GRB 060428B
GCN Circular 5075
Subject
GRB 060428B: spectroscopy
Date
2006-05-05T17:00:58Z (20 years ago)
From
Daniele Malesani at SISSA-ISAS,Trieste,Italy <malesani@sissa.it>
D. Fugazza (INAF/OABr), D. Malesani (SISSA), G. Chincarini (Univ.
Milano-Bicocca & INAF/OABr), S. Covino, P. Romano, G. Tagliaferri
(INAF/OABr), M. Della Valle (INAF/OAA), N. Masetti (INAF/IASF Bo), G.
Andreuzzi, N. Pinilla Alonso (INAF/TNG), report on behalf of a larger
collaboration:
We observed the field of GRB 060428B (Campana et al., GCN 5017; Troja et
al., GCN 5031), possibly an X-ray flash (Sakamoto et al., GCN 5029). We
undertook spectroscopy of the object 3" close to the optical afterglow
(Price et al., GCN 5019; Li et al., GCN 5027; Halpern & Mirabal, GCN
5034), considering it as a potential host galaxy. Low-resolution
spectroscopy (~15 A FWHM) was obtained with TNG+DOLoRes, starting on
2005 May 3.89273, for a total exposure time of 1 hr.
Inspection of the spectrum reveals a smooth, very red continuum. No
prominent features were detected either in emission or in absorption. We
thus consider unlikely that this object is the host galaxy of GRB 060428B.
A plot of the spectrum can be found at the following URL:
http://www.sissa.it/~malesani/GRB/060428B/spectrum.gif
This message can be cited.
GCN Circular 5037
Subject
GRB060428B - SDSS Pre-Burst Observations
Date
2006-04-29T17:10:01Z (20 years ago)
From
Richard J. Cool at U.of AZ/Steward Obs <rcool@as.arizona.edu>
Richard J. Cool (Arizona), Daniel J. Eisenstein (Arizona),
David W. Hogg (NYU), Michael R. Blanton (NYU), David
J. Schlegel (LBNL), J. Brinkmann (APO), Donald Q. Lamb
(Chicago), Donald P. Schneider (PSU), and Daniel E. Vanden
Berk (PSU) report:
The Sloan Digital Sky Survey (SDSS) imaged the field of
burst GRB060428B prior to the burst. As these data should
be useful as a pre-burst comparison and for calibrating
photometry, we are supplying the images and photometry
measurements for this GRB field to the community.
Data from the SDSS, including 5 FITS images, 3 JPGS, and
3 files of photometry and astrometry, are being placed
at http://mizar.as.arizona.edu/~grb/public/GRB060428B
We supply FITS images in each of the 5 SDSS bands of a
8'x8' region centered on the GRB position (ra=235.357
(15:41:25.7), dec=62.0238 (62:01:25.7); GCN 5017),
as well as 3 gri color-composite JPGs (with different
stretches). The units in the FITS images are nanomaggies
per pixel. A pixel is 0.396 arcsec on a side. A nanomaggie
is a flux-density unit equal to 10^-9 of a magnitude
0 source or, to the extent that SDSS is an AB system,
3.631e-6 Jy. The FITS images have WCS astrometric
information.
In the file GRB060428B_sdss.calstar.dat, we report
photometry and astrometry of 303 bright stars (r<20.5)
within 15' of the burst location. The magnitudes presented
in this file are asinh magnitudes as are standard in the
SDSS (Lupton 1999, AJ, 118, 1406). Beware that some of
these stars are not well-detected in the u-band; use the
errors and object flags to monitor data quality.
In the files GRB060428B_sdss.objects_flux.dat and
GRB060428B_sdss.objects_magnitudes.dat, we report
photometry of 501 objects detected within 6' of the GRB
position. We have removed saturated objects and objects
with model magnitudes fainter than 23.0 in the r-band.
The fluxes listed in GRB060428B_sdss.objects_flux.dat
are in nanomaggies while the magnitudes listed in
GRB060428B_sdss.objects_magnitudes.dat are asinh
magnitudes.
**Be aware that at least a portion of the photometry
provided in this release has been flagged as
non-photometric. As photometry for objects with this flag
set may have non-optimal calibration, we do not recommend
these objects be used for photometric calibration.
Non-photometric imaging may still be valuable as a
pre-burst comparison and for astrometric calibration.
All quantities reported are standard SDSS photometry,
meaning that they are very close to AB zeropoints
and magnitudes are quoted in asinh magnitudes.
Photometric zeropoints are known to about 2% rms.
