GRB 050802
GCN Circular 3765
Subject
GRB050802: TNG optical observations
Date
2005-08-05T09:57:55Z (21 years ago)
From
Vincenzo Testa at INAF/Astro. Obs. of Rome <testa@mporzio.astro.it>
V. Testa (INAF-OAR), A.Melandri , L.A. Antonelli, L. Stella (INAF-OAR),
S. Covino, D. Fugazza, G. Tagliaferri (INAF-OAB),
G. Chincarini (Univ. Milano-Bicocca), N. Masetti (INAF-IASF-Bologna),
G. Andreuzzi, M. Pedani (INAF-TNG),
on behalf of the CIBO collaboration report
We imaged the field of GRB050802 (GCN 3734, Band et al.) with the 3.5 m
Italian National Telescope (TNG) (Canary Islands). Observations were
carried out with the optical spectrograph Dolores on August 2.9 UT in 5
filters (U, B, V, R, I) and on August 3.9 UT in 2 filters (V, I).
In all images we detect an object at the position reported by McGowen
et al. (GCN 3739). Therefore, the detected object is identified as the
afterglow candidate reported in GCN 3739. Preliminary photometry shows
the object fading from V~21.1 to V~22.8 and from I~20.5 to I~21.9
between the two epochs.
We note also an extended fainter object near the afterglow in the V
frame obtained on August 3. This object is at the same position as can
be seen in the image linked in GCN 3756, that Fynbo et al. propose as
suspected host galaxy. Further refined analysis is ongoing.
This message may be cited.
GCN Circular 3749
Subject
GRB050802: Tentative absorption redshift
Date
2005-08-03T20:25:25Z (21 years ago)
Edited On
2024-11-18T10:05:30Z (a year ago)
From
Johan U. Fynbo at U.Copenhagen <jfynbo@astro.ku.dk>
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>
Johan P. U. Fynbo, Jesper Sollerman, Brian L. Jensen, Jens Hjorth,
Darach Watson, José María Castro Cerón (DARK cosmology centre/Niels
Bohr Institute), Palle Moller (ESO), Thomas Augusteijn (Nordic Optical
Telescope), Javier Gorosabel (IAA-CSIC), Klaas Wiersema (Amsterdam)
report:
"Using ALFOSC on the Nordic Optical Telescope we have obtained
spectra of the afterglow of GRB 050802 (GCN 3734, 3739) on 2005,
August 2.9 UT. We detect several absorption features which we tentatively
identify as CIV and FeII lines, corresponding to a redshift of
z=1.71. This tentative redshift is at odds with the interpretation
of the UVOT results (GCN 3745). We encourage further observations."
GCN Circular 3745
Subject
GRB 050802: Swift/UVOT optical and UV detections
Date
2005-08-03T15:37:09Z (21 years ago)
From
Katie McGowan at MSSL-UCL <km2@mssl.ucl.ac.uk>
K. McGowan (UCL-MSSL), A. Morgan (PSU), K. Mason (PPARC),
T. Kennedy (UCL-MSSL) report on behalf of the Swift/UVOT team:
The Swift/UVOT began observing the afterglow of
GRB 050802 at 2005-08-02T10:15:14, 286 s after the
BAT trigger (Band et al., GCN 3734). In addition to our
reported detection from the initial V filter observations
(McGowan et al., GCN 3739), we now report that we detect
the afterglow in all six filters.
We extracted data using a 6 arcsec radius aperture
centered on the source position (McGowan et al., GCN 3739)
for the optical filters, a 12 arcsec radius for the W1 and
M2 filters, and 4 arcsec for the W2 filter. If the
significance of the source detection was less than 2 sigma
we determined a 3-sigma limiting magnitude.
The detection in UVW2 implies that the Lyman Limit must be blueward
of 2000 A, and we estimate that the burst is at redshift z < 1.2.
We obtain the following photometry of the afterglow candidate:
Filter Exposure (s) T_mid (s) Magnitude Notes
V 100 336 17.07+/-0.09 detection
V 900 12566 20.35+/-0.09 detection
B 10 437 17.66+/-0.20 detection
B 900 36405 21.10+/-0.08 detection
U 10 423 16.82+/-0.24 detection
U 899.79 35498 20.22+/-0.16 detection
W1 10 409 17.08+/-0.29 detection
W1 100 2296 19.22+/-0.23 detection
M2 278 1316 18.79+/-0.26 detection
M2 3753 28197 21.30+/-0.26 detection
W2 268 1240.5 20.73+/-0.27 detection
W2 3481 25890.5 >22.64 3-sig limit
where T_mid is the midpoint of the exposure post-trigger in seconds.
The magnitudes are based on preliminary zero points, measured in
orbit, and will require refinement with further calibration.
