GRB 050416
GCN Circular 3542
Subject
GRB 050416(a): Host Galaxy Redshift Determination
Date
2005-06-10T00:45:36Z (20 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. B. Cenko, S. R. Kulkarni, A. Gal-Yam (Caltech) and E. Berger
(Carnegie Observatories) report on behalf of the Caltech-NRAO-Carnegie
Collaboration:
We have obtained 2 x 30 minute spectra of the host galaxy of GRB 050416
(a) with the Low Resolution Imaging Spectrometer mounted on the 10-m
Keck I Telescope. Observations were taken on 6 June, 2005 UT. We
identify several emission lines including [OII], H-beta, H-gamma, and H-
delta at a redshift of z = 0.6535 +/- 0.0002.
The spectrum indicates the host galaxy is faint and blue with large
amounts of ongoing star formation. We note the redshift is consistent
with the prediction of Fox (3408) based on the afterglow detection in
the Swift UVOT UVW2 filter.
Using a fluence of 3.8e-7 erg/cm^2 (10 - 350 keV, GCN 3273), we find an
isotropic gamma-ray energy release of 7.0e50 ergs.
GCN Circular 3408
Subject
GRB050416: Afterglow detection at 188 nm with Swift UVOT
Date
2005-05-10T20:46:59Z (20 years ago)
From
Derek Fox at CIT <derekfox@astro.caltech.edu>
Derek B. Fox (Caltech) reports on behalf of a larger collaboration:
"We have created a summed image from the first 10.14 ksec of exposure
on GRB050416 (BAT trigger #114753; Sakamoto et al., GCN 3264) through
the "UVW2" filter of the Swift UVOT. Earlier reports have discussed
the detection of the optical afterglow of this event (Cenko & Fox, GCN
3265) in the U, B, and V filters (Schady et al., GCN 3280). The UVW2
sequence consists of nine ~10-second exposures taken from 4 to 15
minutes after the burst; two ~100-second exposures taken 18 and 29
minutes after the burst, and 11 ~900-second exposures taken from 92
minutes to 2 days after the burst. The final summed frame was
astrometrically registered to the USNO B-1.0 catalog.
At the position of the optical afterglow we detect a source at
>3-sigma confidence with a mean count rate of 6.0 +/- 0.7 cts/ksec
according to the default uvotdetect analysis. Examination of
individual frames suggests that the source is not distinguishable
above background in the individual short (10-s and 100-s) exposures,
being most prominent in the early ~900 second exposures of the
sequence.
The UVW2 filter bandpass is centered at 188 nm with a width of 76 nm.
Since it is unlikely that significant afterglow emission would be
detected blueward of the host galaxy Lyman limit at 91 nm -- with
significant suppression redward to the Lyman-alpha resonance at 122 nm
-- we suggest that this detection implies a redshift constraint for
GRB050416 of z <~ 1.0."
GCN Circular 3312
Subject
GRB 050416: Optical/NIR observations
Date
2005-04-22T02:16:20Z (21 years ago)
From
Paul Price at IfA,UH <price@ifa.hawaii.edu>
P.A. Price (IfA), T. Minezaki (U. Tokyo), L. Cowie (IfA) and Y. Yoshii
(U. Tokyo) report on behalf of the UH-MAGNUM GRB collaboration:
We observed the optical afterglow of GRB 050416 (Cenko & Fox, GCN #3265)
with the automated MAGNUM telescope + MIP dual-beam optical-NIR imager,
commencing at April 16.53 UTC. The observations were performed in poor
seeing with clouds which prevented detection in the I and K bands.
Nevertheless, we detected the afterglow in the R, J and H bands. Based
on comparison with a single USNO-B1 star, we estimate that the optical
afterglow was about R ~ 21.3 mag at the epoch of our observations.
This message may be cited.
GCN Circular 3287
Subject
GRB 050416: Mitsume optical observation
Date
2005-04-17T13:53:02Z (21 years ago)
From
Nobuyuki Kawai at Tokyo Tech <nkawai@hp.phys.titech.ac.jp>
K. Yanagisawa (OAO/NAO), H. Toda, and N. Kawai (Tokyo Tech) report on
behalf of the Mitsume Collaboration:
"The field of GRB050416 (Sakamoto et al.; GCN 3264) was observed by
the 3-color Mitsume 50cm Telescope at Okayama, Japan starting at
13:27 (UT). With the first 60 min exposure, we did not detect a
source brighter than V=18.0, R=19.6, and I=19.0 at the position of
the afterglow reported by Cenko and Fox (GCN 3265)."
