Gamma-ray Burst 111212A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 09:24:06 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     509543,   Seg_Num: 0
  GRB_RA:          310.404d {+20h 41m 37s} (J2000),
                   310.686d {+20h 42m 45s} (current),
                   309.215d {+20h 36m 52s} (1950)
  GRB_DEC:         -68.617d {-68d 37' 01"} (J2000),
                   -68.574d {-68d 34' 25"} (current),
                   -68.795d {-68d 47' 42"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       24631 [cnts]    Image_Peak=380 [image_cnts]
  TRIGGER_DUR:     8.192 [sec] 
  TRIGGER_INDEX:   336     E_range: 25-100 keV
  BKG_INTEN:       179350 [cnts]
  BKG_TIME:        33696.33 SOD {09:21:36.33} UT
  BKG_DUR:         64 [sec]
  GRB_DATE:        15907 TJD;   346 DOY;   11/12/12
  GRB_TIME:        33787.08 SOD {09:23:07.08} UT
  GRB_PHI:         -58.93 [deg]
  GRB_THETA:        36.18 [deg]
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     8.48 [sigma]
  IMAGE_SIGNIF:    8.09 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +3  +2  -2  +0  +0 -57  +0 
  SUN_POSTN:       259.11d {+17h 16m 27s}  -23.06d {-23d 03' 34"}
  SUN_DIST:         55.00 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      101.28d {+06h 45m 07s}  +20.76d {+20d 45' 26"}
  MOON_DIST:       128.87 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.20,-35.08 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      290.71,-48.06 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Coordinates.  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 192.97,-8.30 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 09:27:28 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     509543,   Seg_Num: 0
  GRB_RA:          310.404d {+20h 41m 37s} (J2000),
                   310.686d {+20h 42m 45s} (current),
                   309.215d {+20h 36m 52s} (1950)
  GRB_DEC:         -68.617d {-68d 37' 01"} (J2000),
                   -68.574d {-68d 34' 25"} (current),
                   -68.795d {-68d 47' 42"} (1950)
  GRB_DATE:        15907 TJD;   346 DOY;   11/12/12
  GRB_TIME:        33787.08 SOD {09:23:07.08} UT
  TRIGGER_INDEX:   336
  GRB_PHI:         -58.93 [deg]
  GRB_THETA:        36.18 [deg]
  DELTA_TIME:      45.00 [sec]
  TRIGGER_DUR:     8.192 [sec] 
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     8.48 [sigma]
  IMAGE_SIGNIF:    8.09 [sigma]
  LC_URL:          sw00509543000msb.lc
  SUN_POSTN:       259.11d {+17h 16m 27s}  -23.06d {-23d 03' 34"}
  SUN_DIST:         55.00 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      101.31d {+06h 45m 15s}  +20.75d {+20d 45' 09"}
  MOON_DIST:       128.87 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.20,-35.08 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      290.71,-48.06 [deg] ecliptic lon,lat of the burst (or transient)
  COMMENTS:        SWIFT-BAT GRB Lightcurve.  
  COMMENTS:           
  COMMENTS:        The next comments were copied from the BAT_POS Notice:  
  COMMENTS:        This is a rate trigger.  
  COMMENTS:        A point_source was found.  
  COMMENTS:        This does not match any source in the on-board catalog.  
  COMMENTS:        This does not match any source in the ground catalog.  
  COMMENTS:        This is a GRB.  
  COMMENTS:        This trigger occurred at longitude,latitude = 192.97,-8.30 [deg].  
  

  
• GCN Circular #12667
  S. Campana (INAF-OAB), J. R. Cummings (NASA/UMBC), V. D'Elia (ASDC), P. A. Evans (U Leicester), B. Gendre (ASDC), C. Guidorzi (U Ferrara), O. M. Littlejohns (U Leicester), A. Melandri (INAF-OAB), P. T. O'Brien (U Leicester), C. Pagani (U Leicester), K. L. Page (U Leicester), D. M. Palmer (LANL), P. Romano (INAF-IASFPA), B. Sbarufatti (INAF-OAB/PSU), C. A. Swenson (PSU), E. Troja (NASA/GSFC/ORAU) and B.-B. Zhang (PSU) report on behalf of the Swift Team:
  At 09:23:07 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 111212A (trigger=509543). Swift could not slew immediately to the burst due to an observing constraint. The BAT on-board calculated location is RA, Dec 310.404, -68.617 which is

