//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29397 SUBJECT: GRB 210205A: Swift detection of a burst DATE: 21/02/05 11:27:17 GMT FROM: Scott Barthelmy at NASA/GSFC S. Dichiara (NASA/GSFC/UMCP), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), V. D'Elia (SSDC), P. A. Evans (U Leicester), J.D. Gropp (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift Observatory Team: At 11:11:17 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210205A (trigger=1030629). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 347.257, +56.312 which is RA(J2000) = 23h 09m 02s Dec(J2000) = +56d 18' 45" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve shows a multi-peak structure with a duration of about 35 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. The XRT began observing the field at 11:13:32.2 UT, 134.7 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 347.2214, 56.2943 which is equivalent to: RA(J2000) = 23h 08m 53.13s Dec(J2000) = +56d 17' 39.4" with an uncertainty of 2.6 arcseconds (radius, 90% containment). This location is 95 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 consistent with the Galactic value of 5.15 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 138 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 47% of the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the large, but uncertain, extinction expected. Burst Advocate for this burst is S. Dichiara (dichiara AT umd.edu). 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29398 SUBJECT: GRB 210205A： GWAC-F60A optical upper limit DATE: 21/02/05 11:50:51 GMT FROM: Liping Xin at NAOC, SVOM L. P. Xin(NAOC), J. Wang(GXU), C. Gao(GXU), X. H. Han(NAOC), J. Y. Wei(NAOC), G. W. LI(NAOC), L. H. Li(NAOC), C. Wu(NAOC), X. G. Wang(GXU), E. W. Liang (GXU), R. S. Zhang(NAOC), Y. L. Qiu(NAOC), and J. S. Deng(NAOC) report: We began to observe GRB 210205A (Dichiaraet al., GCN 29397) with Xinglong GWAC-F60A telescope, China, at 11:13:26 (UT), 5th. Feb. 2021, about 129 sec after the burst. A series of R, I, and B band images were obtained. Preliminary analysis shows that no any new optical source are found in single images within the XRT errorbox (Dichiaraet al., GCN 29397). The 3 sigma upper limit is about 17.3 mag in R band at the mean time of 134 sec after the burst, calibrated to the USNO B1.0 catalog. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29399 SUBJECT: GRB 210205A: Enhanced Swift-XRT position DATE: 21/02/05 14:07:37 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 1148 s of XRT Photon Counting mode data and 4 UVOT images for GRB 210205A, 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 = 347.21907, +56.29649 which is equivalent to: RA (J2000): 23h 08m 52.58s Dec (J2000): +56d 17' 47.4" with an uncertainty of 2.0 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29400 SUBJECT: GRB 210205A: BOOTES-4/MET optical upper limit DATE: 21/02/05 15:11:13 GMT FROM: Youdong HU at IAA-CSIC Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report: Following the detection of GRB 210205A by Swift (Dichiara et al. GCNC 29397), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) started to gather images after the twilight as soon as it was possible. No new source is detected within the Swift/XRT enhanced position (Osborne et al. GCNC 29399) down to 18.3 mag in the co-added z-band images (7x120 s) starting at 12:22 UT. The non-detection is consistent with the limits reported by both Swift/UVOT (Dichiara et al. GCNC 29397) and GWAC-F60A (Xin et al. GCNC 29398). We thank the staff at Lijiang observatory for their excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29401 SUBJECT: GRB 210205A: Nanshan/NEXT optical upper limit DATE: 21/02/05 16:20:03 GMT FROM: Dong Xu at NAOC/CAS S.Y. Fu (NAOC), Z.P. Zhu (HUST,NAOC), X. Liu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report: We observed the field of GRB 210205A (Dichiara et al., GCN 29397) using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We obtained 3x40 s, 4x60 s, 12x90 s frames in the Sloan r-band, starting at 12:09:46 UT on 2021-02-05, i.e., 58.5 min after the BAT trigger. No optical source is detected in our stacked image at the enhanced XRT position (Osborne et al., GCN 29399), down to a limiting magnitude of r~19.9, calibrated with the nearby PanSTARRS field. