-XRT observations DATE: 23/03/08 23:17:17 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 230307A (Dalessi et al. GCN Circ. 33407) in a series of observations tiled on the sky. The total exposure time is 8.6 ks, distributed over 32 tiles; the maximum exposure at a single sky location was 1.6 ks. The data were collected between T0+76.4 ks and T0+100.9 ks, and are entirely in Photon Counting (PC) mode. Two X-ray sources have been detected within the improved IPN error box (Kozyrev et al., GCN Circ. 33425), that has been fully covered by Swift/XRT observations. Source 2: RA (J2000): 04h 03m 26.24s = 60.85935° Dec (J2000): -75° 22′ 43.8″ = -75.3788° Error: 3.4″ (radius, 90% conf., enhanced) Count-rate: 0.019 (±0.004) ct s-1 Distance: 36.6 arcsec from IPN position Source 3: RA (J2000): 04h 03m 57.93s = 60.99137° Dec (J2000): -75° 21′ 26.8″ = -75.3574° Error: 7.1″ (radius, 90% conf.) Count-rate: 2.6 (+1.9, -1.3) ×10-3 ct s-1 Distance: 175 arcsec from IPN position Source 2 is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Source 3 is at a position consistent with a QSO candidate (Wu et al., 2023, RAA, 23, 025006) and therefore is likely unrelated to GRB 230307A. Further observations are ongoing. The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00110. This circular is an official product of the Swift-XRT team.
GCN 33430 table
GRB_name GRB230307A
GCN_number 33430
Detection_method IPN Triangulation
Circular_text TITLE: GCN CIRCULAR NUMBER: 33430 SUBJECT: GRB 230307A: Upper limits from a neutrino search with IceCube DATE: 23/03/09 00:17:46 GMT FROM: Jessie Thwaites at IceCube/U Wisc-Madison The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search for track-like muon neutrino events arriving from the direction of GRB 230307A (GCN 33405 (Fermi-GBM)) in a time range of -1 hour/+2 hours from the initial trigger reported by Fermi-GBM (2023-03-07 15:44:06.67 UTC), using the localization area reported by IPN (GCN 33425), during which IceCube was collecting good quality data. Zero track-like events are found coincident with the position of the GRB. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 1.0 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. 90% of events IceCube would detect from a source at this declination with an E^-2 spectrum have energies in the approximate energy range between 90 TeV and 20 PeV. A subsequent search was performed including 2 days of data centered on the Fermi-GBM trigger (2023-03-06 15:44:06.67 UTC to 2023-03-08 15:44:06.67 UTC). In this case, we report a p-value of 1.0, consistent with background expectation. We accordingly derive a time-integrated muon-neutrino flux upper limit for this source of E^2 dN/ dE = 1.1 GeV cm^-2 at 90% CL, under the assumption of an E^-2 power law. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc@icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021)
GCN 33431 table
GRB_name GRB230307A
GCN_number 33431
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 33431 SUBJECT: GRB 230307A: Swift/BAT upper limits on the early afterglow DATE: 23/03/09 01:49:22 GMT FROM: Aaron Tohuvavohu at U Toronto Aaron Tohuvavohu (U Toronto), Jimmy DeLaunay (U Alabama), Samuele Ronchini (Penn State), Tyler Parsotan (GSFC/UMBC), Chris Matzner (U Toronto) report: The extremely bright GRB 230307A (GCN 33425) was detected in prompt emission by Swift/BAT outside the coded field of view, as reported previously. Soon after, a pre-planned observation serendipitously landed the GRB position near the center of the BAT field of view, with settled observations beginning at T0+910s. Using the BAT survey mode data, 300s duration 80-channel Detector Plane Histograms, we search for any detection of continued emission or bright afterglow from the burst between 910 to 1210 seconds after the burst. No emission is detected at the IPN position of the GRB, with a 5 sigma upper limit of 0.00656 mask-weighted counts/s (15-50 keV). Assuming an afterglow spectrum that can be described as a power law with photon index of 2.08 (as found for the BAT afterglow detection in GRB 221009A, Williams et al. 2023), this corresponds to an upper limit of 2.389e-9 erg/cm^2/s (15-50 keV). This constrains GRB 230307A's early afterglow (at T0+1 ks) to be at least ~1.5 orders of magnitude fainter than that of GRB 221009A at comparable times.
GCN 33434 table
GRB_name GRB230307A
GCN_number 33434
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33434 SUBJECT: GRB 230307A: optical upper limit DATE: 23/03/09 09:51:32 GMT FROM: Alberto J. Castro-Tirado at IAA-CSIC I. Pérez-García (IAA-CSIC Granada, Spain), A. Maury (Space Obs, Chile), E. Fernández-García, Y.-D. Hu and A. J. Castro-Tirado (IAA-CSIC and UMA), on behalf of a larger collaboration, report: “Following the detection of the very bright GRB 230307A (Burns et al. GCNC 33414) by Fermi/GBM (the Fermi GBM team, GCNC 33405; Dalessi, GCNC 33407; Dalessi and Roberts, GCNC 33411), GECAM (Xiong et al., GCNC 33406), Solar Orbiter/STIX (Xiao and Krucker, GCNC 33410), AGILE/MCAL (Casentini et al., GCNC. 33412), INTEGRAL/SPI-ACS, Mars-Odyssey/HEND (Kozyrev et al. GCNC 33413), AstroSat/CZTI (Navaneeth et al. GCNC 33415), GRBAlpha (Dafcikova et al. GCNC 33418), VZLUSAT-2 (Ripa et al. GCNC 33424), Konus-WIND (Svinkin et al. GCNC 33427) and Swift-BAT (Tohuvavohu, GCNC 33431), we observed 60% of the preliminary IPN error box (Kozyrev et al. GCNC 33413) with a 0.5m wide-field telescope in the vicinity of the BOOTES-7 astronomical station at San Pedro de Atacama Space Observatory. No optical candidate down to 17.4 mag is found on the images (clear filter, 1.6h co-add) starting at 4:36 on Mar 8 UT (i.e. 12.9 h postburst) within the entire improved IPN position (Kozyrev et al. GCNC 33425).” This message can be quoted.