     RA(J2000) = 20h 41m 37s
     Dec(J2000) = -68d 37' 01"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a weak emission with a duration of at least 20 sec, but a more detailed description will require the ground-linked data. The peak count rate was ~500 counts/sec (15-350 keV), at ~0 sec after the trigger.
  Due to an observing constraint, Swift will not slew until T0+47.6 minutes. There will be no XRT or UVOT data until this time.
  Burst Advocate for this burst is C. A. Swenson (cswenson AT astro.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.)
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 10:32:02 UT
  NOTICE_TYPE:     Swift-XRT Nack-Position
  TRIGGER_NUM:     509543,   Seg_Num: 0
  POINT_RA:        310.503d {+20h 42m 01s} (J2000)
  POINT_DEC:       -68.574d {-68d 34' 26"} (J2000)
  IMG_START_DATE:  15907 TJD;   346 DOY;   11/12/12
  IMG_START_TIME:  37055.04 SOD {10:17:35.04} UT,   3268.0 [sec] since BAT Trigger Time
  COUNTS:          1    Min_needed= 20
  STD_DEV:         0.00   Max_StdDev_for_Good=28.44 [arcsec]
  PH2_ITER:        0    Max_iter_allowed= 4
  ERROR_CODE:      1
  COMMENTS:        SWIFT-XRT Nack Position.  
  COMMENTS:        No source found in the image.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 10:32:57 UT
  NOTICE_TYPE:     Swift-UVOT Source List
  TRIGGER_NUM:     509543,   Seg_Num: 0
  POINT_RA:        310.503d {+20h 42m 01s} (J2000)
  POINT_DEC:       -68.573d {-68d 34' 23"} (J2000)
  POINT_ROLL:      298.719d
  IMG_START_DATE:  15907 TJD;   346 DOY;   11/12/12
  IMG_START_TIME:  37059.56 SOD {10:17:39.56} UT,   3272.5 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        9.877
  N_STARS:         49
  X_OFFSET:        346 [pixels]
  Y_OFFSET:        158 [pixels]
  X_MAX:           1305 [pixels]
  Y_MAX:           1117 [pixels]
  DET_THRESH:      28
  PHOTO_THRESH:    18
  SL_URL:          sw00509543000msufc3272.fits
  SUN_POSTN:       259.16d {+17h 16m 39s}  -23.06d {-23d 03' 47"}
  SUN_DIST:         55.00 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      101.92d {+06h 47m 41s}  +20.66d {+20d 39' 26"}
  MOON_DIST:       128.92 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.24,-35.12 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      290.78,-48.04 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Source List.  
  

• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 10:33:27 UT
  NOTICE_TYPE:     Swift-UVOT Processed Source List
  TRIGGER_NUM:     509543,   Seg_Num: 0
  POINT_RA:        310.503d {+20h 42m 01s} (J2000)
  POINT_DEC:       -68.573d {-68d 34' 23"} (J2000)
  POINT_ROLL:      298.719d
  IMG_START_DATE:  15907 TJD;   346 DOY;   11/12/12
  IMG_START_TIME:  37059.56 SOD {10:17:39.56} UT,   3272.5 [sec] since BAT Trigger Time
  FILTER:          10, White
  BKG_MEAN:        9.877
  N_STARS:         49
  X_OFFSET:        346 [pixels]
  Y_OFFSET:        158 [pixels]
  X_MAX:           1305 [pixels]
  Y_MAX:           1117 [pixels]
  DET_THRESH:      28
  PHOTO_THRESH:    18
  SL_URL:          sw00509543000msufc3272.fits
  SUN_POSTN:       259.16d {+17h 16m 39s}  -23.06d {-23d 03' 47"}
  SUN_DIST:         55.00 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      101.93d {+06h 47m 42s}  +20.66d {+20d 39' 24"}
  MOON_DIST:       128.92 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.24,-35.12 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      290.78,-48.04 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Source List.  
  COMMENTS:        All 4 attachments are included.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 10:34:35 UT
  NOTICE_TYPE:     Swift-UVOT Image
  TRIGGER_NUM:     509543,   Seg_Num: 0
  POINT_RA:        310.503d {+20h 42m 01s} (J2000)
  POINT_DEC:       -68.573d {-68d 34' 23"} (J2000)
  ROLL:            298.719d
  IMG_START_DATE:  15907 TJD;   346 DOY;   11/12/12
  IMG_START_TIME:  37059.56 SOD {10:17:39.56} UT,   3272.5 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     345377867
  X_OFFSET:        665 [pixels]
  Y_OFFSET:        477 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       825
  Y_GRB_POS:       637
  BINNING_INDEX:   1
  IM_URL:          sw00509543000msuni3280.fits
  SUN_POSTN:       259.16d {+17h 16m 40s}  -23.06d {-23d 03' 47"}
  SUN_DIST:         54.99 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      101.94d {+06h 47m 45s}  +20.65d {+20d 39' 18"}
  MOON_DIST:       128.92 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.24,-35.12 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      290.78,-48.04 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Image.  
  COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
  COMMENTS:        The image has 2x2 binning (compression).  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 10:34:52 UT
  NOTICE_TYPE:     Swift-UVOT Processed Image
  TRIGGER_NUM:     509543,   Seg_Num: 0
  POINT_RA:        310.503d {+20h 42m 01s} (J2000)
  POINT_DEC:       -68.573d {-68d 34' 23"} (J2000)
  ROLL:            298.719d
  IMG_START_DATE:  15907 TJD;   346 DOY;   11/12/12
  IMG_START_TIME:  37059.56 SOD {10:17:39.56} UT,   3272.5 [sec] since BAT Trigger Time
  FILTER:          10, White
  EXPOSURE_ID:     345377867
  X_OFFSET:        665 [pixels]
  Y_OFFSET:        477 [pixels]
  WIDTH:           160 [pixels]
  HEIGHT:          160 [pixels]
  X_GRB_POS:       825
  Y_GRB_POS:       637
  BINNING_INDEX:   1
  IM_URL:          sw00509543000msuni3280.fits
  SUN_POSTN:       259.17d {+17h 16m 40s}  -23.06d {-23d 03' 47"}
  SUN_DIST:         54.99 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      101.94d {+06h 47m 46s}  +20.65d {+20d 39' 16"}
  MOON_DIST:       128.92 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.24,-35.12 [deg] galactic lon,lat of the pointing direction
  ECL_COORDS:      290.78,-48.04 [deg] ecliptic lon,lat of the pointing direction
  COMMENTS:        SWIFT-UVOT Processed Image.  
  COMMENTS:        The GRB Position came from the Window Position in the Mode Command.  
  COMMENTS:        The image has 2x2 binning (compression).  
  COMMENTS:        All 4 attachments are included.  
  

