GRB 110625A
GCN Circular 12113
Subject
GRB 110625A, the review of the sky area in plate archives
Date
2011-07-08T10:03:08Z (14 years ago)
From
Valentyna Golovnya at Main Astro Obs,Kyiv <golov_v@ukr.ne>
V.V. Golovnya (Main Astro Obs, Kyiv)
report:
We have undertaken the review of the sky area in vicinity of
GRB 110625A (K.L.Page GCN Circ.12092) on astronegatives,
collected in Ukrainian NAS Main astronomical observatory
plate archive (1976-1996). All the plates with the possible
object appearance are digitized using Microtek ScanMaker
9800XL TMA and Epson Expression 10000XL flatbed scanners and
have been placed into Golosiiv Plate Archive database DBGPA
with open access to them.
The list of plates is given in the table:
YYYYMMDD TimeUT --Plates-- Exp. LimMag Star USNOA2
19770902.184249 GUA040C000707B 47.0 15.00 0900-13913512
19770902.184249 GUA040D000708 47.0 15.45 0900-13913709
19900627.223953 GUA040C001670A 18.0 15.45 0900-13913709
19910612.234249 GUA040C001797 22.5 15.00 0900-13913512
19910615.232702 GUA040C001810 22.5 15.00 0900-13913512
19910719.204216 GUA040C001841 22.5 16.20 0900-13907267
19921130.153019 GUA040C000153B 20.0 12.75 0900-13888502
19921201.154830 GUA040D000160 05.5 12.75 0900-13888502
19921201.154840 GUA040C000161B 15.3 12.75 0900-13888502
19921201.162733 GUA040C000163B 15.0 13.20 0900-13901311
19940714.214044 GUA040C002338 20.5 15.45 0900-13913709
Plates-the plate's identifier in GUA040C and GUA040D archives
of DWA (D/F=400/2000, M=103"/mm) of the Ukrainian NAS
Main Astro obs in Kyiv (Marsden's number - 83)[1].
Exp. - Duration of the maximum exposure (minutes).
LimMag - Limited V mag, derived in the 15 minutes area around
the location given in Page GCN Circ.12092:
RA(J2000): 19h 06m 55.85s, Dec(J2000): +06d 45' 19.2"
Star USNOA2 - Comparison star.
The preview images of 11 areas together with
the 15x15 min.of arc area from SkyMap can be found in
http://gua.db.ukr-vo.org/img/grb/110625A/index.html
The images with full resolution are available via e-mail on
demand.
References:
1.L.Pakuliak DATABASE of GOLOSIIV PLATE ARCHIVE (DBGPA V2.0),
http://gua.db.ukr-vo.org
GCN Circular 12102
Subject
GRB 110625A: Suzaku WAM observation of the prompt emission
Date
2011-06-30T01:17:50Z (14 years ago)
From
Takeshi Uehara at Hiroshima U <uehara@hirax7.hepl.hiroshima-u.ac.jp>
M. Mizuno, T. Uehara, Y. Hanabata, T. Takahashi, M. Ohno, Y. Fukazawa (Hiroshima U.),
S. Sugita (Nagoya U.), K. Yamaoka (Aoyama Gakuin U.), N. Vasquez (Tokyo Tech.),
Y. Terada, M. Tashiro, W. Iwakiri, K. Takahara, T. Yasuda (Saitama U.),
M. Kokubun, T. Takahashi (ISAS/JAXA),
Y. E. Nakagawa (Waseda U.), N. Ohmori, M. Akiyama, M. Yamauchi (Univ.of Miyazaki),
Y. Urata, P. Tsai, C-J. Chuang (NCU), K. Nakazawa, K. Makishima (Univ.of Tokyo),
on behalf of the Suzaku WAM team, report:
The bright GRB 110625A (Swift/BAT trigger #456073 ; Page et el., GCN 12088 ; Fermi/LAT detection ; Tam and Kong GCN 12097, Gruber et al., GCN 12100)
triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 2011-06-25 21:08:22.01 UT (=T0).
