//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17376 SUBJECT: GRB 150202A: Swift detection of a burst DATE: 15/02/02 23:36:34 GMT FROM: Scott Barthelmy at NASA/GSFC H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC), M. M. Chester (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB/PSU) and T. N. Ukwatta (LANL) report on behalf of the Swift Team: At 23:10:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 150202A (trigger=629547). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 39.236, -33.150, which is RA(J2000) = 02h 36m 57s Dec(J2000) = -33d 08' 59" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve show several peaks swith a total duration of about 30 sec. The peak count rate was ~1600 counts/sec (15-350 keV), at ~4 sec after the trigger. The XRT began observing the field at 23:11:30.3 UT, 88.0 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source with an enhanced position: RA, Dec 39.2275, -33.1485 which is equivalent to: RA(J2000) = 02h 36m 54.61s Dec(J2000) = -33d 08' 54.5" with an uncertainty of 2.1 arcseconds (radius, 90% containment). This location is 26 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 in excess of the Galactic value (2.54 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 4.3 (+1.96/-1.74) x 10^21 cm^-2 (90% confidence). UVOT took a finding chart exposure of 250 seconds with the U filter starting 304 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 19.2 mag. Data from the list of sources generated on-board are not available at this time. No correction has been made for the expected extinction corresponding to E(B-V) of 0.02. Burst Advocate for this burst is H. A. Krimm (hans.krimm AT 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: 17381 SUBJECT: GRB 150202A: GROND Upper limits DATE: 15/02/03 05:23:59 GMT FROM: Corentin Delvaux at MPE C. Delvaux, K. Varela and J. Greiner (all MPE Garching) report on behalf of the GROND team: We observed the field of GRB 150202A (SWIFT-629547; Krimm et al., GCN #17376) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla Observatory (Chile). Observations started on February 3rd, 2015, at 00:43 UT, 1.5 hrs after the GRB trigger. They were performed at an average seeing of 1.1" and at an average airmass of 1.7. We do not detect a source inside the 2.1” error circle reported by Krimm et al. (GCN #17376). Based on a total exposure of 2.07 hours in g'r'i'z'and 1.73 hours in JHK, at a midtime of 2 hours after the burst, we measure the following preliminary upper limits (AB magnitudes system): g' > 24.2 mag, r' > 24.7 mag, i' > 24.4 mag, z' > 24.4 mag, J > 22.1 mag, H > 21.5 mag, and K > 18.0 mag. Given magnitudes are calibrated against GROND zeropoints as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.02 mag in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17382 SUBJECT: GRB 150202A: Enhanced Swift-XRT position DATE: 15/02/03 05:35:04 GMT FROM: Phil Evans at U of Leicester A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) report on behalf of the Swift-XRT team. Using 3966 s of XRT Photon Counting mode data and 6 UVOT images for GRB 150202A, 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 = 39.22744, -33.14804 which is equivalent to: RA (J2000): 02h 36m 54.59s Dec (J2000): -33d 08' 53.0" 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: 17390 SUBJECT: GRB 150202A: Swift-XRT refined Analysis DATE: 15/02/03 11:36:04 GMT FROM: Phil Evans at U of Leicester P.A. Evans (U. Leicester), B.P. Gompertz (U. Leicester), V. D'Elia (ASDC), M. de Pasquale (INAF-IASFPA), A. Maselli (INAF-IASFPA), D.N. Burrows (PSU), J.A. Kennea (PSU), V. Mangano (PSU), J.P. Osborne (U. Leicester) and H.A. Krimm report on behalf of the Swift-XRT team: We have analysed 6.0 ks of XRT data for GRB 150202A (Krimm et al. GCN Circ. 17376), from 98 s to 24.9 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. The enhanced XRT position for this burst was given by Beardmore et al. (GCN Circ. 17382). The light curve can be modelled with an initial power-law decay with an index of alpha=0.62 (+0.12, -0.13), followed by a break at T+1352 s to an alpha of 1.26 (+0.30, -0.11). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.00 (+/-0.17). The best-fitting absorption column is 1.7 (+0.6, -0.5) x 10^21 cm^-2, in excess of the Galactic value of 2.5 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 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.7 (+0.6, -0.5) x 10^21 cm^-2 Galactic foreground: 2.5 x 10^20 cm^-2 Excess significance: 4.6 sigma Photon index: 2.00 (+/-0.17) If the light curve continues to decay with a power-law decay index of 1.26, the count rate at T+24 hours will be 2.5 x 10^-3 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.5 x 10^-14 (1.1 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/00629547. This circular is an official product of the Swift-XRT team. //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17392 SUBJECT: GRB 150202A: Swift/UVOT Upper Limits DATE: 15/02/03 19:14:39 GMT FROM: Margaret Chester at PSU M. M. Chester (PSU) and H. A. Krimm (CRESST/GSFC/USRA) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 150202A 93 s after the BAT trigger (Krimm et al., GCN Circ. 17376). No optical afterglow consistent with the XRT position (Beardmore et al. GCN Circ. 17382) 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 93 243 147 >20.6 u_FC 305 555 246 >20.2 white 93 6568 624 >21.5 v 634 6980 530 >20.4 b 560 7617 350 >21.3 u 305 7594 756 >20.7 w1 683 7390 510 >20.9 m2 658 7185 452 >21.7 w2 610 6774 490 >20.7 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998). //////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 17401 SUBJECT: GRB 150202A, Swift-BAT refined analysis DATE: 15/02/04 14:19:35 GMT FROM: Hans Krimm at NASA-GSFC T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), D. M. Palmer (LANL), 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 150202A (trigger #629547) (Krimm, et al., GCN Circ. 17376). The BAT ground-calculated position is RA, Dec = 39.261, -33.132 deg which is RA(J2000) = 02h 37m 02.6s Dec(J2000) = -33d 07' 56.1" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 60%. The mask-weighted light curve shows a complex structure with multiple peaks. The first emission episode runs from T-2 to T+10 sec and then second episode from T+12 to ~T+30 sec. T90 (15-350 keV) is 25.7 +- 4.3 sec (estimated error including systematics). The time-averaged spectrum from T-1.7 to T+27.1 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.50 +- 0.19. The fluence in the 15-150 keV band is 6.1 +- 0.7 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+17.40 sec in the 15-150 keV band is 1.0 +- 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/629547/BA/