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 9472

GRB 090530B: Fermi GBM detection
2009-06-01T14:56:31Z (15 years ago)
Alexander van der Horst at NASA/MSFC <>
A.J. van der Horst (NASA/MSFC/ORAU) reports on behalf of the
Fermi GBM Team:

"At 18:14:24.42 UT on 30 May 2009, the Fermi Gamma-ray Burst Monitor
(GBM) triggered and located GRB 090530B (trigger 265400066 / 090530.760).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 73.2, Dec = +13.8 (J2000 degrees, equivalent to
J2000 4h53m, +13d47'), with a statistical uncertainty of less than 1 degree
(radius, 1-sigma containment, statistical only; there is additionally
a systematic error which is currently estimated to be 2 to 3 degrees).
The angle from the Fermi LAT boresight is 84 degrees.

The GBM light curve of this long and soft GRB consists of a double peaked
FRED, with a total duration (T90) of 194 s (8-1000 keV). The time-averaged
spectrum from T0-3.1 to T0+110.6 s is best fit by a Band function with
alpha = -0.71 +/- 0.06, beta = -2.42 +/- 0.05, and Epeak = 67 +/- 3.
The fluence (8-1000 keV) in this interval is (5.9 +/- 0.4)E-5 erg/cm^2.
The 1-sec peak photon flux measured starting from T0+10.2s in the
8-1000 keV band is 10.8 +/- 2.0 ph/s/cm^2.

The spectral and temporal analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
Looking for U.S. government information and services? Visit