The observed light curve shows a multi-peaked structure (starting at T0-1s, ending
at T0+28s) with a duration
(T90) of about 24 seconds. The fluence in 100 - 1000 keV was 2.54 (+/-0.09) x 10^-05 erg/cm^2.
The 1-s peak flux measured from T0+20s was 13.6 (+/-1.0) photons/cm^2/s in the same energy range.
Preliminary result shows that the time-averaged spectrum from T0-1s to
T0+28s is well fitted by a single power-law with a photon index of 2.26 (+/- 0.09) (chi^2/d.o.f = 31.7/24).
However, there might be some calibration
uncertainties in the flux value because GRB photons came to the WAM detector by passing through the large Ne dewar of the X-ray micro-calorimeter (XRS).
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves for this burst are available at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
GCN Circular 12100
Subject
GRB 110625A: Fermi GBM and LAT observations
Date
2011-06-27T21:24:51Z (14 years ago)
From
David Gruber at MPE <dgruber@mpe.mpg.de>
David Gruber (MPE), Nicola Omodei (Stanford U.), Vandiver Chaplin (UAH),
J. Chiang (KIPAC/SLAC), J. McEnery (NASA/GSFC), J. L. Racusin (NASA/GSFC)
report on behalf of the Fermi GBM and LAT Teams:
At 21:08:18.24 UT on 25 June 2011, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 110625A (trigger 330728900 / 110625881), which
was also detected by the Swift/BAT (Page et al. 2011, GCN 12088). The GBM
on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 88 degrees at the trigger time.
Moreover, this burst was bright enough to result in a Fermi spacecraft
autonomous rapid repoint (ARR) maneuver.
This burst was also independently detected by INTEGRAL SPI-ACS.
The GBM light curve shows several pulses with a duration (T90) of about
27.7 +/- 1.4 s (50-300 keV). The time-averaged spectrum from T0-2.048 s
to T0+60.417 s is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.95 +/- 0.01 and the cutoff
energy, parameterized as Epeak, is 209 +/- 3 keV.
The event fluence (10-1000 keV) in this time interval is
(6.71 +/- 0.02)E-05 erg/cm^2. The 1-sec peak photon flux measured starting
from T0+23.9 s in the 10-1000 keV band is 77.3 +/- 0.7 ph/s/cm^2.
A Band function fits the spectrum equally well with Epeak= 175 +/- 5 keV,
alpha = -0.85 +/- 0.02 and beta = -2.37 +/- 0.05.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.
The ARR maneuver put the GRB inside the Fermi/LAT field of view
for several hundred seconds (from ~100-600 seconds after the GBM trigger).
The Spacecraft continued its maneuver toward the Fermi GBM flight software
reconstructed position, that was off by 68 degrees from the Enhanced Swift/XRT
position (GCN 12092), providing non-optimal exposure for LAT follow-up
observations.
We analyzed the LAT data and we see significant high-energy emission from a
point source coincident with the XRT position, confirming the already
reported results by P.H.T. Tam and A.K.H. Kong (GCN 12097).
We model the source spectrum with a power law model N(e) = N0 e^{\beta}, and
the background including both the contribution from the Galactic diffuse
emission and the isotropic contribution due to the residual contamination of
charged particles.
We detect the GRB in two distinct time periods. In the first time bin (from
237.1 seconds to 316.2 seconds after the GBM trigger), we measure a flux
(100 MeV-10 GeV) of (4.9 +/- 1.9) x 1e-05 ph/cm^2/s and a spectral index beta
of -2.1 +/- 0.3, with a Test Statistic TS=31.
In the second time bin, from 421.7 to 562.3 seconds after the GBM trigger,
the measured flux is (3.7 +/- 1.5) x 1e-5 ph/cm^2/s with spectral index beta
of -3.6 +/- 0.8 and a TS=19 (stat errors only).
