//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18042 SUBJECT: GRB 150722A: Swift detection of a burst DATE: 15/07/22 10:10:55 GMT FROM: Scott Barthelmy at NASA/GSFC F. E. Marshall (NASA/GSFC), S. D. Barthelmy (GSFC), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC) and K. L. Page (U Leicester) report on behalf of the Swift Team: At 09:57:53 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150722A (trigger=649916). Swift did not slew immediately due to earth limb observing constraint. The BAT on-board calculated location is RA, Dec 218.272, -35.197 which is RA(J2000) = 14h 33m 05s Dec(J2000) = -35d 11' 46" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). As is usual for an image trigger (64-sec), there is nothing significant in the real-time TDRSS light curve. Due to an observing constraint, Swift will not slew until T0+50.9 minutes. There will be no XRT or UVOT data until this time. Burst Advocate for this burst is F. E. Marshall (marshall AT milkyway.gsfc.nasa.gov). 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: 18043 SUBJECT: GRB 150722A: Swift-XRT observations DATE: 15/07/22 12:06:05 GMT FROM: Phil Evans at U of Leicester S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), D.N. Burrows (PSU), J.A. Kennea (PSU) and G. Tagliaferri (INAF-OAB) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 150722A at 10:51:48.0 UT, 3234.9 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 218.27775, -35.19644 which is equivalent to: RA(J2000) = 14h 33m 06.66s Dec(J2000) = -35d 11' 47.2" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 17 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 5.92 x 10^20 cm^-2 (Willingale et al. 2013). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18044 SUBJECT: GRB 150722A: Enhanced Swift-XRT position DATE: 15/07/22 14:27:12 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 2194 s of XRT Photon Counting mode data and 6 UVOT images for GRB 150722A, 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 = 218.27800, -35.19588 which is equivalent to: RA (J2000): 14h 33m 6.72s Dec (J2000): -35d 11' 45.2" with an uncertainty of 1.7 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: 18046 SUBJECT: GRB 150722A: Swift/UVOT Upper Limits DATE: 15/07/22 16:38:01 GMT FROM: Paul Kuin at MSSL N. P. M. Kuin (UCL-MSSL) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150722A 3238 s after the BAT trigger (Marshall et al., GCN Circ. 18042). No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. No. 18044) 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 3238 3388 147 >20.6 white 3238 5442 541 >21.6 v 4217 5791 333 >20.0 b 3602 5237 393 >21.0 u 3396 5031 393 >20.6 w1 4627 4827 197 >20.1 m2 4422 4622 197 >20.3 w2 4012 5647 393 >21.4 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.06 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18047 SUBJECT: GRB 150722A: Swift-XRT refined Analysis DATE: 15/07/22 20:57:16 GMT FROM: Alex Amaral-Rogers at U.of Leicester D.N. Burrows (PSU), T.G.R. Roegiers (PSU), B.P. Gompertz (U. Leicester), J.P. Osborne (U. Leicester), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), L.M. McCauley (PSU), A. Amaral-Rogers (U. Leicester) and F. E. Marshall (NASA/GSFC) report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 150722A (Marshall et al. GCN Circ. 18042), from 3.2 ks to 17.3 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Evans et al. (GCN Circ. 18044). The light curve can be modelled with a power-law decay with a decay index of alpha=0.90 (+0.14, -0.13). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.08 (+/-0.13). The best-fitting absorption column is 1.4 (+0.4, -0.3) x 10^21 cm^-2, in excess of the Galactic value of 5.9 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 3.2 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.4 (+0.4, -0.3) x 10^21 cm^-2 Galactic foreground: 5.9 x 10^20 cm^-2 Excess significance: 3.6 sigma Photon index: 2.08 (+/-0.13) If the light curve continues to decay with a power-law decay index of 0.90, the count rate at T+24 hours will be 0.013 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.2 x 10^-13 (5.6 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/00649916. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18048 SUBJECT: GRB 150722A: Swift-BAT refined analysis DATE: 15/07/22 23:51:39 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), 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+243 sec from the recent telemetry downlink, we report further analysis of BAT GRB 150722A (trigger #649916) (Marshall, et al., GCN Circ. 18042). The BAT ground-calculated position is RA, Dec = 218.297, -35.196 deg which is RA(J2000) = 14h 33m 11.3s Dec(J2000) = -35d 11' 45.1" with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 94%. The mask-weighted light curve shows weak, variable emission from prior to T-200 to about T+55 seconds. T90 (15-350 keV) is 67 +- 12 sec (estimated error including systematics). The time-averaged spectrum from T-26.00 to T+48.00 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.79 +- 0.26. The fluence in the 15-150 keV band is 6.1 +- 0.9 x 10^-07 erg/cm2. The 1-sec peak photon flux measured from T+15.00 sec in the 15-150 keV band is 0.4 +- 0.1 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/649916/BA/ [GCN OPS NOTE(22jul15): Per an author's request, the "T-60" was corrected to "T-240".] //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 18049 SUBJECT: GRB 150722A: LCOGT-Sutherland observations DATE: 15/07/23 09:00:59 GMT FROM: Simone Dichiara at Ferrara U/Italy S. Dichiara, C. Guidorzi (U. Ferrara), D. Kopac (LJMU), on behalf of a large collaboration report: One of the LCOGT 1-m telescopes in Sutherland (South Africa) began observing GRB 150722A (Marshall et al. GCN 18042) on July 22 at 17:01:14 UT, i.e. ~7 hours after the BAT trigger with the r' and i' filters. Within the XRT error circle (Evans et al. GCN 18044) we found no new source down to the following limit: Mid time from Total Exp Filter Magnitude trigger (hr) (s) ------------------------------------------------- 7.46 120x15 r' > 20.0 7.90 120x6 i' > 18.8 ------------------------------------------------- Values have been calibrated against nearby USNOB-1 stars (R2 and I).