GRB 050502A
GCN Circular 3332
Subject
GRB 050502A: Redshift measurement based on Keck HIRES Observations
Date
2005-05-02T12:37:32Z (20 years ago)
From
Hsiao-Wen Chen at MIT/CSR <hchen@space.mit.edu>
Jason X. Prochaska (UCO/Lick Obs.), Sara Ellison (U. Victoria),
R. J. Foley (UCB), J. S. Bloom (UCB), & H.-W. Chen (MIT) report on behalf
of the GRAASP collaboration:
"We observed the afterglow of GRB 050502a for 3600s with HIRES on the KeckI
telescope starting at UT 05:53:46 on May 02, 2005, 3.5 hours after the initial
burst. We obtained a low SNR, high resolution spectrum (R~40000). We report
a tentative redshift of z=3.793 based on the following lines of evidence:
1. We detect a prominent flux discontinuity at 4400 Ang, blueward of which no
flux is present. We interpret the flux decrement at 4400 A as the Lyman
limit absorption produced by the host of the GRB.
2. The flux blueward of ~5870 Ang is 'patchy', i.e. indicative of the Lya
forest. A broad absorption feature is present at 5820 Ang, which we
interpret as the Lya absorption due to the ISM of the host galaxy.
3. We identify a strong absorption feature at 6040 Ang, which is consistent
with SiII1260 at z=3.793.
Further analysis is underway.
This message can be cited."
GCN Circular 3335
Subject
GRB 050502a : R band observation at Lulin observatory
Date
2005-05-02T16:49:12Z (20 years ago)
From
Yuji Urata at RIKEN <urata@crab.riken.go.jp>
K. Sanchawala, W.L. Wu, K.Y. Huang, W.H. Ip(NCU),
Y. Qiu, W. Zhou (BAO), Y.Q. Lou (THCA), Y. Urata (RIKEN),
on behalf of EAFON report:
" We have observed the position of GRB 050502a optical afterglow (Yost
et al. GCN 3322) using 1-m telescope at Lulin Observatory,
Taiwan. Under unstable weather condition, single R band image was
taken at 15.59 UT (~ 13.37 hours after the burst). The limiting
magnitude is R~ 21 compared with USNO-B1.0 stars. No source was
detected down to the limiting magnitude at the position.
This message may be cited."
GCN Circular 3340
Subject
GRB050502A: Optical Observations
Date
2005-05-03T02:42:36Z (20 years ago)
From
Aaron Price at AAVSO <aaronp@aavso.org>
D.T. Durig (Cordell-Lorenz Observatory - The University of The South) reports on
behalf of the AAVSO International High Energy Network on optical observations of
GRB050502A (GCN #3323, Gotz et al.):
Durig reports the following rapidly fading behavior:
Date (UT) Mag
02.17880 19.8
02.18243 20.8
02.18606 20.3
02.18969 20.4
02.19331 20.5
02.19694 20.9
02.20056 21.4
02.20418 21.4
02.20781 21.0
02.21144 21.3
Observations were made unfiltered based on a V zeropoint. Uncertainly is +/- 0.4
magnitudes. Details of the observation are below along with a link to the co-added
FITS image.
Full Observation Details
Name: Dr. Douglas T. Durig
email: ddurig@sewanee.edu
Observer: D. T. Durig ( CLW01)
Site: Cordell-Lorenz Observatory
Location: Sewanee, TN, USA
LatitudeLongitude: 35 12 N 85 55 W
Elevation: 600 m
Scope: SCT 0.30 m
ScopeFocalRatio: f/5.8 1766 mm FL
CCDVendor: SBIG ST1001E
CCDDetector: KAF1001E
CCDSize: 1024x1024
CCDPixelScale: 2.8 arc sec/ pixel
CCDFOV: 48x48 full, 12x12 cropped submitted
Object: GRB050502
ObsDate: 2005 05 02
ObsMidPointTime: 2.15912 (04 40 58 UT )
TimePerFrame: 300 sec
NumberOfFrames: 11
Filters: CV
Processing: dark, flat, registered, added, quarter frame cropped
Seeing: 4 to 5 arc sec
LimitingMag (SNR=3): 21.0 ???
Sky: very clear
afterglowmag: 20 fading to 21 during first hour
afterglowerr: 0.4
compstars: 900 USNO B1.0 stars
Report: I could see the afterglow candidate in my first few images but it was
fading fast and I had to stack to see it well in later images.
Ave Position:13 29 46.28 +42 40 27.7
I get the following magnitudes for co-added (10min) frames:
02.17880 19.8 CV
02.18243 20.8 CV
02.18606 20.3 CV
02.18969 20.4 CV
02.19331 20.5 CV
02.19694 20.9 CV
02.20056 21.4 CV
02.20418 21.4 CV
02.20781 21.0 CV
02.21144 21.3 CV
A FITS image has been uploaded to
ftp://ftp.aavso.org/grb/Dr.DouglasT.Durig_GRB050502_2453492.77287_.fits
The AAVSO thanks the Curry Foundation for their continued support of the
AAVSO International High Energy Network.
