- GCN Circular #13000
T. Sakamoto (GSFC/UMBC), C. Graziani (U of Chicago), J. R. Cummings (GSFC/UMBC),
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Automated BAT ground analysis found a burst that occurred at 01:55:39 UT
with a significance of 8.2 sigma (15-200 keV) from the event data.
The event is temporally coincident with the Fermi GBM 352346136. The best
BAT location is RA, Dec = 122.4506, +29.6598 deg, which is
RA(J2000) = 08h 09m 48.14s
Dec(J2000) = +29d 39' 35.3"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
Swift ToO has been requested.
- GCN Circular #13002
T. Sakamoto (GSFC/UMBC), C. Graziani (U of Chicago), J. R. Cummings (GSFC/UMBC),
S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC), E. E. Fenimore (LANL),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU), J. Tueller (GSFC),
T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):
Using the event data from T-220 to T+30 sec (T is the trigger time of the
ground code which is 01:55:30.8 UT), we report further analysis of GRB 120302A
(Sakamoto, et al., GCN Circ. 13000).
The mask-weighted light curve created from the event data shows at least
two peaks, the first starting and also peaking at ~T sec. The second starts
at ~T+10 sec, peaks at ~T+13 sec, and ends at ~T+20 sec. Although there might
be another weak episode starting at ~T+20 sec, it is hard to say conclusively
because the event data ends at T+30 sec. From the BAT raw light curve, the
duration of the event is 35-40 sec long.
The spectrum extracted from T to T+30 sec is best fit by a simple
power-law model. The power law index of the spectrum is 1.4 +- 0.3
(90% confidence). The fluence measured in this interval is 6.6 +-
1.3 x 10^-7 erg/cm2 (15-150 keV) and 1-sec peak flux measured from
T sec in the 15-150 keV band is 0.6 +- 0.3 ph/cm2/s. All the quoted
erros are at the 90% confidence level.
Swift ToO has been approved and the observation is on-going.
- GCN Circular #13003
J. Elliott, J. Greiner, F. Olivares E., A. Rau (all MPE Garching),
T. Kruehler (DARK) report on behalf of the GROND team:
We observed the field of GRB 120302A (Sakamoto et al., GCN #13000)
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP,
120, 405) mounted at the 2.2 m ESO/MPI telescope at La Silla
Observatory (Chile). Observations centered on the BAT position started
on March 3, 2012, at 00:33 UT, 22.6 h after the GRB trigger. They were
performed at an average seeing of 1.4", and average airmass of 2.
A second epoch of GROND observations was taken starting March 4, 2012, at
01:47 UT, only 15 deg from the Moon. The pointing had been slightly shifted
to the south-west to cover the X-ray source in the Swift ToO observation
also in the optical channels. Our images reveal no source within the formal
4.7" XRT error circle centered at RA (2000.0) = 08 09 35.96,
Decl. (2000.0) = 29 37 43.8.
Slightly outside the XRT error circle, we find a source at
RA (2000.0) = 08 09 35.58
Decl. (2000.0) = 29 37 40.7
(+-0.2 arcsec). This source has been constant between our two epochs in JHK.
In the second epoch, we measure for this object (all in the AB system)
g' = 22.5 +/- 0.3
r' = 21.9 +/- 0.2
i' = 21.9 +/- 0.3
z' = 21.4 +/- 0.1
J = 20.9 +/- 0.4
H = 20.3 +/- 0.3
K = 19.7 +/- 0.4
where the optical bands have been calibrated against SDSS, and the NIR bands
against 2MASS. This object is not visible on SDSS images, suggesting a
transient nature. The above magnitudes, after correcting for the small reddening
of E(B-V)=0.04 mag (Schlegel et al. 1998), are well fitted with a power law
of slope 1.4, typical for GRB afterglows. We therefore propose this
source as the candidate afterglow of GRB 120302A. The constant flux during
our two epochs might be the result of a plateau or re-brightening event.
Note, that there is a nearby SDSS source, SDSS J080935.14+293739.8, which based
on our astrometry is definitely a different source, though it is not
detected in our images due to the high background of the nearby Moon.
A finding chart will be placed at http://www.mpe.mpg.de/~jcg/grb120302A.html.
We note that the colors of SDSS J080935.14+293739.8 are not consistent with
an AGN or star. If SDSS J080935.14+293739.8 is a galaxy, the large r'-i'
color might indicate a redshift of about 0.7-0.8. This could potentially
be the host galaxy of GRB 120302A.