  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 12 Dec 11 10:44:27 UT
  NOTICE_TYPE:     Swift-XRT Position
  TRIGGER_NUM:     509543,   Seg_Num: 0
  GRB_RA:          310.4329d {+20h 41m 43.89s} (J2000),
                   310.7148d {+20h 42m 51.54s} (current),
                   309.2441d {+20h 36m 58.57s} (1950)
  GRB_DEC:         -68.6123d {-68d 36' 44.2"} (J2000),
                   -68.5690d {-68d 34' 08.5"} (current),
                   -68.7907d {-68d 47' 26.3"} (1950)
  GRB_ERROR:       3.6 [arcsec radius, statistical plus systematic, 90% containment]
  GRB_INTEN:       1.00e-10 [erg/cm2/sec]
  GRB_SIGNIF:      10.00 [sigma]
  IMG_START_DATE:  15907 TJD;   346 DOY;   11/12/12
  IMG_START_TIME:  37273.00 SOD {10:21:13.00} UT,   3485.9 [sec] since BAT Trigger Time
  TAM[0-3]:        100.00 100.00 100.00 100.00
  AMPLIFIER:       1
  WAVEFORM:        31
  SUN_POSTN:       259.17d {+17h 16m 41s}  -23.06d {-23d 03' 49"}
  SUN_DIST:         54.99 [deg]   Sun_angle= -3.4 [hr] (East of Sun)
  MOON_POSTN:      102.03d {+06h 48m 07s}  +20.64d {+20d 38' 26"}
  MOON_DIST:       128.91 [deg]
  MOON_ILLUM:      97 [%]
  GAL_COORDS:      326.20,-35.09 [deg] galactic lon,lat of the burst
  ECL_COORDS:      290.73,-48.06 [deg] ecliptic lon,lat of the burst
  COMMENTS:        SWIFT-XRT Coordinates.  
  COMMENTS:        This Notice was ground-generated -- not flight-generated.  
  COMMENTS:        TAM values, flux and significance fields are not valid.  
  COMMENTS:        This position was automatically generated on the ground using  
  COMMENTS:        Photon Counting data telemetered via TDRSS (SPER data).  
  COMMENTS:        See http://www.swift.ac.uk/sper/docs.php for details.  
  COMMENTS:        The probability that this is a serendipitous source in the  
  COMMENTS:        SPER window is 2.8% < P(seren) < 6.6%.  
  

• GCN Circular #12669
  J.A. Kennea (PSU), G. Tagliaferri (INAF-OAB), S. Campana (INAF-OAB), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester) and D.N. Burrows (PSU) report on behalf of the Swift-XRT team:
  The XRT began observing the field of GRB 111212A at 10:17:35.0 UT, 3267.9 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source located at RA, Dec 310.43423, -68.61205 which is equivalent to:

     RA(J2000)  = 20h 41m 44.22s
     Dec(J2000) = -68d 36' 43.4"
  

  with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 43 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 (3.07 x 10^20 cm^-2, Kalberla et al. 2005), with an excess column of 2 (+0.94/-0.88) x 10^21 cm^-2 (90% confidence).
• GCN Circular #12670
  J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) report on behalf of the Swift-XRT team.
  Using 2469 s of XRT Photon Counting mode data and 7 UVOT images for GRB 111212A, 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 = 310.43132, -68.61251 which is equivalent to:

  RA (J2000): 20h 41m 43.52s
  Dec (J2000): -68d 36' 45.0"
  

  with an uncertainty of 1.5 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.
• GCN Circular #12671
  T. N. Ukwatta (MSU) S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), S. Campana (INAF-OAB), J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC), (i.e. the Swift-BAT team):
  Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 111212A (trigger #509543) (Campana, et al., GCN Circ. 12667). The BAT ground-calculated position is RA, Dec = 310.442, -68.585 deg, which is

     RA(J2000)  =  20h 41m 46.0s 
     Dec(J2000) = -68d 35' 04.5" 
  

  with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%.
  The mask-weighted light curve shows a FRED-like pulse starting at ~T-2 sec, peaking at ~T+6 sec, and returning to background around T+60 sec. Since Swift slewed due to an observing constraint, the burst location left the BAT FoV at ~T+70 sec, so we can not say if there was further actitivty in the lightcurve.
  The time-averaged spectrum from T-5.77 to T+62.74 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.67 +- 0.18. The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+4.76 sec in the 15-150 keV band is 0.8 +- 0.3 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/509543/BA/
• GCN Circular #12672
  C. A. Swenson (PSU) reports on behalf of the Swift/UVOT team:
  The Swift/UVOT began settled observations of the field of GRB 111212A 3272 s after the BAT trigger (Campana et al., GCN Circ. 12667). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ. 12670) 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          3272         3422          147 >20.3
  white             3272         5481          541 >21.3
  v                 4255         5751          255 >19.2
  b                 3637         5276          393 >20.1
  u                 3432         5071          393 >20.1
  w1                4665         4865          197 >20.1
  m2                4460         4660          197 >20.3
  w2                4050         5687          393 >21.0
  

  The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.05 in the direction of the burst (Schlegel et al. 1998).
• GCN Circular #12674
  B.-B. Zhang (PSU) reports on behalf of the Swift-XRT team:
  We have analysed 6.5 ks of XRT data for GRB 111212A (Campana et al. GCN Circ. 12667), from 3.3 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 Osborne et al. (GCN. Circ 12670).
  The light curve can be modelled with a power-law decay with a decay index of alpha=1.39 (+0.11, -0.10).
  A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.05 (+0.13, -0.07). The best-fitting absorption column is 9.5 (+3.0, -1.6) x 10^20 cm^-2, in excess of the Galactic value of 3.1 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.5 x 10^-11 (4.5 x 10^-11) erg cm^-2 count^-1.
  A summary of the PC-mode spectrum is thus:

  Total column:	     9.5 (+3.0, -1.6) x 10^20 cm^-2
  Galactic foreground: 3.1 x 10^20 cm^-2
  Excess significance: 6.6 sigma
  Photon index:	     2.05 (+0.13, -0.07)
  

  The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00509543.
  This circular is an official product of the Swift-XRT team.
• GCN Circular #12679
  D. A. Kann, A. Rossi (TLS Tautenburg), V. Sudilovsky, P. Schady and J. Greiner, (MPE Garching) report on behalf of the GROND team:
  We observed the field of the Swift GRB 111212A (Swift trigger 509543; Campana et al., GCN #12667) simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP, 120, 405) mounted at the 2.2 m ESO/MPG telescope at La Silla Observatory (Chile). Observations started on December 13, 2011, at 00:35 UT, in twilight, and are centered 0.658 days after the GRB trigger. They were taken at an average seeing of 1".2 and at an airmass of 2. Integration times were 1734 sec in the optical and 2640 sec in the NIR. These observations were obtained under challenging conditions, with thick cirrus preventing guiding.
  A second epoch was obtained on December 14, 2011, starting at 00:57 UT and centered at 1.667 days after the GRB. It was taken at an average seeing of 1".2 and at an airmass of 2. Integration times were 2420 sec in the optical and 2160 sec in the NIR. Conditions were much better, with clear, moonless skies.
  At the position of the X-ray afterglow (Osborne et al., GCN #12670), we do not detect any significant sources in any bands. We derive the following limits (3 sigma, AB magnitude system):
  0.658 days after the trigger:

  g' > 24.1
  r' > 24.2
  i' > 23.4
  z' > 22.8
  J > 20.5
  H > 20.0
  K > 18.1
  

  1.667 days after the trigger:

  g' > 24.8
  r' > 24.8
  i' > 23.8
  z' > 23.4
  J > 21.6
  H > 21.0
  K > 19.3
  

  Magnitudes were calibrated against GROND zero points in g'r'i'z' and 2MASS field stars in JHK.