GRB250617B

This page lists all entries on GRB250617B in GRBweb

Summary Fermi GBM Swift GCN 40760 GCN 40761 GCN 40762 GCN 40763 GCN 40766 GCN 40767 GCN 40768 GCN 40769 GCN 40771 GCN 40772 GCN 40773 GCN 40775 GCN 40776 GCN 40777 GCN 40778 GCN 40789 GCN 40823

Summary table
Variable Value Source
GRB_name_Fermi GRB250617876
T0 21:01:25.884 UTC Fermi_GBM
ra 332.8969° Swift
decl 32.7325° Swift
pos_error 5.70e-05° Swift
T90 31.745 s Fermi_GBM
T90_error 2.896 s Fermi_GBM
T90_start 21:01:25.884 UTC Fermi_GBM
fluence 3.48e-06 erg/cm² Fermi_GBM
fluence_error 5.16e-08 erg/cm² Fermi_GBM
redshift 1.3960 GCN_circulars,Optical
T100 31.745 s
GBM_located False
mjd 60843.875994027774 Fermi_GBM
Fermi GBM table
GRB_name_Fermi GRB250617876
trigger_name bn250617876
ra 332.8971°
decl 32.7331°
pos_error 5.01e+00°
datum 2025-06-17
t_trigger 21:01:28.188 UTC
T90 31.745 s
T90_error 2.896 s
T90_start 21:01:25.884 UTC
fluence 3.48e-06 erg/cm²
fluence_error 5.16e-08 erg/cm²
flux_1024 6.92e+00 erg/cm²/s
flux_1024_error 2.86e-01 erg/cm²/s
flux_1024_time 2.27e+01 erg/cm²/s
flux_64 8.37e+00 erg/cm²/s
flux_64_error 1.33e+00 erg/cm²/s
Swift table
GRB_name GRB250617B
t_trigger 21:01:50.110 UTC
ra 332.8969°
decl 32.7325°
pos_error 5.70e-05°
redshift 1.3960
GCN 40760 table
GRB_name GRB250617B
GCN_number 40760
Detection_method Swift Det
t_trigger 21:01:50.110 UTC
ra 332.9020°
decl 32.7270°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40760 SUBJECT: GRB 250617B: Swift detection of a burst with an optical counterpart DATE: 25/06/17 21:24:27 GMT FROM: David Palmer at LANL K. L. Page (U Leicester), R. Gupta (NASA GSFC), A. Y. Lien (U Tampa), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. H. Siegel (PSU) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 21:01:50.11 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250617B (trigger=1325580). Swift did not slew immediately to the burst. The BAT on-board calculated location is RA, Dec 332.902, +32.727 which is RA(J2000) = 22h 11m 37s Dec(J2000) = +32d 43' 38" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The currently available BAT light curve showed a complex structure with a duration of at least 10 sec. However, the light curve data from ~T+8 s to ~T+100 s is unavailable in the immediate data downlink. The peak count rate was ~900 counts/sec (15-350 keV), at ~0 sec after the trigger. The XRT began observing the field at 21:15:03.4 UT, 793.4 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 332.89735, 32.73270 which is equivalent to: RA(J2000) = 22h 11m 35.36s Dec(J2000) = +32d 43' 57.7" with an uncertainty of 1.9 arcseconds (radius, 90% containment). This location is 24 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. We cannot determine whether the source is fading at the present time. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (9.66 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.7 (+4.15/-3.46) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 150 seconds with the White filter starting 796 seconds after the BAT trigger. There is a candidate afterglow in the rapidly available 2.7'x2.7' sub-image at RA(J2000) = 22:11:35.25 = 332.89686 DEC(J2000) = +32:43:56.9 = 32.73247 with a 90%-confidence error radius of about 0.62 arc sec. This position is 1.9 arc sec. from the center of the XRT error circle. The estimated magnitude is 18.17 with a 1-sigma error of about 0.15. No correction has been made for the expected extinction corresponding to E(B-V) of 0.087. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/)
GCN 40761 table
GRB_name GRB250617B
GCN_number 40761
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40761 SUBJECT: GRB 250617B: SAO RAS optical observations DATE: 25/06/17 22:54:57 GMT FROM: Alexander Moskvitin at SAO RAS A. Moskvitin, O. Spiridonova, Yu. Sotnikova (SAO RAS), A. Ghosh, S. Razzaque (CAPP, University of Johannesburg) We observed the field of the GRB 250617B (Page et al., GCN 40760) with SAO RAS 1-m telescope Zeiss-1000 equipped with CCD-photometer. We obtained series of 60, 120 and 300 sec. exposures in Rc band and also one BVIc series. Observations started on 21:28:06 UT, since 26 minutes after the trigger. The OT (Page et al., GCN 40760) is clearly visible in individual images with the brightness of R = 18.31 +/- 0.04 (t_mid - T0 = 0.5444 hours) and R = 18.66 +/- 0.04 (t_mid - T0 = 0.7635 hours). This preliminary photometry is calibrated against R2 magnitudes of following nearby USNO-B1 stars and not corrected for the Galaxy extinction. R.A. Dec. (2000) R2 22:11:38.4 +32:43:48.4 14.880 22:11:19.9 +32:44:17.5 15.280 22:11:41.0 +32:40:41.2 15.070 22:11:45.2 +32:42:19.8 14.690 Observations are ongoing.