GCN 33437 table
GRB_name GRB230307A
GCN_number 33437
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33437 SUBJECT: GRB 230307A: AstroSat LAXPC detection DATE: 23/03/09 13:15:29 GMT FROM: Tilak Katoch at TIFR Tilak Katoch, H. M. Antia and Parag Shah TIFR, Mumbai, India. Analysis of AstroSat LAXPC data showed the clear detection of a long GRB 230307A. The lightcurve shows the multiple burst profile with the peak triggered at T0 = 15h 44m 03s UT on 07 Mar 2023. The satellite was in a normal operating mode and well before the entry into the SAA region. The lightcurve has a burst profile with T90 = 36 sec. The strongest peak measured have a count rate above the background with 13321 +/- 117 count/sec in LAXPC10 and 4415 +/- 68 count/sec in LAXPC20 at T0+7 sec. Both LAXPC instruments (LAXPC10 and LAXPC20) have registered this burst profile in the light curve. For LAXPC20, the nominal energy range is 3-100 keV, but due to the lower gain in LAXPC10 the energy range is about 30-400 keV. The background subtracted lightcurve with 1 sec time-bin is available at the website: https://www.tifr.res.in/~astrosat_laxpc/grb230307alc.jpg [1] LAXPC was built by TIFR in collaboration with the Indian Space Research Organisation. The Indian Space Research Organisation funded, managed and facilitated the project. Links: ------ [1] https://www.tifr.res.in/~astrosat_laxpc/grb230106lc.jpg
GCN 33438 table
GRB_name GRB230307A
GCN_number 33438
Detection_method IPN Triangulation
Circular_text TITLE: GCN CIRCULAR NUMBER: 33438 SUBJECT: GRB 230307A: ASO-S/HXI detection DATE: 23/03/09 14:33:56 GMT FROM: Tianrui Sun at Purple Mountain Obs,CAS Zhentong Li, Yang Su on behalf of the HXI team report: At 2023-03 07 15:44:09 UT, HXI detected the bright GRB 230307A (Burns et al. GCNC 33414) which was also reported by Fermi/GBM (Fermi GBM Team et al. GCNC 33405; Dalessi, GCNC 33407; Dalessi et al. , GCNC 33411; Dalessi et al. GCNC 33411), GECAM (Xiong et al. GCNC 33406), STIX (Xiao et al. GCNC 33410), AGILE/MCAL (Claudio et al. GCNC 33412), IPN (Kozyrev et al. GCNC 33413, Kozyrev et al. GCNC 33425), AstroSat CZTI (Gaurav et al. GCNC 33415), BARLOG (Jochen et al. GCNC 33416), GRBAlpha (Marianna et al. GCNC 33418), VZLUSAT-2 (Ripa et al. GCNC 33424), Konus-WIND (Svinkin et al. GCNC 33427), Swift (Phil et al. GCNC 33419, GCNC 33431), IceCube (Jessie et al. GCNC 33430) and BOOTES (Alberto et al. GCNC 33434). The GRB signal is spiky with significant responses at energies from ~20 keV to the detection upper limit 300 keV of the HXI scintillation detectors. The signal displays a major peak (> 570 cts/s/detetor) and a faint secondary peak (> 230 cts/s/detetor, with an in-orbit background of ~130 cts/s/detetor). The duration of the major peak is ~16 s and the whole signal lasts for ~40 s. The time resolution of the observed signal is 4 s. The burst mode (res. as high as 0.125s) was not triggered because the GRB was detected by both total flux monitor and background monitor. By examining the count rate distribution of the 99 detectors of HXI, the direction of the GRB was roughly deduced. Hard X-ray Imager (HXI) is one of the three scientific payloads onboard the Advanced Space-based Solar Observatory (ASO-S) satellite, which is China’s first comprehensive solar dedicated space science mission. HXI is designed to investigate the non-thermal high-energy electrons accelerated in solar flares by providing X-ray spectra and images of solar flaring regions in the energy range from 15 to 300 keV. It started to work on 2022-Oct-17 and is currently in the inflight testing phase. The science data will be completely open to the community after the testing phase, i.e., around mid-April 2023. More information about HXI can be found on the ASO-S website: http://aso-s.pmo.ac.cn/en_index.jsp
GCN 33439 table
GRB_name GRB230307A
GCN_number 33439
Detection_method Optical
ra 60.8576°
decl -75.3785°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33439 SUBJECT: GRB 230307A: Possible optical afterglow DATE: 23/03/09 15:14:27 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (Radboud), B. Gompertz (U. Birmingham), K. Ackley (U. Warwick), M. Kennedy (University College Cork), V. Dhillon (U. Sheffield) report on behalf of a larger collaboration: "We observed the IPN localisation (Kozyrev et al. GCN 33425) of GRB 230307A (GBM team GCN 33405, Xiong et al. GCN 33406) with ULTRACAM, mounted on the NTT at La Silla. A total of 200s of exposure (10 x 20s) were obtain simultaneously in the u, g and r filters starting at 01:58:33 UTC approximately 34.3 hours post burst. Observations covered the entirety of the refined IPN localisation. A comparison of the observation with DSS and legacy survey image reveals a weak new optical source at a location of RA(J2000): 04:03:25.83 DEC(J2000): -75:22:42.7 (+/- 0.5”) The source has an r-band magnitude of approximately r=20.5 at the time of these observations. We note that the source is co-incident (1.9” offset) with source 2 identified by the Swift-XRT (Evans, GCN 33419). Combined with the absence of the source in pre-imaging we suggest that this is the afterglow of GRB 230307A. We note that the source has a modest offset (3”) from a very red source identified in the legacy survey and WISE. It is possible that this is host galaxy of the GRB. Spectroscopic observations to obtain the redshift of both afterglow and nearby source are encouraged. "
GCN 33442 table
GRB_name GRB230307A
GCN_number 33442
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33442 SUBJECT: GRB 230307A: Erratum of the GCN 33441 DATE: 23/03/09 17:33:43 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Lipunov (Lomonosov MSU) I am sorry for my mistake in Subject. Correct subject is GRB 230307A: MASTER detection of an object near NTT Optical Afterglow Candidate
GCN 33443 table
GRB_name GRB230307A
GCN_number 33443
Detection_method Optical
ra 60.8576°
decl -75.3785°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33443 SUBJECT: GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate DATE: 23/03/09 18:19:09 GMT FROM: Stephen Smartt at Queen's U/Belfast M. D. Fulton, K. W. Smith, S. Srivastav, D. R. Young, M. Nicholl, M. McCollum, T. Moore, J. Weston (QUB), S. J. Smartt (Oxford/QUB), L. Shingles (GSI/QUB), J. Sommer (LMU/QUB), L. Rhodes (Oxford), L. Denneau, J. Tonry, H. Weiland, A. Lawrence, R. Siverd (IfA, University of Hawaii), N. Erasmus, W. Koorts (South African Astronomical Observatory), A. Jordan, V. Suc (UAI, Obstech), A. Rest (STScI), T.-W. Chen (TUM/MPA), C. Stubbs (Harvard) We report optical observations in the field of the Fermi/GBM-discovered GRB 230307A (Dalessi et al. GCN Circ. 33407) in the context of the detection of a possible optical afterglow by Levan et al. (GCN Circ. 33439). ATLAS is a quadruple 0.5m telescope system with two units in Hawaii, one in Chile and one South Africa (see Tonry et al. 2018, PASP,130:064505), routinely surveying the visible sky on a daily basis. We promptly process all data with our transient science server (Smith et al. 2020, PASP, 132:085002). The ATLAS system observed the field of the GRB 230307A in normal survey mode before the GRB trigger date of MJD 60010.655 (=2023-03-07 15:44:06.67 UT). We forced the photometry at the proposed position of the optical afterglow RA=04:03:25.83, Dec=-75:22:42.7 (J2000) (Levan et al. GCN Circ. 33439; Source 2 from Evans et al. GCN Circ. 33429) thorough our ATLAS forced photometry server (Shingles et al. AstroNote #2021-7, Smith et al. 2020, PASP, 132:085002). We found no historical detections of any excess optical flux at this position. Forced photometry at those coordinates results in the following most recent non-detections in the o-band filter. These measurements are not corrected for any galactic dust extinction. The AB mag are quoted as 2 sigma. +-----------+------------+-----------------+-------------------+ | MJD | Flux (uJy) | Flux Err (duJy) | AB Mag Limit (2σ) | +-----------+------------+-----------------+-------------------+ | 60002.781 | 6.0 | 6.8 | >21.1 | +-----------+------------+-----------------+-------------------+ | 60004.034 | -8.8 | 8.6 | >20.8 | +-----------+------------+-----------------+-------------------+ | 60008.087 | 1.1 | 11.9 | >20.5 | +-----------+------------+-----------------+-------------------+ The candidate optical afterglow from Levan et al. (GCN Circ. 33439) was r=20.5 at MJD=60012.1. We find no sign of the object to similar flux levels before the GRB, which suggests the source is a new transient occurring after MJD 60008. This supports it being the candidate optical afterglow of GRB 230307A.
