- GCN Circular #7903
L. Pacciani, I. Donnarumma, E. Del Monte, M. Feroci, Y. Evangelista,
E. Costa, I. Lapshov, F. Lazzarotto, L. Pacciani, M. Rapisarda,
P. Soffitta, (INAF/IASF Rome), A. Giuliani, S. Vercellone, A. Chen,
S. Mereghetti, A. Pellizzoni, F. Perotti, F. Fornari, M. Fiorini, P. Caraveo,
A. Zambra (INAF/IASF Milan), A. Bulgarelli, F. Gianotti,
M. Trifoglio, G. Di Cocco, C. Labanti, F. Fuschino, M. Marisaldi,
M. Galli, (INAF/IASF Bologna), M. Tavani, G. Pucella, F. D'Ammando, V.
Vittorini, A. Argan, A. Trois (INAF/IASF Rome), G. Barbiellini,
F. Longo (INFN Trieste), P. Picozza, A. Morselli (INFN Roma-2),
M. Prest, E. Vallazza (Universita` dell'Insubria), P. Lipari,
D. Zanello (INFN Roma-1), and P. Giommi, C. Pittori,
(ASDC) and L. Salotti (ASI), on behalf of the AGILE Team, report:
"SuperAGILE detected and localized a gamma ray burst
on June 25th 2008, at 12:28:31 UT. The event was approximately
22 degrees off-axis. The observed duration in the 20-60 keV
energy range is about 80 seconds, with a single peak structure.
The burst was triggered and localized on ground.
The burst position was reconstructed as (RA, Dec) (298.4423 deg,
56.2653 deg), which is:
RA(J2000) = 19h 53m 46.14s
Dec(J2000) = 56d 15' 55.1"
with an uncertainty of 3' radius. The given uncertainty accounts
for both the statistical and systematic errors.
An analysis of the AGILE Gamma Ray Imager (GRID) data is in progress."
This message may be cited.
- GCN Circular #7904
A. de Ugarte Postigo (ESO), F. Aceituno,
A.J. Castro-Tirado, J. Gorosabel (IAA-CSIC)
report on behalf of a larger collaboration:
We have observed the field of GRB080625, detected
by SuperAGILE (Pacciani et al. GCN 7903), from
the 1.5m OSN telescope starting at June 25.8591
(8.14 hours after the burst). Preliminary analysis
does not show any evident new source within the
3' error box as compared with the DSS2 IR frame.
We note, however, that our combined 4x300s I-band
frame yields a limit of I < 21.5, significantly
deeper than the catalogue.
Further imaging is scheduled in order to determine
if any of the objects that we detect at or beyond the
limit of the catalogue is the afterglow of GRB 080625.
- GCN Circular #7905
S. Immler (NASA/CRESST/GSFC) reports on behalf of the Swift/UVOT team:
The Swift Ultra-Violet/Optical Telescope (UVOT) started observing
GRB 080625 (Pacciani et al., GCN Circ. 7903) ~5.0 hours after the
AGILE trigger.
A candidate afterglow is found in UVOT White, v, and b filter
images which cover the entire AGILE error circle. The preliminary
Swift/UVOT position of the optical afterglow candidate is:
RA(J2000) = 19:53:37.06 = 298.4044
DEC(J2000) = +56:16:40.5 = 56.2779
with a 1-sigma error radius of about 0.5 arcsec.
The following table gives the measured magnitudes:
Filter T_start [s] T_stop [s] Exp [s] Magnitude
White 18769 19567 799 20.3 +/- 0.1
White 24551 25179 1427 20.6 +/- 0.1
V 19575 20350 776 19.6 +/- 0.1
B 17964 18762 799 20.1 +/- 0.1
B 23746 24544 799 20.7 +/- 0.2
U 17880 23741 240 >20.4 (3-sigma UL)
The values quoted above are in the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627). No correction has been
made for the expected extinction corresponding to E(B-V) of
0.44 mag in the direction of the burst (Schlegel et al. 1998).
- GCN Circular #7906
M.C. Stroh, C. Pagani and L. Vetere (PSU) report on behalf of the
Swift-XRT team
The Swift-XRT began observations of the SuperAGILE burst GRB 080625
(Pacciani et al., GCN Circ 7903) ~5 hours after the trigger. The data
consist of 3.9 ks observed in Photon Counting mode.