GCN Circular 3744
Subject
GRB050802: CrAO optical observations
Date
2005-08-03T11:02:17Z (21 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
E. Pavlenko, Yu. Efimov, A. Shlyapnikov, A. Baklanov(CrAO), A.Pozanenko
(IKI), M. Ibrahimov (MAO) on behalf of larger GRB follow up collaboration
report:
We observed the error box of GRB050802 (Band et al., GCN 3734) with 2.6m
Shain telescope (CrAO) on August 2 between (UT) 18:46 - 20:40. OT found by
McGowan et al. (GCN 3739) is clearly detected. Preliminary VRI photometry is
following:
Mean time Exposure Filter Magnitude
(UT) s
18:54 60 V 20.6
20:27 2x60 V 21.1
18:48 60 R 20.6
20:36 2x60 R 21.0
18:56 60 I 20.2
20:39 2x60 I 20.6
with a typical error of 0.1m.
Comparing decay index of fading light curve in V between magnitudes obtained
in UVOT observation (McGowan et al. GCN 3739) and our first observation in
18:54, and decay index obtained based on our observations we suggest that
the break of OT light curve occurs between (UT) 19:00 - 20:40. Detailed
analysis is underway.
Finding chart of the OT in V band can be found in
http://grb.rssi.ru/GRB050902.
This message may be cited.
GCN Circular 3742
Subject
GRB050802 radio non-detection
Date
2005-08-03T09:07:09Z (21 years ago)
From
Guy Pooley at MRAO, Cambridge, UK <ggp1@cam.ac.uk>
Guy Pooley (Cavendish Laboratory, University of Cambridge) reports:
An observation of the field of GRB050802 (GCN 3734) was made with
the Ryle Telescope (Cambridge, UK) at 15 GHz from 18:54 to 22:53 UT
on 2005 Aug 02 (mid-observation 10h46m from the trigger), using
the Swift/UVOT position reported in GCN3739.
No source was detected - the formal flux density was -0.02 mJy
with an rms noise of 0.3 mJy.
This message can be cited.
GCN Circular 3740
Subject
GRB 050802: early Swift XRT analysis results
Date
2005-08-02T20:34:15Z (21 years ago)
From
Milvia Capalbi at ISAC/ASDC <capalbi@asdc.asi.it>
M. Capalbi, M. Perri, P. Giommi (ASDC), J. Kennea, D.N. Burrows,
M.Chester (PSU), R. Fink (GSFC) report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from the first orbit observation of
GRB 050802 (Band et al., GCN 3734). The refined coordinates of the X-ray
afterglow are:
RA(J2000) = 14h 37m 06.1s
Dec(J2000) = +27d 47' 11"
This position is 80 arcseconds from the BAT refined position given in
GCN 3737 (Palmer et al.), 6.7 arcseconds from the early XRT position
reported in GCN 3735 (Kennea et al.) and 5.4 arcseconds from the UVOT
position (McGowan et al., GCN 3739). We estimate an uncertainty of 6
arcseconds radius in the derived position.
Data in Photon Counting (PC) mode starts at 10:15:57 UT, 475 seconds
from the BAT trigger. The 0.3-10 keV afterglow light curve shows a
fading which can be fitted with a power law of slope alpha=-0.7+/-0.1 up
to T+2875 s, when the first orbit ends.
A preliminary spectral fit in the 0.3-10.0 keV energy band to the first
orbit gives a spectral power law photon index of 1.9+/-0.1 with
nH=(6.6+/-2.5)E20 cm^-2. The Galactic nH along the line of sight is
1.8E20 cm^-2.
The unabsorbed 0.5-10.0 keV flux at 24 hours after the burst is
estimated to be 3.6E-12 erg cm^-2 s^-1.
GCN Circular 3739
Subject
GRB 050802: Swift/UVOT observations
Date
2005-08-02T17:34:24Z (21 years ago)
From
Katie McGowan at MSSL-UCL <km2@mssl.ucl.ac.uk>
K. McGowan (MSSL), D. Band (GSFC-UMBC), P. Brown,
C. Gronwall (PSU), H. Huckle, B. Hancock (MSSL)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began observing the afterglow of
GRB 050802 at 2005-08-02T10:15:14, 286 s after the
BAT trigger (Band et al., GCN 3734). We detect the
afterglow in the V-band data at a position (J2000,
corrected to the DSS coordinates) of:
RA 14:37:5.69 (+/- 1 arcsec)
Dec +27:47:12.2 (+/- 1 arcsec)
The data are extracted using a 6 arcsec radius aperture
centered on the source position. If the significance of
the source detection was less than 2 sigma we determined a
3-sigma limiting magnitude.
Filter Exposure (s) T_mid (s) Magnitude Notes
V 100 336 17.07+/-0.09 detection
V 10 466 17.32+/-0.20 detection
V 10 550 17.10 3-sig limit
V 10 634 17.17 3-sig limit
V 10 718.5 16.77+/-0.20 detection
V 10 803 17.34 3-sig limit
V 10 887.5 17.04+/-0.20 detection
V 10 972 17.46 3-sig limit
V 100 1463 18.35+/-0.09 detection
V 100 2088 18.81+/-0.09 detection
where T_mid is the midpoint of the exposure post-trigger in seconds.
