GRB200826A

This page lists all entries on GRB200826A in GRBweb

Summary Fermi GBM IPN GCN 28284 GCN 28285 GCN 28286 GCN 28287 GCN 28288 GCN 28289 GCN 28290 GCN 28291 GCN 28293 GCN 28294 GCN 28295 GCN 28300 GCN 28301 GCN 28302 GCN 28306 GCN 28312 GCN 28319 GCN 28410 GCN 28727 GCN 28949 GCN 29029

Summary table
Variable Value Source
GRB_name_Fermi GRB200826187
T0 4:29:52 UTC GCN_circulars,Fermi GBM final loc
ra 6.8167° IPN
decl 34.0333° IPN
pos_error 4.50e-01° IPN
T90 1.136 s Fermi_GBM
T90_error 0.132 s Fermi_GBM
T90_start 4:29:52.603 UTC Fermi_GBM
fluence 4.26e-06 erg/cm² Fermi_GBM
fluence_error 2.24e-08 erg/cm² Fermi_GBM
redshift 0.7481 GCN_circulars,Other
T100 1.739 s
GBM_located False
mjd 59087.18740740741 GCN_circulars,Fermi GBM final loc
Fermi GBM table
GRB_name_Fermi GRB200826187
trigger_name bn200826187
ra 4.6700°
decl 35.2900°
pos_error 3.77e+00°
datum 2020-08-26
t_trigger 4:29:52.571 UTC
T90 1.136 s
T90_error 0.132 s
T90_start 4:29:52.603 UTC
fluence 4.26e-06 erg/cm²
fluence_error 2.24e-08 erg/cm²
flux_1024 3.91e+01 erg/cm²/s
flux_1024_error 4.23e-01 erg/cm²/s
flux_1024_time 0.00e+00 erg/cm²/s
flux_64 6.43e+01 erg/cm²/s
flux_64_error 2.05e+00 erg/cm²/s
IPN table
GRB_name GRB200826A
ra 6.8167°
decl 34.0333°
pos_error 4.50e-01°
redshift 0.7481
GCN 28284 table
GRB_name GRB200826A
GCN_number 28284
Detection_method Fermi GBM final loc
t_trigger 4:29:52 UTC
ra 4.7000°
decl 35.3000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28284 SUBJECT: GRB 200826A: Fermi GBM Final Real-time Localization DATE: 20/08/26 04:40:17 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely SHORT GRB At 04:29:52 UT on 26 Aug 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200826A (trigger 620108997.570644 / 200826187). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 4.7, Dec = 35.3 (J2000 degrees, equivalent to J2000 00h 18m, 35d 17'), with a statistical uncertainty of 1.7 degrees. The angle from the Fermi LAT boresight is 73.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826187/quicklook/glg_skymap_all_bn200826187.png The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826187/quicklook/glg_healpix_all_bn200826187.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200826187/quicklook/glg_lc_medres34_bn200826187.gif
GCN 28285 table
GRB_name GRB200826A
GCN_number 28285
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28285 SUBJECT: Fermi GRB 200826A: Global MASTER-Net observations report DATE: 20/08/26 05:00:17 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva, D.Kuvshinov, D. Cheryasov (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, O.Ershova (Irkutsk State University, API), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), V. Yurkov, A. Gabovich, Yu. Sergienko (Blagoveschensk Educational State University) 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) started inspect of the Fermi GRB 200826A ( Fermi GBM team, GCN 28284) errorbox 18 sec after notice time and 46 sec after trigger time at 2020-08-26 04:30:38 UT, with upper limit up to 18.3 mag. The observations began at zenith distance = 76 deg. The sun altitude is -69.3 deg. The galactic latitude b = -24 deg., longitude l = 116 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1427181 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 51 | 2020-08-26 04:30:38 | MASTER-OAFA | (00h 16m 30.99s , +38d 58m 23.2s) | C | 10 | 16.5 | 102 | 2020-08-26 04:31:24 | MASTER-OAFA | (00h 16m 59.22s , +35d 52m 18.4s) | C | 20 | 17.0 | 159 | 2020-08-26 04:32:16 | MASTER-OAFA | (00h 18m 21.45s , +36d 49m 55.4s) | C | 30 | 17.2 | 214 | 2020-08-26 04:33:06 | MASTER-OAFA | (00h 18m 17.46s , +36d 48m 57.2s) | C | 40 | 17.5 | 278 | 2020-08-26 04:34:05 | MASTER-OAFA | (00h 18m 22.91s , +36d 49m 03.8s) | C | 50 | 17.6 | 353 | 2020-08-26 04:35:15 | MASTER-OAFA | (00h 18m 20.27s , +36d 50m 58.1s) | C | 60 | 17.8 | 442 | 2020-08-26 04:36:34 | MASTER-OAFA | (00h 18m 20.68s , +36d 49m 32.1s) | C | 80 | 17.9 | 552 | 2020-08-26 04:38:14 | MASTER-OAFA | (00h 18m 23.06s , +36d 50m 57.8s) | C | 100 | 17.8 | 683 | 2020-08-26 04:40:15 | MASTER-OAFA | (00h 17m 00.73s , +35d 50m 57.2s) | C | 120 | 18.1 | 837 | 2020-08-26 04:42:34 | MASTER-OAFA | (00h 17m 02.07s , +35d 51m 59.4s) | C | 150 | 18.2 | 1022 | 2020-08-26 04:45:24 | MASTER-OAFA | (00h 17m 08.96s , +35d 51m 02.3s) | C | 180 | 18.3 | 1221 | 2020-08-26 04:48:43 | MASTER-OAFA | (00h 17m 02.21s , +35d 50m 06.3s) | C | 180 | 18.3 | 1421 | 2020-08-26 04:52:03 | MASTER-OAFA | (00h 17m 08.56s , +35d 50m 36.7s) | C | 180 | 18.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 28286 table
