GRB 090515
GCN Circular 9385
Subject
GRB 090515: Swift/BAT spectral lag results
Date
2009-05-17T19:35:45Z (17 years ago)
From
Tilan Ukwatta at GSFC/GWU <tilan.ukwatta@gmail.com>
T. N. Ukwatta (GWU/GSFC), J. Norris (U. Denver), N. Gehrels (GSFC),
S. D. Barthelmy (GSFC) (for the Swift-BAT team):
For GRB 090515 (Beardmore et al. GCN 9356), the BAT team has analyzed
spectral lags for the data from T-0.05 sec to T+0.1 sec using non-mask
weighted light curves with 1 msec time binning. The spectral lags
were measured between standard canonical BAT energy bands: channel 1
(15-25 keV), 2 (25-50 keV), 3 (50-100 keV) and 4 (100-350 keV) are
given below.
Lag Ch3-Ch1 : 3.9 (+2.4, -2.1) msec
Lag Ch3-Ch2 : 3.0 (+1.0, -1.0) msec
Lag Ch4-Ch2 : 2.8 (+1.1, -1.4) msec
Lag Ch4-Ch3 : 1.0 (+1.0, -1.0) msec
Furthermore, Bayesian block analysis, on the light curve time range
from T+10 sec to T+230, yields that there is no apparent
extended emission for this burst.
GCN Circular 9373
Subject
GRB 090515: VLA observations
Date
2009-05-16T04:32:00Z (17 years ago)
From
Edo Berger at Harvard <eberger@cfa.harvard.edu>
E. Berger and W.-f. Fong (Harvard) report:
"We observed the field centered on the XRT error circle of the short GRB
090515 (GCNs #9356,9367) with the VLA at a frequency of 8.46 GHz
starting on 2009 May 16.066 UT (20.8 hours post burst). We do not
detect any sources within the XRT error circle to a 3-sigma limit of 60
microJy."
GCN Circular 9372
Subject
GRB 090515: Lick Upper Limits
Date
2009-05-15T23:42:40Z (17 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, M. Kislak, and M. Ganeshalingam (UC Berkeley) report:
We imaged the field of short GRB 090515 (Beardmore et al., GCN 9356)
with the Nickel 40-inch telescope at Lick Observatory starting at
04:52:57 UT (7.8 minutes after the trigger) in BVRI filters. No object
is detected within the XRT error circle (Osborne et al., GCN 9367) in
any exposure or in stacked frames. Approximate upper limits (relative
to SDSS):
tmid(min) exp(sec) filt lim(mag)
8.3 60 B > 19.9
10.0 60 V > 20.5
22.5 720 I > 20.3
38.1 600 R > 21.3
GCN Circular 9371
Subject
GRB 090515: ROVOR Upper Limit
Date
2009-05-15T23:34:03Z (17 years ago)
From
J. Ward Moody at BYU <rovor.byu@gmail.com>
Cameron J. Pace, Richard L. Pearson, and J. Ward Moody report for
Brigham Young University�s ROVOR team:
We report our observations in the field of GRB 090515 (Swift trigger
352108, Beardmore et al., GCN 9356) beginning 37.73 minutes post-burst
at 05:22:53.376 UT.
Using the 0.41m ROVOR telescope in Delta, Utah, we combined 70 x 60
second exposures in the R-band. No detection of an afterglow was
obtained after stacking the images. An upper limit of 21.4 � 0.1 mag
was found by calibrating the frames using stars in the MRK 501 field.
GCN Circular 9370
Subject
GRB 090515: MMT/MMIRS NIR Upper Limit
Date
2009-05-15T22:59:17Z (17 years ago)
From
Grant Williams at Steward Observatory <ggwilli@gmail.com>
B. McLeod (CfA), G. Williams (MMTO) on behalf of the MMIRS
commissioning team report:
We observed the field of GRB 090515 (Beardmore et al. 2009, GCN 9356)
with the MMIRS instrument on the 6.5-m MMT telescope. �Observations
began at 06:44 UT, approximately 119 minutes after the Swift trigger.