A deep observation is suggested in a few days time, when the Moon does not
disturb so much anymore.
Blue: 4.7" XRT error circle. Black: 2" circle around the SDSS source.
Yellow: 3" circle around the proposed GRB afterglow.
- GCN Circular #13012
T. Sakamoto (GSFC/UMBC), V. Mangano (INAF-IASF/Palermo),
A. Maselli (INAF-IASF/Palermo), M. H. Siegel (PSU),
M. J. R. Cummings (GSFC/UMBC), P.A. Evans (U. Leicester),
F. E. Marshall (NASA/GSFC), K.L. Page (U. Leicester) and
B. Sbarufatti (INAF-OAB/IASFPA) on behalf of the Swift team:
We report further analysis of BAT ground detected GRB 120302A
(Sakamoto, et al., GCN Circ. 13000). By carefully examining the BAT image,
we found a position with a higher significance (9.2 sigma in the 14-200 keV image)
than that originally reported (Sakamoto, et al., GCN Circ. 13000). The best
BAT position is RA, Dec = 122.426, +29.642 deg which is
RA(J2000) = 08h 09m 42.2s
Dec(J2000) = +29d 38' 31.2"
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The center of this position differs by 1.6 arcmin from the position reported
on the initial circular (Sakamoto, et al., GCN Circ. 13000).
A 5 ksec Swift ToO observation was performed on 18:17 UT on March 2
(~16.4 hr after the burst). The XRT observation was performed in PC mode.
Using 666 s of XRT Photon Counting mode data and 1 UVOT image, we find an
astrometrically corrected X-ray position (using the XRT-UVOT alignment and
matching UVOT field sources to the USNO-B1 catalogue; Evans et al. 2009):
RA, Dec = 122.39761, 29.62781 which is equivalent to:
RA(J2000) = 08h 09m 35.43s
Dec(J2000) = +29d 37' 40.1"
with an uncertainty of 3.2 arcsec (radius, 90% confidence). This XRT
refined position is consistent with an afterglow candidate reported by
GROND (Elliott et al., GCN Circ. 13003).
The X-ray light curve shows a roughly constant count rate at the average
level of 1.2e-2 counts s^-1. A fit with a power-law model cannot constrain
the slope. A spectrum formed from the PC mode data can be fitted with an
absorbed power-law with a photon spectral index of 1.29 (+0.68, -0.35). The best-fitting
absorption column is less than 1.9 x 10^21 cm^-2, in excess of the Galactic value
of 3.77 x 10^20 cm^-2 (Kalberla et al. 2005). The observed (unabsorbed) 0.3-10 keV
flux is 6.1 (-2.1,+2.2) x 10^-13 (6.1 (-1.7, +2.3) x 10^-13) erg cm^-2 s^-1.
All the quoted erros are at the 90% confidence level.
The Swift/UVOT data were taken entirely in the u filter. Using the first u
data (T0+58.9 ksec, 1391 s exposure), we find a candidate optical afterglow at:
RA, Dec = 122.39810, 29.62807 which is equivalent to:
RA(J2000) = 08h 09m 35.54s
DEC(J2000) = +29d 37' 41.1"
with a 90%-confidence error radius of about 0.6". The source has a u magnitude of
20.25+/-0.14 (1 sigma) on the system of Breeveld et al. 2011, AIP Conf. Proc. 1358, 373.
This position is consistent with the GROND position. The magnitude is not corrected
for the Galactic extinction due to the reddening of E(B-V) = 0.04 in the direction
of the burst (Schlegel et al. 1998).
The 2nd epoch observation of Swift ToO has been approved. This observation
will be scheduled on March 8.
- GCN Circular #13013
V. Pelassa (UAH)
reports on behalf of the Fermi GBM Team:
"At 01:55:34.00 UT on March 02 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120302A (trigger 352346136 / 120302080),
which was also found in the ground analysis of the Swift/BAT data
(Sakamoto et al. 2012, GCN 13000). The Swift position is within
the 3 sigma statistical error contour of the GBM on-ground location.
The GBM light curve shows a short peak starting at about T-1.5s,
followed by a plateau of about 20s and a weaker emission tail.
The duration (T90) is of about 70 s (50-300 keV), which is
consistent with the light curve observed by Swift considering
the Swift/BAT data stops at T+30s (Sakamoto et al, GCN 13002).
