Gamma-ray Burst 151212A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/MAXI NOTICE
  NOTICE_DATE:     Sat 12 Dec 15 14:56:20 UT
  NOTICE_TYPE:     MAXI Unknown Source Position
  EVENT_ID_NUM:    368487901
  EVENT_RA:         67.95d {+04h 31m 49s} (J2000),
                    68.15d {+04h 32m 37s} (current),
                    67.33d {+04h 29m 19s} (1950)
  EVENT_DEC:        -3.87d {-03d 52' 00"} (J2000),
                    -3.83d {-03d 50' 00"} (current),
                    -3.97d {-03d 58' 21"} (1950)
  EVENT_ERROR:     1.0 [deg radius, stat+sys, 90% containment]
  EVENT_FLUX:      156.0 +- 0.0 [mCrab]
  EVENT_DATE:      17368 TJD;   346 DOY;   15/12/12
  EVENT_TIME:      50427.00 SOD {14:00:27.00} UT
  EVENT_TSCALE:    1s
  EVENT_EBAND:     Low, 2-4 keV
  SUN_POSTN:       259.40d {+17h 17m 35s}  -23.08d {-23d 04' 42"}
  SUN_DIST:        150.94 [deg]
  MOON_POSTN:      274.72d {+18h 18m 54s}  -18.39d {-18d 23' 41"}
  MOON_DIST:       145.66 [deg]
  MOON_ILLUM:      2 [%]
  GAL_COORDS:      199.18,-32.61 [deg] galactic lon,lat of the burst (or transient)       
  ECL_COORDS:       65.50,-25.45 [deg] ecliptic lon,lat of the burst (or transient)       
  COMMENTS:        MAXI Unknown Source Position. GRB or unknown X-ray Transient.
  

• GCN Circular #18685
  S. Nakahira(JAXA), H. Negoro (Nihon U.), S. Ueno, H. Tomida, M. Ishikawa, Y. E. Nakagawa (JAXA), T. Mihara, M. Sugizaki, M. Serino, M. Shidatsu, J. Sugimoto, T. Takagi, M. Matsuoka (RIKEN), N. Kawai, M. Arimoto, T. Yoshii, Y. Tachibana, Y. Ono, T. Fujiwara (Tokyo Tech), A. Yoshida, T. Sakamoto, Y. Kawakubo, H. Ohtsuki (AGU), H. Tsunemi, R. Imatani (Osaka U.), M. Nakajima, K. Tanaka, T. Masumitsu (Nihon U.), Y. Ueda, T. Kawamuro, T. Hori, A. Tanimoto (Kyoto U.), Y. Tsuboi, S. Kanetou, Y. Nakamura, R. Sasaki (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 UT 2015-12-12T14:00:27. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (68.109 deg, -3.775 deg) = (04 32 26, -03 46 30) (J2000) with statistical uncertainties of ~0.5 degree. There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
  The source showed a relatively soft energy spectrum, and a simple power-law fit gives a photon index of 2.25 and the X-ray flux over the scan was 60 +- 12 mCrab (2-10keV, 1 sigma error).
  There was no significant excess flux in the previous transit at UT 12:27 and in the next transit at 15:34 with an upper limit of 20 mCrab for each.
  Detection Information: http://maxi.riken.jp/alert/novae/7368487901/7368487901.htm
• GCN Circular #18686
  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 151212A. Automated analysis of the XRT data will be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00050
  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 #18687
  T.G.R. Roegiers (PSU), S.L. Gibson (U. Leicester), J.P. Osborne (U. Leicester), P. D'Avanzo (INAF-OAB), V. D'Elia (ASDC), A. D'Ai (INAF-IASFPA), L.M. McCauley (PSU), J.A. Kennea (PSU) 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 151212A (Nakahira et al. GCN Circ. 18685) in a series of observations tiled on the sky. The total exposure time is 1.3 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 437 s. The data were collected between T0+8.4 ks and T0+8.6 ks, and are entirely in Photon Counting (PC) mode.
  An uncatalogued X-ray source is detected and is above the RASS limit, and is therefore likely the GRB afterglow. The position of this source is RA, Dec=68.1521, -3.9615 which is equivalent to:

  RA (J2000): 04:32:36.50
  Dec(J2000): -03:57:41.3
  

  with an uncertainty of 5.2 arcsec (radius, 90% confidence). This position is 11.5 arcmin from the MAXI position. We cannot determine at the present time whether the source is fading.
  The results of the XRT-team automatic analysis of the likely afterglow are at http://www.swift.ac.uk/xrt_products/TILED_GRB00050/index_1.php. The results of the full analysis of the tiled XRT observations are available at http://www.swift.ac.uk/xrt_products/TILED_GRB00050.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #18688
  P. Wiseman (MPE Garching), S. Schmidl (TLS Tautenburg) and J. Greiner (MPE Garching) report on behalf of the GROND team:
  We observed the field of GRB 151212A (MAXI trigger; Nakahira et al., GCN #18685) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La Silla Observatory (Chile).
  Observations started at 03:27 UT on December 13, 2015, 13.5 hrs after the GRB trigger. They were performed at an average seeing of 1.7" and at an average airmass of 1.1, and through a significant layer of clouds.
  We detect a single source at the border of the enhanced Swift-XRT error circle (http://www.swift.ac.uk/xrt_positions/00020570/), which we propose is the afterglow, at RA, Dec 68.150, -3.9626, which is equivalent to:

  RA (J2000.0) = 04:32:36.1
  Dec (J2000.0) = -03:57:45.3
  

  with an uncertainty of 0.5" in each coordinate.
  Based on the 72 min of total exposures in g'r'i'z'J and H, at a mid-time of 14.1 hrs after the burst, we measure the following preliminary magnitudes and upper limits (AB magnitude system):

  g' = 24.3 +/- 0.2 mag,
  r' = 23.6 +/- 0.2 mag,
  i' = 23.1 +/- 0.2 mag,
  z' = 23.3 +/- 0.3 mag,
  J > 21.2 mag, and
  H > 20.7 mag.
  

  We cannot say anything about fading at this time, but the power-law-like magnitudes lead us to suspect this is the afterglow.
  Given magnitudes and upper limits are calibrated against SDSS as well as 2MASS field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V)=0.03 mag in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #18689
  M. De Pasquale (PSU) and P. Evans (U. Leicester) report on behalf of the Swift/UVOT team:
  The Swift/UVOT began observing the field of MAXI-detected GRB 151212A (Nahakira et al., GCN Circ. 18685) 42183 s after the trigger. No optical afterglow consistent with the XRT source given by Evans et al. (GCN Circ 18687) is detected in the UVOT exposures.
  Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the summed UVOT exposures is:

  Filter         T_start(s)   T_stop(s)      Exp(s)         Mag
  
  u              42183       48392          2939 >21.4
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #18725
  Y. Kitaoka, T. Sakamoto, A. Yoshida (AGU)
  We observed the field of GRB 151212A detected by MAXI (Nakahira et al., GCN Circ. 18685) with the iTelescope.Net (http://www.itelescope.net) T18 (Plane Wave CDK) telescope located at the AstroCamp Observatory (Nerpio, Spain). 20 images of 60 sec exposures were taken in the Red filter starting from December 12 22:43:00 (UT) about 8.7 hours after the trigger and stopped on December 12 23:17:03 (UT). We do not detect the optical afterglow both in the individual images and the stacked image at the X-ray afterglow position (Roegiers et al., GCN Circ. 18687). The estimated five sigma upper limit of the combined image (total exposure of 1200 sec) is ~17.0 using the USNO-B1 catalog.