GCN 33444 table
GRB_name GRB230307A
GCN_number 33444
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33444 SUBJECT: GRB 230307A: AGILE/MCAL analysis DATE: 23/03/09 19:41:32 GMT FROM: Claudio Casentini at INAF-IAPS C. Casentini (INAF/IAPS), F. Verrecchia (SSDC, and INAF/OAR), A.Ursi (ASI), C. Pittori (SSDC, and INAF/OAR), M. Tavani (INAF/IAPS and Uni. Roma Tor Vergata), F. Lucarelli (SSDC, and INAF/OAR), A. Argan, M. Cardillo, Y. Evangelista, L. Foffano, G. Piano (INAF/IAPS), A. Addis, L. Baroncelli, A. Bulgarelli, A. Di Piano, V. Fioretti, G.Panebianco, N. Parmiggiani (INAF/OAS-Bologna), M. Romani (INAF/OA-Brera), M. Marisaldi (INAF/OAS-Bologna, Bergen University), M. Pilia, A. Trois (INAF/OA Cagliari), I. Donnarumma, E. Menegoni, A. Giuliani (INAF/IASF-Mi) and P. Tempesta (TeleSpazio), report on behalf of the AGILE Team: We carried out further analysis of the AGILE/MCAL data of GRB 230307A (GCNs #33405, #33406, #33407, #33410, #33411, #33412, #33413, #33414, #33415, #33416, #33418, #33419, #33424, #33425, #33427, #33428, #33429 #33430, #33431, #33434, #33437, #33438, #33439, 33442, 33443) The burst released 229697 counts in the detector in 18s, above a background rate of 545 Hz. The spectral analysis shows a clear component up to 8 MeV. The time-integrated spectrum of the burst can be fitted in the energy range 0.6-6.5 MeV with a Band model with alpha = -0.43 (+/-0.06), beta = -5.1 (+/-0.7), peak energy Epeak = 1260 keV (+/- 42 keV). The fit results in a reduced chi-squared of 1.607 (34 d.o.f.) and a fluence of 1.3e-03 erg/cm^2, in the same energy range. MCAL spectrum in the selected 18 s time interval can be found at: http://www.agilescienceapp.it/notices/GRB230307A_AGILE-MCAL_spectral_analysis.png Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html.
GCN 33447 table
GRB_name GRB230307A
GCN_number 33447
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33447 SUBJECT: GRB 230307A: Gemini-South Confirmation of the Optical Afterglow DATE: 23/03/10 03:37:36 GMT FROM: Brendan O'Connor at UMD B. O'Connor (UMD, GWU), S. Dichiara (PSU), E. Troja (UTV, ASU), J. Gillanders (UTV), S. B. Cenko (NASA, UMD), C. Kouveliotou (GWU): We observed GRB 230307A (GBM team GCN 33405, Xiong et al. GCN 33406, Kozyrev et al. GCN 33425) with the GMOS-S instrument mounted on Gemini-South in Cerro Pachon, Chile through Director's Time. Observations began at 00:06:47 UT on 2023-03-10, corresponding to 2.35 d after the GRB trigger. In a 30 s acquisition image, we detect the optical afterglow reported by Levan et al. (GCN 33439) and Lipunov et al. (GCN 33441). With preliminary photometry calibrated to the SkyMapper catalog we derive a magnitude of r~22.0+/-0.3 mag. This confirms fading of the reported counterpart and solidifies the connection to the GRB. Analysis of the spectroscopic observations is underway. We thank the staff of the Gemini Observatory for rapidly approving and executing these observations.
GCN 33448 table
GRB_name GRB230307A
GCN_number 33448
Detection_method MAXI Det
t_trigger 15:58:54 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 33448 SUBJECT: GRB 230307A: MAXI/GSC upper limit DATE: 23/03/10 04:03:34 GMT FROM: Motoko Serino at Aoyama Gakuin U. S. Sugita, M. Serino (AGU), H. Negoro (Nihon U.), T. Mihara (RIKEN), M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima (Nihon U.), T. Kawamuro, S. Yamada, T. Tamagawa, M. Matsuoka (RIKEN), T. Sakamoto, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), Y. Tsuboi, J. Kohara, S. Urabe, S. Nawa, N. Nemoto (Chuo U.), M. Shidatsu, M. Iwasaki (Ehime U.), N. Kawai, M. Niwano, R. Hosokawa, Y. Imai, N. Ito, Y. Takamatsu (Tokyo Tech), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, T. Kurihara (JAXA), Y. Ueda, S. Ogawa, K. Setoguchi, T. Yoshitake, K. Inaba, Y. Nakatani (Kyoto U.), M. Yamauchi, T. Sato, R. Hatsuda, R. Fukuoka, Y. Hagiwara, Y. Umeki (Miyazaki U.), K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) , W. Iwakiri (Chiba U.) report on behalf of the MAXI team: We report the non-detection of MAXI/GSC of GRB 230307A (Fermi-GBM GCN #33405, #33407 #33411; GECAM GCN #33406, Solar Orbiter STIX GCN #33410; AGILE/MCAL GCN #33412; HEND/Mars Odyssey, INTEGRAL SPI-ACS, Swift/BAT GCN #33413; AstroSat CZTI GCN #33415; GRBAlpha GCN #33418; VZLUSAT-2 GCN #33424; Konus-Wind GCN #33427; AstroSat LAXPC GCN #33437; ASO-S/HXI GCN #33438; ). At 15:58:54 UT on 2023-03-07 (888s after the Fermi/GBM trigger), MAXI/GSC scanned the error region of the event. The scan time of the five consecutive scans were 17:31:49 (t0+6463s), 19:04:40 (t0+12034s), 20:37:36 (t0+17610s), 22:10:27 (t0+23181s), and 23:43:22 (t0+28756s). No significant excess emission was detected from the region. Typical 1-sigma upper limits in 2-20 keV for one scan (and six scans) are 20 mCrab (and 8 mCrab).
GCN 33449 table
GRB_name GRB230307A
GCN_number 33449
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33449 SUBJECT: GRB 230307A: GECKO optical observations and detections of the afterglow DATE: 23/03/10 07:42:47 GMT FROM: Myungshin Im at Seoul Nat U Myungshin Im, Gregory S.-H. Paek, Mankeun Jeong, Seo-Won Chang, Hyeonho Choi (SNU), and Chung-Uk Lee (KASI) We covered the localization areas of GRB 230307A (GBM team GCN 33405, Xiong et al. GCN 33406) with the RASA36 telescope at the El Sauce observatory in Chile, and the KMTNet telescopes in SSO, Australia, and SAAO, South Africa. The RASA36 observation started at 2023-03-08-00:52 (UT) or about 9.11 hrs after the burst alert, taking a series of r-band images for about 20 min. The starting times of the KMTNet SSO and SAAO stations are 2023-03-08-09:39 (UT) and 2023-03-08-18:30 (UT) or 17.89 hrs and 26.74 hrs respectively, taking a series of R- and I-band images for about 1 hr at each location. We clearly identify the afterglow (Levan et al. GCN 33439, Lipunov et al. GCN 33441, O'Conner et al. 33447) and confirm its fading nature in all of the time-series KMTNet images, with the photometry roughly consistent with that of the Levan et al. (GCN 33439) report. A weak signal is found in the RASA36 image. Further observations and analysis are being carried out. We thank the KMTNet operators for their support for the KMTNet observations.