The time-averaged spectrum from T0-2 s to T0+67 s is
well fit by a simple power law function with index -1.62 +/- 0.06
(Castor stat 453.64 for 367 d.o.f.), which is consistent with the
results reported by Sakamoto et al (GCN 13002).
The event fluence (10-1000 keV) in this time interval is
(3.84 +/- 0.08)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0-1.536 s in the 10-1000 keV band
is 1.5 +/- 0.2 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."
- GCN Circular #13014
V.V.Golovnya (Main Astro Obs, Kyiv)
report:
We have undertaken the review of the sky area in vicinity of=20
GRB 120302A (T. Sakamoto et al. GCN Circ.13000) on=20
astronegatives, collected in Ukrainian NAS Main astronomical=20
observatory plate archive (1976-1996). All the plates with=20
the possible object appearance are digitized using Microtek=20
ScanMaker 9800XL TMA and Epson Expression 10000XL flatbed=20
scanners and have been placed into Golosiiv Plate Archive=20
database DBGPA with open access to them.
The list of plates is given in the table:
YYYYMMDD/TimeUT --Plates-- Exp. LimMag Star USNOA2=20
19810224/200500 GUA040C001870B 60.2 14.5 1125-05523340
19810224/200504 GUA040D001871 60.2 14.5 1125-05523340
19900222/193842 GUA040C001572 16.0 16.3 1125-05523532
19900224/194049 GUA040C001590 16.0 15.0 1125-05523428
19900303/191807 GUA040C001624 16.0 15.0 1125-05523428
19920226/201021 GUA040C001952 18.0 15.0 1125-05523428
Plates: =96the plates archive identifier of DWA (D/F=3D400/2000,=20
GUA040C, M=3D103"/mm) of the Ukrainian NAS Main Astro obs.
GUA040D (Marsden's number - 83) the plate number [1].
Exp. - Duration of the maximum exposure (minutes).=20
LimM - Limited V mag, derived in the 20 minutes area around=20
the location given in T. Sakamoto et al. GCN Circ.13000:=20
RA(J2000)=3D 08h 09m 48.14s, Dec(J2000)=3D +29d 39'35.3"
Star USNOA2 - Comparison star.
The preview images of 6 areas together with =20
the 25x25 min.of arc area from SkyMap can be found in =20
http://gua.db.ukr-vo.org/img/grb/120302A/index.html
- GCN Circular #13029
I. Bikmaev, R.Zhuchkov , N. Sakhibullin (Kazan Federal University),
R. Burenin, M. Pavlinsky, R. Sunyaev (IKI),
I. Khamitov, Z. Eker (TUG), U. Kiziloglu (METU), E. Gogus (Sabanci Uni.)
report:
The field of GRB 120302A (Sakamoto et al., GCN 13000) was observed
with Russian-Turkish 1.5-m telescope (RTT150, Bakirlitepe, TUBITAK
National Observatory, Turkey) on March 02, 2012, during UT
19:20--20:05, approximately 18 hours after the burst. A serie of 7
exposures by 300 sec each in Rc filter was obtained at moderate
weather conditions and seeing of 1.7 arcsec.
We clearly detected optical source at the position of XRT, UVOT and
GROND OT candidate (Elliott et al., GCN 13003, Sakamoto et al., GCN
13012). In our combined image we estimated brightness of OT as Rc =
21.14+/-0.08, calibrated against USBO-B1.0 star (R2=17.31 mag) at
R.A. (2000.0) = 08:09:36.74, Dec. (2000.0) = +29:37:54.9
We also made a serie of 300 sec exposures on March 08, 2012, UT (mean)
= 21:05. OT is not seen at the limit of combined image of R ~ 22.4
- GCN Circular #13067
V. Mangano, A. Maselli (INAF-IASFPA), and T. Sakamoto (GSFC/UMBC)
report on behalf of the Swift-XRT team:
Swift performed two additional ToO observations of the field of GRB 120302A
on 2012 March 8 (4.3 ks starting at 05:39:10 UT) and on 2012 March 13
(7.4 ks starting at 06:10:37 UT). In both observations the previously
detected
XRT source (Sakamoto, et al., GCN Circ. 13012) is still visible and is
detected
with marginal significance of about 2.5 sigma. The 0.3-10 keV XRT
lightcurve
shows a decay trend, and a fit with a power-law model gives a decay
slope of
0.76 +/- 0.13.
The source is a possible X-ray afterglow candidate for GRB 120302A.
This circular is an official product of the Swift-XRT team.
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