Gamma-ray Burst 181227A

(All information courtesy of the instrument teams.)

Previous IAU Circulars

none

Results of Observations

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Dec 18 06:17:25 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      46
TRIGGER_NUM:     567584225
GRB_RA:           25.533d {+01h 42m 08s} (J2000),
                  25.722d {+01h 42m 53s} (current),
                  25.037d {+01h 40m 09s} (1950)
GRB_DEC:         -50.317d {-50d 19' 00"} (J2000),
                 -50.221d {-50d 13' 16"} (current),
                 -50.568d {-50d 34' 05"} (1950)
GRB_ERROR:       5.23 [deg radius, statistical plus systematic]
GRB_INTEN:       740 [cnts/sec]
DATA_SIGNIF:     32.70 [sigma]
INTEG_TIME:      1.024 [sec]
GRB_DATE:        18479 TJD;   361 DOY;   18/12/27
GRB_TIME:        22620.50 SOD {06:17:00.50} UT
GRB_PHI:          83.00 [deg]
GRB_THETA:       105.00 [deg]
DATA_TIME_SCALE: 1.0240 [sec]
HARD_RATIO:      0.77
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      97%  GRB
2nd_MOST_LIKELY:   2%  Generic Transient
DETECTORS:       0,0,1, 0,0,0, 0,0,0, 0,1,0, 0,0,
SUN_POSTN:       275.92d {+18h 23m 40s}  -23.32d {-23d 19' 28"}
SUN_DIST:         83.96 [deg]   Sun_angle= -7.3 [hr] (East of Sun)
MOON_POSTN:      160.24d {+10h 40m 57s}  +11.90d {+11d 53' 50"}
MOON_DIST:       126.68 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      283.67,-64.87 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      354.69,-54.64 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181227262/quicklook/glg_lc_medres34_bn181227262.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 126.73,12.58 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Dec 18 06:17:37 UT
NOTICE_TYPE:     Fermi-GBM Ground Position
RECORD_NUM:      58
TRIGGER_NUM:     567584225
GRB_RA:           24.990d {+01h 39m 58s} (J2000),
                  25.165d {+01h 40m 40s} (current),
                  24.528d {+01h 38m 07s} (1950)
GRB_DEC:         -56.750d {-56d 45' 00"} (J2000),
                 -56.654d {-56d 39' 14"} (current),
                 -57.003d {-57d 00' 09"} (1950)
GRB_ERROR:       1.69 [deg radius, statistical only]
DATA_SIGNIF:     -214748364.80 [sigma]
DATA_INTERVAL:   2.048 [sec]
GRB_DATE:        18479 TJD;   361 DOY;   18/12/27
GRB_TIME:        22620.50 SOD {06:17:00.50} UT
GRB_PHI:          79.00 [deg]
GRB_THETA:       110.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   4153 (Gnd S/W Version number)
SUN_POSTN:       275.92d {+18h 23m 40s}  -23.32d {-23d 19' 28"}
SUN_DIST:         80.54 [deg]   Sun_angle= -7.3 [hr] (East of Sun)
MOON_POSTN:      160.24d {+10h 40m 58s}  +11.90d {+11d 53' 48"}
MOON_DIST:       123.58 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      289.95,-59.14 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      346.41,-59.25 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181227262/quicklook/glg_lc_medres34_bn181227262.gif
POS_MAP_URL:     http://gcn.gsfc.nasa.gov/notices_f/gbm_gnd_loc_map_567584225.fits
COMMENTS:        Fermi-GBM Ground-calculated Coordinates.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file will not be created/available until ~15 min after the trigger.  
COMMENTS:        The POS_MAP_URL file will not be created/available until ~1.5 min after the notice.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Dec 18 06:17:34 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      59
TRIGGER_NUM:     567584225
GRB_RA:           28.000d {+01h 52m 00s} (J2000),
                  28.170d {+01h 52m 41s} (current),
                  27.552d {+01h 50m 12s} (1950)
GRB_DEC:         -55.867d {-55d 52' 00"} (J2000),
                 -55.773d {-55d 46' 23"} (current),
                 -56.113d {-56d 06' 46"} (1950)
GRB_ERROR:       3.63 [deg radius, statistical plus systematic]
GRB_INTEN:       2729 [cnts/sec]
DATA_SIGNIF:     159.50 [sigma]
INTEG_TIME:      2.048 [sec]
GRB_DATE:        18479 TJD;   361 DOY;   18/12/27
GRB_TIME:        22620.50 SOD {06:17:00.50} UT
GRB_PHI:          81.00 [deg]
GRB_THETA:       110.00 [deg]
DATA_TIME_SCALE: 2.0480 [sec]
HARD_RATIO:      1.07
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,1, 0,0,0, 0,0,0, 0,1,0, 0,0,
SUN_POSTN:       275.92d {+18h 23m 40s}  -23.32d {-23d 19' 28"}
SUN_DIST:         82.43 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      160.24d {+10h 40m 57s}  +11.90d {+11d 53' 48"}
MOON_DIST:       122.63 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      286.27,-59.26 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      349.98,-59.79 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181227262/quicklook/glg_lc_medres34_bn181227262.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 126.73,12.58 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Dec 18 06:17:46 UT
NOTICE_TYPE:     Fermi-GBM Flight Position
RECORD_NUM:      70
TRIGGER_NUM:     567584225
GRB_RA:           28.183d {+01h 52m 44s} (J2000),
                  28.352d {+01h 53m 25s} (current),
                  27.737d {+01h 50m 57s} (1950)
GRB_DEC:         -56.017d {-56d 01' 00"} (J2000),
                 -55.924d {-55d 55' 24"} (current),
                 -56.263d {-56d 15' 44"} (1950)
GRB_ERROR:       3.48 [deg radius, statistical plus systematic]
GRB_INTEN:       4143 [cnts/sec]
DATA_SIGNIF:     340.80 [sigma]
INTEG_TIME:      4.096 [sec]
GRB_DATE:        18479 TJD;   361 DOY;   18/12/27
GRB_TIME:        22620.50 SOD {06:17:00.50} UT
GRB_PHI:          81.00 [deg]
GRB_THETA:       110.00 [deg]
DATA_TIME_SCALE: 4.0960 [sec]
HARD_RATIO:      1.14
LOC_ALGORITHM:   3 (version number of)
MOST_LIKELY:      98%  GRB
2nd_MOST_LIKELY:   1%  Generic SGR
DETECTORS:       0,0,1, 0,0,0, 0,0,0, 0,1,0, 0,0,
SUN_POSTN:       275.92d {+18h 23m 40s}  -23.32d {-23d 19' 28"}
SUN_DIST:         82.44 [deg]   Sun_angle= -7.5 [hr] (East of Sun)
MOON_POSTN:      160.24d {+10h 40m 58s}  +11.90d {+11d 53' 46"}
MOON_DIST:       122.47 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      286.23,-59.08 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      349.91,-59.97 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181227262/quicklook/glg_lc_medres34_bn181227262.gif
COMMENTS:        Fermi-GBM Flight-calculated Coordinates.  
COMMENTS:        This trigger occurred at longitude,latitude = 126.73,12.58 [deg].  
COMMENTS:        The LC_URL file will not be created until ~15 min after the trigger.

