| Summary table |
|---|
| Variable |
Value |
Source |
| GRB_name_Fermi |
GRB081226044 |
|
| T0 |
1:03:37 UTC |
GCN_circulars,Swift Det |
| ra |
120.4780° |
Swift |
| decl |
-69.0140° |
Swift |
| pos_error |
1.63e-02° |
Swift |
| T90 |
0.832 s |
Fermi_GBM |
| T90_error |
1.032 s |
Fermi_GBM |
| T90_start |
1:03:37.334 UTC |
Fermi_GBM |
| fluence |
4.30e-07 erg/cm² |
Fermi_GBM |
| fluence_error |
2.32e-08 erg/cm² |
Fermi_GBM |
| T100 |
1.166 s |
|
| GBM_located |
False |
|
| mjd |
54826.04417824074 |
GCN_circulars,Swift Det |
| Fermi GBM table |
|---|
| GRB_name_Fermi |
GRB081226044 |
| trigger_name |
bn081226044 |
| ra |
120.5000° |
| decl |
-69.0000° |
| pos_error |
7.70e+00° |
| datum |
2008-12-26 |
| t_trigger |
1:03:37.526 UTC |
| T90 |
0.832 s |
| T90_error |
1.032 s |
| T90_start |
1:03:37.334 UTC |
| fluence |
4.30e-07 erg/cm² |
| fluence_error |
2.32e-08 erg/cm² |
| flux_1024 |
2.32e+00 erg/cm²/s |
| flux_1024_error |
2.81e-01 erg/cm²/s |
| flux_1024_time |
-3.20e-01 erg/cm²/s |
| flux_64 |
6.23e+00 erg/cm²/s |
| flux_64_error |
1.37e+00 erg/cm²/s |
| IPN table |
|---|
| GRB_name |
GRB081226A |
| ra |
120.5250° |
| decl |
-69.0000° |
| pos_error |
5.00e-02° |
| Swift table |
|---|
| GRB_name |
GRB081226A |
| t_trigger |
1:03:37 UTC |
| ra |
120.4780° |
| decl |
-69.0140° |
| pos_error |
1.63e-02° |
| T90 |
0.4 s |
| fluence |
9.90e-08 erg/cm² |
| GCN 8729 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8729 |
| Detection_method |
Swift Det |
| t_trigger |
1:03:37 UTC |
| ra |
120.5270° |
| decl |
-69.0060° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8729
SUBJECT: GRB 081226: Swift detection of a possible short-hard burst
DATE: 08/12/26 01:21:22 GMT
FROM: David Burrows at PSU/Swift
O. Godet (U Leicester), W. H. Baumgartner (GSFC/UMBC),
D. N. Burrows (PSU), E. A. Hoversten (PSU), J. A. Kennea (PSU) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 01:03:37 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 081226 (trigger=338177). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 120.527, -69.006 which is
RA(J2000) = 08h 02m 06s
Dec(J2000) = -69d 00' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a short hard burst
structure with a duration of about 0.5 sec. The peak count rate
was ~4000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 01:05:11.9 UT, 94.6 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 120.50054, -69.02994 which is
equivalent to:
RA(J2000) = 08h 02m 0.13s
Dec(J2000) = -69d 01' 47.8"
with an uncertainty of 4.5 arcseconds (radius, 90% containment). This
location is 92 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
1.19e+21 cm^-2 (Kalberla et al. 2005).
The UVOT data has not yet been received so it is not possible to
comment on the UV/optical nature of the burst at this time. There is
a 7th magnitude source nearby which will complicate UVOT observations.