We obtained 27 x 30 second exposures in the K-band. �We do not detect
any afterglow candidate in the XRT error circle in the combined image
to the following 5-sigma limiting magnitude determined using nearby
2MASS stars:
t_start (UT) � � exp t (s) � � t_start-t_0 � � Limit
-----------------------------------------------------------
06:44 � � � �27x30 � � � � � � �119 min � � �K > 19.3
GCN Circular 9369
Subject
GRB 090515: Swift/UVOT Observations
Date
2009-05-15T20:10:18Z (17 years ago)
From
Michael Siegal at Swift/PSU <siegel@astro.psu.edu>
M. H. Siegel (PSU) and A. P. Beardmore (Leicester) report on behalf
of the Swift/UVOT team.
The Swift/UVOT began observing the field of GRB 090515 67s after
the BAT trigger (Beardmore et al., GCN Circ. 9356). Data summed
from the first and second orbits does not reveal a source at the
refined position of the X-ray afterglow (Osborne et al., GCN Circ.
9367).
The 3-sigma upper limits for the finding chart (fc) and
summed exposures are reported below:
FILTER T_start(s) T_stop Exposure Mag/3UL
=============================================================
white fc 67 216 146 > 20.35
white 67 2389 488 > 21.24
white 5901 13321 401 > 21.12
v 608 2439 213 > 19.27
v 6311 7947 393 > 19.62
b 534 2365 194 > 20.15
b 5696 13291 688 > 20.70
u 278 528 245 > 19.83
u 6926 12386 491 > 20.40
uvw1 657 2488 214 > 19.83
uvw1 6722 8290 327 > 20.01
uvm2 805 2291 97 > 19.07
uvm2 6516 8151 393 > 20.16
uvw2 583 2414 213 > 20.11
uvw2 6107 7742 393 > 20.48
=================================================================
The above magnitudes are not corrected for the Galactic extinction
corresponding to a reddening of E_{B-V} = 0.02 (Schlegel et al.,
1998, ApJS, 500, 525). The photometry is on the UVOT photometric
system described in Poole et al. (2008, MNRAS, 383, 627).
GCN Circular 9368
Subject
GRB 090515: Swift-XRT refined analysis
Date
2009-05-15T18:58:27Z (17 years ago)
From
Andy Beardmore at U Leicester <apb@star.le.ac.uk>
A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the
Swift-XRT team :
We have analysed 4.5 ks of XRT data for GRB 090515 (Beardmore et
al. GCN Circ. 9356), from 70 s to 11.5 ks after the BAT trigger. The
data comprise 132 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this
burst was given by Osborne et al. (GCN Circ. 9367).
Initially, the light curve follows a shallow decay from a rate of 30
count s^-1 (at T+70 s), with a decay index of 0.59, out to
approximately T+245 s. The count rate then drops by a factor of
~250 in the next ~70 s (i.e. suggesting a decay index in excess of 10
at this time). The burst is no longer detected beyond the first orbit
to a 3 sigma count rate upper limit of 0.0058 count s^-1 (from T+5.7
to T+11.5 ks).
A spectrum formed from the WT mode data (from T+70 to T+195 s) can be
fitted with an absorbed power-law with a photon spectral index of
1.88 +/- 0.14. The best-fitting absorption column is (6.1 +3.0 -2.8) x
10^20 cm^-2, in excess of the Galactic value of 1.9 x 10^20 cm^-2
(Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV
flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.1
x 10^-11) erg cm^-2 count^-1.
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00352108.
This circular is an official product of the Swift-XRT team.
GCN Circular 9367
Subject
GRB 090515: Enhanced Swift-XRT position
Date
2009-05-15T16:44:21Z (17 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2254 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 090515, 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 = 164.15047, +14.44174 which is equivalent
to:
RA (J2000): 10h 56m 36.11s
Dec (J2000): +14d 26' 30.3"
with an uncertainty of 2.7 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 was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 9365
Subject
GRB 090515: Swift-BAT refined spectral analysis
Date
2009-05-15T15:29:10Z (17 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori.sakamoto-1@nasa.gov>
T. Sakamoto (GSFC/UMBC), A. P. Beardmore (U Leicester)
on behalf of the Swift-BAT team
Based on a further analysis of the BAT spectrum of GRB 090515
(Barthelmy, et al. , GCN Circ. 9364), we found that the spectrum shows
a significant improvement of chi2 by a power-law with an exponential
cutoff (chi squared 52.55 for 56 d.o.f.) over a simple power-law
(chi squared 58.63 for 57 d.o.f.). This fit gives a photon index
-0.05 +- 1.36, and Epeak of 64 +- 23 keV. For this model
the total fluence in the 15-150 keV band is 2.0 +- 0.3 x 10^-8 erg/cm2.
