GRB200228B

This page lists all entries on GRB200228B in GRBweb

Summary Fermi GBM IPN Swift GCN 27253 GCN 27254 GCN 27256 GCN 27263 GCN 27266 GCN 27267 GCN 27268 GCN 27269 GCN 27270 GCN 27271 GCN 27272 GCN 27273 GCN 27274 GCN 27276 GCN 27318

Summary table
Variable Value Source
GRB_name_Fermi GRB200228469
T0 11:14:40.566 UTC Fermi_GBM
ra 252.0464° Swift
decl 16.9852° Swift
pos_error 4.53e-04° Swift
T90 14.08 s Fermi_GBM
T90_error 1.28 s Fermi_GBM
T90_start 11:14:40.566 UTC Fermi_GBM
fluence 6.92e-07 erg/cm² Fermi_GBM
fluence_error 2.48e-08 erg/cm² Fermi_GBM
T100 14.08 s
GBM_located False
mjd 58907.468525069446 Fermi_GBM
Fermi GBM table
GRB_name_Fermi GRB200228469
trigger_name bn200228469
ra 252.0471°
decl 16.9850°
pos_error 9.50e+00°
datum 2020-02-28
t_trigger 11:14:43.894 UTC
T90 14.08 s
T90_error 1.28 s
T90_start 11:14:40.566 UTC
fluence 6.92e-07 erg/cm²
fluence_error 2.48e-08 erg/cm²
flux_1024 1.41e+00 erg/cm²/s
flux_1024_error 1.83e-01 erg/cm²/s
flux_1024_time -3.20e-01 erg/cm²/s
flux_64 4.22e+00 erg/cm²/s
flux_64_error 1.12e+00 erg/cm²/s
IPN table
GRB_name GRB200228B
ra 252.0250°
decl 16.9667°
pos_error 5.00e-02°
Swift table
GRB_name GRB200228B
t_trigger 11:14:41 UTC
ra 252.0464°
decl 16.9852°
pos_error 4.53e-04°
GCN 27253 table
GRB_name GRB200228B
GCN_number 27253
Detection_method Fermi GBM final loc
t_trigger 11:14:43 UTC
ra 258.4000°
decl 9.6000°
Circular_text TITLE: GCN CIRCULAR NUMBER: 27253 SUBJECT: GRB 200228B: Fermi GBM Final Real-time Localization DATE: 20/02/28 11:25:00 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM The Fermi GBM team reports the detection of a likely LONG GRB At 11:14:43 UT on 28 Feb 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 200228B (trigger 604581288.894278 / 200228469). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 258.4, Dec = 9.6 (J2000 degrees, equivalent to J2000 17h 13m, 9d 35'), with a statistical uncertainty of 16.7 degrees. The angle from the Fermi LAT boresight is 62.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200228469/quicklook/glg_skymap_all_bn200228469.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/bn200228469/quicklook/glg_healpix_all_bn200228469.fit The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn200228469/quicklook/glg_lc_medres34_bn200228469.gif
GCN 27254 table
GRB_name GRB200228B
GCN_number 27254
Detection_method Swift Det
t_trigger 11:14:41 UTC
ra 252.0260°
decl 16.9600°
Circular_text TITLE: GCN CIRCULAR NUMBER: 27254 SUBJECT: GRB 200228B: Swift detection of a burst DATE: 20/02/28 11:27:30 GMT FROM: Scott Barthelmy at NASA/GSFC S. Laha (GSFC/UMBC/CRESST), S. D. Barthelmy (GSFC), P. A. Evans (U Leicester), C. Gronwall (PSU), J.D. Gropp (PSU) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team: At 11:14:41 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 200228B (trigger=958733). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 252.026, +16.960, which is RA(J2000) = 16h 48m 06s Dec(J2000) = +16d 57' 37" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a single peak with a duration of about 25 sec. The peak count rate was ~2000 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 11:16:56.8 UT, 135.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 252.04730, 16.98505 which is equivalent to: RA(J2000) = 16h 48m 11.35s Dec(J2000) = +16d 59' 06.2" with an uncertainty of 5.7 arcseconds (radius, 90% containment). This location is 116 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. No spectrum from the promptly downlinked event data is yet available to determine the column density. UVOT data are unavailable at this time. Burst Advocate for this burst is S. Laha (sib.laha AT gmail.com). 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 27256 table
GRB_name GRB200228B
GCN_number 27256
Detection_method Swift-XRT Det
ra 252.0464°
decl 16.9852°
Circular_text TITLE: GCN CIRCULAR NUMBER: 27256 SUBJECT: GRB 200228B: Enhanced Swift-XRT position DATE: 20/02/28 14:16:49 GMT FROM: Phil Evans at U of Leicester P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 87 s of XRT Photon Counting mode data and 1 UVOT images for GRB 200228B, 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 = 252.04640, +16.98523 which is equivalent to: RA (J2000): 16h 48m 11.14s Dec (J2000): +16d 59' 06.8" with an uncertainty of 3.5 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 27263 table