GCN 33453 table
GRB_name GRB230307A
GCN_number 33453
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33453 SUBJECT: TESS Detection of the Optical Afterglow of GRB230307A DATE: 23/03/11 16:52:38 GMT FROM: Roland Vanderspek at MIT R. Vanderspek, M.M. Fausnaugh, R. Jayaraman, G.R. Ricker (MIT), K. Colon and A. Youngblood (GSFC), on behalf of the TESS Team, report: The Transiting Exoplanet Survey Satellite (TESS; Ricker et al. 2015) observed the location of the bright gamma-ray burst GRB230307A during the second orbit of Observation Sector 62. Images of the burst region, located in TESS Camera 4, CCD 4, were captured in the TESS full-frame images (FFIs). The observations of the field were made at a cadence of 200 seconds and were continuous from 3 days before the trigger to 3 days after the trigger. Analysis of the TESS FFIs using TICA (Fausnaugh et al. 2020; doi:10.3847/2515-5172/abd63a ) data confirms the existence of the optical counterpart reported by Levan et al. (GCN Circular 33439), Lipunov et al. (GCN Circular 33441), O'Conner et al. (GCN Circular 33447), and Im et al. (GCN Circular 33449). The signal is seen as a point source brighter than 15th magnitude in a single 200s FFI. The measured position is 4:03:26.5, -75:22:45 with an estimated 1-sigma error of 4”, consistent with previously-reported localizations. TICA data can be found at https://archive.stsci.edu/hlsp/tica.
GCN 33459 table
GRB_name GRB230307A
GCN_number 33459
Detection_method Swift-BAT Det
ra 60.8576°
decl -75.3785°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33459 SUBJECT: GRB 230307A: SOAR/Goodman detection of the possible host galaxy DATE: 23/03/11 21:13:45 GMT FROM: Charles Kilpatrick at Northwestern U C. R. Bom (CBPF), C. D. Kilpatrick (Northwestern), R. Santucci (Universidade Federal de Goiás), A. J. Castro-Tirado (IAA-CSIC and UMA), I. Pérez-García, Y.-D. Hu (IAA-CSIC), F. Navarete (IAG-USP, RSS/NOIRLab), and M. Makler (UNSAM/CBPF), on behalf of a larger collaboration, report: Following the detection of the very bright GRB 230307A (Burns et al. GCNC 33414) by Fermi/GBM (the Fermi GBM team, GCNC 33405; Dalessi, GCNC 33407; Dalessi and Roberts, GCNC 33411), GECAM (Xiong et al., GCNC 33406), Solar Orbiter/STIX (Xiao and Krucker, GCNC 33410), AGILE/MCAL (Casentini et al., GCNC. 33412), INTEGRAL/SPI-ACS, Mars-Odyssey/HEND (Kozyrev et al. GCNC 33413), AstroSat/CZTI (Navaneeth et al. GCNC 33415), GRBAlpha (Dafcikova et al. GCNC 33418), VZLUSAT-2 (Ripa et al. GCNC 33424), Konus-WIND (Svinkin et al. GCNC 33427) Swift-BAT (Tohuvavohu, GCNC 33431) and ASO-S/HXI (Li et al. GCNC 33438), we report z-band imaging and optical spectroscopy of the GRB 230307A from 9 and 10 March 2023 with the Goodman high-throughput imaging spectrograph on the SOAR 4.1m telescope at Cerro Pachón, Chile. The z-band imaging consisted of a cumulative 310s of exposure starting at 2023-03-10T00:13:45 (MJD 60013.0095, 56.5 hr from burst) and 600s starting at 2023-03-11T00:19:08 (MJD 60014.0133, 80.5 hr from burst) at the site of the reported optical counterpart to GRB 230307A (Levan et al. GCNC 33439, Lipunov et al. GCN 33441, Fulton et al. GCNC 33443, O'Connor et al. GCNC 33447, Im et al. GCNC 33449, Vanderspek et al. GCNC 33453). Using forced photometry at the site of the counterpart (RA=04:03:25.83, Dec=-75:22:42.7), we obtained a marginal detection in both epochs of z=21.8+/-0.3 AB mag. The lack of any change between the two epochs suggests we may be seeing a faint background source consistent with the host galaxy of GRB 230307A. We also obtained spectroscopy at the site of the counterpart at 2023-03-10T00:28:17 with the 400 l/mm grating on SOAR/Goodman covering a wavelength range of 3000-7000 angstroms for a cumulative exposure time of 1500s. We oriented the 1.0" Goodman long slit to simultaneously observe the optical afterglow of GRB 230307A and the red source roughly 3 arcseconds to the southwest reported in Levan et al. (GCNC 33439) as a possible host galaxy. There is no signature of emission from the GRB afterglow in our spectra, but we detect red continuum emission from 6000-7000 angstroms consistent with the r=20.8 mag, i=19.5 mag, z=18.9 mag (Legacy Survey DR10; Dey et al., 2019, AJ, 157, 168) to the southwest. Combined with the fact that this source is unresolved in our imaging and has a significant parallax in the Gaia DR3 catalog (Gaia Collaboration et al., 2022), we consider this source to be a foreground star as pointed out by Lipunov et al. (GCNC 33441) and not the host galaxy of GRB 230307A. Based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia e Inovações do Brasil (MCTI/LNA), the US National Science Foundation’s NOIRLab, the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
GCN 33461 table
GRB_name GRB230307A
GCN_number 33461
Detection_method IPN Triangulation
ra 60.8670°
decl -75.3820°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33461 SUBJECT: Further improved IPN localization for GRB 230307A DATE: 23/03/11 22:07:23 GMT FROM: Dmitry Svinkin at Ioffe Institute A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams, J. Benkhoff on behalf of the BepiColombo team, D. Svinkin, D. Frederiks, A. Ridnaia, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, C. Wilson-Hodge, and E. Burns on behalf of the Fermi GBM team, E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu on behalf of the Swift-BAT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: Using the BepiColombo (MGNS) data we have further improved the previous IPN box for GRB 230307A (Kozyrev et al., GCN Circ. 33425). The coordinates of the updated 3 sigma error box are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 60.867 (04h 03m 28s) -75.382 (-75d 22' 57") Corners: 60.846 (04h 03m 23s) -75.417 (-75d 25' 03") 61.006 (04h 04m 01s) -75.357 (-75d 21' 26") 60.889 (04h 03m 33s) -75.348 (-75d 20' 51") 60.728 (04h 02m 55s) -75.408 (-75d 24' 28") --------------------------------------------- The error box area is 8 sq. arcmin, and its maximum dimension is 5 arcmin (the minimum one is 1.8 arcmin). The Sun distance was 80 deg. This box may be further improved. The distance between the IPN box center and X-ray/optical transient position (X-ray Source #2 in Burrows et al., GCN Circ. 33429; Levan et al., GCN Circ. 33439; Lipunov et al. GCN Circ. 33441; O'Connor et al., GCN Circ. 33447; Im et al., GCN Circ. 33449; Vanderspek et al., GCN Circ. 33453) is 15 arcsec, which further strengthen the interpretation of transient as the burst afterglow. An updated triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB230307_T56646/IPN
GCN 33465 table
GRB_name GRB230307A
GCN_number 33465
Detection_method Swift-XRT Other
ra 60.8593°
decl -75.3788°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33465 SUBJECT: GRB 230307A: Swift-XRT afterglow detection DATE: 23/03/13 11:21:46 GMT FROM: Phil Evans at U of Leicester D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA), S. Dichiara (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the Fermi/GBM-detected burst GRB 230307A (Dalessi et al. GCN Circ. 33407). The observations now extend from T0+83.6 ks to T0+437.2 ks. Of the sources reported by Burrows et al. (GCN Circ. 33429), "Source 2" is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 1252 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 60.85935, -75.37884 which is equivalent to: RA (J2000): 04h 03m 26.24s Dec(J2000): -75d 22' 43.8" with an uncertainty of 3.2 arcsec (radius, 90% confidence). This position is 13.3 arcsec from the IPN improved position (Kozyrev et al. GCN Circ. 33461). The light curve can be modelled with a power-law decay with a decay index of alpha=1.1 (+0.6, -0.5). The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021537. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00110. This circular is an official product of the Swift-XRT team.