Burst Advocate for this burst is O. Godet (og19 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.)
|
| GCN 8730 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8730 |
| Detection_method |
Swift-BAT Det |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8730
SUBJECT: GRB 081226: ROTSE-III Optical Limits
DATE: 08/12/26 01:32:34 GMT
FROM: Brad Schaefer at LSU
B. E. Schaefer (Louisiana State), E.S. Rykoff (UCSB), F. Yuan (U Mich),
report on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 081226 (Swift trigger 338177; Godet, GCN 8729), producing
images beginning 8.8 s after the GCN notice time. An automated response
took the first image at 01:04:02.8 UT, 25.4 s after the burst, under
excellent conditions. We took 10 5-sec, 20 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; the field is not crowded. Individual
images have limiting magnitudes ranging from 16.8-17.4; we set the
following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
01:04:02.8 01:04:07.8 5 17.0 25.4 N
01:04:02.9 01:05:19.0 76 17.8 25.5 Y
|
| GCN 8731 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8731 |
| Detection_method |
GROND |
| ra |
120.4997° |
| decl |
-69.0298° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8731
SUBJECT: GRB 081226: GROND afterglow candidate
DATE: 08/12/26 03:08:29 GMT
FROM: Paulo M. J. Afonso at MPE
GRB 081226: GROND afterglow candidate
P. Afonso, T. Kruehler (both MPE Garching), S. Klose (TLS Tautenburg), and
J. Greiner (MPE Garching) report on behalf of the GROND team:
GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI
telescope at La Silla Observatory (Chile),started observations of the field
of GRB 081226 (Godet et al. 2008, GCN #8729) in g'r'i'z'JHK at 01:14 UTC, 11
min after the burst. We detect a faint optical source in the XRT error
circle (Godet et al. 2008, GCN #8729) at:
RA(J2000): 08:01:59.92
DEC(J2000): -69:01:47.4
with uncertainties of 0.5".
At a midtime of 01:57 UTC, we measure a rough preliminary r' band magnitude
of 24.3 calibrated with the GROND zeropoint.
No statement about variability can be made at this point. Observations are
ongoing.
|
| GCN 8732 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8732 |
| Detection_method |
Other |
| ra |
120.5018° |
| decl |
-69.0302° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8732
SUBJECT: GRB 081226: Gemini-South imaging
DATE: 08/12/26 03:26:41 GMT
FROM: Edo Berger at Harvard
E. Berger (Harvard), A. Cucchiara, and D. B. Fox (Penn State) report:
"We imaged the error circle of GRB 081226 (GCN 8729) with GMOS on the
Gemini-S telescope starting on 2008 Dec 26.04 UT. In a single 300 sec
r-band image we detect the object located by GROND within the XRT
error circle (GCN 8731). In addition, we find a second, fainter source
within the error circle at (J2000):
RA = 08:02:00.44
DEC = -69:01:48.9
with an uncertainty of about 0.5" in each coordinate. Additional
observations are on-going to determine if either of these two sources is
fading."
|
| GCN 8733 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8733 |
| Detection_method |
Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8733
SUBJECT: GRB 081226: Gemini-South spectrum of possible afterglow
DATE: 08/12/26 04:51:20 GMT
FROM: Edo Berger at Harvard
E. Berger (Harvard), A. Cucchiara, and D. B. Fox (Penn State) report:
"We obtained spectroscopic observations of the possible afterglow of GRB
081226 (GCNs 8731, 8732) with GMOS on the Gemini-South telescope using the
R400 grating with a central wavelength of 6000A for a total of 2400 sec.
We detect smooth continuum emission but no obvious absorption or emission
features in the wavelength range 4000-8000A. Further analysis is
on-going."
|
| GCN 8735 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8735 |
| Detection_method |
Swift-BAT Det |
| ra |
120.4780° |
| decl |
-69.0140° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8735
SUBJECT: GRB 081226A: Swift-BAT refined analysis
DATE: 08/12/26 16:12:39 GMT
FROM: Scott Barthelmy at NASA/GSFC
H. A. Krimm (GSFC/USRA), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (GSFC/UMBC), E. E. Fenimore (LANL), N. Gehrels (GSFC),
O. Godet (U Leicester) 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-240 to T+962 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 081226A (trigger #338177)
(Godet, et al., GCN Circ. 8729). The BAT ground-calculated position is
RA, Dec = 120.478, -69.014 deg, which is
RA(J2000) = 08h 01m 54.6s
Dec(J2000) = -69d 00' 48.6"
with an uncertainty of 2.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.
