GRB 081210
GCN Circular 8648
Subject
GRB 081210: Swift detection of a burst with optical afterglow
Date
2008-12-10T20:37:36Z (16 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
H. A. Krimm (CRESST/GSFC/USRA), A. P. Beardmore (U Leicester),
P. J. Brown (PSU), D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), C. Guidorzi (UniFE),
S. T. Holland (CRESST/USRA/GSFC), S. D. Hunsberger (PSU),
S. Immler (CRESST/GSFC/UMD), J. A. Kennea (PSU), W.B Landsman (GSFC),
F. E. Marshall (NASA/GSFC), J. P. Osborne (U Leicester),
C. Pagani (PSU), D. M. Palmer (LANL), A. M. Parsons (GSFC),
M. Stamatikos (NASA/ORAU) and E. Troja (INAF-IASFPA) report on behalf
of the Swift Team:
At 20:19:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 081210 (trigger=337073). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 70.458, -11.266 which is
RA(J2000) = 04h 41m 50s
Dec(J2000) = -11d 15' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a double-peaked
structure with a duration of about 30 sec, followed by an additional
peak at T+140 s. The peak count rate was ~5000 counts/sec
(15-350 keV), at ~18 sec after the trigger.
The XRT began observing the field at 20:20:46.1 UT, 71.9 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 70.4853, -11.2568 which is equivalent to:
RA(J2000) = 04h 41m 56.47s
Dec(J2000) = -11d 15' 24.4"
with an uncertainty of 5.4 arcseconds (radius, 90% containment). This
location is 101 arcseconds from the BAT onboard position, within the
BAT error circle. The full field-of-view light curve shows a strong flare
at T+140 s, coincident with a flare seen in the BAT. No event data are yet
available to determine the column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 1.35e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 80 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
RA(J2000) = 04:41:56.20 = 70.48417
DEC(J2000) = -11:15:26.7 = -11.25741
with a 90%-confidence error radius of about 0.64 arc sec. This position is 4.6
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.12 with a 1-sigma error of about 0.15. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.08. The afterglow is detected
in the UVOT u filter, so the redshift must be less than approximately 3.3.
Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.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 8649
Subject
GRB 081210: Swift-BAT refined analysis
Date
2008-12-10T23:52:21Z (16 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.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),
J. Tueller (GSFC), T. N. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-240 to T+651 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 081210 (trigger #337073)
(Krimm, et al., GCN Circ. 8648). The BAT ground-calculated position is
RA, Dec = 70.485, -11.263 deg, which is
RA(J2000) = 04h 41m 56.5s
Dec(J2000) = -11d 15' 46.0"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 96%.
The mask-weighted light curve shows several peaks. The first starts at
~T-30 sec. The second and brightest peaks at ~T+18 sec. The third peaks
at T+135 sec. There is possible forth peak at T+180 sec.
T90 (15-350 keV) is 146 +- 8 sec (estimated error including systematics).
The time-averaged spectrum from T-12.9 to T+143.0 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.42 +- 0.14. The fluence in the 15-150 keV band is 1.8 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+17.97 sec in the 15-150 keV band
is 2.5 +- 0.2 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/337073/BA/
GCN Circular 8650
Subject
GRB 081210: Enhanced Swift-XRT position
Date
2008-12-11T01:31:00Z (16 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 2098 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 081210, 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 = 70.4841, -11.2577 which is equivalent
to:
RA (J2000): 04h 41m 56.19s
Dec (J2000): -11d 15' 27.8"
with an uncertainty of 1.7 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
http://www.swift.ac.uk/xrt_positions/Goad.pdf), the current algorithm is an
extension of this method.
This circular was automatically generated, and is an official product of the
Swift-XRT team.
GCN Circular 8652
Subject
GRB 081210: Swift-XRT refined analysis
Date
2008-12-11T09:02:37Z (16 years ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
P.A. Evans, K.L. Page (U. Leicester) and H.A. Krimm (CRESST/GSFC/USRA)
report on behalf of the Swift-XRT team:
We have analysed 4.9 ks of XRT data for GRB 081210 (Krimm et al., GCN
Circ. 8648), beginning 78 s after the BAT trigger. The first 387 s were
obtained in Windowed Timing (WT) mode and the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Osborne et al. (GCN Circ 8650).
The light curve shows an initial period of flaring activity. A strong
peak is seen at T+138 s coincident with the third peak seen by the BAT
(Barthelmy et al. GCN Circ. 8649). Further peaks are seen at T+219 s,
317 s and 391 s. During this time the underlying light curve, while
difficult to constrain, is clearly decaying, with a power-law index of
around 1.5. Around T+5000 s the decay flattens, to a slope of 0.74
(+/-0.24).
A spectrum formed from the PC mode data, i.e. after the flaring activity
has ceased, can be fitted with an absorbed power-law with a photon
index of 1.91 (+/-0.12). The best-fitting absorption column is 6.1
(+2.5, -1.5) x 10^20 cm^-2, consistent with the Galactic value in the
direction of the burst (4.6 x 10^20 cm^-2, Kalberla et al. 2005). The
counts to observed 0.3-10 keV flux conversion factor deduced from this
spectrum is 4.2 x 10^-11 erg cm^-2 count^-1.
