GRB 080822
GCN Circular 8112
Subject
GRB 080822: Swift detection of a short burst
Date
2008-08-22T13:08:50Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. T. Holland (CRESST/USRA/GSFC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
O. Godet (U Leicester), C. Guidorzi (INAF-OAB), J. A. Kennea (PSU),
V. Mangano (INAF-IASFPA), J. Mao (INAF-OAB),
F. E. Marshall (NASA/GSFC), P. T. O'Brien (U Leicester),
J. P. Osborne (U Leicester), C. Pagani (PSU),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. Perri (ASDC),
T. Sakamoto (NASA/UMBC), B. Sbarufatti (INAF-IASFPA),
R. L. C. Starling (U Leicester), G. Stratta (ASDC) and
T. N. Ukwatta (GSFC/GWU) report on behalf of the Swift Team:
At 12:41:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 080822 (trigger=321174). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 75.270, +45.272 which is
RA(J2000) = 05h 01m 05s
Dec(J2000) = +45d 16' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single spike
with a duration of less than 128 msec. The peak count rate
was ~10000 counts/sec (15-350 keV), at ~0 sec after the trigger.
The XRT began observing the field at 12:43:16.3 UT, 77.1 seconds after
the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued
X-ray source with an enhanced position: RA, Dec 75.27800, 45.27623
which is equivalent to:
RA(J2000) = 05h 01m 6.72s
Dec(J2000) = +45d 16' 34.4"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 25 arcseconds from the BAT onboard position, within the BAT
error circle.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (5.22e+21
cm^-2, Kalberla et al. 2005), with an excess column of 3.6
(+3.64/-2.95) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 83 seconds after the BAT trigger. No
afterglow candidate is apparent in the initial data products. The
TDRSS source list 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)
= 1.29 mag.
We note that the XRT position is 10.8 arcsec from the catalog position
of the ROSAT source 2RXP J050107.7+451637.
Burst Advocate for this burst is S. T. Holland (sholland 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 8113
Subject
New Soft Gamma Repeater 0501+4516 was GRB 080822
Date
2008-08-22T13:30:44Z (17 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), A. P. Beardmore (U Leicester),
D. N. Burrows (PSU), J. R. Cummings (NASA/UMBC),
N. Gehrels (NASA/GSFC), C. Guidorzi (INAF-OAB),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
J. Mao (INAF-OAB), F. E. Marshall (NASA/GSFC), C. Pagani (PSU),
D. M. Palmer (LANL), M. Perri (ASDC), T. Sakamoto (NASA/UMBC),
T. N. Ukwatta (GSFC/GWU) and L. Vetere (PSU) report on behalf of the
Swift Team:
At 13:12:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a second outburst from a new SGR source 0501+4516 (trigger=321177)
which was previously reported as GRB 080822 (Holland et al, GCN Circ 8112).
Swift was already looking at this location from the trigger on this source
of ~30 min earlier. The BAT on-board calculated location is
RA, Dec 75.265, +45.272, which is
RA(J2000) = 05h 01m 04s
Dec(J2000) = +45d 16' 20"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows a single spike
with a duration of less than 128 msec. The peak count rate
was ~17000 counts/sec (15-350 keV), at ~0 sec after the trigger.
GCN Circular 8114
Subject
GRB 080822 (SGR 0501+4516): archival optical observations
Date
2008-08-22T17:49:29Z (17 years ago)
From
Denis Denissenko at IKI, Moscow <denis@hea.iki.rssi.ru>
D. V. Denisenko (Space Research Institute, Moscow, Russia) reports:
Analysis of the Palomar Observatory Sky Survey plates available at
http://archive.stsci.edu/cgi-bin/dss_plate_finder has revealed a
variable object at the following position:
RA (J2000.0) = 05 01 06.47
Dec (J2000.0) = +45 16 28.0
with an uncertainty of 0.2". This is 7" from the XRT position of GRB
080822 reported by Holland et al. (GCN 8112), thus formally outside the
reported 90% error circle with the radius of 2.6".
The above mentioned star is present in USNO-B1.0 catalogue as USNO-B1
1352-0128683 (RA = 05 01 06.42, Dec = +45 16 27.6) with the following
magnitudes:
B1=19.11, R1=15.99, B2=17.74, R2=15.97, I=16.52.
Animation of two Blue and two Red plates, as well as color-combined
(BRIR) images covering 101"x101" area around the variable star are
available at <http://hea.iki.rssi.ru/~denis/SGR0501+4516.html>.
It should be also noted that the variable object is located 16" from the
ROSAT source 1RXS J050107.9+451631 (catalog position error 13") with the
hardness ratios HR1=0.96+/-0.08, HR2=1.00+/-0.12. These values are
typical for X-ray binaries, including X-ray transients. Thus, the
variable star is most likely associated with the ROSAT source. The
optical spectroscopy of this star is encouraged. Also the follow-up
X-ray observations of SGR 0501+4846 are required to reveal its true
nature, improve the position accuracy and check the possible identification.
This message can be cited.
GCN Circular 8122
Subject
New Soft Gamma Repeater 0501+4516 (GRB 080822): GLAST Burst Monitor detection
Date
2008-08-23T10:01:50Z (17 years ago)
From
Andreas von Kienlin at MPE <azk@mpe.mpg.de>
Andreas von Kienlin (MPE), N.P. Bhat (UAH), E. Bissaldi (MPE),
M.S. Briggs (UAH), V. Connaughton (UAH), R. Diehl (MPE),
G.J. Fishman (NASA/MSFC), L. Gibby (NASA/MSFC), J. Greiner (MPE),
A.S. Hoover (LANL), A.J. van der Horst (NASA/ORAU), R.M. Kippen (LANL),
C. Kouveliotou (NASA/MSFC), G.G. Lichti (MPE), C.A. Meegan (NASA/MSFC),
S. McBreen (MPE), W.S. Paciesas (UAH), R.D. Preece (UAH), H. Steinle (MPE),
M.S. Wallace (LANL), and C.A. Wilson-Hodge (NASA/MSFC)report:
"At 12:41:59 UT on 2008 Aug 22, the GLAST Burst Monitor (GBM) triggered
on the new Soft Gamma Repeater 0501+4516 (GRB 080822)
(GBM 080822.529 / trigger 241101720), reported by SWIFT
(Holland et al., GCN Circ. 8112, Barthelmy et al, GCN Circ. 8113
and GCN Circ. 8119).
The on-ground calculated location, using the GBM trigger data, is
RA = 86.2, Dec = +43.5 (J2000 degrees),(equivalent to J2000 05h 45m, +43d
30'),
with an uncertainty of 3.3 degrees (radius, 1-sigma containment, statistical
only). The true location error is 8.0 degrees for this soft, short event.
This event has a duration of about 80 ms. The spectrum in the
10 keV to 100 keV energy band is well fit by a power law function
with an index of -1.6 +/-0.1. The high temperature for an
optically thin thermal bremsstrahlung (OTTB) fit is: 71 +/-13 keV.
These results are consistent with the trigger clearly being seen to 100 keV.
The spectral analysis results presented above are preliminary."