The mask-weighted light curve shows a single spike starting at T+0.0 and
ending at T+0.4 sec. T90 (15-350 keV) is 0.4 +- 0.1 sec (estimated error
including systematics).
The time-averaged spectrum from T-0.1 to T+0.5 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.36 +- 0.29. The fluence in the 15-150 keV band is 9.9 +- 1.8 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.30 sec in the 15-150 keV band
is 2.4 +- 0.4 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/338177/BA/
|
| GCN 8736 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8736 |
| Detection_method |
Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8736
SUBJECT: GRB 081226: Second epoch of Gemini-South imaging
DATE: 08/12/26 16:27:15 GMT
FROM: Edo Berger at Harvard
E. Berger, A. M. Soderberg (Harvard), A. Cucchiara, and D. B. Fox (Penn
State) report:
"We re-observed the error circle of GRB 081226 (GCN 8729) with GMOS on the
Gemini-South telescope on 2008 Dec 26.349 UT (7.31 hours post burst). A
comparison to our first epoch of imaging, taken on 2008 Dec 26.112 UT
(1.62 hours post burst; GCN 8732), reveals that neither of the two objects
within the XRT error circle (GCN 8732) have varied in brightness. This
is confirmed using digital image subtraction with the ISIS package."
|
| GCN 8737 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8737 |
| Detection_method |
Swift-UVOT Other |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8737
SUBJECT: GRB 081226A: Swift UVOT Upper Limits
DATE: 08/12/26 18:03:45 GMT
FROM: Erik Hoversten at Swift/Penn State
E. A. Hoversten (PSU) and O. Godet (U Leicester) report on behalf of
the Swift UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 08226A 156s after the BAT trigger (Godet et al., GCN 8729).
We do not detect any source at the Swift XRT position. The white
filter observation was skipped due to a 7th magnitude star in the field.
The UVOT upper limits are around 20th magnitude so the non-detections do
not conflict with the possible optical afterglow detections in GCN
8731 and GCN 8732 at 24th magnitude. UVOT magnitude 3-sigma upper
limits are reported in the following table:
Filter T_start T_stop Exp(s) Mag (3-sigma upper limit)
-------------------------------------------------------------
v 461 2276 233 > 19.24
b 410 2226 228 > 20.13
u 155 2051 833 > 20.87
uvw1 510 2176 213 > 19.71
uvm2 486 2151 213 > 19.51
uvw2 436 2252 233 > 19.83
The quoted upper limits have not been corrected for the expected
Galactic extinction along the line of sight of E_(B-V) = 0.16 mag.
All photometry is on the UVOT photometric system described in Poole et
al. (2008, MNRAS, 383, 627).
|
| GCN 8738 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8738 |
| Detection_method |
Swift-XRT Other |
| ra |
120.5015° |
| decl |
-69.0292° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8738
SUBJECT: GRB 081226: Swift-XRT refined analysis
DATE: 08/12/26 22:40:57 GMT
FROM: Olivier Godet at U.of Leicester
O. Godet (U Leicester) on behalf the Swift-XRT team:
The Swift-XRT started observing the field of GRB 081226 (trigger number
338177, Godet et al., GCN Circ. 8729) at 2008-12-26 01:05:11.9 UT, 94.5
seconds after the trigger. Using 11.6 ks of photon counting (PC) mode data,
the best XRT position is located at RA, Dec 120.50152, -69.02924 which is
equivalent to:
RA(J2000) = 08h 02m 00.36s
Dec(J2000) = -46d 01' 45.2"
with an uncertainty of 4.7 arcseconds (radius, 90% containment). This
location is 2.8 arcseconds from the XRT position given in Godet et al. (GCN
Circ. 8729). It is also consistent with the position of the possible
optical counterpart reported by Afonso et al. (GCN Circ. 8731).
The X-ray light curve presently spans 11.6 ks of PC mode data from T+109 s
to T+42 ks. Due to poor statistics, it is difficult to properly model the
light-curve, which shows a decay (with a slope around 1.8) possibly followed
by a flattening at later time.