The Fermi LAT point of contact for this burst is Nicola Omodei (nicola.omodei@gmail.com).
The Fermi LAT is a pair conversion telescope designed to cover the energy band
from 20 MeV to greater than 300 GeV. It is the product of an international
collaboration between NASA and DOE in the U.S. and many scientific institutions
across France, Italy, Japan and Sweden.
GCN Circular 12099
Subject
GRB 110625A: Swift/UVOT Upper Limits
Date
2011-06-27T19:57:15Z (14 years ago)
From
Stephen Holland at USRA/NASA/GSFC/SSC <Stephen.T.Holland@nasa.gov>
S. T. Holland (CRESST/USRA/GSFC) and K. L. Page (U Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT observed the field of GRB 110625A starting 127 s
after the BAT trigger (Page et al., 2011, GCNC 12088). Settled
observations started at 205 s. We do not detect an optical afterglow
(or the source reported by Im et al., 2011, GCNC 12095) at the
UVOT-enhanced XRT position (Page, et al., 2011, GCNC 12092) in any of
the UVOT filters. Preliminary 3-sigma upper limits for detecting a
source in the finding charts and in the co-added images, are
Filter TSTART TSTOP Exposure Mag
------------------------------------------------
u (FC) 205 455 246 >20.7
858 1008 147 >20.4
v 511 1233 97 >19.5
b 460 1332 117 >20.6
u 205 1307 471 >21.1
uvw1 560 1282 78 >19.5
uvm2 535 703 39 >18.4
uvw2 486 1339 98 >19.8
------------------------------------------------
The quoted magnitudes and upper limits have not been corrected
for the large, but uncertain, Galactic extinction along the line of
sight to this burst (E_{B-V} = 10.52 mag, Schlegel et al. 1998, ApJS,
500, 525).
GCN Circular 12098
Subject
GRB 110625A: 1.23m CAHA I-band observations
Date
2011-06-26T23:50:14Z (14 years ago)
From
Javier Gorosabel at IAA-CSIC <jgu@iaa.es>
J. Gorosabel (IAA-CSIC), V. Terron (IAA-CSIC), P. Ferrero (IAC),
M. Jelinek (IAA-CSIC), P. Kubanek (IAA-CSIC & U. Valencia),
M. Fernandez (IAA-CSIC), report on behalf of a larger collaboration:
"We observed the field of GRB 110625A (Page et al., GCN 12088)
with the 1.23m telescope of Calar Alto observatory. We obtained
45x60s I-band images on June 25.88457--25.93027 UT
(i.e, starting 5.32 min after the trigger).
In the co-added image, we detect a source at RA(J2000)=19:06:55.88,
DEC(J200)=06:45:19.4 (+/-0.5") which is consistent with the objects
reported by Im et al. (GCN 12095) and Filgas et al. (GCN 12096).
Using as photometric reference the USNO B1.0 star located at RA(J2000)
= 19:06:56.17, DEC(J2000)=06:44:25.9 with I=16.56, we derived a
preliminary magnitude of I=20.6 (Vega system) for the object
inside the XRT error circle.
This magnitude might indicate some degree of fading with respect
to the i-band AB mag reported by Filgas et al. (GCN 12096).
However, we are still cautious on the possible association
of this object with the GRB.
Further multi-band observations are encouraged."
[GCN OPS NOTE(27jun11): Per author's request, the "July" in the
second sentence was changed to "June".]
GCN Circular 12097
Subject
GRB 110625A: Fermi LAT detection
Date
2011-06-26T19:52:11Z (14 years ago)
From
Thomas P.H. Tam at Nat.Tsing Hua U. <grbtom@gmail.com>
P.H.T. Tam and A.K.H. Kong (NTHU) report:
We report on the detection of >100 MeV gamma-ray emission from the direction
of GRB 110625A (Swift trigger
456073; Page et al., GCN #12088) using the Fermi Large Area Telescope
(LAT).
