GRB 090815

A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team: 

"At 07:12:12.45 UT on 15 August 2009, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 090815 (trigger 272013134 / 090815300).

The on-ground calculated location, using the GBM trigger 
data, is RA = 41.7, DEC = -2.0 (J2000 degrees, equivalent 
to 02h 47m, -02d 00'), with an uncertainty of 7.6 degrees 
(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 87 degrees.

The GBM light curve shows two broad pulses with a duration 
(T90) of about 200 s (8-1000 keV). The time-averaged spectrum 
from T0-5.120 s to T0+24.576 s is well fit by a simple power 
law function with index -1.5 +/- 0.1 (chi squared 261 for 241 d.o.f.).

The event fluence (8-1000 keV) in this time interval is 
(3.4 +/- 0.3)E-06 erg/cm^2. The 1.024-sec peak photon flux measured 
starting from T0+ 3.072 s in the 8-1000 keV band 
is 1.9 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary; 
final results will be published in the GBM GRB Catalog."

C. Ferrigno (ISDC, Versoix/IAAT, Tuebingen), D.Gotz (CEA-Saclay),  
S.Mereghetti, A.Paizis (IASF-Milano), E. Bozzo, M. Beck (ISDC,  
Versoix), and J.Borkowski (CAMK, Torun) on behalf of the IBAS  
Localization Team report:

A faint long GRB with duration of about 100 s has been detected by  
IBAS in IBIS/ISGRI data at 23:00:17 UTC on August 15th. No automatic  
alert has been issued because the trigger was at low significance.

Interactive off-line analysis has allowed to confirm the GRB nature of  
the trigger.

The refined coordinates (J2000) are:

RA:   306.13 [degrees]   DEC: -6.17 [degrees]

with an uncertainty of 3 arcmin (90% c.l.).

The soft spectrum of the GRB (only detected in the 20-40 keV energy  
range) and the long, slowly rising light curve may indicate a highly  
redshifted burst. Follow-up observations at other wavelengths are  
encouraged.

The light curve of the GRB will be posted at http://ibas.iasf-milano.inaf.it/IBAS_Results.html

This message can be cited.





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Carlo Ferrigno Institut f�r Astronomie
und Astrophysik T�bingen (IAAT)
and
ISDC Data Centre for Astrophysics
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