GRB_name GRB200826A
GCN_number 28286
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28286 SUBJECT: GRB 200826A: BALROG localization (Fermi Trigger 620108997 / GRB 200826187) DATE: 20/08/26 05:19:26 GMT FROM: Jochen Greiner at MPE,Garching F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 620108997 at 04:29:52 on 26 Aug. 2020 were automatically 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) = 7.0+/-2.1 deg Decl.(2000.0) = 36.1+/-2.4 deg We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB200826187/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB200826187/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB200826187/json
GCN 28287 table
GRB_name GRB200826A
GCN_number 28287
Detection_method Fermi GBM Det
t_trigger 4:29:52.570 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 28287 SUBJECT: GRB 200826A: Fermi GBM observation DATE: 20/08/26 17:18:41 GMT FROM: Joe Mangan at UCD J.Mangan (UCD), R.Dunwoody (UCD) and C.Meegan (UAH) report on behalf of the Fermi GBM Team: "At 04:29:52.57 UT on 26 August 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 200826A (trigger 620108997 / 200826187). The on-ground calculated location, using the GBM trigger data, was reported in GCN 28284. The GBM light curve shows an exceptionally bright short GRB with a duration (T90) of about 1.14 s (50-300 keV). The time-averaged spectrum from T0-0.29 s to T0+1.76 s is best fit by a Band function with Epeak = 89.8 +/- 3.7 keV, alpha = -0.41 +/- 0.07, and beta = -2.4 +/- 0.1 The event fluence (10-1000 keV) in this time interval is (4.8 +/- 0.1)E-06 erg/cm^2. The 1.024-sec peak photon flux measured starting from T0 s in the 10-1000 keV band is 39.06 +/- 0.42 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 28288 table
GRB_name GRB200826A
GCN_number 28288
Detection_method AstroSat CZTI
Circular_text TITLE: GCN CIRCULAR NUMBER: 28288 SUBJECT: GRB 200826A: AstroSat CZTI detection DATE: 20/08/26 19:40:25 GMT FROM: Soumya Gupta at IUCAA/ASTROSAT S. Gupta, V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (IUCAA/TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed the detection of a bright short GRB 200826A, which was also detected by Fermi GBM (GCN #28284), Global MASTER-Net (Lipunov V. et al., GCN #28285) and BALROG (Kunzweiler F. et al., GCN #28286). The source was clearly detected in the 40-200 keV energy range. The light curve showed a single peak of emission peaking at 2020-08-26 04:29:51.529 UT. The measured peak count rate associated with the burst is 686 +/- 34 cts/s above the background in the combined data of four quadrants, with a total of 1383 +/- 10 cts. The local mean background count rate was 537 +/- 2 cts/s. Using cumulative rates, we measure a T90 of 1.95 +/- 0.01 s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a single peak of emission peaking at 2020-08-26 04:29:51.000 UT. The measured peak count rate is 735 +/- 53 cts/s above the background in the combined Veto data of four quadrants, with a total of 1043 +/- 42 cts. The local mean background count rate was 1870 +/- 16 cts/s. We measure a T90 of 2.17 +/- 0.23 s from the cumulative Veto light curve. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.
GCN 28289 table
GRB_name GRB200826A
GCN_number 28289
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28289 SUBJECT: GRB 200826A: AGILE detection DATE: 20/08/26 20:30:44 GMT FROM: Francesco Verrecchia at SSDC,INAF-OAR C. Pittori, F. Verrecchia (SSDC, and INAF/OAR), A. Ursi (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), F. Longo (Univ. Trieste and INFN Trieste), N. Parmiggiani (INAF/OAS-Bologna), F. Lucarelli, (SSDC, and INAF/OAR), A. Argan, M. Cardillo, C. Casentini, Y. Evangelista, G. Piano (INAF/IAPS), A. Bulgarelli, V. Fioretti, F. Fuschino (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), A. Giuliani (INAF/IASF-Mi), report on behalf of the AGILE Team: The AGILE satellite detected the short burst GRB 200826A at T0=2020-08-26 04:29:52 (UTC), reported by Fermi-GBM (GCN #28284, trigger 620108997.570644 / 200826187). The event was detected by the scientific ratemeters of the Super-AGILE (SA; 18-60 keV) detector. The light curve shows a single peak profile, lasting 0.5 s and releasing ~84 counts above an average background rate of about 40 counts/s. The short burst was observed at an off-axis angle of about 54 degrees. The Super-AGILE light curve can be found here: https://tools.ssdc.asi.it/ImgView/Agile/SA-TOT_GRB200826A_lcr28 Additional analysis of AGILE data is in progress.