GCN 33466 table
GRB_name GRB230307A
GCN_number 33466
Detection_method Fermi GBM Det
ra 60.6000°
decl -75.4000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33466 SUBJECT: GRB 230307A: soft X-ray detection with LEIA DATE: 23/03/13 11:24:55 GMT FROM: LEIA Team at NAOC/CAS M.J. Liu, Y.L. Wang, Y. Liu, C. Zhang, Z.X. Ling, H.Q. Cheng, C.Z. Cui, D.W. Fan, H.B. Hu, J.W. Hu, M.H. Huang, C.C. Jin, D.Y. Li, J.Q. Li, H.Y. Liu, H. Sun, H.W. Pan, W.X. Wang, Q.Y. Wu, X.P. Xu, Y.F. Xu, H.N. Yang, M. Zhang, W.D. Zhang, Z. Zhang, D.H. Zhao, and W. Yuan (NAOC, CAS), report on behalf of the LEIA and Einstein Probe team: The prompt emission of the extremely bright long-duration GRB 230307A (Fermi/GBM detection: GCN 33405, 33407, 33411, 33414; GECAM-B detection: GCN 33406; Solar Orbiter STIX detection: GCN 33410; AGILE/MCAL detection: GCN 33412, 33444; IPN triangulation: GCN 33413; AstroSat detection: GCN 33415; BALROG localization: GCN 33416; GRBAlpha detection: 33418, VZLUSAT-2: GCN 33424, Konus-Wind GCN 33427, AstroSat CZIT: 33415, Swift/BAT upper limits: GCN 33431, AstroSat LAXPC detection: GCN 33437, ASO-S/HXI detection: GCN 33438, MAXI/GSC upper limit: GCN 33448) was detected by LEIA (Lobster Eye Imager for Astronomy) in the soft X-ray 0.5-4 keV band during one of its monitoring observations of the Large Magellanic Cloud. The observation was conducted from 2023-03-07T15:43:41 (25 s earlier than the Fermi GBM trigger time at 2023-03-07T15:44:06) to 2023-03-07T16:02:00 with a net exposure of 761 s. The GRB was detected within the extended FoV (about 0.6 deg outside the nominal 18.6deg x 18.6deg FoV) of LEIA, and the on-ground calculated position is RA=60.6, Dec=-75.4, with an estimated 3-sigma error of 10 arcmin, which is consistent with the IPN localizaition (GCN 33461). The lightcurve shows a burst profile which peaked at 2023-03-07T15:44:13 in 0.5 - 4.0 keV, and droped quickly to a level comparable to the detection sensitivity within about 200 s. Given that the source is outside the nominal FoV, the estimation of the source flux is complex and subject to further investigation and will be published later. LEIA also conducted follow-up observations in 6 successive orbits covering the entire IPN error box from 2023-03-09UT00:47:26 to 2023-03-09UT10:32:34. The total good exposure is around 4000 s and no significant emission was detected. The derived upper limit of the LEIA is around 1e-11 erg/cm^2/s in the energy band of 0.5 - 4.0 keV. LEIA (Zhang et al, ApJL, 941, 2) is a soft X-ray monitor (0.5 - 4.0 keV) with a FoV of 340 square degrees aboard the SATech-01 satellite of the CAS, launched on July 27, 2022. The above result is preliminary and the final result will be published elsewhere.
GCN 33471 table
GRB_name GRB230307A
GCN_number 33471
Detection_method Swift-UVOT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 33471 SUBJECT: GRB 230307A: Swift/UVOT detection DATE: 23/03/13 15:54:52 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL), and C. Salvaggio (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began observations of the field of GRB 230307A 99.5 ks after the Fermi/GBM-detected trigger (Dalessi et al., GCN 33407). A fading source consistent with the enhanced XRT position (Burrows et al., GCN 33465) and consistent with the optical counterpart reported by Levan et al. (GCN 33439), Lipunov et al. (GCN 33441), Fulton et al. (GCN 33443), O'Connor et al. (GCN 33447), Im et al. (GCN 33449), Vanderspek et al. (GCN 33453) and Bom et al. (GCN 33459) is detected in the initial UVOT exposures. Detections and 3 sigma upper limits are given in the following table: Filter T_start(s) T_stop(s) Exp(s) Mag white 99525 110441 2265 21.28 +/- 0.16 white 133031 208070 2931 22.09 +/- 0.32 white 212899 420530 3418 >22.25 u 83621 88252 422 >20.44 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.084 in the direction of the burst (Schlegel et al. 1998).
GCN 33472 table
GRB_name GRB230307A
GCN_number 33472
Detection_method INTEGRAL
Circular_text TITLE: GCN CIRCULAR NUMBER: 33472 SUBJECT: GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow DATE: 23/03/13 16:54:30 GMT FROM: Volodymyr Savchenko at ISDC,U of Geneve At the time of the very bright GRB 230307A (GCN #33405, GCN #33406, GCN #33407, GCN #33410, GCN #33411, GCN #33412, GCN #33413, GCN #33414, GCN #33415, GCN #33416, GCN #33418, GCN #33419, GCN #33424, GCN #33425, GCN #33427, GCN #33428, GCN #33429, GCN #33430, GCN #33431, GCN #33434, GCN #33437, GCN #33438, GCN #33439, GCN #33442, GCN #33443, GCN #33444, GCN #33447, GCN #33448, GCN #33449, GCN #33453, GCN #33459, GCN #33461, GCN #33465, GCN #33466), INTEGRAL was pointing 74 deg from the GRB direction. Such an exceptionally high flux lead to a detection in various ratemeters of INTEGRAL often causing saturation. From moderately saturated SPI-ACS observation, we can estimate a likely close lower limit on the total flux in 75 - 2000 keV energy range at the level of 0.0015 erg cm-2 s-1 in the time range T0 to T0+130.0s where T0 = 2023-03-07T15:44:07. We note that despite the GRB brightness, both SPI-ACS and PICsIT observations do not reveal early afterglow and no emission past T0+129~s, with an approximate upper limit on average 75-2000 keV flux between T0+129s and of T0+259 s at the level of 5.8e-09 erg cm-2 s-1 (see also GCN#33431). A ToO pointed observation was carried out from 2023-03-08 11:35:00 (T0 + 19.8 hours) to 2023-03-09 02:18:20 (T0 + 34.6 hours) with a total exposure time of 28.2 ks (for ISGRI). Since the observation was scheduled when the refined IPN localization was not yet available, the position of the candidate GRB optical and X-ray afterglow ((GCN #33429, GCN #33439, GCN #33443, GCN #33447, GCN #33449, GCN #33459, GCN #33465)) was observed at an offset of 1.3 deg, reducing somewhat the effective exposure of JEM-X compared to an optimal pointing. We do not find any significant signal, and put a limit on any source within the IPN error box, including also to the possible X-ray and optical afterglow, at the level of 4.2e-11 erg cm-2 s-1 in the 3-200 keV energy range, assuming a powerlaw spectrum with a slope of -2. This limit is about 1.2 orders of magnitude lower than the detection in the case of GRB 221009A. We are grateful to the INTEGRAL Ground Segment team for the quick scheduling of these observations. All of the results except PICsIT were produced MMODA platform (https://www.astro.unige.ch/mmoda/).
