Fermi GBM Observations of SGR J1935+2154
ATel #14359; O. J. Roberts (USRA), J. Wood (USRA), R. Hamburg (UAH), A. von Kienlin (MPE), P. Veres (UAH) and G. Younes (GWU)
on 31 Jan 2021; 00:48 UT
Credential Certification: Oliver Roberts (oliver.roberts@nasa.gov)
Subjects: X-ray, Gamma Ray, Soft Gamma-ray Repeater
At 15:23:29.92 UTC on January 29th 2020, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located a burst from SGR 1935+2154 (trigger 633626614 / 210129641). SGR J1935 bursts were also reported by Konus-Wind (Ridnaia et al., GCN 29373), GECAM (Y. Huang et al., GCN 29363) and Swift-BAT (Ridania et al., GCN 29365). The GBM on-ground location is consistent with the known position of the SGR.
This burst has a duration (T90) of about 0.1 seconds. It is adequately fit by a power law function with an exponential high-energy cutoff. The power law index is 0.2 (+0.2/-0.2) and the cutoff energy, parameterized as Epeak, is 32.9 (+0.6/-0.6) keV. The event fluence (10-1000 keV) from T0-0.064s to T0+0.064s is (5.2 +/- 0.1)E-7 erg/cm^2. The average photon flux in the 10-1000 keV band during this period is 94.6 +/- 1.9 ph/s/cm^2. The spectrum is also well fit using a double blackbody (BB+BB) fit, with low and high temperatures of 6.2 (+0.6/-0.7) and 12.5 (+1.6/-1.3) keV, respectively. There are two additional bursts that also appear to be from SGR J1935, about 354s after the trigger time.
Fermi GBM also triggered on multiple bursts from SGR J1935+2154 on January 24th, 28th, 29th and 30th, with a fraction of these being misclassified as GRBs. The IDs, METs and times of these triggers are:
January 30th:
210130876 / 633733287 (21:01:22.91 UTC)
210130112 / 633667276 (02:41:11.35 UTC)
210130008 / 633658270 (00:11:05.37 UTC)
January 29th:
210129886 / 633647760 (21:15:55.98 UTC)
210129441 / 633609344 (10:35:39.94 UTC)
210129292 / 633596405 (07:00:00.99 UTC)
210129116 / 633581187 (02:46:22.58 UTC)
January 28th
210128983 / 633569707 (23:35:02.48 UTC)
January 24th
210124867 / 633214108 (20:48:24.00 UTC)
210124325 / 633167319 (07:48:34.36 UTC)
The spectral analysis results presented above are preliminary. We encourage multiwavelength observations, especially at radio wavelengths, to follow-up this most recent activation. For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/
