Gamma-ray Burst 150801A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Sat 01 Aug 15 05:31:40 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:    235016520 
  EVENT_RA:        255.93d {+17h 03m 42s} (J2000),
                   256.14d {+17h 04m 33s} (current),
                   255.24d {+17h 00m 58s} (1950)
  EVENT_DEC:        -9.44d {-09d 26' 08"} (J2000),
                    -9.46d {-09d 27' 24"} (current),
                    -9.37d {-09d 21' 59"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      200.0 +- 0.0 [mCrab] 
  EVENT_DATE:      17235 TJD;   213 DOY;   15/08/01
  EVENT_TIME:      4746.00 SOD {01:19:06.00} UT
  EVENT_TSCALE:    30s
  EVENT_EBAND:     Medium, 4-10 keV
  SUN_POSTN:       131.11d {+08h 44m 26s}  +18.09d {+18d 05' 20"}
  SUN_DIST:        126.10 [deg]  
  MOON_POSTN:      320.63d {+21h 22m 30s}  -11.68d {-11d 40' 38"}
  MOON_DIST:        63.30 [deg]
  MOON_ILLUM:      99 [%]
  GAL_COORDS:       11.25, 18.84 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      255.73, 13.31 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.
  

• GCN Circular #18102
  M. Ishikawa, S. Nakahira (JAXA), H. Negoro, (Nihon U.), S. Ueno, H. Tomida, M. Kimura, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, Y. Tachibana, T. Yoshii (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, R. Imatani (Osaka U.), M. Nakajima, T. Masumitsu, K. Tanaka (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori (Kyoto U.), Y. Tsuboi, S. Kanetou (Chuo U.), M. Yamauchi, D. Itoh (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Morii (ISM) report on behalf of the MAXI team:
  The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 01:18:55 UT. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (256.013 deg, -9.523 deg) = (17 04 03, -09 31 22) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.26 deg and 0.25 deg, respectively. The roll angle of long axis from the north direction is 50.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
  Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners:

  (R.A., Dec) = (255.708 deg, -10.291 deg) = (17 02 49, -10 17 28) (J2000)
  (R.A., Dec) = (255.273 deg, -9.991 deg) = (17 01 05, -09 59 28) (J2000)
  (R.A., Dec) = (256.932 deg, -8.065 deg) = (17 07 43, -08 03 53) (J2000)
  (R.A., Dec) = (257.356 deg, -8.376 deg) = (17 09 25, -08 22 32) (J2000)
  

  The X-ray flux averaged over the scan was 103 +- 21 mCrab (4-10keV, 1 sigma error). There was no significant excess flux in the previous transit at 23:46 UT on 31 July and in the next transit at 02:51 UT with an upper limit of 20 mCrab for each.
• GCN Circular #18103
  P. A. Evans (U. Leicester) reports on behalf of the Swift team:
  Swift has initiated a series of observations, tiled on the sky, of the MAXI GRB 150801A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00047
  Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. The probability of finding serendipitous sources, unrelated to the MAXI event is high: any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration.
  Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).
  This circular is an official product of the Swift-XRT team.
• GCN Circular #18112
  A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), D.N. Burrows (PSU), T.G.R. Roegiers (PSU), L.M. McCauley (PSU), A.P. Beardmore (U. Leicester), B.P. Gompertz (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:
  Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 150801A (Ishikawa et al. GCN Circ. 18102) in a series of observations tiled on the sky. The total exposure time is 3.8 ks, distributed over 4 tiles; the maximum exposure at a single sky location was 1.6 ks. The data were collected between T0+50.8 ks and T0+62.9 ks, and are entirely in Photon Counting (PC) mode.
  No X-ray sources have been detected. The 3-sigma upper limit in the field (not including the regions where the tiles overlap) ranges from ~0.006 to ~0.009 ct s^-1, corresponding to a 0.3-10 keV observed flux of 2.4e-13 to 3.8e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum).
  The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00047.
  This circular is an official product of the Swift-XRT team.