GCN NOTICE

TITLE:           GCN/FERMI NOTICE
NOTICE_DATE:     Thu 27 Dec 18 06:26:12 UT
NOTICE_TYPE:     Fermi-GBM Final Position
RECORD_NUM:      0
TRIGGER_NUM:     567584225
GRB_RA:           24.220d {+01h 36m 53s} (J2000),
                  24.399d {+01h 37m 36s} (current),
                  23.749d {+01h 35m 00s} (1950)
GRB_DEC:         -56.120d {-56d 07' 11"} (J2000),
                 -56.024d {-56d 01' 24"} (current),
                 -56.374d {-56d 22' 27"} (1950)
GRB_ERROR:       1.00 [deg radius, statistical only]
GRB_DATE:        18479 TJD;   361 DOY;   18/12/27
GRB_TIME:        22620.50 SOD {06:17:00.50} UT
GRB_PHI:          79.00 [deg]
GRB_THETA:       109.00 [deg]
E_RANGE:         44.032 - 279.965 [keV]
LOC_ALGORITHM:   41531 (Gnd S/W Version number)
SUN_POSTN:       275.92d {+18h 23m 42s}  -23.32d {-23d 19' 27"}
SUN_DIST:         80.46 [deg]   Sun_angle= -7.2 [hr] (East of Sun)
MOON_POSTN:      160.32d {+10h 41m 18s}  +11.87d {+11d 52' 13"}
MOON_DIST:       124.30 [deg]
MOON_ILLUM:      74 [%]
GAL_COORDS:      290.29,-59.88 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS:      346.67,-58.50 [deg] ecliptic lon,lat of the burst (or transient)
LC_URL:          http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181227262/quicklook/glg_lc_medres34_bn181227262.gif
LOC_URL:         http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2018/bn181227262/quicklook/glg_locplot_all_bn181227262.png
COMMENTS:        Fermi-GBM Final Position.  
COMMENTS:        This Notice was ground-generated -- not flight-generated.  
COMMENTS:        The LC_URL file should be available by the time this FINAL notice is produced.  
COMMENTS:        This notice was generated completely by automated pipeline processing.  
COMMENTS:        This is likely a Long GRB.  
COMMENTS:           
COMMENTS:        NOTE: This GBM event is temporally(0.0<100sec) coincident with the INTEGRAL_SPIACS event (trignum=8184).