All the quoted errors are at the 90% confidence level.
GCN Circular 9364
Subject
GRB 090515: Swift-BAT refined analysis
Date
2009-05-15T12:44:58Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
A. P. Beardmore (U Leicester), 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), 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 sets from T-60 to T+243 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 090515 (trigger #352108)
(Beardmore, et al., GCN Circ. 9356). The BAT ground-calculated position is
RA, Dec = 164.166, 14.469 deg, which is
RA(J2000) = 10h 56m 39.8s
Dec(J2000) = +14d 28' 09.5"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 86%.
The mask-weighted light curve shows a single peak with a slightly longer
fall time than rise time. The total width is about 0.075 sec.
T90 (15-350 keV) is 0.036 +- 0.016 sec (estimated error including systematics).
The time-averaged spectrum from T+0.008 to T+0.056 sec is best fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.6 +- 0.2. The fluence in the 15-150 keV band is
2.1 +- 0.4 x 10^-8 erg/cm2. The 1-sec peak photon flux measured from
T-0.30 sec in the 15-150 keV band is 5.7 +- 0.9 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/352108/BA/
GCN Circular 9362
Subject
GRB 090515: Gemini-N upper limit
Date
2009-05-15T09:00:11Z (17 years ago)
From
Antonino Cucchiara at PSU <cucchiara@astro.psu.edu>
A. Cucchiara, D. B. Fox (PSU), N. Tanvir (U. Leicester), E. Berger
(Harvard U.),
John Graham (STScI / JHU) and A. Levan (U. Warwick) report:
On May 15.28 UT we observed the field of the short GRB 090515 (Beardmore
at al,
GCN 9356) with Gemini GMOS-N. We took a sequence of 6 images of 300 sec
each in R band.
No clear afterglow candidate has been found in the XRT error circle (GCN
9356)
at the limiting magnitude of R ~ 25.4.
We also note the presence of a galaxy on the north edge of the XRT error
circle,
at the following position:
RA: 10:56:36.46
Dec: +14:26:31.91
with a 0.3 arcsecond error in both coordinates.
The magnitude of this galaxy is R = 22.90 +- 0.18 (calibrated using the
SDSS star
at RA = 10:56:35.74 , Dec = 14:26:49.6).
We thank the Gemini staff for performing these observations.
GCN Circular 9361
Subject
GRB 090515: WIYN NIR Upper Limit
Date
2009-05-15T08:47:58Z (17 years ago)
From
Adria C. Updike at Clemson U <aupdike@clemson.edu>
Adria C. Updike, Ginger Bryngelson (Clemson University) and Peter A. Milne
(Steward Observatory) report:
We observed the field of GRB 090515 (GCN 9356, Beardmore et al.) with the
3.5m WIYN telescope and the NIR imager WHIRC located at Kitt Peak National
Observatory beginning 1 hour after the trigger. Observations consisted
of J-band exposures at high airmass. In a stacked image consisting of 20
x 2min J-band exposures (T_0 = 1.4 hours after trigger), we detect no new
objects down to a limiting magnitude of J > 19.0 mag (upon comparison to
the 2MASS catalog). No further observations are planned.
GCN Circular 9360
Subject
GRB 090515: Super-LOTIS Upper Limits
Date
2009-05-15T08:00:24Z (17 years ago)
From
Grant Williams at Steward Observatory <ggwilli@gmail.com>
G. G. Williams (MMTO), A. Updike (Clemson), and P. A. Milne (Steward
Observatory), on behalf of the Super-LOTIS Collaboration, report:
The robotic 0.6-m Super-LOTIS telescope began observing the error box
of GRB 090515 (Swift Trigger 352108, Beardmore et al. GCN 9356) at
04:45:52 UT, 43 seconds after the trigger. Our initial observations
include 5 x 10s exposures, 5 x 20s exposures, and 30 x 60s exposures,
all in the R-band.