GRB_name GRB200228B
GCN_number 27263
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 27263 SUBJECT: GRB 200228B: KAIT Optical Upper Limit DATE: 20/02/28 19:09:52 GMT FROM: Weikang Zheng at UC Berkeley WeiKang Zheng and Alexei V. Filippenko (UC Berkeley) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, responded to Swift GRB 200228B (Laha et al., GCN 27254) starting at 11:21:06 UT, 395 s after the burst. Observations were performed with an automatic sequence in the clear (roughly R), V, and I filters, and the exposure time was 20 s per image. We do not detect any optical afterglow candidate within the enhanced XRT position error circle (Evans et al., GCN 27256), neither in single image, nor in the co-add images. The typical limiting magnitude of our single clear image is about 18.0 mag calibrated to the Pan-STARRS1 catalog.
GCN 27266 table
GRB_name GRB200228B
GCN_number 27266
Detection_method Fermi GBM Det
t_trigger 11:14:43.890 UTC
Circular_text TITLE: GCN CIRCULAR NUMBER: 27266 SUBJECT: GRB 200228B: Fermi GBM observation DATE: 20/02/28 20:54:53 GMT FROM: Joshua Wood at MSFC/Fermi-GBM E. Bissaldi (Politecnico and INFN Bari), C. Meegan (UAH), and J. Wood (NASA/MSFC) report on behalf of the Fermi GBM Team: "At 11:14:43.89 UT on 28 February 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB 200228B (trigger 604581288 / 200228469), which was also detected by the Swift/BAT (Laha et al. 2020, GCN 27254). The GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight at the GBM trigger time is 59 degrees. The GBM light curve shows a single emission episode with a duration (T90) of about 14 s (50-300 keV). The time-averaged spectrum from T0-4 s to T0+11 s is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is -1.17 +/- 0.33 and the cutoff energy, parameterized as Epeak, is 76 +/- 16 keV. The event fluence (10-1000 keV) in this time interval is (1.30 +/- 0.18)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.3 s in the 10-1000 keV band is 1.4 +/- 0.2 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 27267 table
GRB_name GRB200228B
GCN_number 27267
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 27267 SUBJECT: GRB 200228B: RATIR Optical Observations DATE: 20/02/28 21:07:26 GMT FROM: Emma Margarita Pereyra Talamantes at IA-UNAM Ensenada Margarita Pereyra (UNAM), Nat Butler (ASU), Alan M. Watson (UNAM), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 200228B (Laha et al., GCN Circ. 27254) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2020/02 28.48 to 2020/02 28.53 UTC (0.27 to 1.52 hours after the BAT trigger), obtaining a total of 0.62 hours exposure in the r and i bands. For a source within the Swift-XRT enhanced error circle (Evans et al., GCN Circ. 27256), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 21.48 i > 21.40 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir. -- *Dr. Margarita Pereyra * *FFTF, Schlumberger Foundation Alumnae* ---------------------------------------------------------------------------------------------------------------- *Catedrático Conacyt* *Instituto de Astronomía de la UNAM,* *Km. 107 Carretera Tijua**na-Ensenada, * *Ensenada Baja California, México. C.P. 22860* Oficina: 405 Skype: margarita-pereyra
GCN 27268 table
GRB_name GRB200228B
GCN_number 27268
Detection_method Swift-UVOT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 27268 SUBJECT: GRB 200228B: Swift/UVOT Upper Limits DATE: 20/02/28 22:23:32 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and S. L. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 200228B 137 s after the BAT trigger (Laha et al., GCN Circ. 27254). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. #27256 is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 137 387 246 >20.1 v 4992 10685 676 >20.1 b 4580 6012 393 >20.6 u 137 5807 442 >20.4 w1 5402 5602 197 >19.5 m2 5197 5396 197 >19.8 w2 4786 6218 393 >19.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.092 in the direction of the burst (Schlegel et al. 1998).