If the light curve continues to decay with a power-law decay index of
0.74, the count rate at T+24 hours will be 0.017 count s^-1,
corresponding to an observed (unabsorbed) flux of 6.73 x 10^-13 (8.02 x
10 ^-13) erg cm^-2 s^-1.
The results of the xrt automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00337073.
This circular is an official product of the Swift-XRT team.
GCN Circular 8654
Subject
GRB 081210: Swift/UVOT refined analysis
Date
2008-12-11T18:59:03Z (16 years ago)
From
Stefan Immler at NASA/GSFC <stefan.m.immler@nasa.gov>
S. Immler (CRESST/UMD/GSFC), S. T. Holland (CRESST/USRA/GSFC), and H. A.
Krimm (CRESST/GSFC/USRA) report on behalf of the Swift UVOT team:
Further analysis of Swift Ultraviolet/Optical Telescope (UVOT) data of
GRB 081210 (Krimm et al., GCN Circ. 8648), starting 80 sec after the BAT
trigger, gives a detection of an optical source consistent with the
enhanced XRT position (Osborne et al., GCN Circ 8650) in the white and u
filters at 12.6-sigma and 3.8-sigma levels of confidence, respectively.
The source is not detected in any of the other UVOT filters at the
limiting magnitudes reported below.
Filter Tstart(s) Tstop(s) Exp(s) Magnitude
wh 80 1009 318 19.91+/-0.08
u 292 716 265 20.15+/-0.29
b 548 741 39 >19.78 (3-sigma UL)
uvw2 598 5251 235 >20.47 (3-sigma UL)
v 622 816 244 >19.99 (3-sigma UL)
uvm2 647 840 136 >19.55 (3-sigma UL)
uvw1 672 866 39 >18.74 (3-sigma UL)
The values quoted above are in the UVOT photometric system (Poole et al.
2008, MNRAS, 383, 627) and are not corrected for the expected Galactic
extinction along the line of sight which corresponds to a reddening of
E(B-V) = 0.077 mag (Schlegel et al. 1998).
The event data in the white filter shows a flare peaking at
approximately 130 s after the BAT trigger, which approximately coincides
with the flare seen in the X-ray light curve (Evans et al., GCN Circ 8652).
GCN Circular 8659
Subject
GRB 081210, SMARTS optical/IR observations
Date
2008-12-12T01:42:28Z (16 years ago)
From
Bethany Cobb at UC Berkeley <bcobb@astro.berkeley.edu>
B. E. Cobb (UC Berkeley) reports:
Using the ANDICAM instrument on the 1.3m telescope at CTIO, we
obtained optical/IR imaging of the error region of GRB 081210
(Krimm et al. GCN 8648) with a mid-exposure time of ~6.2 hours
post-burst (2008-12-11 02:33 UT). Total summed exposure
times amounted to 36 minutes in I and 30 minutes in J.
The GRB's optical afterglow (Krimm et al. GCN 8648)
is not detected to an approximate limiting magnitude
of I>22.3 and J>20.0. (Optical photometry is calibrated against
Landolt standard stars and IR photometry is calibrated
against 2MASS stars in the field.)
GCN Circular 8660
Subject
GRB 081210: Xinglong TNT R band Upper Limits
Date
2008-12-12T03:12:49Z (16 years ago)
From
L.P. Xin at NAOC <xlp@bao.ac.cn>
X.F. Wang, L.P. Xin, Y.L. Qiu, J.Y. Wei, j. Wang, J.Y. Hu,
J.S. Deng, W.K. Zheng on behalf of EAFON report:
We have observed GRB081210 (Krimm et al, GCN 8648)
with Xinglong TNT telescope from Dec.11th,13:38:47(UT),
17.33 hr after the burst. After combined 6*600s R band
images, no afterglow was detected with the 3 sigma
upper limits of 19.571, at the mean time of 17.814 hr
after the burst.
This message may be cited.
For more information about Xinglong GRBs Follow-up
observations, please visit the website:
http://www.xinglong-naoc.org/grb/
GCN Circular 8667
Subject
GRB 081210: optical observations
Date
2008-12-14T17:44:38Z (16 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V. Rumyantsev (CrAO), A. Pozanenko (IKI) on behalf of larger GRB follow up
collaboration report:
We observed the error box of Swift GRB 081210 (Krimm et al, GCN 8648) in R
band on Dec. 10 between (UT) 22:31:15 - 23:05:19 with Shajn telescope of
CrAO. Inside the enhanced XRT error box (Osborne et al. GCN 8650) we do not
detect optical afterglow (Krimm et al, GCN 8648). A photometry based on
0787-0047183 USNO B1.0 star (04:41:55.26 -11:14:39.0) assuming R2=16.33 is
following:
T0+ Filter, Exp., UL
(h) (s) (3 sigma)
2.487 R 29x60 >20.0