GCN 40762 table
GRB_name GRB250617B
GCN_number 40762
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40762 SUBJECT: GRB 250617B: Ondrejov D50 optical afterglow detection DATE: 25/06/17 22:55:14 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov M. Jelinek, J. Strobl, F. Novotny, A. Malenakova and R. Hudec (ASU CAS Ondrejov) report: We observed the position of the Swift-detected GRB 250617B (Page et al. GCN 40760) with the D50 telescope of the Astronomical Institute Ondrejov, near Prague, Czech Republic. Our observation started at 21:29:35 UT, i.e. 27.8 min after the initial trigger and was performed without filter. We detect the optical afterglow (Page et al. GCN 40760) in a combined image with exp. mean time ~37.3 min after trigger (exposed 21:29:35-21:39:35 UT). The AB magnitude of the object at this frame is R = 18.64 +/- 0.27. We can confirm a decaying nature of the object with a temporal decay index of alpha = 0.85 ± 0.13.
GCN 40763 table
GRB_name GRB250617B
GCN_number 40763
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40763 SUBJECT: GRB 250617B: Fermi GBM Final Localization DATE: 25/06/18 00:14:26 GMT FROM: sumanbala2210@gmail.com The Fermi GBM team reports the detection of a likely LONG GRB "At 21:01:28.19 UT on 17 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250617B (trigger 771886893/250617876). It is also detected by Swift-BAT/XRT (Page et al. 2025, GCN 40760) The Fermi GBM on-ground location is consistent with the Swift-XRT position. The angle from the Fermi LAT boresight is 91 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250617876/quicklook/glg_skymap_all_bn250617876.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250617876/quicklook/glg_healpix_all_bn250617876.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250617876/quicklook/glg_lc_medres34_bn250617876.gif"
GCN 40766 table
GRB_name GRB250617B
GCN_number 40766
Detection_method Fermi GBM Det
t_trigger 21:01:28.190 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 40766 SUBJECT: GRB 250617B: Fermi GBM Observation DATE: 25/06/18 04:32:42 GMT FROM: sumanbala2210@gmail.com S. Bala (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 21:01:28.19 UT on 17 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250617B (trigger 771886893/250617876). which was also detected by Swift BAT (Page et al. 2025, GCN 40760). The Fermi GBM on-ground location is consistent with the Swift BAT position. The angle from the Fermi LAT boresight is 91 degrees. The GBM light curve consists of two distinct emission episodes with a duration (T90) of about 32 s (50-300 keV). The time-averaged spectrum from T0-4.6 to T0+32.3 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.2 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 40 +/- 2 keV. The event fluence (10-1000 keV) in this time interval is (3.4 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+23 s in the 10-1000 keV band is 6.9 +/- 0.3 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 40767 table
GRB_name GRB250617B
GCN_number 40767
Detection_method Swift-XRT Det
ra 332.8967°
decl 32.7325°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40767 SUBJECT: GRB 250617B: Enhanced Swift-XRT position DATE: 25/06/18 04:53:33 GMT FROM: Phil Evans at U of Leicester J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team. Using 1717 s of XRT Photon Counting mode data and 2 UVOT images for GRB 250617B, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 332.89670, +32.73250 which is equivalent to: RA (J2000): 22h 11m 35.21s Dec (J2000): +32d 43' 57.0" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team.