GCN 27269 table
GRB_name GRB200228B
GCN_number 27269
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 27269 SUBJECT: Swift GRB 200228B: Global MASTER-Net observations report DATE: 20/02/29 00:12:08 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), H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE), 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 200228B ( S. Laha et al., GCN 27254) errorbox 45652 sec after trigger time at 2020-02-28 23:55:33 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 51 deg. The sun altitude is -41.7 deg. The galactic latitude b = 34 deg., longitude l = 36 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1300236 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 45742 | MASTER-Kislovodsk | C | 180 | 18.4 | 45742 | MASTER-Kislovodsk | C | 180 | 18.6 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited.
GCN 27270 table
GRB_name GRB200228B
GCN_number 27270
Detection_method Swift-XRT Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 27270 SUBJECT: GRB 200228B: Swift-XRT refined Analysis DATE: 20/02/29 05:26:50 GMT FROM: Kim Page at U.of Leicester K.L. Page (U. Leicester) and S. Laha (GSFC/UMBC/CRESST) report on behalf of the Swift-XRT team: We have analysed 4.6 ks of XRT data for GRB 200228B (Laha et al. GCN Circ. 27254), from 143 s to 18.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 27256). The light curve can be modelled with a power-law decay with a decay index of alpha=0.65 (+0.10, -0.12). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 3.0 (+0.8, -0.7). The best-fitting absorption column is 1.6 (+0.8, -0.6) x 10^22 cm^-2, in excess of the Galactic value of 6.4 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 (2.3 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.6 (+0.8, -0.6) x 10^22 cm^-2 Galactic foreground: 6.4 x 10^20 cm^-2 Excess significance: 4.3 sigma Photon index: 3.0 (+0.8, -0.7) If the light curve continues to decay with a power-law decay index of 0.65, the count rate at T+24 hours will be 4.9 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x 10^-13 (1.1 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/00958733. This circular is an official product of the Swift-XRT team.
GCN 27271 table
GRB_name GRB200228B
GCN_number 27271
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 27271 SUBJECT: GRB 200228B: Liverpool Telescope imaging DATE: 20/02/29 13:57:42 GMT FROM: Daniel Perley at Liverpool JMU D. A. Perley and A. M. Cockeram (LJMU) report: On 2020-02-29 UT we obtained imaging of the position of GRB 200228B (Fermi GBM team, GCN 27253; Laha et al., GCN 27254) using the 2m robotic Liverpool Telescope. We collected 3x120s of exposure time in each of the the i-band and z-band filters, beginning at 05:53:44 and ending at 06:07:33 (UTC). No unambiguous source is detected in either stacked image, although a possible marginal (~3-sigma) source is present close to the center of the latest enhanced XRT error circle in the z-band image. Photometry of this potential source (calibrating relative to PS1 catalog stars in the field) gives an approximate magnitude of z = 21.7 +/- 0.3. 3-sigma limits are: dt(days) filter mag 0.7794 i >22.6 0.7844 z >21.7 We additionally note that Pan-STARRS1 imaging of the field shows several faint, probably-resolved sources close to the survey detection limit inside or closely outside the XRT error circle, which could represent a possible host galaxy or host group. Imaging of the field is available at: http://www.astro.ljmu.ac.uk/~aridperl/grb/200228b/GRB200228B_LT_PS1.png (The enhanced XRT error circle is shown in cyan with the marginal "detection" highlighted in red.) DisclaimerNone