GCN 28290 table
GRB_name GRB200826A
GCN_number 28290
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28290 SUBJECT: GRB 200826A: Tiled Swift observations DATE: 20/08/26 20:46:44 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 200826A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00093 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 28291 table
GRB_name GRB200826A
GCN_number 28291
Detection_method IPN Triangulation
t_trigger 4:29:53 UTC
ra 6.8170°
decl 34.0380°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28291 SUBJECT: IPN triangulation of GRB 200826A (short/bright) DATE: 20/08/26 21:28:52 GMT FROM: Dmitry Svinkin at Ioffe Institute K. Hurley, on behalf of the IPN, I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team, D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team, A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report: The short-duration, bright GRB 200826A (Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 28284; Mangan et al., GCN Circ. 28287; BALROG localization: Kunzweiler et al., GCN Circ. 28286; AstroSat-CZTI detection: Gupta et al., GCN Circ. 28288; AGILE detection: Pittori et al., GCN Circ. 28289) has been detected by Fermi (GBM trigger 620108997), Konus-Wind, INTEGRAL (SPI-ACS), AstroSat (CZTI), AGILE (SA), and Mars-Odyssey (HEND), so far, at about 16193 s UT (04:29:53). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 6.817 (00h 27m 16s) +34.038 (+34d 02' 18") Corners: 7.081 (00h 28m 19s) +34.000 (+34d 00' 00") 6.808 (00h 27m 14s) +34.222 (+34d 13' 21") 6.553 (00h 26m 13s) +34.075 (+34d 04' 31") 6.826 (00h 27m 18s) +33.854 (+33d 51' 14") --------------------------------------------- The error box area is 288 sq. arcmin, and its maximum dimension is 27 arcmin (the minimum one is 15 arcmin). The Sun distance was 126 deg. This box may be improved. The IPN localization is consistent with, but reduces the area of, the Fermi RoboBA and BALROG localizations (GCN Circ. 28284 and 28286). A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB200826_T16195/IPN The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN 28293 table
GRB_name GRB200826A
GCN_number 28293
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28293 SUBJECT: GRB200826A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 620108997) DATE: 20/08/26 22:32:02 GMT FROM: Tomas Ahumada at U. of Maryland Ana Sagues Carracedo (OKC), Harsh Kumar (IITB), Tomas Ahumada (UMD), Igor Andreoni (Caltech), Shreya Anand (Caltech), Robert Stein (DESY), Michael Coughlin (UMN), Leo Singer (NASA/GSFC) on behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations We observed the localization region of the short GRB200826A (trigger 620108997) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi satellite with the Palomar 48 inch telescope equipped with the 47 square degree Zwicky Transient Facility (ZTF) camera. We obtained a series of g- and r-band images covering 185.5 square degrees beginning at 09:22:55 UT on 2020 Aug 26 (about 5 hours after the burst trigger time). This corresponds to ~77.5% of the probability enclosed in the GRB localization map (GCN 28284). Each exposure was 300s, reaching a g-band median depth of 22.3 mag and r-band median depth of 22.1 mag. The median limiting magnitude of the last 5 survey-mode nights (30 sec exposures) was g ~ 20.6 mag and r ~ 20.0 mag, limiting our capability to temporally constrain some of our faintest transients. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC (Masci et al. 2019). We queried the ZTF alert stream using Kowalski (Duev et al. 2019) and AMPEL (Nordin et al. 2019). We required at least 2 detections separated by at least 15 minutes to select against moving objects. Furthermore, we cross-matched our candidates with the Minor Planet Center to flag known asteroids, reject stellar sources (Tachibana and Miller 2018), and apply machine learning algorithms (Duev et al. 2019, Mahabal et al. 2019). We require no spatially coincident ZTF alert to be issued before the detection time of the GBM trigger. The candidates within the 95% probability contour of the GRB localization map that passed the automatic selection criteria and human vetting are presented in the table below. +----------------------------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | g-r |MJD | Notes | +----------------------------------------------------------------------------------------------------+ | ZTF20abwyple | AT2020sbi | 1.3824038 | 37.3638915 | r | 21.2 | 0.11 | 0.13 | 2459087.9109491 | (a) | | ZTF20abwyueq | AT2020sbn | 9.2615748 | 39.6340049 | r | 21.8 | 0.13 | 0.08 | 2459087.9219444 | (a) | | ZTF20abwyzdb | AT2020sbp | 9.2046817 | 43.6712369 | r | 21.7 | 0.17 | 0.4 | 2459087.9219444 | (b) | | ZTF20abwytgj | AT2020sbc | 5.7051754 | 29.8539268 | r | 22.0 | 0.19 | 0.09 | 2459087.9181366 | (a) | | ZTF20abwysgz | AT2020sbm | 8.2746333 | 30.7142518 | r | 20.2 | 0.05 | 0.1 | 2459087.9181366 | (a) | | ZTF20abwywiz | AT2020sbv | 1.4094587 | 36.2573281 | r | 21.9 | 0.21 | 0.45 | 2459087.9145486 | (b) | | ZTF20abwyrop | AT2020sbd | 359.33861 | 31.1190224 | r | 21.5 | 0.12 | 0.22 | 2459087.9145486 | (c) | | ZTF20abwyxpj | AT2020sbs | 12.411974 | 31.7868639 | r | 21.8 | 0.16 | 0.35 | 2459087.9181366 | (c)(d) | | ZTF20abwypor | AT2020sbk | 6.8956443 | 37.2409844 | r | 21.5 | 0.13 | 0.15 | 2459087.9109491 | (c) | | ZTF20abwyvrl | AT2020sbj | 2.7749043 | 37.6768649 | r | 21.9 | 0.21 | 0.34 | 2459087.9109491 | (a) | | ZTF20abwypqf | AT2020sbl | 5.1321015 | 39.4099175 | r | 21.8 | 