GCN 40768 table
GRB_name GRB250617B
GCN_number 40768
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40768 SUBJECT: GRB 250617B: GOTO optical upper limit DATE: 25/06/18 06:29:28 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK A. Kumar, B. P. Gompertz, G. Ramsay, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, D. O'Neill, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022; Dyer et al. 2024) in response to the Swift/BAT and Fermi/GBM detected GRB 250617B (Page et al., GCN 40760; Fermi GBM Team, GCN 40763). Targeted observations were performed by GOTO-North at 2025-06-18T01:03:23 (4.03 hours after the trigger). The observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. We do not detect the optical afterglow of GRB 250617B (Page et al., GCN 40760; Moskvitin et al., 40761; Jelinek et al., 40762) down to a 3-sigma limiting magnitude of L > 20.3 AB mag. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).
GCN 40769 table
GRB_name GRB250617B
GCN_number 40769
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40769 SUBJECT: Swift GRB 250617B: Global MASTER-Net observations report DATE: 25/06/18 06:36:55 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 250617B ( K. L. Page et al., GCN 40760) errorbox 30652 sec after notice time and 30775 sec after trigger time at 2025-06-18 05:34:46 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 80 deg. The sun altitude is -74.8 deg. The galactic latitude b = -19 deg., longitude l = 89 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2906362 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 30866 | MASTER-OAFA | C | 180 | 17.3 | 31415 | MASTER-OAFA | C | 60 | 17.4 | 31495 | MASTER-OAFA | C | 60 | 17.7 | 32132 | MASTER-OAFA | C | 180 | 18.2 | 32767 | MASTER-OAFA | C | 60 | 18.1 | 32845 | MASTER-OAFA | C | 60 | 18.1 | 33417 | MASTER-OAFA | C | 180 | 18.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 40771 table
GRB_name GRB250617B
GCN_number 40771
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40771 SUBJECT: GRB 250617B: NUTTelA-TAO early time optical observations DATE: 25/06/18 08:09:56 GMT FROM: Bruce Grossan at LBNL/UCB SSL B. Grossan (UCB, NU) , T. Komesh (NU), Z. Maksut (NU), D. Berdikhan (NU), M. Krugov (FAI), G. F. Smoot (HKUST, UCB, NU), E. Abdikamalov (NU) report on behalf of the Energetic Cosmos Laboratory: The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 250617B on receipt of an automated GCN / BAT position alert, observing in Sloan g' and r' bands with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14). We find a fading OT consistent with the position given in Palmer, 2025 (GCN 40760). We received the alert and started observations at UT 2025-06-17 21:02:48 (58 seconds between GRB trigger time and notice receipt/response time). Stabilized images commenced at 21:03:10, 80 s after trigger. Observations were made under good conditions for more than 1300 s. The early measurements were sufficiently bright that they are visible in our short frames with no co-addition. Below, we give a selection of these measurements(irregular sampling due to changes in exposure time, camera mode,etc.) Note that these data provide essentially full-time coverage, nearly simultaneous in both bands. We report the following results: ---------------------------------------------------------------------------- g' tstart(*) tm-ttrig(s) g' err r' err exposure_time (s) ------------ ---------- ----- ------ ------ ----- ----------------- 21:03:10.4 80.5 15.29 0.06 14.75 0.09 3.0 21:03:40.4 110.5 15.54 0.10 14.90 0.10 3.0 21:04:46 176 16.12 0.09 15.69 0.04 30.0 21:09:46 476 17.40 0.10 17.02 0.07 30.0 21:15:45 835 17.87 0.12 17.67 0.08 60.0 21:18:45 1015 18.36 0.12 17.81 0.09 60.0 21:23:45 1315 UL18.72 18.00 0.11 60.0 (*) Times for r' are about 1.8 s before times for g'; times are UT June 17. "tm-ttrig" gives the mid time of the exposure minus the trigger time. The Sloan filter g', err, r', err are given in magnitudes. UL denotes no detection; 5 sigma upper limit only. Conditions at later times than given in the table showed a significant deterioriation in stability and sensitivity and so are omitted. ----------------------------------------------------- Because of the very good, quite early, time coverage thus far, we encourage observers capable of longer-term observations (12 hours+) to attempt additional g',r' (and other filters) coverage. We caution the reader that these are preliminary results, without color or other corrections, and will likely change in small measure. Please also note that times are approximate. We welcome requests for additional data and collaboration. ---------------------------------- NU = Nazarbayev University, Nur-Sultan, Kazakhstan UCB = University of California, Berkeley, USA HKUST = Hong Kong University of Science and Technology FAI = Fesenkov Astrophysical Institute, Kazakhstan The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.