GCN 33475 table
GRB_name GRB230307A
GCN_number 33475
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33475 SUBJECT: GRB 230307A: ATCA radio detection DATE: 23/03/14 05:23:06 GMT FROM: Gemma Anderson at Curtin U G. E. Anderson (Curtin Uni.), J. K. Leung (U. Sydney), T. Murphy (U. Sydney), E. Lenc (CSIRO) L. Rhodes (U. Oxford), A. J. van der Horst (GWU), G. Rowell (U. Adelaide) We observed GRB 230703A (Fermi GBM Team GCN 33405) with the Australia Telescope Compact Array (ATCA) between 2023-03-12_02:30 UT and 2023-03-12_07:30 UT (~4.5 days post-burst). In our preliminary analysis, we detect a radio source coincident with the X-ray (Burrows et al. GCN 33429, GCN 33465) and optical (Levan et al. GCN 33439) counterpart with a flux density of 120+/-30 microJy/beam at 9 GHz. We also obtain an 3 sigma upper limit of 90 microJy/beam at 5.5 GHz. We thank CSIRO staff for supporting these observations. The ATCA is part of the Australia Telescope National Facility which is funded by the Australian Government for operation as a National Facility managed by CSIRO. We acknowledge the Gomeroi people as the traditional owners of the Observatory site.
GCN 33478 table
GRB_name GRB230307A
GCN_number 33478
Detection_method Other
ra 60.8190°
decl -75.3790°
Circular_text TITLE: GCN CIRCULAR NUMBER: 33478 SUBJECT: GRB 230307A: Far off-axis NuSTAR detection of the GRB DATE: 23/03/14 21:10:47 GMT FROM: Brian Grefenstette at Caltech/NuSTAR B.W. Grefenstette (Caltech) on behalf of the NuSTAR Team After notification of the GRB 230307A via numerous GCNs, we searched the NuSTAR event stream for signals near the time of the GRB. Using a nominal position of RA:60.819 Dec:-75.379 (GCN #33425) we estimate the GRB was ~140-deg away from the telescope boresight (e.g., coming through the side of the instrument). Even so, we clearly see the GRB in the CsI anti-coincidence shields in both of the NuSTAR telescopes. In the 1-sec time resolution shield data we see bursts in excess of 25,000 cps above the LLD in the shield at 2023-03-07T15:44:07.5 and a brighter second peak at 2023-03-07T15:44:11.5, along with a dip at 2023-03-07T15:44:23.5 as also seen in the GRBAlpha (GCN 33418) lightcurves. The energy scale for the LLD on the CsI is not well calibrated for incident gamma-rays, but this can roughly be interpreted as counts above ~100 keV. The GRB is also seen in the CdZnTe X-ray detectors of both telescopes. The high rate of shield hits and the temporal variations in the intrinsic flux makes interpreting the CdZnTe lightcurve difficult. NuSTAR detected roughly 1000 events per telescope during the burst, with measured rates on the order of 5 50 counts per second throughout the burst and energies ranging from a few keV up to the saturation level of the detectors around 250 keV. We clearly see that the GRB is resolved into several peaks, with significant relative spectral evolution between the first and second peaks with the second peak seen to have slightly lower energies in the X-rays, though whether this is instrument or intrinsic remains to be seen.
GCN 33485 table
GRB_name GRB230307A
GCN_number 33485
Detection_method Optical
ra 60.8280°
decl -75.3819°
redshift 0.0650
Circular_text TITLE: GCN CIRCULAR NUMBER: 33485 SUBJECT: GRB 230307A: Continued Gemini-South observations confirm rapid optical fading DATE: 23/03/17 16:06:24 GMT FROM: James Gillanders at University of Rome Tor Vergata J. Gillanders (UTV), B. O'Connor (UMD, GWU), S. Dichiara (PSU), and E. Troja (UTV, ASU) report on behalf of a larger team: We re-observed the field of GRB 230307A (GBM team GCN 33405, Xiong et al. GCN 33406) with the GMOS-S spectrograph at Gemini-South through Director's Discretionary Time (PI: O’Connor). Our initial epoch was carried out at 2.4 d post-burst. We performed 4x1000 s exposures with the R400 grating covering wavelengths 4100-9200 angstroms. The brightness in the initial acquisition image (r~22 AB mag) was reported in O'Connor et al. (GCN 33447). A weak trace is visible from this position down to ~5300 angstroms, which sets an upper limit of z<4.3 to the GRB redshift. No obvious emission or absorption features are visible in the spectrum. Our slit also covered a nearby bright galaxy at an offset of ~30”. We estimate a redshift z~0.065 from Halpha, N II, and S II emission lines. If this galaxy (RA=+60.8280, DEC=-75.3819) is the host, then the GRB would have a projected offset of ~40 kpc. The probability of chance coincidence is ~0.08. Our latest observations were carried out in z-band at approximately 8.4 d post-burst. A faint source is significantly detected at the location of the optical counterpart (Levan et al. GCN 33439, O'Connor et al. GCN 33447), and indicates a rapid fading of the afterglow by approximately 2 mag with respect to earlier measurements. This suggests that the source reported by Bom et al. (GCN 33459) is not the GRB host galaxy. Additionally, the observed power-law temporal slope of ~-2 appears consistent with a jet-break. We thank Andrew Levan for providing an initial finding chart and the staff of the Gemini Observatory for rapidly approving and executing these observations.
GCN 33551 table
GRB_name GRB230307A
GCN_number 33551
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33551 SUBJECT: GRB 230307A: Bad Time Intervals for Fermi GBM data DATE: 23/04/01 01:57:34 GMT FROM: Sarah Dalessi at UAH S. Dalessi (UAH) reports on behalf of the Fermi GBM Team: "The Fermi Gamma-ray Burst Monitor data for GRB 230307A has a period of bad time intervals, affecting all data types. At particularly high rates the TTE data has data loss due to the bandwidth limit between the instrument and the spacecraft. CTIME and CSPEC data experience deadtime but do not experience similar losses due to electronics bandwidth. However, at particularly high rates both CTIME and CSPEC are affected by pulse pile-up, which will distort the spectra (see https://arxiv.org/abs/2303.14172). For CTIME and CSPEC, pulse pile-up occurs for GRB pulses during the time interval of 2.5-11.0 seconds for the BGO detector B1 and the interval 2.5-7.5 seconds for the NaI detector Na, with T0 referenced to the GBM trigger time. The TTE losses happen within these time intervals, with packet losses for high-rate GRB pulses between 3 to 7 seconds. We recommend the exclusion of these time intervals for GBM analysis of this burst, as well as caution in using bins adjacent to these selections. Additionally, due to the orientation of the burst, we recommend only using BGO detector B1 and NaI detector Na for analysis of this burst. All the other detectors either have >60deg source angles or are blocked by the spacecraft itself."
GCN 33558 table
GRB_name GRB230307A
GCN_number 33558
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33558 SUBJECT: GRB 230307A: Chandra late-time detection of the X-ray afterglow DATE: 23/04/03 17:31:15 GMT FROM: Wen-fai Fong at Northwestern U A. Rouco Escorial (ESA/ESAC), B. Gompertz (U. Birmingham), W. Fong (Northwestern), A. J. Levan (Radboud), J. Rastinejad (Northwestern), E. Berger (Harvard) report: "The Chandra X-ray Observatory observed the extremely bright long-duration GRB 230307A (Fermi GBM Team, GCN 33405; Xiong et al., GCN 33406; Dalessi et al., GCN 33407, 33411; Burns et al., GCN 33414) starting on 2023 April 1st 21:30:20 UT, with a median observation time of ~25.4 days post-trigger. We obtained an ACIS-S observation under Directors Discretionary Time (Proposal 24408902, ObsID 27778; PI: Fong), with an effective exposure time of ~16.8 ks. At the XRT position (Evans et al. GCN 33429), we identify 4 net counts, compared to an expected background of ~0.2 counts. Using the method of Kraft, Burrows & Nousek (1991ApJ 374 444) for the confidence limits in the low counts regime this suggests the detection of a source at >3-sigma confidence. We infer a count rate of ~2.4E-4 counts/seconds. Performing a joint spectral fit with the Swift/XRT data we obtain an X-ray flux of FX ~ 1.1e-14 erg/s/cm2. Combining this Chandra observation with earlier XRT data, we infer a power-law decline with a decay index (FX~t^alpha) of alpha~-1.3. We thank Pat Slane, Harvey Tananbaum and the CXO staff for the rapid approval and planning of these observations."