0.21 | 0.0 | 2459087.9109491 | (a) | | ZTF20abwyrzs | AT2020sbo | 359.79701 | 32.1773094 | r | 21.6 | 0.17 | 0.09 | 2459087.9145486 | (a)(d)(e) | | ZTF20abwzabz | AT2020sbr | 12.580528 | 42.6494866 | r | 21.9 | 0.16 | 0.02 | 2459087.9219444 | (b)(e) | | ZTF20abwysmm | AT2020sbt | 11.333202 | 33.4189371 | r | 21.5 | 0.14 | 0.0 | 2459087.9181366 | (d)(e) | +----------------------------------------------------------------------------------------------------+ Notes: (a) offset from a galaxy (b) nuclear (c) hostless (d) PS1 detection at source position (e) possible point-like source underneath We checked for galaxies in the GLADE catalog (Dalya et al. 2018) around 100 arcsec of each candidate in the table above. We found crossmatches for ZTF20abwysgz, which is 25.8 arcsec or 81.7 kpc away from a GLADE galaxy, and ZTF20abwyrzs, 35.9 arcsec or 163.1 kpc offset. However, there are several ZTF sources closer in the image to both candidates, which makes an association between the ZTF candidates and GLADE galaxies improbable. In fact, many candidates (including ZTF20abwysgz and ZTF20abwyrzs) appear to be a few arcseconds offset from their possible host galaxies: name | separation | -------------+-------------- ZTF20abwyple | ~2.7 arcsec | ZTF20abwypqf | ~1.1 arcsec | ZTF20abwyple | ~2.6 arcsec | ZTF20abwyueq | ~1.9 arcsec | ZTF20abwytgj | ~2.0 arcsec | ZTF20abwysgz | ~1.6 arcsec | ZTF20abwyvrl | ~2.3 arcsec | ZTF20abwypqf | ~5.3 arcsec | ZTF20abwyrzs | ~5.0 arcsec | Follow-up observations of these candidates is encouraged. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019).
GCN 28294 table
GRB_name GRB200826A
GCN_number 28294
Detection_method Konus-Wind Det
t_trigger 4:29:55.106 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 28294 SUBJECT: Konus-Wind detection of GRB 200826A DATE: 20/08/27 13:29:13 GMT FROM: Anna Ridnaia at Ioffe Institute A. Ridnaia, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 200826A (Fermi-GBM detection: The Fermi GBM Team, GCN Circ. 28284; Mangan et al., GCN Circ. 28287; BALROG localization: Kunzweiler et al., GCN Circ. 28286; AstroSat-CZTI detection: Gupta et al., GCN Circ. 28288; AGILE detection: Pittori et al., GCN Circ. 28289; IPN triangulation: Hurley et al., GCN Circ. 28291) triggered Konus-Wind at T0=16195.106 s UT (04:29:55.106). The burst light curve shows a multipeaked pulse which starts at ~T0-0.1 s with a total duration of ~1.6 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB200826_T16195/ As observed by Konus-Wind, the burst had a fluence of 3.30(-0.42,+0.47)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.560 s, of 9.04(-2.49,+2.63)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = 1.27(-1.78,+4.03), the high-energy photon index beta = -2.32(-0.25,+0.19), the peak energy Ep = 67(-17,+31) keV (chi2 = 50/59 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN 28295 table
GRB_name GRB200826A
GCN_number 28295
Detection_method IPN Triangulation
redshift 0.7140
Circular_text TITLE: GCN CIRCULAR NUMBER: 28295 SUBJECT: GRB200826A: Zwicky Transient Facility Identifies Optical Afterglow Candidate of a Fermi Short GRB (Trigger 620108997) DATE: 20/08/27 16:42:00 GMT FROM: Tomas Ahumada at U. of Maryland Tomas Ahumada (UMD), Shreya Anand (Caltech), Robert Stein (DESY), Harsh Kumar (IITB), Ana Sagues Carracedo (OKC), Igor Andreoni (Caltech), Michael Coughlin (UMN), Leo Singer (NASA/GSFC), Mansi Kasliwal (Caltech), Daniel Perley (LJMU), Brad Cenko (NASA/GSFC), Varun Bhalerao (IITB), David Kaplan (UWM) on behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations We continued a second night of monitoring the localization region of the short GRB200826A (Fermi trigger 620108997; GCN 28284, 28287) with the Zwicky Transient Facility (first night summary in Sagues Carracedo et al. GCN 28293). Each exposure was 600s, reaching a g-band median depth of 22.3 mag and r-band median depth of 22.3 mag. IPN also triangulated this GRB (Hurley et al. GCN 28291). Our total coverage was >99% of the joint Fermi-IPN localization. We followed standard candidate vetting procedures. We identify the following compelling candidate for the optical afterglow: +-------------------------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr |MJD | +---------------+-----------+-----------+-------------+--------+-------+--------+-----------------+ | ZTF20abwysqy | AT2020scz | 6.7855741 | +34.0273043 | g | 20.86 | 0.04 | 2459087.9181366 | +---------------+-----------+-----------+-------------+--------+-------+--------+-----------------+ ZTF20abwysqy faded by >1.7 mag in 22.5 hours in the g-band. We ran forced photometry and we obtained the following light curve: +----------+--------+-------+--------+--------+ Time (Hrs) | Filter | Mag | MagErr | Limmag | +----------+--------+-------+--------+--------+ | 5.07 | g | 20.86 | 0.048 | 22.50 | | 5.53 | r | 20.70 | 0.050 | 22.28 | | 6.67 | g | 20.96 | 0.168 | 21.24 | | 27.5 | g | - | - | 22.53 | | 29.1 | r | - | - | 21.31 | | 30.9 | g | - | - | 21.21 | +----------+--------+-------+--------+--------+ ZTF20abwysqy is spatially coincident with X-ray Source 3 reported by the Neil Gehrels Swift Observatory (GCN 28290, https://www.swift.ac.uk/xrt_products/TILED_GRB00093/) with a separation of 2" from the XRT position that has an uncertainty of 2.7". It also has a faint underlying galaxy counterpart within 0.35" (Legacy Survey (LS) DR8 photometric redshift z = 0.714 +- 0.137 and LS DR8 r-mag = 22.55). We strongly encourage multi-wavelength follow-up. ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia. ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). -- Tomás Ahumada (he/his) Ph.D. Student Department of Astronomy University of Maryland, College Park NASA Goddard Space Flight Center, Code 661 B.Sc. Astronomy, Pontificia Universidad Católica de Chile
