//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22243 SUBJECT: GRB 171212A: Swift detection of a burst or a Galactic transient DATE: 17/12/12 12:21:26 GMT FROM: David Palmer at LANL A. Tohuvavohu (PSU), A. P. Beardmore (U Leicester), D. N. Burrows (PSU), P. D'Avanzo (INAF-OAB), A. Deich (PSU), S. W. K Emery (UCL-MSSL), P. A. Evans (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU), N. P. M. Kuin (UCL-MSSL), F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the Swift Team: At 11:57:21 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 171212A (trigger=796778). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 293.900, +20.568 which is RA(J2000) = 19h 35m 36s Dec(J2000) = +20d 34' 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 120 sec. The peak count rate was ~800 counts/sec (15-350 keV), at ~90 sec after the trigger. The XRT began observing the field at 11:58:52.7 UT, 91.0 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 293.91826, 20.59159 which is equivalent to: RA(J2000) = 19h 35m 40.38s Dec(J2000) = +20d 35' 29.7" with an uncertainty of 3.9 arcseconds (radius, 90% containment). This location is 104 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 http://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.23 x 10^22 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 1.28e-08 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 99 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 large, but uncertain, extinction expected. Because this event is very close to the Galactic plane (lat=0.03 degrees) it is possibly a Galactic transient, in which case it takes the name 'Swift J1935.7+2036'. Burst Advocate for this burst is A. Tohuvavohu (aaronb AT swift.psu.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/too.html.) //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22245 SUBJECT: GRB 171212A: Enhanced Swift-XRT position DATE: 17/12/12 16:09:49 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 1519 s of XRT Photon Counting mode data and 4 UVOT images for GRB 171212A, 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 = 293.91782, +20.59204 which is equivalent to: RA (J2000): 19h 35m 40.28s Dec (J2000): +20d 35' 31.3" with an uncertainty of 2.3 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: 22246 SUBJECT: GRB 171212A/Swift J1935.7+2036: TSHAO optical observations DATE: 17/12/12 19:18:46 GMT FROM: Alexei Pozanenko at IKI, Moscow E. Mazaeva (IKI), A. Pozanenko (IKI), I. Reva (FAPHI), M. Krugov (FAPHI), A. Kusakin (FAPHI), A. Volnova (IKI) report on behalf of larger GRB follow-up collaboration: We observed the field of GRB 171212A (Tohuvavohu et al., GCN 22243) with Zeiss-1000 1-m telescope of Tien Shan Astronomical Observatory starting on Dec. 12 (UT) 12:21:15. We took several images in R-filter. Within enhanced Swift-XRT error circle (Evans et al. GCN 22245) we do not detect any object. Preliminary photometry of initial combined images is following. Date UT start t-T0 Filter Exp. OT Err. ULim (mid, days) (s) 2017-12-12 12:21:15 0.01896 R 3*120 n/d n/d 20.0 2017-12-12 12:21:15 0.02728 R 13*120 n/d n/d 21.1 The photometry is based on several nearby USNO-B1.0 stars USNO-B.1_id R2 1105-0415742 17.60 1105-0415769 17.54 1105-0415805 16.38 1106-0408959 17.07 1105-0415666 16.91 //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22248 SUBJECT: GRB 171212A/Swift J1935.7+2036: Swift/UVOT Upper Limits DATE: 17/12/12 22:16:30 GMT FROM: Alice Breeveld at MSSL-UCL A. A. Breeveld (UCL-MSSL) and A. Tohuvavohu (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 171212A 99 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 22243). No optical afterglow consistent with the enhanced XRT position (Evans et al., GCN Circ. 22245) 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 99 249 147 >20.3 u_FC 257 507 246 >19.8 white 99 5510 383 >20.8 v 588 5921 235 >19.0 b 513 6581 275 >20.1 u 257 6536 468 >20.1 w1 638 6331 236 >19.5 m2 5926 6125 197 >19.3 w2 738 5716 216 >19.5 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 7.95 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22251 SUBJECT: GRB 171212A: Swift-XRT refined Analysis DATE: 17/12/13 12:21:03 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), S. J. LaPorte (PSU), J.A. Kennea (PSU), B. Sbarufatti (INAF-OAB/PSU), S.L. Gibson (U. Leicester) and A. Tohuvavohu report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 171212A (Tohuvavohu et al. GCN Circ. 22243), from 81 s to 29.5 ks after the BAT trigger. The data comprise 347 s in Windowed Timing (WT) mode (the first 8 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 22245). The late-time light curve (from T0+5.1 ks) can be modelled with a power-law decay with a decay index of alpha=1.2 (+0.4, -0.3). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.83 (+/-0.08). The best-fitting absorption column is 4.73 (+0.23, -0.22) x 10^22 cm^-2, in excess of the Galactic value of 1.2 x 10^22 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 8.1 x 10^-11 (1.9 x 10^-10) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 4.73 (+0.23, -0.22) x 10^22 cm^-2 Galactic foreground: 1.2 x 10^22 cm^-2 Excess significance: 26.2 sigma Photon index: 1.83 (+/-0.08) If the light curve continues to decay with a power-law decay index of 1.2, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.2 x 10^-13 (2.8 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/00796778. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 22253 SUBJECT: GRB 171212A/Swift J1935.7+2036: Swift-BAT refined analysis DATE: 17/12/13 13:56:37 GMT FROM: Amy Lien at GSFC A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), H. A. Krimm (NSF/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU), A. Tohuvavohu (PSU), T. N. Ukwatta (LANL) (i.e. the Swift-BAT team): Using the data set from T-240 to T+1004 sec from the recent telemetry downlink, we report further analysis of BAT GRB 171212A (trigger #796778) (Tohuvavohu et al., GCN Circ. 22243). The BAT ground-calculated position is RA, Dec = 293.920, 20.597 deg which is RA(J2000) = 19h 35m 40.8s Dec(J2000) = +20d 35' 49.6" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask-weighted light curve shows a multi-peaked structure that starts at ~ T-30 s and ends at ~T+100 s, with some weak emissions lasting till ~ T+370 s. T90 (15-350 keV) is 320 +- 72 sec (estimated error including systematics). The time-averaged spectrum from T-28.82 to T+371.18 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 2.23 +- 0.14. The fluence in the 15-150 keV band is 3.4 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+90.68 sec in the 15-150 keV band is 0.7 +- 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/796778/BA/