GCN 33569 table
GRB_name GRB230307A
GCN_number 33569
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33569 SUBJECT: GRB 230307A: JWST observations consistent with the presence of a kilonova DATE: 23/04/05 19:08:10 GMT FROM: Andrew Levan at U.of Leicester A. J. Levan (Radboud), B. P. Gompertz (U. Birmingham), D. B. Malesani (Radboud/DAWN NBI), N. R. Tanvir (Leicester), E. Burns (LSU), R. Salvaterra (INAF/IASF-Mi), K. Ackley (U. Warwick), G. P. Lamb (LJMU), J. Fynbo (DAWN NBI), B. Schneider (MIT), P. Jakobsson (U. Iceland), L. Izzo (DARK/NBI), A. Fruchter (STScI), D. Watson (DAWN NBI), M. Kennedy (UCC), J. Hjorth (DARK/NBI), G. Pugliese (API UvA), K. Bhirombhakdi (STScI), V. S. Dhillon (Sheffield/IAC) report for a larger collaboration. "We obtained observations of the exceptionally bright, long-duration GRB 230307A (Fermi GBM team, GCN 33405; Xiong et al., GCN 33406; Xiao & Krucker, GCN 33410; Cosentini et al., GCN 33412; Navaneeth et al., GCN 33415) with the James Webb Space Telescope on 5 April 2023 (about 28.8 days after the GRB). Observations were obtained with NIRCam in the F070W, F115W, F150W, F277W, F356W and F444W filters. At the location of the optical afterglow (Levan et al., GCN 33439) we find a faint source with F150W(AB) ~ 28.4 +/- 0.3. From our provisional analysis, the source appears point-like, without any evident extension. It is thus unlikely to be due to an underlying host galaxy. The lack of a host galaxy in observations of this depth is unusual for a long GRB, particularly for one as bright as GRB 230307A. In addition, observations in the redder bands show a much brighter source, with F444W(AB)~24.5 +/- 0.1, consistent with a power-law slope of approximately nu^-3 through the redder bands. We suggest that the very red colour and the absence of a host galaxy make a kilonova the most likely interpretation. In this case the burst may arise from a compact binary ejected from the nearby galaxy at z=0.065, which is ~40 kpc away in projection (Gillanders et al. GCN 33485).3 Further analysis is ongoing. We thank the staff of STScI for their work to get these observations rapidly scheduled, in particular Katey Alatalo, Alaina Henry, Armin Rest and Wilson Skipper."
GCN 33577 table
GRB_name GRB230307A
GCN_number 33577
Detection_method Fermi GBM Other
redshift 0.0650
Circular_text TITLE: GCN CIRCULAR NUMBER: 33577 SUBJECT: GRB 230307A: short mininum variability timescale compatible with a merger origin DATE: 23/04/06 11:06:22 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy A.E. Camisasca, C. Guidorzi, M. Bulla (Ferrara U.), L. Amati, A. Rossi (INAF-OAS), G. Stratta, P. Singh (Goethe U. Frankfurt) on behalf of a larger collaboration report: "We determined the minimum variability timescale (MVT) of GRB230307A (Fermi GBM team, GCN 33405; Xiong et al., GCN 33406; Xiao & Krucker, GCN 33410; Cosentini et al., GCN 33412; Navaneeth et al., GCN 33415) from the Fermi/GBM light curve (NaI detectors 10 and 6) following the prescriptions of Camisasca et al. (2023), i.e. as the minimum full width half maximum (FWHM_min) of all statistically significant pulses, and found FWHM_min = 28 (-7, +10) ms. Combined with the T90=34.56 +- 0.6 s (Fermi GBM team, GCN 33405), in the T90-FWHM_min plot GRB230307A (purple star in the Figure below) lies in the region populated by other long-lasting merger candidates, such as also GRB191019A (green star in Figure; Levan et al. 2023; Lazzati et al. 2023). In particular, it lies very close to the merger GRB211211A (Gompertz et al. 2023; Mei et al. 2022; Rastinejad et al. 2022; Troja et al 2022; Yang et al 2022). Despite its long duration and complex light curve, its short MVT therefore supports the merger origin for GRB230307A, as suggested by the possible evidence for kilonova emission reported by Levan et al. (GCN 33569). In addition, assuming a redshift z=0.065 (Gillanders et al. GCN 33485), a fluence of 3.6e-3 erg cm-2 (Svinkin et al. GCN 33427) would correspond to Eiso=3.7e52 erg. Combined with Ep~1 MeV (Svinkin et al.), the position of GRB230307A in the Ep-Eiso plane seems to be more compatible with short rather than long GRBs. http://www.fe.infn.it/u/guidorzi/T90_vs_FWHMmin_neu.pdf (Figure adapted from Camisasca et al. 2023) References - Camisasca et al., 2023, A&A, 671, A112, https://doi.org/10.1051/0004-6361/202245657 - Gompertz et al., 2023, Nature Astronomy, 7, 67 - Lazzati et al., 2023, arXiv:2303.12935 - Levan et al., 2023, arXiv:2303.12912 - Mei et al., 2022, Nature, 612, 236 - Rastinejad et al., 2022, Nature, 612, 223 - Troja et al., 2022, Nature, 612, 228 - Yang et al., 2022, Nature, 612, 232
GCN 33578 table
GRB_name GRB230307A
GCN_number 33578
Detection_method Other
redshift 0.0650
Circular_text TITLE: GCN CIRCULAR NUMBER: 33578 SUBJECT: GRB 230307A: good match with kilonova models DATE: 23/04/06 14:41:22 GMT FROM: Cristiano Guidorzi at Ferrara U,Italy M. Bulla, A.E. Camisasca, C. Guidorzi (Ferrara U.), L. Amati, A. Rossi (INAF-OAS), G. Stratta, P. Singh (Goethe U. Frankfurt) on behalf of a larger collaboration report: We compared kilonova models computed with the latest version of the radiative transfer code POSSIS (Bulla 2023, MNRAS, 520, 2558) to photometric data of a faint source associated with GRB 230307A as reported by Levan et al. (GCN 33569). Assuming a redshift z=0.065 (Gillanders et al. GCN 33485) and a Galactic extinction of E(B-V)=0.0743 mag (Schlafly & Finkbeiner 2011, ApJ, 737, 103), we find a reasonably good match to observations in both the F150W and F444W filters for a model viewed along the jet axis (face-on) and with two ejecta components: 1) a dynamical ejecta component with a mass of 0.005 Msun, an average velocity of 0.25c and an average electron fraction Ye=0.15; 2) and a disk-wind ejecta component with a mass of 0.05 Msun, an average velocity of 0.1c and an average electron fraction Ye=0.3 (see figure at the link below). This supports the claim of kilonova emission by Levan et al. (GCN 33569) and strengthens the interpretation of GRB 230307A as a merger event, as also suggested by the properties of the gamma-ray prompt emission (Camisasca et al. GCN 33577). Further analysis is ongoing. Figure: https://drive.google.com/file/d/1XhpfwCXQxWWS_G7WQ1fUSZKSiZXnwXiJ/view?usp=sharing
GCN 33579 table
GRB_name GRB230307A
GCN_number 33579
Detection_method Konus-Wind Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 33579 SUBJECT: GRB 230307A: further analysis of the Konus-Wind detection and rest-frame energetics DATE: 23/04/06 16:11:37 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, D. Frederiks, A. Ridnaia, A. Tsvetkova, and A. Lysenko on behalf of the Konus-Wind team, report: Following the probable host galaxy identification (Gillanders et al. GCN Circ. 33485; Levan at al., GCN Circ. 33569), we present a further analysis of the KW detection (Svinkin et al., GCN Circ. 33427) of the extremely bright, long-duration GRB 230307A (GCNs 33405, 33406, 33407, 33410, 33411, 33412, 33413, 33414, 33415, 33416, 33418, 33424, 33425, 33461). As measured by KW the burst durations are T50=9.17+/-0.04 s and T90 = 31.2 +/-0.4 s, both in the 100-1700 keV energy band. The refined burst fluence is 4.05(-0.03,+0.03)x10^-3 erg/cm2, and a 64-ms peak flux, measured from T0+6.224 s, is 6.85(-0.27,+0.27)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Assuming the redshift of the host galaxy z=0.065 (GCN 33485) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is (4.21+/-0.03)x10^52 erg, the peak luminosity L_iso is (7.58 +/-0.33)x10^51 erg/s, the rest-frame peak energy of the time-integrated spectrum, Ep,i,z is (933+/-12) keV, and the rest-frame peak energy at the peak luminosity Ep,p,z is (1388+/-52) keV. With these values, GRB 230307A is outside the 90% prediction band of both 'Amati' and 'Yonetoku' relations built for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021). In both Eiso-Ep,i,z and Liso-Ep,p,z planes, GRB 230307A is shifted towards the short-hard (Type I, merger-origin) GRB population, see http://www.ioffe.ru/LEA/GRBs/GRB230307_T56645/GRB230307A_rest_frame.pdf The analysis of KW data is ongoing and its results will be reported elsewhere.