Analysis of the data from the other filters is ongoing.
The magnitudes are based on preliminary zero points, measured in
orbit, and will require refinement with further calibration.
GCN Circular 3738
Subject
GRB 050802 : Lulin Optical follow-up observation
Date
2005-08-02T15:31:06Z (21 years ago)
From
Yuji Urata at RIKEN <urata@crab.riken.go.jp>
Y. Sato (Tokyo Univ.), N. Awajiya (Tokyo Gakugei Univ.),
D. Kinoshita, K-Y. Huang, W-H. Ip(NCU),
Y. Urata (RIKEN) on behalf of EAFON report:
" We have imaged the entire error region of GRB 050802 (Band et
al. #3734) using the imaging polarimeter PICO with Lulin One-meter
Telescope. After end of twilight, the observation was started at 12:42
(0.107 days after the burst). We have obtained 12 x 300 sec i'-band
images. These images show no optical counterpart brighter than
i'=17.2. These 3-sigma limiting magnitudes are derived from the
USNO-B1.0 catalog.
This message may be cited."
GCN Circular 3737
Subject
GRB 050802: Swift-BAT refined analysis
Date
2005-08-02T15:16:08Z (21 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
D. Palmer (LANL), L. Barbier (GSFC), S. Barthelmy (GSFC),
P. Boyd (GSFC-UMBC), J. Cummings (GSFC/NRC), E. Fenimore (LANL),
N. Gehrels (GSFC), D. Hullinger (UMD), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
G. Sato (ISAS), J. Tueller (GSFC), W. Voges (MPE),
on behalf of the Swift-BAT team:
At 10:08:02 UT Swift-BAT detected GRB 050802 (trigger=148646)
(GCN Circ 3734, Band, et al.). The refined BAT ground position
is (RA,Dec) = 219.287, +27.806 {14h37m08.9s, 27d48'21.6"} [deg; J2000]
+-3 arcmin, (95% containment). The partial coding was 27%.
The light curve has a 5 second rise time to the first and largest
of 3 symmetrical peaks in the interval T-5 to T+13 seconds. There
is a hint of a small peak at T+30 seconds. T90 (15-350 keV) is
(13 +- 2) seconds (estimated error including systematics).
The power law index of the time-averaged spectrum is 1.6 +- 0.1.
The fluence in the 15-350 keV band is (2.8 +- 0.3) x 10^-6 erg/cm2.
The 1-s peak photon flux measured from T0-0.4 second in the 15-350 keV
band is (3.3 +- 0.5) ph/cm2/s. All the quoted errors are at the 90%
confidence level.
There was no BAT Position GCN Notice on this burst, because none was
transmitted from the spacecraft. The cause is being investigated.
GCN Circular 3735
Subject
GRB 050802: XRT position
Date
2005-08-02T13:21:55Z (21 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
J.A. Kennea, D.N. Burrows (PSU) report on behalf of the Swift/XRT Team:
We have analysed the downlinked data on GRB 050802 (GCN 3734) and have
found a fading uncatalogued X-ray source at the following coordinates:
RA (J2000): 14:37:05.8,
Dec(J2000): 27:47:05.6,
with an error radius of 8 arcseconds (90% containment). This source is 87
arcseconds from the BAT position reported in GCN 3734. Further detailed
analysis of XRT data will be reported in a later GCN.
GCN Circular 3734
Subject
GRB 050802: Swift Gamma-ray Burst
Date
2005-08-02T11:53:01Z (21 years ago)
From
David L. Band at NASA/GSFC <dband@lheapop.gsfc.nasa.gov>
D. Band (GSFC-UMBC), C. Markwardt (GSFC-UMD), M. Perri
(ASDC), K. McGowan (MSSL), C. Gronwall (PSU), K. Page (U.
Leicester), J. Racusin (PSU), D. Burrows (PSU), N. Gehrels
(GSFC), J. Kennea (PSU), report on behalf of the Swift
Team:
At 10:08:02 UT, Swift-BAT triggered and located GRB050802
(trigger=148646). The spacecraft slewed immediately. The
BAT on-board calculated location is RA,Dec 219.287, +27.806
{+14h 37m 09s, +27d 48' 23"} (J2000), with an uncertainty
of 3 arcmin (radius, 90% containment, stat+sys). The BAT
light curve has a total duration of ~20 sec. The peak
count rate was ~2000 counts/sec (15-350 keV).
The XRT began observing at 10:12:51 UT, 289 seconds after
the BAT trigger. XRT was unable to centroid on any source,
however the downlinked lightcurve and raw spectrum show a
bright variable source is present in the XRT field of view.
There are no catalogued X-ray sources in the field,
suggesting that this bright source is the GRB afterglow.
Swift-UVOT began observations after the slew, however, the
UVOT dark burst image did not come down via TDRSS so no
information is available at this time. Detailed analysis
will be performed when data is available after the next
Malindi pass.
[GCN OPS NOTE(02aug05): Per author's request, The "05080"
in the Subject-line was changed "050802".]