GCN Circular 3286
Subject
GRB 050416 : optical observation at Xinglong observatory
Date
2005-04-17T08:56:06Z (21 years ago)
From
Yuji Urata at RIKEN <urata@crab.riken.go.jp>
Y. Qiu, C.L. Lu (BAO), Y.Q. Lou (THCA), K.Y. Huang (NCU), Y. Urata (RIKEN)
on behalf of EAFON report
" We have imaged the GRB 050416 optical afterglow position (Bradley et
al, GCN 3265) using 0.8-m telescope at XingLong Observatory, China.
The observations started at 18.65 UT (~ 7.57 hours after the
burst). Due to the bad weather condition (seeing ~ 4"), the limiting
magnitude of our R band co-added image is ~ 18.6 compared with
USNOB1.0 stars. No new source was detected under the limiting
magnitude.
This message may be cited."
GCN Circular 3280
Subject
GRB 050416: Swift/UVOT refined analysis
Date
2005-04-17T00:22:59Z (21 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL), T. Sakamoto (GSFC/NRC), K. McGowan (MSSL), P. Boyd
(GSFC/UMBC), P. Roming (PSU), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of
the Swift UVOT team.
Starting with the data taken ~207s after the BAT trigger (Sakamoto et al., GCN
3264) we have co-added the early time data of GRB 050416 in each of the
Ultra-Violet/Optical Telescope (UVOT) U, B, and V bands. The co-added images
are made up of 9 x 10s exposures. A source is detected at the position of the
afterglow (Cenko & Fox, GCN 3265) in the U and B band with magnitudes U = 19.34
+/- 0.2 and B = 19.85 +/- 0.2. No source is detected in the V co-added
image down to a 5-sigma limiting magnitude V > 19.57. There is ~173s
difference between the start of the finding chart exposure, in which a
source was detected (Schady et al., 3276) and the co-added image.
The magnitudes are based on preliminary zero-points, measured in orbit and will
require refinement with further calibration.
GCN Circular 3276
Subject
GRB 050416: Swift/UVOT detection of afterglow emission
Date
2005-04-16T19:13:08Z (21 years ago)
From
Patricia Schady at MSSL/Swift <ps@mssl.ucl.ac.uk>
P. Schady (MSSL), T. Sakamoto (GSFC/NRC), K. McGowan (MSSL), P. Boyd
(GSFC/UMBC), P. Roming (PSU), J. Nousek (PSU), N. Gehrels (GSFC), on behalf of
the Swift UVOT team.
The Swift Ultra-Violet/Optical Telescope (UVOT) began settled observations of
the field of GRB 050416 (Sakamoto et al; GCN 3264) at 11:05:49 UT, 65s
after the BAT trigger. A comparison of the 100s finding chart in the V
filter against the Digitized Sky Survey reverals a new source inside the
XRT error circle at
RA = 12 33 54.56 Dec = +21 03 27.73
and consistent with the P60 positition reported by Bradley Cenko & Fox (GCN
3265). The V band magnitude is V = 19.38. The magnitude is based on preliminary
zero-points, measured in orbit and will require refinement with further
calibration.
Further detailed analysis is ongoing.
GCN Circular 3275
Subject
GRB050416: Refined Swift-XRT analysis
Date
2005-04-16T18:37:28Z (21 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
G. Cusumano, V. La Parola, T. Mineo, V. Mangano (IASF/Palermo), G.
Chincarini, S. Campana, G. Tagliaferri, P. Romano, P. Giommi, M. Perri
(INAF-OAB), M. Capalbi (ASDC), D. N. Burrows, J. A. Kennea (PSU), N.
Gehrels (NASA/GSFC)
We have analyzed the Swift-XRT data from the first orbit observation of
GRB050416 (Sakamoto et al. 2005, GCN3264). The new refined coordinates
are:
RA(J2000) = 12:33:54.8
Dec(J2000) = +21:03:25.1
This position is 17.7 arcseconds from the BAT position given in GCN 3273
(Sakamoto et al. 2005) and 1.3 arcsec from the preliminary XRT position
(GCN3268, Kennea et al. 2005). We estimate an uncertainty of 5 arcseconds
radius (90% containment).