GCN Circular #23569
E. Bissaldi (Politecnico & INFN Bari) and P. Veres (UAH) report on behalf of the Fermi GBM Team:
"At 06:17:00.50 UT on 27 December 2018, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 181227A (trigger 567584225 / 181227262).
The on-ground calculated location, using the GBM trigger data, is
RA, Dec = 24.2, -56.1
(J2000 degrees), with an uncertainty of 1 degree (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32]).
The angle from the Fermi LAT boresight at the GBM trigger time is 110 degrees.
The GBM light curve consists of two peaks with a duration (T90) of about 13 s (50-300 keV). The time-averaged spectrum from T0-0.3 s to T0+19.8 s is best fit by a Band function with Epeak = 85 +/- 1 keV, alpha = 0.33 +/- 0.02, and beta = -3.08 +/- 0.05.
The event fluence (10-1000 keV) in this time interval is (6.85 +/- 0.05)E-5 erg/cm^2. The 1-sec peak photon flux measured starting from T0+8.9 s in the 10-1000 keV band is 110.5 +/- 1.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
GCN Circular #23577
K. Hurley, on behalf of the IPN,
I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, A. Kozlova and T. Cline on behalf of the Konus-Wind team,
A. Goldstein, M. S. Briggs, and C. Wilson-Hodge on behalf of the Fermi GBM team,
A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo, and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,
S. Barthelmy, J. Cummings, H. Krimm, and D. Palmer, on behalf of the Swift-BAT team,
and
W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr, on behalf of the GRS-Odyssey GRB team, report:
The long-duration GRB 181227A (Fermi-GBM detection: Bissaldi & Veres, GCN Circ. 23569) was detected by Fermi (GBM trigger 567584225), Konus-Wind, INTEGRAL (SPI-ACS), Mars-Odyssey (HEND), and Swift (BAT) at about 22620 s UT (06:17:00). The burst was detected by Swift (BAT) during the slew and no event data were captured (Sakamoto, Lien, and Pal'shin, priv. comm.).
We have triangulated it to a preliminary, 3 sigma error box whose coordinates are:
```
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    29.889 (01h 59m 33s) -53.321 (-53d 19' 14")
  Corners:
    30.664 (02h 02m 39s) -52.621 (-52d 37' 16")
    30.861 (02h 03m 27s) -53.105 (-53d 06' 19")
    27.501 (01h 50m 00s) -54.693 (-54d 41' 35")
    27.344 (01h 49m 22s) -54.208 (-54d 12' 30")
  ---------------------------------------------
```
The error box area is about 1.13 sq. deg, and its maximum dimension is 2.79 deg (the minimum one is 27.84 arcmin). The Sun distance was about 84 deg.
This box may be improved.
A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB181227_T22619/IPN/
The Konus-Wind time history and spectrum will be given in a forthcoming GCN Circular.
GCN Circular #23589
D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline on behalf of the Konus-Wind team, report:
The long-duration, bright GRB 181227A (Fermi-GBM detection: Bissaldi & Veres, GCN Circ. 23569; IPN triangulation: Hurley et al., GCN Circ. 23577) triggered Konus-Wind at T0=22619.317 s UT (06:16:59.317).
The burst light curve shows a single emission episode which starts at ~T0-0.5 s and has a total duration of ~17 s. The emission is seen up to ~10 MeV.
As observed by Konus-Wind, the burst had a fluence of 5.91(-0.12,+0.12)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+8.944 s, of 1.39(-0.15,+0.16)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+18.688 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.66(-0.07,+0.07), the high energy photon index beta = -3.53(-0.24,+0.18), the peak energy Ep = 93(-2,+2) keV (chi2 = 72/96 dof).
The spectrum near the maximum count rate (measured from T0+8.192 to T0+8.960 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.35(-0.14,+0.15), the high energy photon index beta = -4.34(-5.66,+0.70), the peak energy Ep = 117(-5,+5) keV (chi2 = 31/46 dof).
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB181227_T22619/
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
GCN Circular #23591
S. Sugita, A. Yoshida, T. Sakamoto, V. Pal'shin (AGU), Y. Kawakubo (LSU), A. Tezuka, S. Matsukawa, H. Onozawa, T. Ito, H. Morita, Y. Sone (AGU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN), I. Takahashi (IPMU), Y. Asaoka, S. Ozawa, S. Torii (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), W. Ishizaki (ICRR), M. L. Cherry (LSU), S. Ricciarini (U of Florence), A. V. Penacchioni, P. S. Marrocchesi (U of Siena), and the CALET collaboration:
The long soft GRB 181227A (Fermi GBM detection: Bissaldi & Veres, GCN Circ. 23569; IPN Triangulation: Hurley et al., GCN Circ. 23577; Konus-Wind observation: Svinkin et al., GCN Circ. 23589) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 06:17:09.332 UTC on 27 December 2018. Because of a problem in one of the ground alert processing scripts, the GCN notice was not distributed automatically for this event.
Since the burst incident direction was at ~110 deg relative to the detector's axes, the signal is barely seen in the HXM detectors, and it was heavily attenuated in the SGM detector.
The burst light curve shows a single emission episode which starts at T-9.0 sec and ends at T+7.1 sec. The T90 and the T50 durations measured by the SGM data are 13.9 +- 2.4 sec and 5.9 +- 2.3 sec (40-1000 keV), respectively.
The ground processed light curve is available at
http://cgbm.calet.jp/cgbm_trigger/ground/1229926558/
The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at the Waseda University.

Back to JG's homepage

Jochen Greiner, last update: 09-Jan-2019 [Disclaimer]