GCN 27272 table
GRB_name GRB200228B
GCN_number 27272
Detection_method Swift-BAT Det
Circular_text TITLE: GCN CIRCULAR NUMBER: 27272 SUBJECT: GRB 200228B: RATIR Optical Observations DATE: 20/02/29 15:51:14 GMT FROM: Rosa Leticia Becerra Godinez at Inst. de Astronoma,UNAM Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H. Lee (UNAM), Michael G. Richer (UNAM), Ori Fox (STScI), J. Xavier Prochaska (UCSC), Josh Bloom (UCB), Antonino Cucchiara (UVI), Eleonora Troja (GSFC), Owen Littlejohns (ASU), Enrico Ramirez-Ruiz (UCSC), Jesús González (UNAM), Carlos Román-Zúñiga (UNAM), Harvey Moseley (GSFC), John Capone (UMD), V. Zach Golkhou (U. Wash.), and Vicki Toy (UMD) report: We observed the field of GRB 200228B (Fermi GBM team, GCN 27253, Laha, et. al. GCN 27254) with the Reionization and Transients Infrared Camera (RATIR; www.ratir.org) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2020/02 29.36 to 2020/02 29.53 UTC (21.40 to 25.38 hours after the BAT trigger), obtaining a total of 2.27 hours exposure in the r and i bands. For a source within the Swift-XRT enhanced error circle (Evans et al., GCN Circ. 27256), in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 23.19 i > 23.11 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB. We thank the staff of the Observatorio Astronómico Nacional in San Pedro Mártir.
GCN 27273 table
GRB_name GRB200228B
GCN_number 27273
Detection_method Swift-BAT Det
ra 252.0070°
decl 16.9640°
Circular_text TITLE: GCN CIRCULAR NUMBER: 27273 SUBJECT: GRB 200228B: Swift-BAT refined analysis DATE: 20/02/29 23:49:33 GMT FROM: Amy Lien at GSFC C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+297 sec from the recent telemetry downlink, we report further analysis of BAT GRB 200228B (trigger #958733) (Laha et al., GCN Circ. 27254). The BAT ground-calculated position is RA, Dec = 252.007, 16.964 deg which is RA(J2000) = 16h 48m 01.8s Dec(J2000) = +16d 57' 50.3" with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 31%. The mask-weighted light curve shows a weak pulse that starts at ~T-1 s, peaks at ~T+2 s, and ends at ~T+7 s. T90 (15-350 keV) is 7.37 +- 1.58 sec (estimated error including systematics). The time-averaged spectrum from T-0.84 to T+6.97 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.27 +- 0.36. The fluence in the 15-150 keV band is 3.0 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+1.32 sec in the 15-150 keV band is 1.0 +- 0.4 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at http://gcn.gsfc.nasa.gov/notices_s/958733/BA/
GCN 27274 table
GRB_name GRB200228B
GCN_number 27274
Detection_method Swift Other
Circular_text TITLE: GCN CIRCULAR NUMBER: 27274 SUBJECT: GRB 200228B: LCO Optical Upper Limit DATE: 20/03/01 11:29:15 GMT FROM: Robert Strausbaugh at U. of the Virgin Islands R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration: We observed Swift GRB 200228B (Laha et al., GCN 27254) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 29, from 10:52 to 11:42 UT (corresponding to 23.4 to 24.5 hours after the GRB trigger time) with the Bessel I and R filters. We performed a series of 10x120s exposures in I and R. We do not detect any uncatalouged sources in the individual frames (nor in stacked images) in the Swift error region. Using the USNO-B.1 catalog as reference, we obtain the following 3-sigma upper limits in stacked images: R > 22.08 I > 20.77 R.S. is funded by NSF AST grant #1831682
GCN 27276 table
GRB_name GRB200228B
GCN_number 27276
