//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29442 SUBJECT: GRB 210209A: Swift detection of a burst DATE: 21/02/09 21:51:50 GMT FROM: David Palmer at LANL S. Laha (GSFC/UMBC/CRESST), S. D. Barthelmy (GSFC), J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU), F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 21:39:44 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 210209A (trigger=1031636). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 328.096, +43.559 which is RA(J2000) = 21h 52m 23s Dec(J2000) = +43d 33' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a double-peaked structure with a duration of about 110 sec. The peak count rate was ~1600 counts/sec (15-350 keV), at ~5 sec after the trigger. The XRT began observing the field at 21:41:41.0 UT, 116.5 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 328.12298, 43.55745 which is equivalent to: RA(J2000) = 21h 52m 29.52s Dec(J2000) = +43d 33' 26.8" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 70 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. No spectrum from the promptly downlinked event data is yet available to determine the column density. The initial flux in the 2.5 s image was 3.98e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 126 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 100% 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 expected extinction corresponding to E(B-V) of 0.285. 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/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29443 SUBJECT: GRB 210209A: Enhanced Swift-XRT position DATE: 21/02/10 01:26:18 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 1987 s of XRT Photon Counting mode data and 4 UVOT images for GRB 210209A, 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 = 328.12225, +43.55698 which is equivalent to: RA (J2000): 21h 52m 29.34s Dec (J2000): +43d 33' 25.1" with an uncertainty of 1.5 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. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29449 SUBJECT: GRB 210209A: Swift-XRT refined Analysis DATE: 21/02/10 08:13:33 GMT FROM: Phil Evans at U of Leicester M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and S. Laha report on behalf of the Swift-XRT team: We have analysed 6.3 ks of XRT data for GRB 210209A (Laha et al. GCN Circ. 29442), from 122 s to 24.0 ks after the BAT trigger. The data comprise 139 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 29443). The late-time light curve (from T0+4.3 ks) can be modelled with a power-law decay with a decay index of alpha=0.88 (+/-0.09). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.81 (+0.07, -0.04). The best-fitting absorption column is consistent with the Galactic value of 3.7 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 1.91 (+0.07, -0.05) and a best-fitting absorption column consistent with the Galactic value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.0 x 10^-11 (5.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.67 (+0.14, -0.00) x 10^21 cm^-2 Galactic foreground: 3.7 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.91 (+0.07, -0.05) If the light curve continues to decay with a power-law decay index of 0.88, the count rate at T+24 hours will be 0.046 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.9 x 10^-12 (2.6 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/01031636. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29453 SUBJECT: GRB 210209A: Swift/UVOT Upper Limits DATE: 21/02/10 14:39:45 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (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 210209A 127 s after the BAT trigger (Laha et al., GCN Circ. 29442). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 29443) 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 127 276 147 >20.3 u_FC 285 535 246 >19.4 white 127 952 275 >20.4 v 615 4730 236 >19.1 b 540 733 39 >18.8 u 285 5225 345 >19.8 w1 664 5140 236 >19.7 m2 639 4934 236 >19.4 w2 590 4525 236 >20.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.286 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29455 SUBJECT: GRB 210209A: MITSuME Akeno optical upper limits DATE: 21/02/10 14:59:37 GMT FROM: Ryohei Hosokawa at Tokyo Institute of Technology R. Hosokawa, R. Adachi, K. L. Murata, M. Niwano, F. Ogawa, N. Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N. Kawai (TokyoTech) report on behalf of the MITSuME collaboration: We observed the field of GRB 210209A (Laha et al. GCN #29442, Evans et al. GCN #29443, Perri et al. GCN #29449, Breeveld et al. GCN #29453) with the optical three color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The observation with a series of 60 sec exposures started at 2021-02-10 08:49:41 UT(11.2 hour after the Swift BAT trigger). Since the first 17 images were taken under high airmass conditions, we stacked the images with good conditions. We did not find any new point sources within the enhanced Swift XRT circle (Evans et al. GCN #29443) in all three bands. We obtained the 5-sigma limits of the stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits ------------------------------------------------------------------------------------------------ 11.2 09:14:41 600 g'>17.2,Rc>17.6,Ic>17.1 ------------------------------------------------------------------------------------------------ T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used the PS1 catalog for flux calibration. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29458 SUBJECT: Swift GRB 210209A: Global MASTER-Net observations report DATE: 21/02/10 16:19:13 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 210209A ( S. Laha et al., GCN 29442) errorbox 66257 sec after notice time and 66326 sec after trigger time at 2021-02-10 16:05:10 UT, with upper limit up to 17.5 mag. Observations started at twilight. The observations began at zenith distance = 60 deg. The sun altitude is -11.3 deg. The galactic latitude b = -8 deg., longitude l = 92 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1543975 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 66416 | MASTER-Tavrida | C | 180 | 17.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29460 SUBJECT: GRB 210209A: BOOTES-4/MET optical upper limit DATE: 21/02/10 16:29:26 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 210209A by Swift (Laha et al. GCNC 29442), 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 (Evans et al. GCNC 29443) down to 19.8 mag in the co-added images (15x60 s, clear filer) starting at 12:13 UT on Feb 10. The non-detection is consistent with the limits reported by both Swift/UVOT (Breeveld et al. GCNC 29453) and MITSuME (Hosokawa et al. GCNC 29455). We thank the staff at Lijiang observatory for their excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29479 SUBJECT: GRB 210209A: Swift-BAT refined analysis DATE: 21/02/11 16:37:16 GMT FROM: Hans Krimm at NSF/NASA-GSFC S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), 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+800 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210209A (trigger #1031636) (Laha, et al., GCN Circ. 29442). The BAT ground-calculated position is RA, Dec = 328.097, 43.545 deg which is RA(J2000) = 21h 52m 23.3s Dec(J2000) = +43d 32' 40.4" with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment). The partial coding was 96%. The mask-weighted light curve shows a double-peaked structure running from roughly T-35 sec to T+140 seconds. The two peaks were at T+3 sec and T+65 sec. T90 (15-350 keV) is 139.4 +- 21.5 sec (estimated error including systematics). The time-averaged spectrum from T-40.34 to T+134.72 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.52 +- 0.12. The fluence in the 15-150 keV band is 2.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+2.68 sec in the 15-150 keV band is 0.6 +- 0.2 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/1031636/BA/