The GRB position was outside the LAT field of view (i.e., >75 deg with
respect to the LAT boresight) at the burst
onset (T0; 2011-06-25 UT 21:08:28; GCN #12088). However, prominent emission
up to several GeV was detected
from the GRB direction around T0+200s to T0+500s, during which the light
curve seems to resemble a double-peak
structure. Using the data obtained from the above period, we localized the
LAT emission at RA, DEC (J2000 deg) =
286.6, 6.9, with a statistical error of ~0.3 deg (68% CL), which is
compatible with the refined Swift/XRT position (Page
et al., GCN #12092). A preliminary spectral fit gives a photon spectral
index of around -3 at energies above 100
MeV.
GCN Circular 12096
Subject
GRB 110625A: GROND detection of a source inside the XRT error circle
Date
2011-06-26T16:13:01Z (14 years ago)
From
Jochen Greiner at MPI <jcg@mpe.mpg.de>
R. Filgas (MPE Garching), A. Rossi, A.D. Kann (both TLS Tautenburg),
A. Rau and J. Greiner (both MPE Garching) report on behalf of the GROND team:
We observed the field of GRB 110625A (Swift trigger 456073; Page et
al., GCN #12088) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La Silla
Observatory (Chile).
Observations started at 02:24 UT on June 26, 5.3 hours after the GRB
trigger, continued until 03:11 UT, and were obtained at high airmass.
A second epoch was obtained starting at 05:35, 8.46 hours after the burst,
and finished at 07:06 UT.
Inside the refined XRT error circle (Page et al., GCN #12092) we found a
single source at
RA,DEC (J2000)= 19:06:55.89, +06:45:19.5
(+-0.3"), consistent with the source reported by Im at al., GCN #12095.
Over the course of 5 hrs, no variability is detected in relative photometry
measured against a field star at RA,DEC(J200)=19:06:56.99,+06:45:20.4
with z_AB = 19.4 mag.
We measure the following magnitudes (all in AB) from the first 1440s and
1200s of exposure in g'r'i'z' and JHK, respectively:
g' > 24.3
r' = 24.1 +/- 0.2
i' = 22.6 +/- 0.1
z' = 21.5 +/- 0.1
J = 21.1 +/- 0.7
H > 18.6
K > 17.8
The photometry were derived by calibration against GROND zeropoints and
2MASS field stars and are not corrected for the Galactic foreground extinction
corresponding to a reddening of E_(B-V) ~ 10.5 mag in the direction of the burst
(Schlegel et al. 1998).
Given the lack of variability and a color much bluer than would be expected
according to the strong foreground extinction, we suggest that this
optical/near-IR source is likely a Galactic object unrelated to GRB 110625A.
GCN Circular 12095
Subject
GRB 110625A: NIR Source
Date
2011-06-26T15:06:17Z (14 years ago)
From
Myungshin Im at Seoul Nat U <mim@astro.snu.ac.kr>
Myungshin Im, Ji Hoon Kim, Dohyeong Kim, and Duho Kim
(CEOU/Seoul National University), on behalf of a larger collaboration
We observed GRB 110625A (Page et al. GCN 12088) in zYHK filters
with UKIRT starting at 2011 June 26,10:08:47 UT. Within the enhanced XRT
error circle (Page et al. GCN 12092), we detect a NIR source in all the
filters, whose coordinate is
RA=19:06:55.8, Dec=06:45:19.2
with positional error of ~0.5". K-band magnitude is found to be
about 17.5 mag, calibrated against a 2MASS star at (19:06:55.65, 06:45:16.2)
The variability of the source is being examined with additional data.
GCN Circular 12094
Subject
GRB 110625A: Konkoly observations
Date
2011-06-26T14:50:30Z (14 years ago)
From
Janos Kelemen at Konkoly Obs/Hungary <kelemen@konkoly.hu>
J. Kelemen,(Konkoly Obs.)
on behalf of the GRB OT observing program at the Konkoly Observatory.