We do not detect any variable sources or afterglow candidates within
the XRT error box in our earliest exposure to the following 3-sigma
limiting magnitude determined using nearby USNO-B1.0 stars. We also
do not detect any afterglow candidate in later images and sets of
combined images:
t_start (UT) exp t (s) t_start-t_0 (s) Limit
----------------------------------------------------------------
04:45:52 10 43 R > 17.7
GCN Circular 9359
Subject
GRB 090515: PAIRITEL Upper Limits
Date
2009-05-15T06:42:34Z (17 years ago)
From
Adam Morgan at PSU/Swift-UVOT <qmorgan@gmail.com>
A. N. Morgan, B. E. Cobb, C. Klein, and J. S. Bloom (UC Berkeley) report:
We observed the field of GRB 090515 (Beardmore et al. 2009, GCN 9356)
with the 1.3-m PAIRITEL located at Mt Hopkins, Arizona. Observations
began at 2009-05-15 05:11 UT, 26 minutes after the Swift Trigger. We
detect no afterglow at the XRT position in a mosaic with an effective
exposure time of ~330 seconds.
The preliminary photometry (calibrated to 2MASS) yields:
post_burst
t_mid(min) exp(s) filt U. Limit (3 sig)
30 330 J > 18.0
30 330 H > 17.2
30 330 K > 15.1
All magnitudes are given in the Vega system. No correction for
Galactic extinction has been made to the above reported values.
GCN Circular 9358
Subject
GRB 090515: KAIT optical upper limits
Date
2009-05-15T05:57:53Z (17 years ago)
From
Ryan Chornock at UC Berkeley <chornock@astro.berkeley.edu>
W. Li, R. Chornock, and A. V. Filippenko (UC Berkeley) report on
behalf of the KAIT GRB team:
The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory responded to
the Swift trigger of GRB 090515 (Beardmore et al., GCN 9356) and began a
sequence of filtered and unfiltered 20s images followed by a set of three 180s
unfiltered images. We detect no new source within the XRT error circle
(Beardmore et al., GCN 9356). Individual unfiltered 20s exposures starting at
04:59:09 UT have 3-sigma limiting magnitudes (calibrated to USNO B1) of about
mag 19.1. Our combined set of 3x180s unfiltered images has an upper limit of
about mag 20.5 at a midpoint of 05:19:47 UT.
GCN Circular 9357
Subject
GRB 090515: ROTSE-III Optical Limits
Date
2009-05-15T05:08:31Z (17 years ago)
From
Wiphu Rujopakarn at U AZ/Steward <wiphu@as.arizona.edu>
W. Rujopakarn (Steward Observatory), B. E. Schaefer (Louisiana State), and
E.S. Rykoff (UCSB), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
090515 (Swift trigger 352108; Beardmore et al., GCN 9356), producing
images beginning 6.5 s after the GCN notice time. An automated response
took the first image at 04:45:27.5 UT, 18.0 s after the burst, under fair
conditions. We took 10 5-sec and 10 20-sec exposures. These unfiltered
images are calibrated relative to USNO A2.0 (R). Imaging is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle or the XRT error circle, for both single
images and coadding into sets of 10. Individual images have limiting
magnitudes ranging from 16.4-17.8; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
04:45:27.5 04:45:32.5 5 16.4 18.0 N
04:45:27.5 04:46:34.6 67 18.4 18.0 Y
GCN Circular 9356
Subject
GRB 090515: Swift detection of a short burst
Date
2009-05-15T04:56:51Z (17 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. P. Beardmore (U Leicester), J. A. Kennea (PSU),
C. B. Markwardt (CRESST/GSFC/UMD), P. T. O'Brien (U Leicester),
K. L. Page (U Leicester), D. M. Palmer (LANL),
B. A. Rowlinson (U Leicester), M. H. Siegel (PSU),
M. Stamatikos (NASA/ORAU) and T. N. Ukwatta (GSFC/GWU) report on
behalf of the Swift Team:
At 04:45:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090515 (trigger=352108). Swift slewed immediately to the burst.
The BAT on-board calculated location is RA, Dec 164.171, +14.456 which is
RA(J2000) = 10h 56m 41s
Dec(J2000) = +14d 27' 22"
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 0.1 sec. The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 04:46:13.3 UT, 63.8 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 164.15224, 14.44099 which
is equivalent to:
RA(J2000) = 10h 56m 36.54s
Dec(J2000) = +14d 26' 27.6"
with an uncertainty of 4.8 arcseconds (radius, 90% containment). This
location is 84 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of
1.94e+20 cm^-2 (Kalberla et al. 2005).
The initial flux in the 2.5 s image was 5.22e-10 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 72 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.02.
Burst Advocate for this burst is A. P. Beardmore (apb AT star.le.ac.uk).
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.)