Skip to main content
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