Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 22584

GRB 180402A, Swift-BAT refined analysis
2018-04-02T19:58:51Z (6 years ago)
Amy Lien at GSFC <>
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 180402A (trigger #821103)
(Lien et al., GCN Circ. 22580).  The BAT ground-calculated position is
RA, Dec = 251.923, -14.928 deg which is
  RA(J2000)  =  16h 47m 41.6s
  Dec(J2000) = -14d 55' 41.6"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.

The mask-weighted light curve shows a single short pulse that starts
at ~T0, peaks at ~0.1 s, and ends at ~0.3 s T90 (15-350 keV) is 0.18 +- 0.03 sec
(estimated error including systematics). The ground analysis confirmed
that the additional variation seen in the raw light curve are indeed from
MAXI J1820+070 (Lien et al., GCN Circ. 22580).

The time-averaged spectrum from T+0.05 to T+0.26 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
0.52 +- 0.30.  The fluence in the 15-150 keV band is 1.4 +- 0.2 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.34 sec in the 15-150 keV band
is 1.8 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence

The results of the batgrbproduct analysis are available at
Looking for U.S. government information and services? Visit