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 27276 SUBJECT: GRB 200228B: Mondy, TSHAO, AbAO and CrAO optical observations, afterglow candidate DATE: 20/03/01 15:21:19 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), S. Belkin (IKI), E. Klunko (ISTP), A. Kusakin (FAPHI), I. Reva (FAPHI), V. Rumyantsev (CrAO), R. Ya. Inasaridze (AbAO), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 200228B (Laha et al., GCN 27254; Fermi GBM Team, GCN 27253) with AZT-33IK 1.5-m telescope of Sayan observatory (Mondy) starting on Feb. 28 (UT) 19:24:43. We detected an optical object near the enhanced XRT position of the XRT afterglow (Evans et al., GCN 27256). The object is absent in the Pan-STARRS DR1 catalog. The coordinates of the object are (J2000) 16:48:10.88 +16:59:04.5 with uncertainty of 0.5 arcsec in both coordinates. Next we observed the filed with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on Feb. 28 (UT) 23:08:56, Abastumani starting on Feb. 29 (UT) 01:38:45, Tien Shan Astronomical Observatory starting on Feb. 29 (UT) 23:08:56, and CrAO starting on Mar. 01 (UT) 00:58:28. Preliminary photometry of the object and the field is following. Date UT start t-T0 Filter Exp. OT Err UL(3sigma) telescope (mid, days) (s) 2020-02-28 19:24:43 0.351 R 15*120 21.8 0.3 21.7 AZT-33IK 2020-02-28 23:08:56 0.516 R 3480 n/d n/d 22.3 Z-1000 2020-02-29 01:38:45 0.616 R 46*60 n/d n/d 21.8 AS-32 2020-02-29 22:22:37 n/a R 5040 n/a n/a n/a Z-1000 2020-03-01 00:58:28 1.594 R 31*120 22.05 0.09 23.8 ZTSh Photometry is based on the USNO-B2.0 nearby stars. USNO-B1.0 R2 1069-0297786 18.42 1069-0297719 18.25 1069-0297797 14.78 The finding chart is available at http://193.232.11.154/GRB200228B/GRB200228B_AZT33IK_Z1000_ZTSh_FC.png (or http://grb.iki.rssi.ru/GRB200228B/GRB200228B_AZT33IK_Z1000_ZTSh_FC.png ). We suggest this object is a candidate in the afterglow of GRB 200228B after at least two epoch detections (see above), possible variability and absence of the bright object (R ~ 22) in the Pan-STARRS DR1. We did not detect any object at the position of NIR- candidate (Perley and Cockeram, GCN 27271).
GCN 27318 table
GRB_name GRB200228B
GCN_number 27318
Detection_method Optical
Circular_text TITLE: GCN CIRCULAR NUMBER: 27318 SUBJECT: GRB 200228B: continued optical observations DATE: 20/03/05 18:07:39 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Pozanenko (IKI), S. Belkin (IKI), R. Ya. Inasaridze (AbAO), E. Klunko (ISTP), A. Kusakin (FAPHI), I. Reva (FAPHI), V. Rumyantsev (CrAO), E. Mazaeva (IKI), A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We continue observations of the OT (Pozanenko et al., GCN 27276) associated with GRB 200228B (Laha et al., GCN 27254; Fermi GBM Team, GCN 27253) with AZT-33IK 1.5-m telescope of Sayan observatory (Mondy) and AS-32 telescope of Abastumani Astrophysical observatory. The OT is well observable (see photometry below in the table) and current XRT position ( https://www.swift.ac.uk/xrt_positions/00958733/ ) coincides with position of the OT. Preliminary photometry of the object following. Date UT start t-T0 Filter Exp. OT Err UL(3sigma) telescope (mid, days) (s) 2020-03-03 01:36:36 3.6186 R 58*60 21.65 0.13 22.6 AS-32 2020-03-03 21:03:33 4.4228 R 20*120 22.2 0.4 22.0 AZT-33IK 2020-03-04 23:44:59 5.5488 R 80*60 21.93 0.17 22.6 AS-32 Photometry is based on the USNO-B2.0 nearby stars used in previous observations (GCN 27276). The light curve in R-filter is available at http://grb.rssi.ru/GRB200228B/GRB200228B_lc_2.png We urge on spectroscopic and multicolor photometry to classify the OT.