GCN 40772 table
GRB_name GRB250617B
GCN_number 40772
Detection_method Optical
ra 332.8967°
decl 32.7324°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40772 SUBJECT: GRB 250617B: SVOM/VT optical observation DATE: 25/06/18 08:16:40 GMT FROM: SVOM_group Y.N. Ma, L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), Z. Q. Wang (GXU), W. K. Zheng (UCB), Y. F. Liang (PMO) report on behalf of the SVOM/VT team. SVOM/VT performed a Target of Opportunity observation of GRB 250617B detected by Swift-BAT（Page et al., GCN 40760; Osborne et al., GCN 40767) and Fermi-GBM (Bala et al., GCN 40766). The observation began at 2025-06-18T01:18:40 UTC, 4.281 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The afterglow (Page et al., GCN 40760; Moskvitin et al., GCN 40761; Jelinek et al., GCN 40762) is detected using VT X-band data, at R.A., Dec 332.89675, 32.73242 degrees: RA (J2000) = 22:11:35.22 Dec (J2000) = +32:43:56.72 with an uncertainty of 0.5 arcsec. The magnitudes in both channels are: date-obs (UT) | exposure time (s) | band | mag (AB) | mag err -----------------------|-------------------|------|----------|-------- 2025-06-18T02:24:34.50 | 70 | VT_B | 21.10 | 0.12 2025-06-18T02:24:34.50 | 70 | VT_R | 20.11 | 0.08 Our photometry was not corrected for Galactic extinction. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
GCN 40773 table
GRB_name GRB250617B
GCN_number 40773
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 40773 SUBJECT: GRB 250617B: Swift-XRT refined Analysis DATE: 25/06/18 08:23:52 GMT FROM: Phil Evans at U of Leicester M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-OAR), M. Perri (SSDC & INAF-OAR), J.A. Kennea (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.3 ks of XRT data for GRB 250617B, from 779 s to 31.0 ks after the trigger. The data comprise 7 s in Windowed Timing (WT) mode (taken while Swift was slewing), with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=0.90 (+/-0.06). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.16 (+0.19, -0.18). The best-fitting absorption column is 1.9 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 9.7 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.3 x 10^-11 (4.8 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.9 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 9.7 x 10^20 cm^-2 Excess significance: 3.0 sigma Photon index: 2.16 (+0.19, -0.18) If the light curve continues to decay with a power-law decay index of 0.90, the count rate at T+24 hours will be 0.025 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.3 x 10^-13 (1.2 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01325580. This circular is an official product of the Swift-XRT team.
