GRB 090621A
GCN Circular 9763
Subject
GRB 090621A: MAGIC telescope GeV observation
Date
2009-08-11T07:00:09Z (16 years ago)
From
Markus Garczarczyk at MPI/MAGIC <garcz@mppmu.mpg.de>
Carosi A. (INAF Rome), Gaug M. (IAC Tenerife),
Antonelli L.A. (INAF Rome), Bastieri D. (Univ. Padova),
Becerra Gonzalez J. (IAC Tenerife), Covino S. (INAF Rome),
Galante N. (MPI Munich), Garczarczyk M. (IFAE Barcelona),
La Barbera A. (INAF Palermo), Longo F. (INFN Trieste),
Scapin V. (Univ. Udine) and Spiro S. (INAF Rome)
for the MAGIC collaboration
The MAGIC Imaging Atmospheric Cherenkov Telescope performed a follow-up
observation of the BAT burst GRB090621A (Curran et al., GCN Circ. 9540).
The burst was also triggered by Fermi-GBM (Arne Rau, GCN Circ. 9556)
We received the GCN alert at 04:23:38 UT (T0+55s). Data taking with MAGIC
started at 04:36:18 UT (T0+815s), when the GRB zenith angle reached
46 degrees. The observation continued for 1833 s.
No evidence for VHE gamma-ray emission above the analysis threshold
of 196 GeV was found. The observation was carried out in twilight
condition.
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): 0.25 * 10^-10 erg cm^-2 s^-1
E(300 - 1000 GeV): 0.10 * 10^-10 erg cm^-2 s^-1
for the whole time of observation (from 04:36:18 UT to 05:06:51 UT).
We can also exclude emission of a constant flux in any 100s time bin
smaller than:
E(175 - 300 GeV): 2.74 * 10^-10 erg cm^-2 s^-1
E(300 - 1000 GeV): 1.01 * 10^-10 erg cm^-2 s^-1
for a time window from 04:36:18 UT to 05:06:51 UT
This message can be cited.
GCN Circular 9567
Subject
GRB 090621A: Enhanced Swift-XRT position
Date
2009-06-24T09:24:00Z (16 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K.L. Page, P.A. Evans and M.R. Goad (U. Leicester) report
on behalf of the Swift-XRT team:
Using 5877 s of XRT Photon Counting mode data and 11 UVOT
images, we find an astrometrically corrected X-ray position (using the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1
catalogue): RA, Dec = 11.02150, 61.94110 which is equivalent to:
RA (J2000): 00 44 5.16
Dec (J2000): +61 56 28.0
with an uncertainty of 1.4 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, arXiv:0812.3662).
This circular is an official product of the Swift-XRT team.
GCN Circular 9564
Subject
GRB 090621A: GRT Optical Observation
Date
2009-06-23T02:08:36Z (16 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori.sakamoto-1@nasa.gov>
T. Sakamoto (UMBC/GSFC), D. Donato (ORAU/GSFC), N. Gehrels (GSFC),
T. Okajima (JHU/GSFC), T.N. Ukwatta (GWU/GSFC), Y. Urata (NCU),
C.A. Wallace (FGCU)
We observed the field of GRB 090621A detected by Swift
(trigger #355303; Curran et al., GCN #9540) with the 14-inch
Goddard Robotic Telescope (GRT) located at the Goddard Geophysical
and Astronomical Observatory (http://cddisa.gsfc.nasa.gov/ggao/).
100 set of 30 sec exposures were taken in the R filter starting
from June 21 05:00:15 (UT) about 37.3 min after the trigger and
stopped on June 21 05:56:22 (UT). We do not detect the optical
afterglow both in the individual images and the combined image
inside the XRT position (Page et al., GCN #9543). The estimated
three sigma upper limit of the combined image (total exposure
of 2850 sec; excluding five bad quality images) is ~17.9 mag using
the USNO-B1 catalog.
GCN Circular 9546
Subject
GRB 090621A: Swift-BAT refined analysis
Date
2009-06-22T01:14:19Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
P.A. Curran (MSSL-UCL), E. E. Fenimore (LANL), N. Gehrels (GSFC),
H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
A. M. Parsons (GSFC), T. Sakamoto (GSFC/UMBC), G. Sato (ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090621A (trigger #355303)
(Curran, et al., GCN Circ. 9540). The BAT ground-calculated position is
RA, Dec = 10.987, 61.938 deg, which is
RA(J2000) = 00h 43m 56.8s
Dec(J2000) = +61d 56' 17.6"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 77%.
The mask-weighted light curve shows two small precursor peaks starting
at ~T-30 sec, peaking at ~T-20 and T+10 sec, and returning to background
at ~T+100 sec. Then the mmain emission starts at ~T+210 sec, peaks at ~T+240
and T+265 sec, and returns to background around T+350 sec.
T90 is not possible because of a lack of the complete set of event by event
data set for this burst. This also prevents giving spectral results.