//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29970 SUBJECT: GRB 210509A: Swift detection of a burst DATE: 21/05/09 14:45:48 GMT FROM: David Palmer at LANL K. L. Page (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU), F. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift Observatory Team: At 14:32:20 UT, the Swift Burst Alert Telescope (BAT) triggered and located a GRB 210509A (trigger= 1047531). Swift did not slew immediately due to an observing constraint. The BAT on-board calculated location is RA, Dec 350.352, +6.675 which is RA(J2000) = 23h 21m 25s Dec(J2000) = +06d 40' 31" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). Due to telemetry limitations, no further BAT data will be available until the ground-station pass data has been processed. Due to an observing constraint, Swift will not slew until T0+50 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29971 SUBJECT: GRB 210509A: Swift-XRT observations DATE: 21/05/09 16:06:58 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU), M. Perri (SSDC & INAF-OAR) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 210509A at 15:45:53.0 UT, 4412.6 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 350.37430, 6.67134 which is equivalent to: RA(J2000) = 23h 21m 29.83s Dec(J2000) = +06d 40' 16.8" with an uncertainty of 4.4 arcseconds (radius, 90% containment). This location is 80 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 7.11 x 10^20 cm^-2 (Willingale et al. 2013). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29972 SUBJECT: GRB 210509A: BOOTES-4/MET optical upper limit DATE: 21/05/09 22:07:09 GMT FROM: Youdong HU at IAA-CSIC T.-R. Sun, 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 210509A by Swift (Page et al. GCNC 29970), we triggered the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) starting on May 9 at 19:32 UT (~5 hr after trigger) with non-optimal conditions (passing clouds and the target being at high airmass). No optical source is detected at the position reported by Swift-XRT (Evans et al. GCNC 29971) down to 17.2 mag in the co-added image (clear filter). Additional observations are ongoing. We thank the staff at Lijiang observatory for their excellent support. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29973 SUBJECT: GRB 210509A: Enhanced Swift-XRT position DATE: 21/05/10 01:13:40 GMT FROM: Phil Evans at U of Leicester M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1722 s of XRT Photon Counting mode data and 5 UVOT images for GRB 210509A, 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 = 350.37564, +6.67126 which is equivalent to: RA (J2000): 23h 21m 30.15s Dec (J2000): +06d 40' 16.5" with an uncertainty of 2.5 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: 29974 SUBJECT: Swift GRB 210509A: Global MASTER-Net observations report DATE: 21/05/10 02:23:02 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-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210509A ( K. L. Page et al., GCN 29970) errorbox 41751 sec after notice time and 41820 sec after trigger time at 2021-05-10 02:09:20 UT, with upper limit up to 16.0 mag. The observations began at zenith distance = 77 deg. The sun altitude is -39.8 deg. The galactic latitude b = -50 deg., longitude l = 88 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=1610042 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 41910 | MASTER-SAAO | C | 180 | 16.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29975 SUBJECT: GRB 210509A: Swift-BAT refined analysis DATE: 21/05/10 04:33:00 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC), K. L. Page (U Leicester), 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-60 to T+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 210509A (trigger #1047531) (Page et al., GCN Circ. 29970). The BAT ground-calculated position is RA, Dec = 350.363, 6.650 deg which is RA(J2000) = 23h 21m 27.2s Dec(J2000) = +06d 39' 01.1" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 95%. The mask-weighted light curve shows several overlapping pulses that start at ~T-2 s and end at ~T+8 s. The burst went out of the BAT FOV at ~T+77 s. T90 (15-350 keV) is 8.22 +- 0.75 sec (estimated error including systematics). The time-averaged spectrum from T-1.65 to T+7.63 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 0.76 +- 1.00, and Epeak of 33.0 +- 8.3 keV (chi squared 70.16 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 3.1 +- 0.4 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+3.24 sec in the 15-150 keV band is 1.2 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index of 2.18 +- 0.17 (chi squared 78.23 for 57 d.o.f.). 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/1047531/BA/ //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29977 SUBJECT: GRB 210509A: Swift-XRT refined Analysis DATE: 21/05/10 08:38:51 GMT FROM: Phil Evans at U of Leicester J.A. Kennea (PSU), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU) and K.L. Page report on behalf of the Swift-XRT team: We have analysed 7.2 ks of XRT data for GRB 210509A (Page et al. GCN Circ. 29970), from 3.2 ks to 56.6 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Goad et al. (GCN Circ. 29973). The light curve can be modelled with a power-law decay with a decay index of alpha=1.11 (+0.20, -0.17). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.63 (+0.36, -0.16). The best-fitting absorption column is consistent with the Galactic value of 7.1 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 4.0 x 10^-11 (4.4 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 7.1 (+/-8.9) x 10^20 cm^-2 Galactic foreground: 7.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.63 (+0.36, -0.16) If the light curve continues to decay with a power-law decay index of 1.11, the count rate at T+24 hours will be 2.2 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.7 x 10^-14 (9.6 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01047531. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29978 SUBJECT: GRB 210509A: Swift/UVOT Upper Limits DATE: 21/05/10 10:10:56 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 210509A 3202 s after the BAT trigger (Page et al., GCN Circ. 29970). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 29971) 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 3202 3352 147 >20.8 white 3202 4585 344 >21.0 v 3358 4934 332 >19.0 b 4180 4380 197 >19.5 u 3974 4174 197 >19.6 w1 3769 3969 197 >19.5 m2 3563 3763 197 >20.3 w2 4592 4792 197 >19.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.074 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 29979 SUBJECT: GRB 210509A: RATIR Optical and NIR Upper Limits DATE: 21/05/10 14:11:26 GMT FROM: Alan M Watson at 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 210509A (Page et al., GCN Circ. 29970) with the Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson Telescope at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir from 2021/05 10.47 to 2021/05 10.48 UTC (19.34 to 19.70 hours after the BAT trigger), obtaining a total of 0.21 hours exposure in the r and i bands and 0.08 hours exposure in the Z, Y, J, and H bands. For a source within the Swift-XRT error circle, in comparison with the SDSS DR9 and 2MASS catalogs, we obtain the following upper limits (3-sigma): r > 21.28 i > 21.09 Z > 18.17 Y > 19.19 J > 19.57 H > 17.30 These magnitudes are in the AB system and are not corrected for Galactic extinction in the direction of the GRB.