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29402 SUBJECT: Swift GRB 210205A: Global MASTER-Net observations report DATE: 21/02/05 17:40:09 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-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210205A ( S. Dichiara et al., GCN 29397) errorbox 21040 sec after notice time and 21101 sec after trigger time at 2021-02-05 17:02:58 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 49 deg. The sun altitude is -22.7 deg. The galactic latitude b = -4 deg., longitude l = 109 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1540460 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 21191 | MASTER-Tavrida | C | 180 | 14.5 | 21191 | MASTER-Tavrida | C | 180 | 14.8 | 22639 | MASTER-Tavrida | C | 180 | 17.4 | 22639 | MASTER-Tavrida | C | 180 | 17.1 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29403 SUBJECT: GRB 210205A: Swift/UVOT Upper Limits DATE: 21/02/05 18:16:08 GMT FROM: Alexander Belles at PSU/Swift A. Belles (PSU) and S. Dichiara (NASA/GSFC/UMCP) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210205A 139 s after the BAT trigger (Dichiara et al., GCN Circ. 29397). No optical afterglow consistent with the XRT position (Osborne et al. GCN Circ. 29399) 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 white_FC 139 289 147 >20.5 white 139 4057 344 >20.6 v 4268 4468 197 >19.4 b 3652 5159 265 >20.1 u 297 5084 255 >19.7 w1 4678 4878 197 >19.9 m2 4473 4673 197 >20.8 w2 4063 4263 197 >19.3 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.716 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29406 SUBJECT: GRB 210205A: MITSuME Ishigaki optical observation DATE: 21/02/05 22:01:18 GMT FROM: Takashi Horiuchi at Ishigakijima Astronomical Obs Takashi Horiuchi, Hidekazu Hanayama (NAOJ), Katsuhiro L. Murata, Yoichi Yatsu, Nobuyuki Kawai (Tokyo Tech) report on behalf of the MITSuME collaboration: We observed the field of GRB 210205A (Dichiara et al., GCN 29397) with the optical three color (g', Rc, and Ic) CCD cameras attached to the 105 cm Murikabushi telescope of Ishigakijima Astronomical Observatory, Okinawa, Japan. The observation with a series of 60 sec exposures started on 2021-02−05 11:22:29 UT (2 min after Swift BAT trigger). We stacked the 25 images and did not find any new point sources other than the USNO-B1.0 sources from the stacked images. We obtained the SN = 10 limits as follows. T0+[min] MID-UT T-EXP[sec] SN=10 limits ------------------------------------------------------------------------------------------------ 2 2021-02-05T11:36:37 1500 g' > 18.7, Rc > 19.0, Ic > 17.8 ------------------------------------------------------------------------------------------------ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29407 SUBJECT: GRB 210205A: Swift-XRT refined Analysis DATE: 21/02/05 22:52:15 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU) and S. Dichiara report on behalf of the Swift-XRT team: We have analysed 6.1 ks of XRT data for GRB 210205A (Dichiara et al. GCN Circ. 29397), from 143 s to 28.3 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Osborne et al. (GCN Circ. 29399). The light curve can be modelled with a power-law decay with a decay index of alpha=1.10 (+0.10, -0.11). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.1 (+0.5, -0.4). The best-fitting absorption column is 8.0 (+4.0, -2.8) x 10^21 cm^-2, consistent with the Galactic value of 5.1 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.3 x 10^-11 (8.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 8.0 (+4.0, -2.8) x 10^21 cm^-2 Galactic foreground: 5.1 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 2.1 (+0.5, -0.4) If the light curve continues to decay with a power-law decay index of 1.10, the count rate at T+24 hours will be 1.6 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 6.8 x 10^-14 (1.3 x 10^-13) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01030629. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29409 SUBJECT: GRB 210205A: Swift-BAT refined analysis DATE: 21/02/06 03:36:38 GMT FROM: Amy Lien at GSFC S. D. Barthelmy (GSFC), J. R. Cummings (CPI), S. Dichiara (NASA/GSFC/UMCP), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210205A (trigger #1030629) (Dichiara et al., GCN Circ. 29397). The BAT ground-calculated position is RA, Dec = 347.264, 56.311 deg which is RA(J2000) = 23h 09m 03.3s Dec(J2000) = +56d 18' 41.2" with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment). The partial coding was 18%. The mask-weighted light curve shows a multi-peaked structure that starts at ~ T-7 s and ends at ~T+20 s. The main peak in the structure occurs at ~T+6 s. T90 (15-350 keV) is 22.70 +- 4.18 sec (estimated error including systematics). The time-averaged spectrum from T-7.35 to T+20.07 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.27 +- 0.31. The fluence in the 15-150 keV band is 8.7 +- 1.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+5.98 sec in the 15-150 keV band is 1.6 +- 0.5 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/1030629/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29526 SUBJECT: GRB 210205A: observations with the 3.6m DOT, a potential dark burst? DATE: 21/02/18 09:07:31 GMT FROM: Rahul Gupta at ARIES, India S. B. Pandey, R. Gupta, A. Kumar, Dimple, A. Ghosh, A. Aryan, and K. Misra (ARIES) on behalf of a larger collaboration report: GRB 210205A was detected by the Swift Burst Alert Telescope (BAT) at 11:11:17 UT on 5th Feb 2021 (GCN 29397). The prompt emission mask-weighted BAT light curve consists of a multi-peaked structure with a T90 duration of 22.70 +- 4.18 sec in 15-350 keV energy range (GCN 29409). We compare the reported value of BAT fluence and peak photon flux for this GRB (GCN 29409) with all the BAT detected samples, we find this burst is positioned nearly the middle of this distribution. The Swift XRT detected an X-ray afterglow ~ 134.7 sec after the BAT trigger (GCN 29397). The X-ray light curve could be best described with a simple power-law model with a temporal index of 1.100 (+0.092, -0.101) and the afterglow is fainter (0.016 x 10^-11 erg/cm2/s, at 11-hour post burst) than typical X-ray afterglows. As no red-shift has been reported for this source, we modeled the time-averaged XRT spectrum (T0 + 143 to 39716 s) considering red-shift = 2, roughly average red-shift value for long GRBs. The spectrum could be modeled using an absorption power-law with following spectral parameters: NH_host= 5.34 (-4.58,+6.18) * 10^{22} cm^{-2} and \beta_x= 1.11 (-0.37,+0.40). Considering the adiabatic deceleration without energy injection, closure relations indicate that the X-ray afterglow could be best described with \nu > \nu_c spectral regime for ISM as well as WIND medium for the electron energy index p ~ 2.22. Many optical telescopes searched for the optical afterglow but no counterpart associated with this burst was detected to deeper limits at early epochs(GCN 29397, 29398, 29400, 29401, 29402, 29403, and 29406). So, we performed the search for the optical counterpart of this XRT localized GRB 210205A (GCN 29399) using the 4Kx4K CCD Imager (Pandey et al. 2017, arXiv:1711.05422v1) mounted at the axial port of the 3.6m Devasthal Optical Telescope (DOT) of ARIES Nainital. Multiple frames having exposure times of 300s each were taken in R and I filters. We do not find any evidence of an afterglow candidate inside the XRT error circle, consistent with other non-detections. We constrain the following 3-sigma upper limits. T-T0 (days) Exp. (s) Filter OT UL Telescope 1.0921 2*300 R NA 22.8 3.6m DOT 1.1033 2*300 I NA 22.6 3.6m DOT The limiting magnitudes quoted are not corrected for the Galactic and Host extinction in the direction of the burst. Considering no spectral break between X-ray and optical frequencies, we extrapolated the X-ray spectral index towards optical frequencies. We found that using reported limiting values at optical (Galactic extinction corrected) roughly lie below the extrapolated X-ray power-law slope, suggesting that this burst could be a potential dark GRB candidate either highly extinguished or as a high redshift event. 3.6m Devasthal Optical Telescope (DOT) is a recently commissioned facility in the Northern Himalayan region of India (long:79 41 04E, lat:29 21 40N, alt:2540m) owned and operated by the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital (https://www.aries.res.in). Authors of this GCN circular thankfully acknowledge consistent support from the staff members to run and maintain the 3.6m DOT. This circular may be cited.