GCN Circular 3341
Subject
GRB 050502A: WSRT Radio Observations
Date
2005-05-03T12:36:59Z (20 years ago)
From
Alexander van der Horst at U of Amsterdam <avdhorst@science.uva.nl>
A.J. van der Horst, R.A.M.J. Wijers and K. Wiersema (University of
Amsterdam) report on behalf of a larger collaboration:
"We observed the position of the GRB 050502A afterglow at 1.4 and 4.9 GHz
with the Westerbork Synthesis Radio Telescope at May 2 16.33 UT to May 3
4.31 UT, i.e. 14.10 - 26.08 hours after the burst (GCN 3323).
We do not detect a radio source at the position of the optical afterglow
(GCN 3322). The formal flux measurements for a point source at the
location of the optical afterglow is 0 +/- 28 microJy at 1.4 GHz, and -69
+/- 29 microJy at 4.9 GHz."
This message may be cited.
GCN Circular 3342
Subject
GRB 050502a: RBO Observations
Date
2005-05-03T15:03:37Z (20 years ago)
From
Melissa Nysewander at UNC,Chapel Hill <mnysewan@physics.unc.edu>
D. Allen, J. Silvey and R. Canterna report on behalf of the RBO Team of the
FUN GRB Collaboration:
We observed the position of the afterglow of GRB 050502a (Yost et al., GCN
3322; Gotz et al., GCN 3323) with the Red Buttes Observatory 24-inch
telescope under high humidity and non photometric conditions.
We do not detect the afterglow down to the following values:
UT Start Time Filter Limiting
Since GRB (hr) Magnitude
08:04 5.83 R 19.1
09:08 6.90 R 20.1
09:19 7.08 I 18.3
10:40 8.43 I 19.0
10-sigma limiting magnitudes were derived from the USNO-B1.0 catalogue.
GCN Circular 3344
Subject
GRB050502a: P60 Observations
Date
2005-05-03T21:02:27Z (20 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. Bradley Cenko and Derek B. Fox report on behalf of the Caltech-NRAO-
Carnegie GRB Collaboration:
We have imaged the field of GRB050502a (GCN 3323) with the automated
Palomar 60-inch Telescope. Observations consisted of 30 x 120 s
exposures in the Kron R band. We detect no emission at the position of
the afterglow reported by Yost et. al. (GCN 3322). Our 3-sigma limiting
magnitude, estimated by comparison with several Guide Star Catalog
sources in the field, is approximately R > 21.5.
GCN Circular 3345
Subject
GRB050502a: P60 Observations (Correction)
Date
2005-05-03T21:37:41Z (20 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. Bradley Cenko and Derek B. Fox report on behalf of the Caltech-NRAO-
Carnegie GRB Collaboration:
We have imaged the field of GRB050502a (GCN 3323) with the automated
Palomar 60-inch Telescope. Observations consisted of 30 x 120 s
exposures in the Kron R band, taken at a mean epoch of 9:30 May 3 UT (~
30.3 hours after the burst). We detect no emission at the location of
the afterglow reported by Yost et. al. (GCN 3322). Our limiting
magnitude, estimated by comparison with several Guide Star Catalog
sources in the field, is approximately R > 21.5.
GCN Circular 3363
Subject
GRB 050502a: Optical Observations
Date
2005-05-06T01:03:13Z (20 years ago)
From
Nestor Mirabal at U Michigan <mirabal@umich.edu>
N. Mirabal (U. Michigan), M. Boettcher, J. Shields, M. Joshi (Ohio U.),
and J. P. Halpern (Columbia U.) report on behalf of the MDM GRB follow-up
team:
"We monitored the optical afterglow (Yost et al., GCN #3322) of GRB
050502a with the MDM 1.3m telescope beginning on 2005 May 2.163 UT and
spanning from 1.8 hr to 8.2 hr after the burst. Preliminary photometry
referenced to a USNO-B1.0 star at (J2000) R.A. 13:29:59.84, Decl.
+42:43:00.2 listed as R = 16.01, indicates that the OT faded from
approximately R~19.3 on May 2.163 to R~21.4 on May 2.36, and continued to
decline until the end of the monitoring period. The corresponding
power-law decay index is -1.44 +/- 0.2. This is steeper than the decay
index of -1.03 estimated from the earlier observations of Yost et al.
(GCN #3322)."
GCN Circular 3374
Subject
GRB 050502a: Swift XRT Upper Limit
Date
2005-05-06T20:50:21Z (20 years ago)
From
Cheryl Pauline Hurkett at Leicester U <cph9@star.le.ac.uk>
C. Hurkett, K.Page, J. P. Osborne (U Leicester), B. Zhang (UNLV), J.
Kennea, D. N. Burrows (PSU) and N. Gehrels (NASA/GSFC) report on behalf of
the Swift XRT team:
The Swift XRT observed the INTEGRAL burst GRB 050502a for ~2.5ks from
13:17 UT to 18:42 UT on 02 May 2005; for ~2.5 ks from 15:00 UT to 20:01 UT
on 03 May 2005 and for ~43 ks from 00:28 on 04 May 2005 to 23:10 on 05 May
2005.
In the first observation (02 May 2005) we detect no source in a 20
arcsec radius circle centred at the position of the optical counterpart
identified by Yost et al 2005 (GCN 3322), with a 90% confidence upper
limit of 1.03e-3 counts/s (0.2 - 10.0 keV).
Combining data from all three observations, we obtain 35.5 ks of good
data after normal data screening. We still detect no source in a 20 arcsec
radius circle centred at this position, with a 90% confidence upper limit
of 1.8e-4 counts/s (0.2 - 10.0 keV). Assuming a Crab-like spectrum, this
corresponds to 7e-15 ergs/cm2/s (0.5 - 10.0 keV).
Compared to other Swift XRT afterglows, GRB 050502a is unusually faint
at these times.