GCN 33580 table
GRB_name GRB230307A
GCN_number 33580
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 33580 SUBJECT: GRB 230307A: JWST NIRSpec observations, possible higher redshift DATE: 23/04/06 17:00:47 GMT FROM: Andrew Levan at U.of Leicester A.J. Levan (Radboud), D. Watson (DAWN/NBI), J. Hjorth (DARK/NBI), N. R. Tanvir (Leicester), D. B. Malesani (Radboud, DAWN/NBI), E. Burns (LSU), B. P. Schneider (MIT), J. P. U. Fynbo (DAWN/NBI), S. D. Vergani (CNRS-Paris Observatory), W. Fong (Northwestern), A. Fruchter (STScI), G. Pugliese (API/UvA), S. Smartt (Oxford) report for a larger collaboration: “In addition to the JWST/NIRCam observations of GRB 230307A (Fermi GBM team, GCN 33405) reported in GCN 33569, we also obtained observations with NIRSpec on 5 April 2023. The observations were obtained for a total integration time of approximately 1 hour, using the prism to obtain a spectrum in the range 0.5-5.5 um. The trace confirms the spectral shape measured from NIRCam observations. Blueward of 2 um, the source has a flat spectrum, but low signal to noise, and a strong upturn redward of 2 um. We note the presence of two weak, narrow emission features in the spectrum, both of which are offset from the trace by approximately 0.1-0.2". These are consistent with the H-alpha and [O III] (5007 AA) emission lines at z = 3.87. Excess flux in the spectrum is also visible at the location of H-beta at this redshift. If the GRB is from a low redshift merger, as suggested by GCN 33569, then this could only be explained by a chance alignment with an unrelated background galaxy. It is hard to quantify this possibility, given that we could be seeing both transient and galaxy light, however the chances are clearly low. Alternatively, the lines could be from the host galaxy, implying that GRB 230307A lies at z = 3.87. The very red colours of the continuum source would not naturally match the expectations of any afterglow models at z = 3.87, but in fact could be consistent with those of a dusty, red galaxy. Given only one epoch in the mid-IR is available, we cannot rule out this possibility, although such a galaxy would be extremely compact, and the transient would have to decay very steeply since the last ground-based observations. We note that, at this redshift, GRB 230307A would be by far the most energetic burst ever detected, with E_iso ~ 10^56 erg. This would be an order of magnitude more energetic than any of the ~500 GRBs with available isotropic energy releases. This may require a unique progenitor system.”
GCN 33635 table
GRB_name GRB230307A
GCN_number 33635
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33635 SUBJECT: GRB 230307A: iTelescope optical upper limit (likely) DATE: 23/04/16 15:31:19 GMT FROM: Filipp Dmitrievich Romanov at Amateur astronomer On 2023-03-09 I observed the field of GRB 230307A (Fermi GBM team, GCN Circ. 33405) remotely using the telescope T17 (0.43-m f/6.8 reflector + CCD) of iTelescope.Net in Siding Spring Observatory (Australia). Ten images with exposures of 300 seconds and Ic filter (Astrodon Johnson-Cousins Ic) were obtained, the midtime of the stacked image is 10:52:40.7 UT (1.8 d. after the trigger). I did not detect a clear optical afterglow near the Swift-XRT position (Burrows et al., GCN Circ. 33465), but in this area in the stacked image there is what I can consider a noise (SNR <2), but I do not exclude that it may be faint afterglow near the upper limit of about 20 magnitudes in this band.
GCN 33747 table
GRB_name GRB230307A
GCN_number 33747
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 33747 SUBJECT: GRB 230307A: JWST second-epoch observations DATE: 23/05/08 21:30:32 GMT FROM: Andrew Levan at Radboud University A.J. Levan (Radboud), N. R. Tanvir (U. Leicester), E. Burns (LSU), G.P. Lamb (LJMU), J. P. U. Fynbo (DAWN/NBI), A.S. Fruchter (STScI), K. Bhirombhakdi (STScI), P O’Brien (U. Leicester), P. Jakobsson (U. Iceland), D. B. Malesani (Radboud and DAWN/NBI), B. P. Gompertz (U. Birmingham), A. Martin-Carrillo (UCD), D. Watson (DAWN/NBI), S. Smartt (Oxford) , J. Hjorth (DARK/NBI) report for a larger collaboration: We obtained a second epoch of JWST observations of the exceptionally bright GRB 230307A (Fermi GBM team, GCN 33405; Xiong et al., GCN 33406; Xiao & Krucker, GCN 33410; Cosentini et al., GCN 33412; Navaneeth et al., GCN 33415) on 8 May 2023 (about 62 days post-burst). Imaging was obtained with NIRCam in the F115W, F150W, F277W and F444W filters and spectroscopy with the NIRSpec prism. The source at the location of the optical/IR afterglow (Levan et al., GCNs 33439, 33569) is still detected but has faded significantly, particularly in the redder bands. In the F444W filter, it faded by 2.7 mag. This result confirms that the very red continuum noted in the first epoch by Levan et al. (GCN 33569) is due to a variable source and does not contain a significant contribution from any underlying host. However, we do note the presence of a faint galaxy, approximately 0.3” from the burst position, which is plausibly the source of the emission lines seen in previous NIRSpec spectroscopy (Levan et al., GCN 33580). Although further analysis is required, the rapid IR fading is consistent with the expectations of kilonova emission. If that interpretation is correct, the higher redshift source has to be an unrelated background galaxy, aligned by chance with the GRB. Alternatively, if associated with the galaxy at z = 3.87, the counterpart would have exhibited unprecedented temporal and chromatic behaviour.