GRB 090916
GCN Circular 9913
Subject
GRB 090916: Swift detection of a short burst
Date
2009-09-16T07:30:36Z (16 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
E. Troja (NASA/GSFC/ORAU), A. P. Beardmore (U Leicester),
E. A. Hoversten (PSU), H. A. Krimm (CRESST/GSFC/USRA),
C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
P. Romano (INAF-IASFPA), A. Rowlinson (U Leicester) and
M. H. Siegel (PSU) report on behalf of the Swift Team:
At 07:00:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090916 (trigger=362818). Swift did not slew to the GRB
due to a Moon constraint. The BAT on-board calculated location is
RA, Dec 126.579, +25.933 which is
RA(J2000) = 08h 26m 19s
Dec(J2000) = +25d 55' 60"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single
short spike structure with a duration of about ~0.4 sec, followed
by ~8 seconds of low-energy emission. The peak count rate
was ~2500 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift cannot immediately slew to
the BAT position. There will thus be no XRT or UVOT data for this
trigger until later today.
Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/too.html.)
GCN Circular 9915
Subject
GRB 090916, Swift-BAT refined analysis
Date
2009-09-16T12:54:14Z (16 years ago)
From
Hans Krimm at NASA-GSFC <hans.a.krimm@nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), J. R. Cummings
(GSFC/UMBC),
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),
E. Troja (GSFC/ORAU), J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-239 to T+963 sec from the recent telemetry
downlink,
we report further analysis of the short BAT GRB 090916 (trigger #362818)
(Troja, et al., GCN Circ. 9913). The BAT ground-calculated position is
RA, Dec = 126.582, 25.941 deg which is
RA(J2000) = 08h 26m 19.6s
Dec(J2000) = +25d 56' 27.3"
with an uncertainty of 2.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 34%.
The mask-weighted light curve consisted of a single peak of 0.32 sec
duration
starting at T-0.128 sec, followed by low-level emission extending out to
about
T+70 sec. T90 (15-350 keV) is 63.4 +- 15.2 sec (estimated error including
systematics).
The time-averaged spectrum from T-0.0 to T+68.5 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.42 +- 0.33. The total fluence in the 15-150 keV band is
9.5 +- 1.8 x 10-7 erg/cm2. The peak second starting from T-0.036 sec is
best fit by a simple power-law model. The power law index of the peak-second
spectrum is 1.41 +- 0.28. The 1-sec peak fluence in the 15-150 keV band is
1.5 +- 0.26 x 10-7 erg/cm2. The 1-sec peak photon flux in the
15-150 keV band is 1.9 +- 0.3 ph/cm2/sec. All the quoted errors are at the
90% confidence level.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/362818/BA/
GCN Circular 9921
Subject
Short-Duration GRB 090916: Skynet/PROMPT Observations
Date
2009-09-17T02:52:44Z (16 years ago)
From
Josh Haislip at U.North Carolina <haislip@physics.unc.edu>
J. Haislip, D. Reichart, K. Ivarsen, A. LaCluyze, A. Foster, J. Moore, A.
Oza, M. Schubel, J. Styblova, A. Trotter, J. A. Crain, and M. Nysewander
report:
Skynet observed the Swift/BAT localization of short-duration GRB 090916
(Troja et al., GCN 9913) with four of the 16" PROMPT telescopes at CTIO
beginning 2.6 hours after the trigger in UVRI through high airmass.
We do not detect any uncatalogued sources. Stacking only images that
increase the limiting magnitude yields:
mean 1-sig. 1-sig.
time 3-sig. sys. stat.
since lim. cal. cal. cal.
trig. tel. exp. fil. mag. stars* unc. unc.
(h) (# x s) (mag) (mag)
2.7 PROMPT-3 6 x 80 U 17.7 14 SDSS 7 1.137 0.011
2.7 PROMPT-2 6 x 80 V 18.8 88 SDSS 7 0.020 0.001
2.7 PROMPT-5 6 x 80 I 18.6 56 SDSS 7 0.073 0.000
2.7 PROMPT-4 6 x 80 R 19.4 44 SDSS 7 0.005 0.000
* Transformed using Jester et al., 2005, ApJ, 130, 873.
GCN Circular 9925
Subject
GRB 090916: Swift-XRT upper limit
Date
2009-09-18T15:44:29Z (16 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A. P. Beardmore, K. L. Page (U. Leicester) and E. Troja (NASA/GSFC/ORAU)
report on behalf of the Swift-XRT team :
Due to a Moon constraint, the Swift-XRT could not observe the field of
the BAT short GRB 090916 (Troja et al., GCN Circ. 9913) until 9.3
hours after the trigger. In 12.3 ks of Photon Counting mode data (from
33.5 to 126.6 ks after the trigger) we do not detect any source
within the BAT refined error circle of Barthelmy et al. (GCN Circ. 9915).
The 3 sigma upper limit 0.3-10 keV count rate is 8 x 10^-4 count s^-1,
which corresponds to an observed flux limit of 3 x 10^-14 erg cm^-2 s^-1
(assuming a typical count-to-observed flux conversion factor of
3.8 x 10^-11 erg cm^-2 ct^-1, Evans et al., 2009, MNRAS, 397, 1177).
This circular is an official product of the Swift-XRT team.