None of the photometry is corrected for dust extinction.
The Schlegel, Finkbeiner, and Davis (1998) predictions
for this region are A_U=0.073 mag, A_g=0.054 mag, A_r =
0.039 mag, A_i=0.030 mag, and A_z=0.021 mag.
There are currently no objects within 6 arcminutes of the
GRB position in the SDSS spectroscopic database.
SDSS astrometry is generally better than 0.1 arcsecond
per coordinate. Users requiring high precision astrometry
should take note that the SDSS astrometric system can
differ from other systems such as those used in other
notices; we have not checked the offsets in this region.
More detailed information pertaining to our SDSS GRB
releases can be found in our initial data release paper
(Cool et al. 2006, astro-ph/0601218). See the SDSS DR4
documentation for more details: http://www.sdss.org/dr4.
These data have been reduced using a slightly different
pipeline than that used for SDSS public data releases.
We cannot guarantee that the values here will exactly match
those in the data release in which these data are included.
In particular, we expect the photometric calibrations to
differ by of order 0.01 mag.
This note may be cited, but please also cite the SDSS data
release paper, Adelman-McCarthy et al. (2006, ApJS, in
press, astro-ph/0507711), when using the data or referring
to the technical documentation.
GCN Circular 5036
Subject
GRB060428B: optical observation
Date
2006-04-29T17:06:34Z (20 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), and A.Pozanenko (IKI) on behalf
of larger GRB follow up collaboration report:
We observed the optical afterglow (Price et al. GCN5019; Li et al. GCN5027)
of Swift GRB060428B (Campana et al. GCN 5017) in the R band with Shajn 2.6m
telescope of CrAO between April 28 (UT) 18:43 -- 20:41, i.e. 9.8 -- 11.8 hrs
after the burst onset. The afterglow is visible on a combined image of a
total exposure 3240 sec in a tail of the nearby galaxy (Halpern et al.
GCN5034) and precise photometry is underway. Based on USNO A2.0 we estimate
limiting magnitude of the combined image as R=24.3.
Combined image can be found in
http://grb.rssi.ru/GRB060428/grb060428_ZTSH_R.gif
The message may be cited.
GCN Circular 5035
Subject
GRB060428B: possible detection of an optical counterpart by Swift/UVOT.
Date
2006-04-29T16:13:07Z (20 years ago)
From
Massimiliano de Pasquale at MSSL-UCL <mdp@mssl.ucl.ac.uk>
M. De Pasquale (UCL-MSSL), S. Campana (INAF-OAB) report on
behalf of the Swift/UVOT team:
The Swift/UVOT began taking data on the field of GRB060428B
at 08:57:52 UT on 2006-04-28, 194 s after the BAT trigger
(Campana et al., GCN 5017).
At the position of the optical afterglow claimed by Price et
al. (GCN 5019) and Li et al. (GCN 5027), inside the XRT error
circle (Troja et al., GCN 5031), we find a source near the
detection limits in the V band and in the White filter, not
present in the USNO B1.0 catalogue. The source is present in
the first ~1000 seconds of observations, with a significance
of ~3 sigma. It is not detected later.
Filter T_range(s) Exp(s) Mag
V 194-1233 356 19.5 +0.5 -0.3
V 5630-16900 1081 >20.4
White 211-960 227 19.7 +/- 0.3
White 5247-18579 1135 >20.7
The upper limits quoted above are at the 3 sigma level.
The source is not detected in any of the other filters. The
fading behaviour may indicate that it is the GRB060428B optical
afterglow, however we do caution that detections are marginal
and the results suffer from a contamination by an extended
source, the galaxy quoted by Helpern et al. in GCN 5034. An
association with the GRB cannot be excluded.
No other afterglow candidate was detected at the refined XRT
position in summed images from any of the filters down to the
following three-sigma upper limits:
Filter T_range(s) Exp(s) 3sigma U.L.
V 194-16900 1441 20.5
B 413-17812 1308 21.4
U 390-16900 1357 21.1
UW1 367-19996 1227 20.6
UM2 443-12022 1358 20.6
UW2 323-6894 383 20.2
White 212-18579 1363 20.8
These upper limits are uncorrected for the estimated
Galactic reddening of E_{B-V} = 0.01 mag (Schlegel et al. 1998).