GCN 28300 table
GRB_name GRB200826A
GCN_number 28300
Detection_method Swift-XRT Other
ra 6.7847°
decl 34.0267°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28300 SUBJECT: GRB 200826A: Swift-XRT afterglow detection DATE: 20/08/28 15:55:28 GMT FROM: Boris Sbarufatti at PSU A. D'Ai (INAF-IASFPA), B. Sbarufatti (PSU), S. R. Oates (U. Birmingham), D.N. Burrows (PSU), J. D. Gropp (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and P.A. Evans (U. Leicester) report on behalf of the Swift team: Swift-XRT has performed follow-up observations of theFermi/GBM and IPN detected burst GRB 200826A (Gupta et al. GCN Circ. 28288, Hurley et al., GCN Circ. 28291) in a series of observations tiled on the sky. The total exposure time is 7.4 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 5.2 ks. The data were collected between T0+59.9 ks and T0+169.6 ks, and are entirely in Photon Counting (PC) mode. Seven uncatalogued X-ray sources are detected, of which one ("Source 3") is consistent with ZTF20abwysqy, reported by ZTF (Ahumada et al. GCN Circ. 28293 and 28295). Source 3 is fading with 3-sigma significance, and is therefore likely the GRB afterglow. Using 1504 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 = 6.78466, +34.02670 which is equivalent to: RA (J2000): 00h 27m 08.32s Dec(J2000): +34d 01' 36.1" with an uncertainty of 3.3 arcsec (radius, 90% confidence). This position is 104 arcsec from the Fermi/GBM position. The light curve can be modelled with a power-law decay with a decay index of alpha=1.3 (+0.7, -0.5). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.8 (+0.6, -0.5). The best-fitting absorption column is 2.2 (+2.5, -1.6) x 10^21 cm^-2, consistent with the Galactic value of 6.0 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 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.2 (+2.5, -1.6) x 10^21 cm^-2 Galactic foreground: 6.0 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.8 (+0.6, -0.5) The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/xrt_products/TILED_GRB00093/Source3.php. The results of the full analysis of the tiled XRT observations are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00093. The Swift/UVOT began observations of the optical counterpart ZTF20abwysqy, 140ks after the Fermi/GBM trigger (Fermi GBM Team, GCN Circ. 28284). A source consistent with ZTF20abwysqy is detected in the UVOT summed exposures. ZTF20abwysqy is consistent with XRT source 3, however no earlier UVOT photometry is avaliable since XRT source 3 is outside of the field of view for all earlier tiles. The UVOT detection is possibly explained by the underlying galaxy emission. The preliminary detection 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 140782 169578 5032 21.86 +/- 0.13 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.07 in the direction of the burst (Schlegel et al. 1998). This circular is an official product of the Swift-XRT and Swift-UVOT teams.
GCN 28301 table
GRB_name GRB200826A
GCN_number 28301
Detection_method Konus-Wind Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 28301 SUBJECT: GRB 200826A: further analysis of the Konus-Wind data and classification DATE: 20/08/28 18:29:11 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, D. Frederiks, A. Ridnaia, and A. Tsvetkova, on behalf of the Konus-Wind team, report: Following the X-ray afterglow detection (GCN 28300) and the identification of possible optical transient (GCN 28295) spatially coincident with the X-ray source, we present a further analysis of the KW detection of the short-duration, soft-spectrum, bright GRB 200826A (GCNs 28284, 28287, 28288, 28289, 28294). As observed by KW the burst duration is T50=0.286+/-0.029 s (T90 = 0.772+/-0.188 s). The position of the GRB 200826A in the hardness-duration diagram (logT50-logHR32) of 1610 KW bright GRBs (Svinkin et al., JPhCS 1400, 2, 022010, 2019) suggests that the burst comes from the long/soft GRB population. The figure showing the hardness-duration diagram is available at http://www.ioffe.ru/LEA/GRBs/GRB200826_T16195/GRB200826A_HRT50.png The contours denote the 1 and 3 sigma confidence regions for two-dimensional Gaussian distributions. The HR32 is the ratio of counts in the 200-760 keV and 50-200 keV bands accumulated during burst duration. The vertical dashed line at T50=0.7 s marks the boundary used by Svinkin et al. 2019 to distinguish between short and long KW GRBs. Assuming the redshift of an underlying galaxy z=0.714 (GCN 28295) 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 ~4.7x10^51 erg, the peak luminosity L_iso is ~1.6x10^52 erg/s, and the rest-frame peak energy of the time-integrated spectrum, Ep,i, is ~115 keV. With these values, GRB 200826A is within the 1 sigma prediction band of both 'Amati' and 'Yonetoku' relations built for 138 Type II (long/soft) GRBs with known z (Tsvetkova et al., ApJ 850 161, 2017). Meanwile, in both Eiso-Ep,z and Liso-Ep,z planes, the GRB 200826A position is inconsistent with short-hard (Type I) GRB population, see http://www.ioffe.ru/LEA/GRBs/GRB200826_T16195/GRB200826A.pdf Thus, from the analysis of the KW detection, we conclude, that, GRB 200826A may be classified as Type II (long/soft, core-collapse origin).
