GRB 060421
GCN Circular 4986
Subject
Possible GRB060421: BART limits
Date
2006-04-21T07:45:54Z (19 years ago)
Edited On
2024-11-18T10:10:32Z (7 months ago)
From
Martin Jelinek at Inst.Astrophys.Andalucia,Granada <mates@iaa.es>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Leo P. Singer at NASA/GSFC <leo.p.singer@nasa.gov>
Jan Strobl, Martin Topinka, Martin Nekola and René Hudec
(ASU Ondrejov, Czech Republic),
Petr Kubánek (ISDC Versoix, Swtzerland and ASU Ondrejov)
and Martin Jelínek (IAA Granada)
report
Robotic telescope BART located in Ondrejov observatory in
Czech Republic, followed the Swift trigger 206257 (Goad et al,
GCN 4985). The observation in fully automatic mode (under
control of RTS2), started 33.7s after the Swift trigger time.
We did not find any new optical source. Particularly we set
the following limits:
Tmean Exp limit
44s 20s B>14.2
98.0s 20s V>15.2
152s 20s i>15.3
206s 20s z>14.3
184s 8x45s R>15.3
The magnitudes are calibrated against USNO-A2.0.
GCN Circular 4992
Subject
GRB 060421: Swift-XRT refined analysis
Date
2006-04-21T15:32:18Z (19 years ago)
From
Kim Page at U.of Leicester <kpa@star.le.ac.uk>
M.R. Goad, K.L. Page (U Leicester) and D.N. Burrows (PSU) report on
behalf of the Swift-XRT team:
We have analysed the first 14 ks of Photon Counting (PC) mode data,
starting 97 seconds after the BAT trigger time, determining a refined
position of
RA (J2000): 22 54 32.63
Dec(J2000): +62 43 50.07
with an estimated uncertainty of 3.8 arcsec (90% containment). This is 1.7
arcsec from the initial XRT position given by Goad & Page in GCN 4987 and
16.2 arcsec from the on-board BAT position quoted in GCN 4985 (Goad et
al.)
The X-ray source was initially quite faint, with a peak count rate of only
~1 count s^-1. The light-curve shows a flat decay of alpha = 0.49 +/-
0.29, breaking to a steeper slope of alpha = 1.54 +/- 0.36, approximately
1500 seconds after the burst.
Because of the faintness of the afterglow, only 3 seconds of data were
obtained in Windowed Timing mode before switching into PC. The first orbit
of PC data (97-717 seconds post-trigger) can be modelled with a simple
power-law of Gamma = 1.54 +/- 0.34, with the Galactic absorbing column of
1e22 cm^-2. The observed (unabsorbed) flux over 0.3-10 keV for this time
period is 3.78e-11 (5.64e-11) erg cm^-2 s^-1.
Assuming the current rate of decay continues, the estimated count rate at
24 hours is 4.2e-3 count s^-1, corresponding to an observed (unabsorbed)
flux of 4.55e-14 (6.38e-14) erg cm^-2 s^-1.
This circular is an official product of the Swift-XRT team.
GCN Circular 4993
Subject
GRB 060421: Swift-BAT Refined Analysis
Date
2006-04-21T15:34:38Z (19 years ago)
From
Louis M Barbier at NASA/GSFC/Swift <lmb@cosmicra.gsfc.nasa.gov>
E. Fenimore (LANL), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/ORAU), N. Gehrels (GSFC), D. Hullinger (BYU-Idaho),
H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (ISAS),
J. Tueller (GSFC), on behalf of the Swift-BAT team:
Using the data set from T-120 to T+78 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 060421
(trigger #206257) (Goad, et al., GCN 4985). The BAT ground-calculated position
is (RA,Dec) = 343.627, 62.730 deg {22h 54m 30.4s, 62d 43' 47.0"} (J2000)
+- 0.8 arcmin, (radius, sys+stat, 90% containment). The partial coding was 82%.
The mask-weighted light curve shows one strong peak followed by
several smaller peaks extending out to 10 seconds after the trigger.