The PC X-ray spectrum from the same interval can be well fit by an absorbed
power-law with a photon index of 2.60 +1.61/-0.98 and a column density of
(6.4 +8.8/-4.6) x 10^21 cm^-2 (the Galactic value is 1.19 x 10^21 cm^-2 in
the direction of the burst - Kalberla et al. 2005). The observed 0.4-10.0
keV flux is (1.8 +0.8/-1.3) x 10^-13 erg cm^-2 s^-1 which corresponds to
an unabsorbed flux of (4.7 +1.4/-2.5) x 10^-13 erg cm^-2 s^-1.
No more Swift observations are planned for this burst.
This is an official product of the Swift-XRT team.
|
| GCN 8785 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8785 |
| Detection_method |
Fermi GBM Det |
| t_trigger |
1:03:37.530 UTC |
| ra |
119.0100° |
| decl |
-73.8000° |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8785
SUBJECT: Fermi/GBM detection of GRB 081226A
DATE: 09/01/07 16:48:20 GMT
FROM: Chryssa Kouveliotou at MSFC
Chryssa Kouveliotou (NASA/MSFC), Valerie Connaughton (UAHuntsville) report on behalf of the Fermi GBM Team:
"At 01:03:37.53 UT on 26 December 2008, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 081226 (trigger 251946218, trigcat 081226044), which was also detected by the SWIFT-BAT (Godet et al. 2008, GCN 8729). The on-ground calculated location, using the GBM trigger data, is RA = 119.01, DEC = -73.8 (J2000 degrees, equivalent to 07 h 56.04 m, -73 d 48'), with an uncertainty of 13.2 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees). The GBM on-ground location is consistent with the Swift position.
The angle from the Fermi LAT boresight is 110 degrees.
The GBM light curve is a single pulse with a duration (T90) of about 1.7 s (20-775 keV). The time-averaged spectrum from T0-0.215 s to T0+0.233 s is best fit by a simple power law function with index 1.17 +/- 0.08 (chi squared 188 for 228 d.o.f.).
The event fluence (50-300 keV) in this time interval is (2.1 +/- 0.1)E-7 erg/cm^2. The 0.256-sec peak photon flux measured starting from T0-0.151 s in the 50-300 keV band is 3.2 +/- 0.1 ph/s/cm^2.
The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
|
| GCN 8952 table |
|---|
| GRB_name |
GRB081226A |
| GCN_number |
8952 |
| Detection_method |
Optical |
| Circular_text |
TITLE: GCN CIRCULAR
NUMBER: 8952
SUBJECT: Radio observation of GRB 081226a with ATCA
DATE: 09/03/09 06:03:08 GMT
FROM: Aquib Moin at CIRA/ATNF
Aquib Moin (Curtin Institute of Radio Astronomy / Australia Telescope
National Facility), Steven Tingay (Curtin Institute of Radio Astronomy),
Chris Phillips (Australia Telescope National Facility), Gregory Taylor
(University of New Mexico), Mark Wieringa (Australia Telescope National
Facility) and Ralph Martin (Perth Observatory) report:
We observed the GROND position of the GRB081226a afterglow (GCN 8731) at
4.800 and 4.928 GHz with the Australia Telescope Compact Array (ATCA)
between 01:00:00 UT and 22:00:00 UT on February 21/22, 2009.
We did not detect a radio source at the position of the GRB081226a (GCN
8731). The data at 4.800 and 4.928 GHz were merged and the radio flux
density at the GRB optical afterglow position found out to be 0.115 +/-
0.180 mJy/beam (1-sigma).
The Australia Telescope Compact Array (/ Parkes telescope / Mopra
telescope / Long Baseline Array) is part of the Australia Telescope
which is funded by the Commonwealth of Australia for operation as a
National Facility managed by CSIRO.
See the 4.800 & 4.928 GHz combined image at:
http://cira.ivec.org/dokuwiki/doku.php/grb/grb081226a/grb081226a_field_image
|