GCN 40775 table
GRB_name GRB250617B
GCN_number 40775
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40775 SUBJECT: GRB 250617B: COLIBRÍ optical observations DATE: 25/06/18 10:25:49 GMT FROM: Sarah Antier at OCA Sarah Antier (OCA/IJCLAB), Diego López-Cámara (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the GRB 250617B (Page et al., GCN 40760; Fermi GBM Team, GCN 40763) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-06-18 08:09:20 to now UTC (started 11.12 hours after the trigger) and obtained a series of 1 min exposure images in the i filter. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1/SkyMapper catalog, is in the AB system, and is not corrected for Galactic extinction. We detected the optical counterpart Page et al., GCN Circ. 40760 (also reported by Moskvitin et al. (GCN 40761), Jelinek et al. (GCN 40762), Grossan et al. (GCN 40771), and Ma et al. (GCN 40772)), at a preliminary magnitude using a 6-min stack image at the beginning of the observations: i = 21.17 +/- 0.16 Further observations are ongoing. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN 40776 table
GRB_name GRB250617B
GCN_number 40776
Detection_method Optical
redshift 1.3960
Circular_text TITLE: GCN CIRCULAR NUMBER: 40776 SUBJECT: GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396 DATE: 25/06/18 10:49:27 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group G. Corcoran (UCD), M. Garnichey (LUX-Paris Obs.), B. Schneider (LAM), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. Saccardi (CEA/Irfu), S. D. Vergani (LUX-Paris Obs.), report on behalf of a larger collaboration: We observed the field of GRB 250617B detected by Swift (Page et al., GCN 40760) and Fermi (Fermi GBM team, GCN 40763; Bala & Meegan, GCN 40766), using the ESO VLT UT3 (Melipal) with the X-shooter. Our spectra cover the wavelength range 3000-25000 AA, and consist of 4 exposures of 900 s each. The observation mid time was 2025 Jun 18.375 UT (11.96 hr after the GRB). In images taken with the acquisition camera, we clearly detect in the g, r, and z bands the optical counterpart reported by Page et al. (GCN 40760), Moskvitin et al. (GCN 40761), Jelinek et al. (GCN 40762), Grossan et al. (GCN 40771), Ma et al. (GCN 40772), Schneider et al. (GCN 40774) and Antier et al. (GCN 40775). We measure a preliminary magnitude: r = 21.30 +/- 0.04 (AB) at mid time 11.21 hr after trigger. The photometric calibration was performed using nearby stars from the Pan-STARRS catalog and the magnitude is not corrected for Galactic extinction. In a preliminary reduction of the spectra, we detect a continuum over the entire covered wavelength range. From the detection of multiple absorption lines, which we interpret as Mg II doublet (2796, 2804) and Fe II, we infer a redshift of z = 1.396. At a consistent redshift, we also detect emission lines due to [O II] doublet and H-alpha from the GRB host galaxy. We acknowledge excellent support from the ESO observing staff in Paranal.
GCN 40777 table
GRB_name GRB250617B
GCN_number 40777
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40777 SUBJECT: GRB 250617B: Kilonova-Catcher optical afterglow detection DATE: 25/06/18 11:19:22 GMT FROM: Damien Turpin at CEA-Saclay D. Turpin (CEA-Saclay/Irfu), M. Freeberg (KNC), C. Andrade(UMN), M. Pillas (ULiege), M. Tanasan (NARIT), S. Antier (OCA/IJCLAB) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 250617B (Page et al., GCN 40760) detected by Swift/BAT with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with the TEC160FL telescope operated by M. Freeberg starting from T_GRB+10hr. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we marginally detect the optical afterglow at the position reported by Swift/UVOT (Page et al., GCN 40760), SAO RAS (Moskvitin et al., GCN 40761), Ondrejov D50 (Jelinek et al., GCN 40762), NUTTelA-TAO (Grossan et al., GCN 40771), SVOM/VT (Mat et al., GCN 40772), NOT (Schneider et al., GCN 40774), COLIBRÍ (Antier et al., GCN 40775) and VLT/X-shooter (Corcoran et al., GCN 40776) We report our follow-up results in the table below: +---------------+-------------+--------------+----------------+--------------+ | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | +===============+=============+==============+================+==============+ | 10.8 | 18 x 300s | r (AB) | 20.85 +/- 0.29 | TEC160FL | +---------------+-------------+--------------+----------------+--------------+ All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the sloan images were calibrated using the PanSTARRS DR1 catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).