GCN 28302 table
GRB_name GRB200826A
GCN_number 28302
Detection_method VLA Det
ra 6.7856°
decl 34.0273°
Circular_text TITLE: GCN CIRCULAR NUMBER: 28302 SUBJECT: GRB 200826A: VLA Detection at 6 GHz DATE: 20/08/28 19:27:02 GMT FROM: Kate Alexander at Northwestern U K. D. Alexander, W. Fong, K. Paterson, and J. Rastinejad (Northwestern) report on behalf of a larger collaboration: We observed the Fermi GRB 200826A (Fermi GBM Team GCN 28284; Mangan et al. GCN 28287) at a mean frequency of 6 GHz with the Karl G. Jansky Very Large Array (VLA; Program 19B-217) beginning 2020 August 28.47 UT (2.28 days after the burst). We detect a radio source with a preliminary flux density of ~40 microJy at: RA (J2000) = 00:27:08.54 Dec (J2000) = +34:01:38.37 with an uncertainty of 0.3 arcsec in each coordinate. This position is fully consistent with the position of the optical afterglow candidate ZTF20abwysqy (Ahumada et al. GCN 28295) and the catalogued galaxy. The position is also on the outskirts of the Swift/XRT afterglow position (D'Ai et al. GCN 28300; 90% confidence). Follow-up observations are planned. We thank the VLA staff for rapidly executing these observations.
GCN 28306 table
GRB_name GRB200826A
GCN_number 28306
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 28306 SUBJECT: GRB 200826A: Kitab optical observations DATE: 20/08/29 10:22:06 GMT FROM: Alexei Pozanenko at IKI, Moscow S. Belkin (IKI), A. Zhornichenko (KIAM), A. Pozanenko (IKI), N. Pankov (HSE), E. Mazaeva (IKI), A. Volnova (IKI), Sh. Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN: We observed the field of a Fermi short GRB 200826A (Fermi GBM team, GCN 28284; Kunzweileret al., GCN 28286; Manganal., GCN 28287) with Kitab-ISON RC-36 telescope in Clear filter. In particular we cover a whole region of IPN localization (Hurley et al., GCN 28291). The optical afterglow ZTF20abwysqy/AT2020scz (Carracedo et al., GCN 28293; Ahumada et al., GCN 28295) is not detected. Preliminary photometry of the filed is following Date, UT start, t-T0, Exp., Filter, OT, Err., UL (mid, days) 2020-08-26 22:22:17 0.76626 3720 CR n/d n/d 20.2 2020-08-27 22:08:30 1.73515 5520 CR n/d n/d 20.4 The photometry is based on nearby USNO-B1.0 stars, R2 magnitudes USNO-B1.0_id R2 1238-0009330 16.37 1239-0009591 16.56
GCN 28312 table
GRB_name GRB200826A
GCN_number 28312
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 28312 SUBJECT: GRB 200826A: Lowell Discovery Telescope observations of ZTF20abwysqy DATE: 20/08/29 19:16:00 GMT FROM: Simone Dichiara at UMCP/NASA/GSFC S.Dichiara (UMD, NASA-GSFC), S.B. Cenko (NASA-GSFC), E. Troja (UMD, NASA-GSFC), P. Gatkine (UMD), J.M. Durbak (UMD), A. Kutyrev (UMD, NASA-GSFC), S. Veilleux (UMD), report on behalf of a larger collaboration: We observed at the position of the optical transient ZTF20abwysqy reported by Ahumada el al. (GCN Circ. 28287) as a possible afterglow candidate for GRB 200826A (Fermi GBM team, GCN 28284, Mangan et al., GCN Circ. 28287) and coincident with the X-ray Source 3 reported by D'Ai et al. (GCN Circ. 28300). We use the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery Telescope (LDT) at Happy Jack, AZ. Observations started on August 29, 10:04:56 UT (3.23 days after the Fermi trigger) taking 8 exposures of 180 s each with SDSS r filter. Observations were taken at an airmass of about 1 and seeing of 1.4". We detect the underlying galaxy reported by Ahumada el al. (GCN Circ. 28287) with magnitude r=22.60 +/- 0.03 AB mag. We do not find any other source at the reported position down to a 3-sigma field limit of r>24.5 AB mag. Magnitudes are calibrated against the SDSS catalog and not corrected for Galactic extinction. We thank the staff of the Lowell Discovery Telescope for assistance with these observations.
