Gamma-ray Burst 181224A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN/BACODINE POSITION NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Dec 18 13:37:07 UT
  NOTICE_TYPE:     Swift-BAT GRB Position
  TRIGGER_NUM:     878911,   Seg_Num: 0
  GRB_RA:          125.931d {+08h 23m 43s} (J2000),
                   126.184d {+08h 24m 44s} (current),
                   125.266d {+08h 21m 04s} (1950)
  GRB_DEC:          +6.206d {+06d 12' 20"} (J2000),
                    +6.143d {+06d 08' 36"} (current),
                    +6.368d {+06d 22' 04"} (1950)
  GRB_ERROR:       3.00 [arcmin radius, statistical only]
  GRB_INTEN:       2815 [cnts]    Image_Peak=172 [image_cnts]
  TRIGGER_DUR:     1.024 [sec] 
  TRIGGER_INDEX:   146     E_range: 25-100 keV
  BKG_INTEN:       17902 [cnts]
  BKG_TIME:        48993.86 SOD {13:36:33.86} UT
  BKG_DUR:         8 [sec]
  GRB_DATE:        18476 TJD;   358 DOY;   18/12/24
  GRB_TIME:        49011.59 SOD {13:36:51.59} UT
  GRB_PHI:         -171.26 [deg]
  GRB_THETA:        29.94 [deg]
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     10.14 [sigma]
  IMAGE_SIGNIF:    8.72 [sigma]
  MERIT_PARAMS:     +1  +0  +0  +0  +2  -1  -5  +0 +80  +0 
  SUN_POSTN:       272.93d {+18h 11m 43s}  -23.41d {-23d 24' 31"}
  SUN_DIST:        143.66 [deg]   Sun_angle= 9.8 [hr] (West of Sun)
  MOON_POSTN:      119.74d {+07h 58m 57s}  +20.59d {+20d 35' 39"}
  MOON_DIST:        15.74 [deg]
  MOON_ILLUM:      95 [%]
  GAL_COORDS:      218.02, 23.33 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      126.74,-12.77 [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 = 214.64,-17.57 [deg].  
  

• red DSS finding chart ps-file
  
  
• GCN NOTICE
  

  TITLE:           GCN/SWIFT NOTICE
  NOTICE_DATE:     Mon 24 Dec 18 13:40:44 UT
  NOTICE_TYPE:     Swift-BAT GRB Lightcurve
  TRIGGER_NUM:     878911,   Seg_Num: 0
  GRB_RA:          125.931d {+08h 23m 43s} (J2000),
                   126.184d {+08h 24m 44s} (current),
                   125.266d {+08h 21m 04s} (1950)
  GRB_DEC:          +6.206d {+06d 12' 20"} (J2000),
                    +6.143d {+06d 08' 36"} (current),
                    +6.368d {+06d 22' 04"} (1950)
  GRB_DATE:        18476 TJD;   358 DOY;   18/12/24
  GRB_TIME:        49011.59 SOD {13:36:51.59} UT
  TRIGGER_INDEX:   146
  GRB_PHI:         -171.26 [deg]
  GRB_THETA:        29.94 [deg]
  DELTA_TIME:      -11.00 [sec]
  TRIGGER_DUR:     1.024 [sec] 
  SOLN_STATUS:     0x3
  RATE_SIGNIF:     10.14 [sigma]
  IMAGE_SIGNIF:    8.72 [sigma]
  LC_URL:          sw00878911000msb.lc
  SUN_POSTN:       272.93d {+18h 11m 44s}  -23.41d {-23d 24' 31"}
  SUN_DIST:        143.66 [deg]   Sun_angle= 9.8 [hr] (West of Sun)
  MOON_POSTN:      119.78d {+07h 59m 07s}  +20.59d {+20d 35' 24"}
  MOON_DIST:        15.73 [deg]
  MOON_ILLUM:      95 [%]
  GAL_COORDS:      218.02, 23.33 [deg] galactic lon,lat of the burst (or transient)
  ECL_COORDS:      126.74,-12.77 [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 = 214.64,-17.57 [deg].  
  

  
• GCN Circular #23554
  A. Melandri (INAF-OAB), S. D. Barthelmy (GSFC), M. G. Bernardini (INAF-OAB), P. D'Avanzo (INAF-OAB), A. Y. Lien (GSFC/UMBC) and B. Sbarufatti (PSU) report on behalf of the Neil Gehrels Swift Observatory Team:
  At 13:36:51 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 181224A (trigger=878911). Swift did not slew to the burst because of the Moon constraint. The BAT on-board calculated location is RA, Dec 125.931, +6.206, which is

     RA(J2000)  =  08h 23m 43s
     Dec(J2000) = +06d 12' 20"
  

  with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curves one peak with a total duration of about 15 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger.
  Due to a Moon observing constraint, Swift cannot slew to the BAT position until 08:10 UT on 2018 December 26. There will thus be no XRT or UVOT data for this trigger before this time.
  Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). 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 Circular #23555
  H. A. Krimm (NSF/USRA), S. D. Barthelmy (GSFC), J. R. Cummings (CPI), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC), A. Melandri (INAF-OAB), 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+450 sec from the recent telemetry downlink, we report further analysis of BAT GRB 181224A (trigger #878911) (Melandri et al., GCN Circ. 23554). The BAT ground-calculated position is RA, Dec = 125.949, 6.194 deg which is

    RA(J2000)  =  08h 23m 47.7s
    Dec(J2000) = +06d 11' 39.9"
  

  with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment). The partial coding was 80%.
  The mask-weighted light curve shows a single-peaked structure that starts at ~ T-12 s, peaks at ~ T+1 s, one ends at ~ T+4 s. T90 (15-350 keV) is 12.5 +- 4.2 sec (estimated error including systematics).
  The time-averaged spectrum from T-12.04 to T+3.30 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.27 +- 0.20. The fluence in the 15-150 keV band is 4.9 +- 0.6 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from T+0.48 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/878911/BA/