GCN 40778 table
GRB_name GRB250617B
GCN_number 40778
Detection_method Swift-UVOT Det
ra 332.8969°
decl 32.7325°
Circular_text TITLE: GCN CIRCULAR NUMBER: 40778 SUBJECT: GRB 250617B: Swift/UVOT Detection DATE: 25/06/18 13:09:34 GMT FROM: Mike Siegel at PSU/Swift MOC M. H. Siegel (PSU) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250617B 797 s after the BAT trigger (Page et al., GCN Circ. 40760). A source consistent with the XRT position (Osborne et al., GCN Circ 40767) is detected in the initial UVOT exposures. The lack of detection in the uvw2 and uvm2 filters would be consistent with the redshift reported by Corcoran et al. (GCN Circ. 40776). The preliminary UVOT position is: RA (J2000) = 22:11:35.25 = 332.89686 (deg.) Dec (J2000) = +32:43:57.1 = 32.73253 (deg.) with an estimated uncertainty of 0.44 arc sec. (radius, 90% confidence). Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white 797 946 147 18.18 +/- 0.05 v 1130 2528 172 18.72 +/- 0.19 b 1229 1596 58 18.91 +/- 0.18 u 1204 1397 39 18.10 +/- 0.19 w1 1179 2408 156 19.32 +/- 0.28 m2 1155 2384 117 >18.3 w2 1106 2507 175 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.087 in the direction of the burst (Schlegel et al. 1998).
GCN 40789 table
GRB_name GRB250617B
GCN_number 40789
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 40789 SUBJECT: GRB 250617B: Nickel telescope optical observations DATE: 25/06/20 00:49:40 GMT FROM: Weikang Zheng at UC Berkeley Eli Gendreau-Distler, Gracelynn Jost, William Wu, WeiKang Zheng and Alex Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: We observed the field of GRB 250617B (Page et. al, GCN 40760; The Fermi GBM team, GCN 40763) with the 1-m Nickel telescope located at Lick observatory, California. Observations were performed in R band with 600s x 5 exposure time started at 09:46 UT on June 18. We clearly detected the optical afterglow (Page et. al, GCN 40760, Moskvitin et. al, GCN 40761, Jelinek et. al, GCN 40762; Kumar et. al, GCN 40768; Lipunov et. al, GCN 40769; Grossan et. al, GCN 40771; Ma et. al, GCN 40772; Schneider et. al, GCN 40774; Antier et. al, GCN 40775; Corcoran et. al, GCN 40776; Turpin et. al, GCN 40777; Siegel & Page, GCN 40778; Pankov et al., GCN 40783) in our coadd image with 21.4 +/- 0.1 mag at a mid time of 13.10 hours after the burst.
GCN 40823 table
GRB_name GRB250617B
GCN_number 40823
Detection_method Optical
redshift 1.3960
Circular_text TITLE: GCN CIRCULAR NUMBER: 40823 SUBJECT: GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24 DATE: 25/06/25 15:10:36 GMT FROM: Alexander Moskvitin at SAO RAS A. Moskvitin, O. Spiridonova (SAO RAS), N. Pankov (HSE, IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of GRB follow-up and IKI-GRB-FuN collaborations. We observed the field of the GRB 250617B (Page et al., GCN 40760; Fermi GBM team, GCN 40763; Bala and Meegan, GCN 40766; Osborne et al., GCN 40767; Williams et al., GCN 40773; Laha et al., GCN 40812) at the redshift of z = 1.396 (Corcoran et al., GCN 40776) with the 1.5-meter AZT-33IK telescope of Mondy observatory on 2025-06-23 and with the 1-m telescope Zeiss-1000 of the SAO RAS on 2025-06-24. The OT (Page et al., GCN 40760; Moskvitin et al., GCN 40761; Jelinek et al., GCN 40762; Grossan et al., GCN 40771; Ma et al., GCN 40772; Antier et al., GCN 40775; Corcoran et al., GCN 40776; Turpin et al., GCN 40777; Siegel and Page, GCN 40778; Pankov et al., GCN 40783; Gendreau-Distler et al., GCN 40789; Calapai, GCN 40804; also detected in NIR by Schneider et al., GCN 40774) is marginally detected in AZT-33IK stacked image and clearly detected in Zeiss-1000 stacked image. Preliminary results are as following. Date UT start t-T0 Exp. Filter OT Err. UL telescope (mid, days) (s) (3 sigma) 2025-06-23 16:37:49 5.84791 45*120 R 22.9 0.4 22.7 AZT-33IK 2025-06-24 22:44:03 7.09417 12*300 Rc 23.4 0.2 23.9 Zeiss-1000 This photometry is based on the USNO-B1.0 stars given in Moskvitin et. al, (GCN 40761) and has not corrected for the Galactic extinction.