[vsnet-grb-info 5941] GRB080330: MAGIC telescope GeV observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7585
SUBJECT: GRB080330: MAGIC telescope GeV observation
DATE:    08/04/11 23:41:23 GMT
FROM:    Markus Garczarczyk at MPI/MAGIC  <garcz at mppmu.mpg.de>

Gaug M., Garczarczyk M., Antonelli A., Bastieri D., Covino S., Galante N., 
La Barbera A., Longo F. and Scapin V. for the MAGIC collaboration

The MAGIC Imaging Atmospheric Cherenkov Telescope performed a follow-up 
observation of the BAT burst GRB080330 (GCN circular 7537, Mao et al.).
We received the GCN alert at 03:41:33 UT (T0+16s), data taking with MAGIC 
started at 03:42:47 UT (T0+91s), short after the prompt emission phase 
measured to be T90=61+/-9s. The observation was carried out at a zenith 
angle of 48 degrees. The observation continued for 1039s.

No evidence for VHE gamma-ray emission above the analysis threshold of
313 GeV was found. The observation was carried out in (less sensitive) 
moon-observation mode.

A preliminary analysis, for the hypothesis of steady emission and 
assumption of a differential photon spectral index of -2.5, yields the 
following 95% CL differential flux upper limits, including a 30% 
systematic uncertainty on the telescope efficiency:

E (175- 300 GeV): 0.36 * 10^-10 erg/cm^-2/s
E (300-1000 GeV): 0.49 * 10^-10 erg/cm^-2/s
for a time window from 03:42:47 UT to 03:59:01 UT

We can also exclude emission of a constant flux in any 100s time bin 
smaller than:

E (175- 300 GeV): 8.42 * 10^-10 erg/cm^-2/s
E (300-1000 GeV): 2.05 * 10^-10 erg/cm^-2/s
for a time window from 03:42:47 UT to 03:59:01 UT

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