GCN Circular 5034
Subject
GRB 060428B: MDM Observations
Date
2006-04-29T12:08:19Z (20 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern (Columbia U.) and N. Mirabal (U. Michigan) report:
"We observed the optical afterglow (Price et al. GCN 5019; Li et al. GCN 5027)
of Swift GRB 060428B (Campana et al. GCN 5017) in the R band on the MDM 1.3m
telescope during the period April 29.15-29.49 UT, or 18.6-26.8 hours after
the burst. The fading noted by Abe et al. (GCN 5021) has continued. We
estimate R~22.5 at 24 hours post-burst based on calibration with Landolt
standard stars. We note that all of the objects within 25" of the transient
appear to be galaxies, including one having R=19.4 that is only 3" to the
east.
A combined image of 1 hour total exposure at 24 hours post-burst is available
at
http://www.astro.columbia.edu/~jules/grb/060428b/mdm.jpg
This message may be cited."
GCN Circular 5031
Subject
GRB060428B: Swift XRT Team refined analysis
Date
2006-04-28T21:03:14Z (20 years ago)
From
Eleonora Troja at INAF-IASFPA <nora@ifc.inaf.it>
E. Troja (INAF-IASFPA), V. Mangano (INAF-IASFPA),
P. Romano (INAF-OAB), D. N. Burrows (PSU)
report on behalf of the Swift XRT Team:
We have analyzed the XRT data of the first four orbits of
GRB060428B (Campana et al 2006, GCN 5017).
The data set consists of 205 s exposure in Windowed
Timing (WT) mode followed by 8.4 ks exposure in Photon
Counting (PC) mode.
The refined position of the source is
RA (2000) = 15h 41m 25.57s
Dec (2000) = +62d 01' 28.94"
with an uncertainty of 3.8 arcsec (90% confinement).
This position was evaluated from PC data of the orbits
2-4,
that are not affected by pile-up.
This position is 3.35 arcsec from the onboard
detected position (Campana et al 2006, GCN 5017) and
1.4 arcsec from the optical afterglow candidate found by
Price et al 2006 (GCN 5019). To evaluete this offset
we used the KAIT coordinates from Li et al.(GCN 5027).
The 0.2-10 keV X-ray light curve shows an initial very
fast decay with slope -4.4 +/- 0.07, a break at 689 +/- 28
s
from the trigger and then a decay slope of -0.89 +/- 0.06.
The WT spectrum from the first orbit was fitted with an
absorbed power law model and showed a photon index of
2.82 +/- 0.08 (90% confidence level).
The WT spectrum covers the 212-418 s time interval.
The spectrum shows evidence of an absorption column at the
level of (6.7 +/- 0.7) x 10^20 cm^-2 in excess with
respect
to the Galactic value of 1.7 x 10^20 cm^-2.
The 0.2-10 keV unabsorbed flux is 9.8 x 10^-10 ergs cm^-2
s^-1.
The PC spectrum of the orbits 2-4 (time interval 4.4-18.5
ks) is well
fit by an absorbed powerlaw model with photon index 2.08
+/- 0.16.
The 0.2-10 keV unabsorbed flux is 1.6^-12 ergs cm^-2 s^-1.
If decaying at the present rate the source will reach the
flux level of 2.6^-13 erg cm^-2 s^-1 (corresponding to
a count rate level of 5 x 10^-3 counts s^-1)
after one day.
This Circular is an official product of the Swift XRT
Team.
GCN Circular 5029
Subject
GRB 060428B: Refined analysis of the Swift-BAT burst
Date
2006-04-28T18:41:16Z (20 years ago)
From
Scott Barthelmy at NASA/GSFC <Scott@lheamail.gsfc.nasa.gov>
T. Sakamoto (NASA/ORAU), L. Barbier (GSFC), S. Barthelmy (GSFC),
S. Campana (INAF-OAB), J. Cummings (NASA/ORAU), E. Fenimore (LANL),
N. Gehrels (GSFC), D. Hullinger (BYU-Idaho), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
G. Sato (ISAS), J. Tueller (GSFC), M. Koss (UMD), M. Stamatikos (NASA/ORAU)
on behalf of the Swift-BAT team:
Using the data set from T-239 to T+963 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 060428B (trigger #207399)
(Campana, et al., GCN 5017). The BAT ground-calculated position is RA,Dec =
235.378,+62.027 deg {15h 41m 30.8s,+62d 1' 35.8"} (J2000) +- 1.7 arcmin,
(radius, sys+stat, 90% containment). The partial coding was 74%.
The mask-weighted lightcurve shows a broad peak starting at T-20 sec
until ~T+44 sec. T90 (15-350 keV) is 58 +- 3 sec (estimated error
including systematics).