We observed the field of GRB 110625A (trigger=456073) using the Swift-XRT
position provided by K.L. Page et al. (GCN 12088) with a 60/90 cm Schmidt
telescope located at the Mountain Station of the Konkoly Observatory. We
coadded 4 CCD images with 300 sec exposure time each. After checking the
coadded frame we did not find any OT brighter than 21.5 mag in R the band
within the XRT error circle.
The photometry based on UCAC-3 stars around the field.
Time from
the trigger magnitude Band
----------------------------------------
5829 sec 21.5 +/- 0.2 R Upper Limit!
GCN Circular 12093
Subject
Konus-Wind observation of GRB 110625A
Date
2011-06-26T13:56:21Z (14 years ago)
From
Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>
S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin,
P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf
of the Konus-Wind team, report:
The long bright GRB 110625A (Swift-BAT trigger #456073:
Page et al., GCN 12088; Palmer et al., GCN 12091)
triggered Konus-Wind at T0=76105.088s UT (21:08:25.088)
The burst light curve consists of several multi-peaked pulses,
a total duration of the burst is ~60 s.
The emission is seen up to ~8 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB110625_T76105/
As observed by Konus-Wind the burst
had a fluence of (6.1 � 0.6)x10-5 erg/cm2,
and a 64-ms peak flux, measured from T0+20.992 s,
of (1.5 � 0.2)x10-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum of the burst
(from T0 to T0+58.880 s) is best fitted
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -1.05 (-0.08, +0.08),
the high energy photon index beta = -2.7 (-0.5, +0.2),
the peak energy Ep = 190(-14, +17) keV,
chi2 = 79.7/87 dof.
The spectrum at the maximum count rate
(measured from T0+20.992 to T0+21.504 s) is best fitted
in the 20 keV - 10 MeV range by the GRB (Band)
model, for which:
the low-energy photon index alpha = -0.8 (-0.2, +0.2),
the high energy photon index beta = -2.5 (-0.5, +0.2),
the peak energy Ep = 168(-24, +40) keV,
chi2 = 45.2/46 dof.
All the quoted results are preliminary.
All the quoted errors are at the 90% confidence level.
GCN Circular 12092
Subject
GRB 110625A: Swift-XRT refined Analysis
Date
2011-06-26T11:56:14Z (14 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
K. L. Page (U Leicester) reports on behalf of the Swift-XRT team:
We have analysed 4.1 ks of XRT data for GRB 110625A (Page et al. GCN
Circ. 12088), from 129 s to 34.9 ks after the BAT trigger. The data
comprise 96 s in Windowed Timing (WT) mode (the first 10 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The best available XRT position (using the promptly downlinked
event data, the XRT-UVOT alignment and matching UVOT field sources to
the USNO-B1 catalogue) is RA, Dec = 286.7327, 6.7553 which is
equivalent to:
RA (J2000): 19 06 55.85
Dec(J2000): +06 45 19.2
with an uncertainty of 2.1 arcsec (radius, 90% confidence).
The light curve can be modelled with an initial power-law decay with an
index of alpha=1.12 (+0.04, -0.03), followed by a break at T+18.7 ks to
an alpha of 2.7 (+7.3, -1.2). There are insufficient data to constrain
this steeper decay well at this time.
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.5 (+/-0.4). The
best-fitting absorption column is 6.3 (+1.1, -1.0) x 10^22 cm^-2, in
excess of the Galactic value of 1.4 x 10^22 cm^-2 (Kalberla et al.
2005). The PC mode spectrum has a photon index of 1.8 (+/-0.4) and a
best-fitting absorption column of 5.9 (+1.3, -1.1) x 10^22 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum is 1.1 x 10^-10 (3.2 x 10^-10) erg cm^-2
count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 5.9 (+1.3, -1.1) x 10^22 cm^-2
Galactic foreground: 1.4 x 10^22 cm^-2
Excess significance: 8.7 sigma
Photon index: 1.8 (+/-0.4)
The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00456073.