GCN 28319 table
GRB_name GRB200826A
GCN_number 28319
Detection_method Optical
redshift 0.4606
Circular_text TITLE: GCN CIRCULAR NUMBER: 28319 SUBJECT: GRB 200826A DATE: 20/08/30 07:28:22 GMT FROM: Barry Rothberg at Large Binocular Telescope Obs B. Rothberg (LBTO/George Mason University), O. Kuhn (LBTO), C. Veillet (LBTO), S. Allanson (LBTO). We observed the optical afterglow of GRB 200826A (Gupta et al. GCN Circ. 28288, Hurley et al., GCN Circ. 28291) using the Large Binocular Telescope Observatory equipped with the Multi-Object Double Spectrographs (MODS). Our spectra cover the wavelength range 0.38-1.0 microns. The observations consist of 4 exposures of 900 seconds each in three of the four available channels (MODS-1 Red, MODS-2 Blue, and MODS-2 Red). The observation mid time was 09:39 UT 28 Aug 2020. In two 60 second acquisition images taken simultaneously wiith the g-sloan and r-sloan filters we measure a magnitude of g=22.96 +/- 0.07 and r=22.15 +/- 0.07 (both ABmags). The photometry was calibrated against the DR12 catalog magnitudes of nearby stars (Alam et al. 2015, ApJS 219,12A). The acquisition images were taken at 08:52:34 and 08:54:35 UT 28 Aug 2020. The spectroscopic observations were taken at a Position Angle = 17 degrees in order to cover both GRB 200826A and a possible nearby galaxy 15" NE. The observations used a 1" wide slit and the spectra were extracted for both sources using a 1" wide aperture. We clearly detect a continuum from 0.38-0.9 microns. From the detection of multiple emission features, which we interpret as [OII], [NeIII], H-gamma, H-beta, [OIII]/4959, [OIII]/5007, we calculate a redshift of 0.7481 +/-0.0003. The nearby galaxy, 15" NE, is determined to be unrelated to GRB 200826A. From the detection of multiple emission features which we interpret as [OII]/5007, [NII]/6548, H-alpha, [NII]/6583, [SII]/6716, and [SII]/6730, we infer a redshift of 0.1730 +/- 0.0003. Additional spectroscopic observations are planned. We acknowledge and heartily thank the rest of the LBTO staff for excellent support in readying the telescope for nighttime on-sky activities during these chaotic times. B. Rothberg also acknowledges the assistance of R.T. Gatto.
GCN 28410 table
GRB_name GRB200826A
GCN_number 28410
Detection_method Fermi GBM Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28410 SUBJECT: GRB 200826A: uGMRT radio upper limit at 1.25 GHz DATE: 20/09/11 17:23:21 GMT FROM: Sonalika Purkayastha at NCRA-TIFR P. Chandra (NCRA-TIFR), S. Purkayastha (NCRA-TIFR), V. Bhalerao (IIT-B), H. Kumar (IIT-B), M. Kasliwal (IPAC) We observed the Fermi short GRB200826A (Fermi GBM Team GCN 28284; Mangan et al. GCN 28287) with the Giant Metrewave Radio Telescope (uGMRT), India, beginning 2020 September 9.53 UT (14.47 days after the burst) at a central frequency of 1.25 GHz. We report non-detection of radio afterglow from GRB200826A, with no evidence of radio emission above a 3-sigma upper limit of 48.6 microJy/beam. The final image has a resolution of 4.13 arcsec by 1.65 arcsec at a position angle of 83.10 degrees. We thank the staff of the GMRT that made these observations possible.
GCN 28727 table
GRB_name GRB200826A
GCN_number 28727
Detection_method Other
redshift 0.7481
Circular_text TITLE: GCN CIRCULAR NUMBER: 28727 SUBJECT: GRB200826A: GMOS-N detection of a supernova bump DATE: 20/10/21 18:40:54 GMT FROM: Tomas Ahumada at U. of Maryland Tomas Ahumada (UMD), Leo Singer (NASA GSFC), Harsh Kumar (IITB), and Simeon Reusch (DESY) report on behalf of the ZTF and GROWTH collaborations: We imaged position of ZTF20abwysqy/AT2020scz (Ahumada et al. GCN 28295), the afterglow of GRB 200826A (GCN 28284) with the Gemini Multi-Object Spectrograph (GMOS-N) mounted on the Gemini-North 8-meter telescope on Mauna Kea, on 2020-09-23 and 2020-10-10. Each epoch consisted of 14 r- and i- band 200s exposures. We reduced and co-added the images from each epoch using DRAGONS, a Python-based data reduction platform provided by the Gemini Observatory. We subtracted the coadded images of the two epochs using HOTPANTS. A source is detected on 2020-09-23 at the position of the afterglow with i = 23.9 AB mag and r > 23.5 AB mag. At host galaxy's redshift of z = 0.7481 (GCN 28319) and assuming Planck 2015 cosmological parameters, the absolute magnitude of the GMOS-N detection is M_i = -19.5 AB mag. At this time, a kilonova would have an absolute magnitude of M_i >~ -14.5 AB mag whereas a SN1998bw-like supernova would have an absolute magnitude of M_i ~ -19 AB mag. Since the GMOS-N detection is consistent with a supernova but not a kilonova, we conclude that GRB 200826A was powered by a collapsar rather than a neutron star merger. We thank the Gemini Observatory Director for awarding this observing time and the Gemini staff for help with planning and for executing the observations. -- Tomas Ahumada (he/him) Ph.D. Student Department of Astronomy University of Maryland, College Park NASA Goddard Space Flight Center, Code 661 B.Sc. Astronomy, Pontificia Universidad Católica de Chile
