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 30121

NICER discovery of 3.86 s pulsations from a new magnetar: SGR J1555.2-5402
2021-06-03T16:59:30Z (3 years ago)
Nanda Rea at CSIC-IEEC <>
F. Coti Zelati, A. Borghese, N. Rea (ICE-CSIC), G. L. Israel
(INAF-OAR), P. Esposito (IUSS Pavia), T. Enoto (RIKEN), K. Gendreau
(NASA/GSFC) S. Campana (INAF-OAB) on behalf of a larger collaboration

On 2021 June 03 at 09:45:46 UT, the Swift Burst Alert Telescope (BAT)
triggered on a short X-ray burst from a direction close to the
Galactic plane. The short duration of the burst led to its tentative
association to a newly discovered magnetar, SGR J1555.2-5402 (GCN
#30120). NICER started observing the field at 12:32:00 UT, and
Swift/XRT observed at 10:53:43 UT, only a few hours after the
Swift/BAT trigger. We report on the preliminary analysis of the data
available so far, which total to an exposure time of about 1.6 ks for
NICER, and 1.6ks for Swift/XRT.

Swift/XRT finds a new X-ray source at a position (3.67 arcsec error) of:
RA (2000) = 15 55 08.556,
Dec (2000) -54 03 38.74

SGR J1555.2-5402 is detected in NICER at a count rate of about 4.5
counts/s (not background-subtracted) in the energy range 1-8 keV. We
also detected coherent pulsations at high confidence level at a period
of P=3.8611(1) s (uncertainty in parenthesis at 1 sigma; we used event
times not corrected for the solar system barycentre), which confirms
that the short burst was indeed emitted by a new magnetar. Results
from a more detailed analysis will be reported later on.
Looking for U.S. government information and services? Visit