GRB 090417A, GRB 090417
GCN Circular 9160
Subject
VLA observations of short burst GRB 090417A
Date
2009-04-19T13:23:35Z (17 years ago)
From
Poonam Chandra at U Virginia/NRAO <pc8s@virginia.edu>
P. Chandra (RMC) and D. A. Frail (NRAO) report on behalf of a larger
collaboration:
"We have used the Very Large Array (VLA) to image a field centered on
the 2MASS galaxy suggested by Fox (GCN #9134) to be a possible host of
the short duration burst 090417A (GCN # 9133, 9138). The VLA observed
the burst at a frequency of 8.46 GHz on two epochs, April 17.92 UT and
April 18.90 UT. Within a radius of 1.5 arcmin around the 2MASS galaxy
there are no radio sources detected at either epoch to a 4-sigma limit
of 104 uJy and 84 uJy, respectively. No further observations are planned.
The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc."
GCN Circular 9138
Subject
GRB 090417A: Swift-BAT refined analysis
Date
2009-04-17T19:50:47Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
W. H. Baumgartner (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (GSFC/UMBC),
E. E. Fenimore (LANL), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
V. Mangano (INAF-IASFPA), C. B. Markwardt (GSFC/UMD), D. M. Palmer (LANL),
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-119 to T+261 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090417A (trigger #349447)
(Mangano, et al., GCN Circ. 9133). The BAT ground-calculated position is
RA, Dec = 34.993, -7.141 deg which is
RA(J2000) = 02h 19m 58.3s
Dec(J2000) = -07d 08' 28.9"
with an uncertainty of 2.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 30%.
The mask-weighted light curve shows a single peak starting at T-0.06 sec,
peaking at T+0.04 sec, and ending at T+0.09 sec. There appears to be
no extended emmission out to T+55 sec, at which point the burst location
went out of the BAT FOV during a planned target slew. T90 (15-350 keV)
is 0.072 +- 0.018 sec (estimated error including systematics).
The time-averaged spectrum from T-0.0 to T+0.1 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index -0.65 +- 2.11,
and Epeak of 40.3 +- 12.7 keV (chi squared 67.41 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 1.9 +- 0.5 x 10^-8 erg/cm2
and the 1-sec peak flux measured from T-0.46 sec in the 15-150 keV band is
3.6 +- 1.0 ph/cm2/sec. A fit to a simple power law gives a photon index
of 2.99 +- 0.36 (chi squared 77.85 for 57 d.o.f.). 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/349447/BA/
GCN Circular 9137
Subject
GRB 090417A: Early-type nature of the putative host
Date
2009-04-17T17:35:29Z (17 years ago)
From
Josh Bloom at UC Berkeley <jbloom@astron.berkeley.edu>
J. S. Bloom (UC Berkeley), D. Fox (PSU), N. R. Tanvir, P. T. O'Brien
(U. Leicester), William Lee (UNAM), J. X. Prochaska (UCO/Lick) report:
We further note that the galaxy possibly associated (Fox GCN 9134)
with GRB 090417A (Mangano et al., GCN 9133) appears both visually and
spectrally to be of an early-type (smooth morphology, prominent Ca
H&K). In the 6df spectrum (O'Brien & Tanvir, GCN 9136), there is some
low-level H�� emission apparent suggesting some low-level star-
formation. However no other Balmer lines appear prominently detected
and there is no apparent [OIII] or [OII] as seen in the host galaxies
of essentially all long-soft GRB (LSB) hosts. Without a detailed
analysis, we classify this galaxy as a S0/lenticular or (more likely)
an elliptical. Given the connection of several other SHBs to
ellipticals at moderate redshift, we feel this identification can be
taken as weak observational support for a connection between this
galaxy and 090417A and further suggests that the burst was unlikely to
be due to an SGR flare-type event (O'Brien & Tanvir, GCN 9136). The
fact that the galaxy is at the edge of the BAT error circle does not
necessarily argue against it being the host: the offset from the
center of the circle, which amounts to ~320 kpc at this redshift, is
certainly within the range of plausible natal kicks of a compact
binary progenitor (~1 Gyr merger time for a 500 km/s kick).
GCN Circular 9136
Subject
GRB 090417A: nearby galaxy redshift
Date
2009-04-17T16:27:39Z (17 years ago)
From
Nial Tanvir at IofA U.Cambridge <nrt@ast.cam.ac.uk>
P. T. O'Brien and N. R. Tanvir (U. Leicester) report:
We note that the bright 2MASS galaxy at the edge of the BAT error
circle, pointed out by Fox (GCN 9134), has a spectrum measured as part
of the 6dF survey, which gives a redshift of z=0.088. This
corresponds to a luminosity distance of about 400 Mpc in standard
cosmology, which would be very large for an SGR giant flare, but quite
plausible for a short-GRB comparable in luminosity to several others
which have been seen at moderate redshifts.
The spectrum can be seen at the following link:
http://www-wfau.roe.ac.uk/6dFGS/cgi-bin/show.cgi?release=dr3&name=g0219477-071201&tid=-1&specid=123101
GCN Circular 9134
Subject
GRB 090417: 2MASS galaxy within BAT Localization
Date
2009-04-17T14:11:21Z (17 years ago)
From
Derek Fox at PSU <dfox@astro.psu.edu>
D. B. Fox (Penn State) reports:
"I note the presence of a bright (J_tot=13.4 mag) galaxy, 2MASX
J02194771-0712008, within the BAT localization region of the
Swift-detected short burst GRB 090417 (Mangano et al., GCN 9133).
Considering the average sky density of 2MASS extended source catalog
objects of this magnitude or brighter, the presence of such a galaxy
within a region of 3-arcmin radius is suggestive at roughly
97%-confidence."
GCN Circular 9133
Subject
GRB 090417: Swift detection of a short burst
Date
2009-04-17T13:37:57Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
V. Mangano (INAF-IASFPA), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), D. N. Burrows (PSU),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
C. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),
E. A. Hoversten (PSU), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), N. P. M. Kuin (MSSL),
C. B. Markwardt (CRESST/GSFC/UMD), F. E. Marshall (NASA/GSFC),
J. P. Osborne (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), M. Perri (ASDC), P. Romano (INAF-IASFPA),
B. A. Rowlinson (U Leicester), B. Sbarufatti (INAF-IASFPA),
M. C. Stroh (PSU), T. N. Ukwatta (GSFC/GWU), L. Vetere (PSU) and
H. Ziaeepour (UCL-MSSL) report on behalf of the Swift Team:
At 13:17:23 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090417 (trigger=349447). Swift did not slew immediately
due to a Sun constraint.
The BAT on-board calculated location is
RA, Dec 34.995, -7.181 which is
RA(J2000) = 02h 19m 59s
Dec(J2000) = -07d 10' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 0.1 sec. The peak count rate
was ~3200 counts/sec (15-350 keV), at ~0 sec after the trigger.
Due to an observing constraint, Swift cannot slew to the BAT position.
There will thus be no XRT or UVOT data for this trigger. This location
will not come out of constraint until 02 Jun 2009.
Burst Advocate for this burst is V. Mangano (vanessa AT ifc.inaf.it).
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.)