The time-averaged spectrum from T-23.8 to T+41.9 is best fit by a power law
with an exponential cutoff. This fit gives a photon index 0.94 +- 1.30,
and Epeak of 21.7 +- 14.0 keV (chi squared 68.81 for 56 d.o.f.).
For this model the total fluence in the 15-150 keV band is
7.2 +- 0.9 x 10^-7 erg/cm2 and the 1-sec peak flux measured from T+20.78 sec
in the 15-150 keV band is 0.6 +- 0.1 ph/cm2/sec. A fit to a simple power law
gives a photon index of 2.58 +- 0.19 (chi squared 75.57 for 57 d.o.f.).
All the quoted errors are at the 90% confidence level.
GCN Circular 5028
Subject
GRB 060428B: Xinglong I-band limit
Date
2006-04-28T17:38:45Z (20 years ago)
From
W.K. Zheng at NAOC <zwk@bao.ac.cn>
Y.Q. Lou, X.F. Wang (THCA), M.Zhai, Y.L. Qiu, J.Y. Wei, J.Y. Hu,
J.S. Deng (NAOC) K.Y. Huang (NCU), Y. Urata (Saitama Univ.)
on behalf of EAFON report:
We have observed the field of GRB060428B (GCN 5017) with the Xinglong 0.8m
telescope 3.54 hours after the burst, The candidate (GCN 5019) do not appear within
our 7x600s combined I-band image. Upper limit is 19.1(SN=3) Mag .
This message may be cited.
GCN Circular 5027
Subject
GRB 060428B: KAIT observations
Date
2006-04-28T17:18:35Z (20 years ago)
From
Weidong Li at UC Berkeley KAIT/LOSS <weidong@astron.berkeley.edu>
From alex@wormhole.Berkeley.EDU Fri Apr 28 10:07:14 2006
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W. Li, R. Chornock, N. Butler, J. Bloom, and A. V. Filippenko (University of
California, Berkeley), on behalf of the KAIT GRB team, report:
The robotic 0.76-m Katzman Automatic Imaging Telescope (KAIT)
at Lick Observatory observed GRB 060428B, detected with Swift
(Trigger 207399; Campana et al. GCN 5017). The automatic sequence
started at 08:57:50, 192 s after the burst. In a 15 s unfiltered
image, no afterglow candidate is detected to a limiting magnitude
of 18.7 (from comparison with the USNO B1.0 catalog). Our real-time
image processing software detected the optical afterglow candidate
reported by Price et al. (GCN 5019) in a 60 s unfiltered image started
at 642 s after the burst, with the following precise (+/- 0.3") position:
RA = 15:41:25.63 Dec = +62:01:30.3 (J2000.)
A table of photometry (3-sigma limits and detections) is reported
below. The photometry of the afterglow candidate suggests a flat
luminosity evolution from 10 to 35 minutes after the burst, but
we caution that the photometry may suffer larger uncertainties than
reported due to relatively poor detections and the contamination of a
nearby source.
======================================================================
Start UT t(GRB) exposure(s) Filter 3sigma-limit detection
08:57:50 192s 15.0 clear 18.7
08:58:27 229s 15.0 V 16.9
08:58:57 259s 15.0 I 17.2
08:59:28 290s 20.0 clear 19.0
09:00:04 326s 45.0 V 17.7
09:01:04 386s 45.0 I 18.3
09:02:05 427s 45.0 clear 19.2
09:03:07 489s 60.0 V 17.9
09:04:23 565s 60.0 I 18.3
09:05:40 642s 60.0 clear 19.58 +/- 0.13
09:10:51 953s 120.0 clear 19.64 +/- 0.13
09:18:51 1433s 240.0 clear 19.40 +/- 0.11
09:30:55 2157s 360.0 clear 19.52 +/- 0.11
========================================================================
GCN Circular 5023
Subject
GRB060428B, optical observation
Date
2006-04-28T15:08:51Z (20 years ago)
From
Eri Sonoda at U of Miyazaki/Japan <sonoda@astro.miyazaki-u.ac.jp>
E.Sonoda,S.Maeno,M.Yamauchi
(University of Miyazaki)
We have observed the field covering the error circle of
GRB060428B (GCN 5017) with the unfiltered CCD camera on
the 30-cm telescope at University of Miyazaki.
The observation was started 12:02:52 UT, ~3.14 hour
after the Swift trigger time.
We have compared our data of 30 sec exposures
with the USNO-A2.0 catalog, there is no new source
at the position reported by P.A.Price et al.(GCN 5019).
The upper limits are as follows:
--------------------------------------------------------------
Start(UT) End(UT) Num. of frames Limit (mag.)