T90 (15-350 keV) is 11 +- 1 sec (estimated error including systematics).
The time-averaged spectrum from T-3.8 to T+10.9 is well fit by
a simple power-law model. The power law index of the time-averaged
spectrum is 1.53 +- 0.07. The fluence in the 15-150 keV band is
1.2 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from
T+2.28 sec in the 15-150 keV band is 3.0 +- 0.2 ph/cm2/sec. All the quoted
errors are at the 90% confidence level.
Based on the shape of the light curve and the hard spectrum, we believe that this
is a GRB, however, we can not rule out a hard x-tray transient nature
of this event.
GCN Circular 4994
Subject
GRB060421: Swift/UVOT observations
Date
2006-04-21T17:04:13Z (19 years ago)
From
Peter Brown at PSU <pbrown@astro.psu.edu>
P. J. Brown (PSU), M. R. Goad (U Leicester),
S. T. Holland (GSFC/USRA), & P. O'Brien (U Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began taking settled exposures of the
field of GRB0604213 at 2006-04-21 00:40:48,
84 s after the BAT trigger (Goad et al., GCN 4985).
Within the revised XRT error circle (Goad, Page,
& Burrows GCN 4992) we detect a V=19.0 +/- 0.2 source at
22:54:32.18, +62:43:49.5 (+/- 1") which is coincident
with 2MASS 22543217+6243493 and also visible in the
DSS. This source does not vary over ~5 hours of
observations and is not considered an afterglow
candidate.
We do not detect this or any other sources in
summed images from any of the other filters down
to the following three-sigma upper limits.
Filter T_range(s) Exp(s) 3sig_UL
V 84-17355 1700 19.0
B 562-23873 1116 20.6
U 538-23145 2035 20.5
UVW1 514-22233 2204 20.2
UVM2 490-18091 2074 20.4
UVW2 578-16442 1318 20.2
These upper limits are uncorrected for extinction.
The Galactic latitude is +2.83 degrees and the
Schlegel et al. (1998) reddening in this direction
is E(B-V)=1.28 mag. As noted in GCN 4985 the
Cepheus OB3 molecular cloud association in our Galaxy
is near this line of sight.
GCN Circular 4999
Subject
GRB 060421: TTT Observations
Date
2006-04-24T02:50:10Z (19 years ago)
From
Chelsea Louise MacLeod at UNC-Chapel Hill/PROMPT <chelseam@physics.unc.edu>
C. MacLeod, J. Harvey, A. Trotter, M. Nysewander, A. LaCluyze, D. Reichart,
A. Crain, K. Ivarsen, A. Foster, J. Haislip, J. Kirschbrown, and J.
Carpenter report on behalf of the UNC team of the FUN GRB Collaboration:
Skynet observed the localization of GRB 060421 (Goad et al., GCN 4985; Goad
& Page, GCN 4987; Goad, Page & Burrows, GCN 4992) with 14.5-inch TTT in
Colorado beginning 2.2 hours after the burst in variable conditions:
Filter Start (UT) Stop (UT) Exposures Total (min)
Red* 02:49:45 03:12:03 6 x 160s 16.0
Green** 03:13:48 03:34:41 6 x 160s 16.0
Blue 03:35:51 03:54:51 5 x 160s 13.3
Red* 03:57:17 04:15:58 5 x 160s 13.3
Green** 04:19:00 05:00:41 11 x 160s 29.3
Blue 05:02:14 05:42:19 11 x 160s 29.3
Red* 05:44:56 06:28:07 11 x 160s 30.7
+ 1 x 80s
Green** 06:29:39 07:12:54 11 x 160s 29.3
Blue 07:14:37 07:55:35 11 x 160s 29.3
Red* 07:57:16 09:20:36 19 x 160s 50.7
Green** 09:22:42 10:45:43 21 x 160s 56.0
Blue 10:48:00 11:06:50 5 x 160s 13.3
* Approximates R band
** Approximates V band
No new source is found to V > 18.3 mag (3 sigma; calibrated to five NOMAD
stars) at 4.0 hours after the burst.