This circular is an official product of the Swift-XRT team.
GCN Circular 12091
Subject
GRB 110625A: Swift-BAT refined analysis
Date
2011-06-26T06:32:26Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
D. M. Palmer (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA),
C. B. Markwardt (GSFC), K. L. Page (U Leicester), T. Sakamoto (GSFC/UMBC),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+602 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 110625A (trigger #456073)
(Page, et al., GCN Circ. 12088). The BAT ground-calculated position is
RA, Dec = 286.751, 6.755 deg, which is
RA(J2000) = 19h 07m 00.3s
Dec(J2000) = +06d 45' 17.8"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 5%.
The mask-weighted light curve shows a series of peaks starting at ~T-12 sec,
with major peaks at ~T-5, ~T+2, ~T+13 and ~T+18, followed by a long tail
ending at ~T+350 sec. T90 (15-350 keV) is 44.5 +- 10.1 sec
(estimated error including systematics).
The time-averaged spectrum from T-6.2 to T+140.3 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.44 +- 0.04. The fluence in the 15-150 keV band is 2.8 +- 0.1 x 10^-5 erg/cm2.
The 1-sec peak photon flux measured from T+13.74 sec in the 15-150 keV band
is 49.5 +- 2.4 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/456073/BA/
GCN Circular 12089
Subject
GRB 110625A: ROTSE-III Optical Limits
Date
2011-06-25T22:24:00Z (14 years ago)
From
Weikang Zheng at U.of Michigan <zwk@umich.edu>
W. Zheng (U Mich) and W. Rujopakarn (Steward), report on behalf of the ROTSE
collaboration:
ROTSE-IIId, located at the Turkish National Observatory at Bakirlitepe,
Turkey, responded to GRB 110625A (Swift trigger 456073; Page et al., GCN
12088), producing images beginning 6.8 s after the GCN notice time. An
automated response took the first image at 21:08:48.8 UT, 20.3 s after the
burst, and during the gamma-ray emission, under fair conditions. We took 10
5-sec, 10 20-sec and 110 60-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 15.5-16.6; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
21:08:48.8 21:10:56.3 127 16.9 20.3 Y
21:11:05.2 21:15:42.8 277 17.5 156.7 Y
21:15:51.7 21:20:29.5 277 17.5 443.2 Y
GCN Circular 12088
Subject
GRB 110625A: Swift detection of a burst
Date
2011-06-25T21:25:19Z (14 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
K. L. Page (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), J. R. Cummings (NASA/UMBC),
V. D'Elia (ASDC), S. T. Holland (CRESST/USRA/GSFC),
F. E. Marshall (NASA/GSFC), C. Pagani (U Leicester),
D. M. Palmer (LANL), P. Romano (INAF-IASFPA), C. J. Saxton (UCL-MSSL),
M. H. Siegel (PSU), M. C. Stroh (PSU) and T. N. Ukwatta (MSU) report
on behalf of the Swift Team:
At 21:08:28 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110625A (trigger=456073). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 286.750, +6.753, which is
RA(J2000) = 19h 07m 00s
Dec(J2000) = +06d 45' 10"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows several bright peaks
with a total duration of about 60 sec. The peak count rate
was ~20,000 counts/sec (15-350 keV), at ~13 sec after the trigger.
The XRT began observing the field at 21:10:48.8 UT, 140.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 286.73189, 6.75386
which is equivalent to:
RA(J2000) = 19h 06m 55.65s
Dec(J2000) = +06d 45' 13.9"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 64 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 does not constrain the column density.
The initial flux in the 2.5 s image was 1.72e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 250 seconds with the U filter starting
205 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 19.2 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 18.0 mag. No
correction has been made for the large, but uncertain extinction expected.
Burst Advocate for this burst is K. L. Page (kpa 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.)