--------------------------------------------------------------
12:02:52 12:11:28 8 ~12.8
12:11:52 12:41:28 24 ~16.9
12:42:56 12:47:02 4 ~17.9
---------------------------------------------------------------
GCN Circular 5021
Subject
GRB 060428b : Kiso R-band limit
Date
2006-04-28T13:16:35Z (20 years ago)
From
Yuji Urata at Saitama U <urata@crystal.heal.phy.saitama-u.ac.jp>
M.Abe (ISAS/JAXA), Y. Sarugaku, H.Mito (Tokyo Univ.), Y.L. Qiu,
W.K. Zheng (NAOC), K.Y. Huang(NCU), Y. Urata (Saitama Univ.)
on behalf of EAFON report:
"We have observed the GRB 060428B field (GCN #5017) using Kiso 1.05m
telescope. The R and B band observations were started from 2.3 hours
after the burst (after end of twilight). The limiting magnitude
derived from USNOB1.0 is R=20.7 (SN=3). The candidate (GCN #5019) do
not appear brighter than the limiting magnitude. This result indicates
that the candidate is afterglow of GRB 060428B.
Further analysis is in progress."
This message may be cited.
GCN Circular 5019
Subject
GRB 060428b: Optical afterglow candidate
Date
2006-04-28T11:15:34Z (20 years ago)
From
Paul Price at IfA,UH <price@ifa.hawaii.edu>
P.A. Price (IfA, Hawaii), T. Minezaki (IoA, Tokyo), L.L. Cowie, Y.
Kakazu (IfA, Hawaii) and Y. Yoshii (IoA, Tokyo) report:
We have observed the XRT localisation of GRB 060428B (GCN #5017) with
the robotic MAGNUM telescope. Observations were made under clouds in R
and I bands starting at 2006 Apr 28.38 UTC, with interruptions due to
weather. Observations consisted of 10 x 65 sec exposures in R-band.
We identify a source in the combined image, which does not appear to be
in the DSS 2 red plate. While a precise astrometric solution is not yet
available, our estimate of the position is approximately 3 arcsec west
of the USNO-B1 source 1520-0246226 (at 15:41:25.96 +62:01:30.160 J2000),
or around
15:41:25.5 +62:01:30 J2000
The source is approximately R ~ 19.6 mag at the time of our observations
(from comparison with the USNO-B1 catalogue), and also appears in
subsequent I-band and R-band combined images.
An image of the field is available at
http://www.ifa.hawaii.edu/~price/grb060428b.jpg
GCN Circular 5017
Subject
GRB 060428B: Swift detection of a burst
Date
2006-04-28T09:31:30Z (20 years ago)
From
Scott Barthelmy at NASA/GSFC <Scott@lheamail.gsfc.nasa.gov>
S. Campana (INAF-OAB), S. D. Barthelmy (GSFC), D. N. Burrows (PSU),
J. R. Cummings (NASA/ORAU), N. Gehrels (NASA/GSFC),
C. B. Markwardt (GSFC/UMD), K. L. Page (U Leicester),
D. M. Palmer (LANL), P. Romano (INAF-OAB) and D. E. Vanden Berk (PSU)
report on behalf of the Swift Team:
At 08:54:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 060428B (trigger=207399). Swift slewed immediately to the burst.
The BAT on-board calculated location is RA,Dec 235.350,+62.010
{15h 41m 24s,+62d 00' 36"} (J2000) with an uncertainty of 3 arcmin
(radius, 90% containment, including systematic uncertainty). This is
an image trigger (128 sec), so the lightcurve does not show any significant
activity (as is typical).
The XRT began observing the field at 08:58:02 UT, 204 seconds after the
BAT trigger. XRT found a bright, fading X-ray source
located at RA(J2000) = 15h 41m 25.6s, Dec(J2000) = +62d 01' 25.6", with an
estimated uncertainty of 5.0 arcseconds (90% confidence radius).
This location is 51 arcseconds from the BAT on-board position, within
the BAT error circle. The initial flux in the 2.5s image was
2.3e-09 erg/cm2/s (0.2-10 keV).
UVOT took a finding chart exposure of 100 seconds with the White
(160-650 nm) filter starting 212 seconds after the BAT trigger,
and of 400 sec. with the V filter starting at 965 seconds after
the BAT trigger. No afterglow candidate has been found in the
initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The 3-sigma V band upper limit is about
19.1 mag. The 8'x8' region for the list of sources generated
on-board 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) of 0.01.