We detect an X-ray counterpart at position: RA, Dec = 298.40420,
56.27747 which is equivalent to:
RA (J2000): 19 53 37.0
Dec (J2000): +56 16 38.9
with an uncertainty of 4 arcsec (radius, 90% confidence). This is
consistent with the UVOT position (Immler, GCN 7905).
We are unable to determine whether the source is decaying at this
time. Observations are continuing and further analysis regarding the
fading nature of this source will be issued as the data become
available.
The spectrum can be fitted with a powerlaw with an intrinsic absorbing
column of (2.5+/-0.9) e21 cm-2 and photon index 2.31+/- 0.17. The
observed (unabsorbed) 0.3-10 keV flux is 2.91 (3.00) e-12 erg cm-2 s-1.
This circular is an official product of the Swift-XRT team.
- GCN Circular #7907
A. de Ugarte Postigo (ESO), F. Aceituno,
A.J. Castro-Tirado, J. Gorosabel (IAA-CSIC)
report on behalf of a larger collaboration:
We have observed again the field of GRB 080625 (Pacciani et al.
GCN 7903) using the 1.5m OSN telescope at Sierra Nevada
Observatory (Granada, Spain) at a mean epoch of 14.76h after the
burst. The object identified by Immler et al. (GCN 7905) is well
detected in this and in our previous epoch (GCN 7904). A preliminary
photometry against USNO-B1.0 stars shows the object decaying, as
seen in the following table:
t-t0 (hours) Exp (s) I mag
8.325 4x300 19.3+/-0.2
14.769 3x300 20.0+/-0.2
- GCN Circular #7908
S. Immler (NASA/CRESST/GSFC) reports on behalf of the Swift/UVOT team:
Swift Ultra-Violet/Optical Telescope (UVOT) follow-up observations
of GRB 080625 (Pacciani et al., GCN Circ. 7903), starting ~25.9 hrs
after the AGILE trigger, confirm the fading of the optical afterglow
(Immler et al., GCN Circ. 7905; de Ugarte Postigo et al., GCN Circ. 7907).
The following magnitude is measured in the co-added image obtained
in the White filter:
Filter T_start [s] T_stop [s] Exp [s] Magnitude
White 93,092 162,754 5,776 21.3 +/- 0.1
The magnitude quoted above is in the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627). No correction has been
made for the expected extinction corresponding to E(B-V) of
0.14 mag in the direction of the burst (Schlegel et al. 1998).
Note the corrected value for the extinction compared to Immler
2008 (GCN Circ. 7905).
- GCN Circular #7930
T. Uehara, Y. Hanabata, Y. Fukazawa, T. Takahashi, C. Kira (Hiroshima U.),
M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA),
K. Yamaoka, S. Sugita (Aoyama Gakuin U.),
K. Onda, M. Tashiro, Y. Terada, Y. Urata, A. Endo, N. Kodaka,
K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.),
Y. E. Nakagawa, T. Tamagawa (RIKEN), T. Enoto, K. Nakazawa,
K. Makishima (Univ. of Tokyo), E. Sonoda, M. Yamauchi, H. Tanaka,
R. Hara (Univ. of Miyazaki), S. Hong (Nihon U.),
on behalf of the Suzaku WAM team, report:
The long GRB 080625 (SuperAGILE ; Marco et al., GCN 7903)
was detected by the the Suzaku Wide-band All-sky Monitor (WAM) which covers an
energy range of 50 keV - 5 MeV at 12:28:41 UT on 25 July 2008 (=T0).
The observed light curve shows a single peak, starting at T0s, ending
at T0+62s with a duration
(T90) of about 62 seconds. The fluence in 100 - 1000 keV was 2.3(+1.3/-0.7) E-6 erg/cm^2.
The 1-s peak flux measured from T0+33s was 0.4(+0.2/-0.3) photons/cm^2/s in the same
energy range.
Preliminary result shows that the time-averaged spectrum from T0-15s to
T0+50s is well fitted by a single power-law with a photon index
of 1.7 (+1.2/-0.8) (chi^2/d.o.f = 9.6/8) at the 120 - 500 keV bandpass.
All the quoted errors are at statistical 90% confidence level,
in which the systematic uncertainties are not included.
The light curves with 1-sec time resolution for this burst will be appeared at:
http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/untrig/grb_table.html
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