GCN 28949 table
GRB_name GRB200826A
GCN_number 28949
Detection_method Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 28949 SUBJECT: GRB 200826A: TNG and LBT constraints on a supernova bump DATE: 20/11/24 10:54:35 GMT FROM: Andrea Rossi at INAF A. Rossi (INAF-OAS), P. D'Avanzo (INAF-OAB), V. D'Elia (ASI-SSDC), A. Melandri (INAF-OAB) and E.Palazzi (INAF-OAS) on behalf of the CIBO collaboration, and B. Rothberg (LBTO/GMU), O. Kuhn, C. Veillet (LBTO) report: We searched for a supernova bump associated to ZTF20abwysqy/AT2020scz (Ahumada et al. GCN 28295), the afterglow of GRB 200826A (Fermi, GCN 28284; Ridnaia et al., GCN 28294), which energetics are consistent with being a long/soft event (Svinkin et al., GCN 28301). We obtained two series of r-sdss images with the Italian 3.6m TNG telescope equipped with DOLORES. The first set consists in a series of 13 x 240 s obtained on 2020-09-27 at a midtime 02:01 UT (~32 days after the burst). A second set of 26x200 s of exposure time each have been obtained on 2020-11-09. Another two series of r-sdss images have been obtained with the MODS double imager and spectrographs mounted on LBT. Both series consists of 13x180 sec r-band images with the MODS double imager and spectrographs mounted on LBT and otained on 2020-09-28 and 2020-11-13. Image subtraction between the two TNG observing epochs and between the two LBT/MODS observing epochs using HOTPANTS (v5.1.11) does not reveal the source found by Ahumada et al. (GCN 28727) and constrain the presence of a SN bump beyond the conservative 5 sigma limit of r>25 in both TNG and LBT first epochs. Assuming that the supernova responsible for the bump detected by Ahumada et al. is similar to SN1998bw, at the redshift of GRB 200826A z=0.748 (Rothberg et al., GCN 28319) its brightness would be r~24.8, that includes the foreground Galactic extinction on the line of sight of GRB 200826A (A_V=0.184; Schlafly & Finkbeiner 2011). Our non detection then might indicate that the supernova detected by Ahumada et al. was at least 10% faster and/or fainter than SN1998bw. At the position of the afterglow we clearly detect the host galaxy of GRB 200826A, for which we report r=23.33+-0.09 in all observations, calibrated against SDSS field stars. We acknowledge the excellent support from the TNG staff, in particular W. Boschin, and the LBTO and LBT-INAF staff, particularly A. Cardwell, F. Cusano, S. Paiano and D. Paris, in obtaining these observations.
GCN 29029 table
GRB_name GRB200826A
GCN_number 29029
Detection_method Other
redshift 0.7481
Circular_text TITLE: GCN CIRCULAR NUMBER: 29029 SUBJECT: GRB 200826A: GMOS-N detected source magnitude (Correction) DATE: 20/12/11 23:06:21 GMT FROM: Tomas Ahumada at U. of Maryland Tomas Ahumada (UMD), Harsh Kumar (IITB), Christoffer Fremling (Caltech), Leo Singer (NASA GSFC) report on behalf of the ZTF and GROWTH collaborations: Reanalysing the data used in Ahumada et al. GCN 28727, we provide a revised magnitude of the source detected in the Gemini Multi-Object Spectrograph (GMOS-N) i-band image of ZTF20abwysqy/AT2020scz (Ahumada et al. GCN 28295). We imaged the region of GRB 200826A (GCN 28284) with GMOS-N, mounted on the Gemini-North 8-meter telescope on Mauna Kea, on three nights: 2020-09-23 (2459115.9675 mjd), 2020-10-10 (2459133.8039 mjd) and 2020-11-08 (2459167.9342 mjd). Each epoch consisted of 14 r- and i- band 200s exposures. We reduced and co-added the images from each epoch using DRAGONS, a Python-based data reduction platform provided by the Gemini Observatory. We subtracted the coadded images using HOTPANTS and PyZOGY independently. We now present the revised magnitudes using a zero-point calculated using 23 stars in the field from the SDSS catalog. We apologize for any possible confusion caused by the erroneously reported photometry in GCN 28727. In the 2020-09-23 images, a source is detected at the position of the afterglow with i = 25.49 +- 0.15 mag, but not in r-band up to r > 25.6 AB mag. In the 2020-10-10 images, we do not detect a transient in either filter up to a 5-sigma limit of i > 25.4 mag and r > 25.5 mag. At the host galaxy's redshift of z = 0.7481 (GCN 28319) and assuming Planck 2015 cosmological parameters, the absolute magnitude of the GMOS-N detection is M_i = -17.9 AB mag. We thank the Gemini Observatory Director for awarding this observing time and the Gemini staff for help with planning and executing the observations. -- Tomas Ahumada (he/him) Ph.D. Student Department of Astronomy University of Maryland, College Park NASA Goddard Space Flight Center, Code 661 B.Sc. Astronomy, Pontificia Universidad Católica de Chile