The [0.2-10] keV light curve in Photon Counting (PC) mode starts ~90
seconds from the BAT trigger (T0). We clearly detect a rapidly fading
source. The light curve can be fitted with a single power law with alpha=
-0.6 +/- 0.3.
A preliminary spectral fit to the PC data gives a spectral power law
photon index of 2.02+/-0.21 in the [0.2-10] keV band, with a column
density of (0.25+/-0.05)E22 cm^-2 (the Galactic line-of-sight absorption
is 2.06E20 cm^-2). The average estimated unabsorbed 0.2-10 keV flux is
1.7E-11 erg cm^-2 s^-1.
GCN Circular 3274
Subject
GRB050416: Maidanak optical observations
Date
2005-04-16T17:45:24Z (21 years ago)
From
Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>
B. Kahharov, M. Ibrahimov, D. Sharapov (MAO), A.Pozanenko (IKI)
V.Rumyantsev (CrAO), G.Beskin (SAO) on behalf of larger collaboration
report:
We observed the Swift GRB050416 (Sakamoto et al. GCN3264) with 1.5m
telescope of the Maidanak Astronomical Observatory (MAO), Uzbekistan The
observation started at (UT) 15:34 , April 16 in R and B bands. We found a
source at the position afterglow (Cenko & Fox GCN3265). A preliminary
R-photometry of first frames against of USNO-B1.0 Catalog is the following:
Mean time Exposure Mag.
(UT) (s)
15:44 3x300 20.85 +/- 0.12
Observation is continuing.
GCN Circular 3273
Subject
GRB 050416: Swift-BAT refined analysis
Date
2005-04-16T16:25:32Z (21 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), E. Fenimore (LANL), N. Gehrels (GSFC),
D. Hullinger (UMD), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS),
M. Suzuki (Saitama), M. Tashiro (Saitama U.), J. Tueller (GSFC),
on behalf of the Swift/BAT team:
At 11:04:44.5 UT Swift-BAT detected GRB 050416 (trigger=114753)
(GCN Circ 3264, Sakamoto et al.). The refined BAT ground position
is (RA,Dec) = 188.490, 21.053, [deg; J2000] +- 3 arcmin, (95%
containment). This is 0.7 arc minutes from the position determined
by the XRT (GCN Circ 3268, Kennea, et al.).
The BAT mask weighted light curve shows a single peak of about one
second duration followed by a small bump. Most of the emission is
in the 15-50 keV band. T90 (15-350 keV) is (2.4 +- 0.2) seconds
(estimated error including systematics).
The photon index of the spectrum is 2.9 +- 0.2. The fluences in
the 15-50 keV band and in the 15-350 keV band are
(2.8 +- 0.2) x 10^-7 erg/cm2 and (3.8 +- 0.4) x 10^-7 erg/cm2 respectively.
The peak photon fluxes in the 15-50 keV band and in the 15-350 band are
(4.4 + 0.8) ph/cm2/s and (4.8 +- 0.6) ph/cm2/s respectively. All the
quoted errors are in 90% confidence level.
The BAT team cautions that while there appears to be a deficit of
counts below 20 keV, this is likely due to systematic errors in the
response matrix being accentuated by the steep spectrum.
GCN Circular 3272
Subject
GRB 050416: ART observations
Date
2005-04-16T16:09:24Z (21 years ago)
From
Ken ichi Torii at RIKEN <torii@crab.riken.go.jp>
K. Torii (Osaka U.) reports
"The error region of GRB 050416 (Sakamoto, et al. GCN 3264) was
observed with the ART 14 inch telescope. VRcIc imaging started at
11:05:36 UT (52s after trigger) and 60s exposure was repeated.
As a result of the preliminary analyses, the optical afterglow (Cenko
and Fox GCN 3265; Anderson, et al. GCN 3266) is not detected in our
frames and the following upper limit is derived relative to USNO-A2.0
(R) magnitude.
Start(UT) Magnitude Exposure
11:07:53 >16.6Rc 60s
"
GCN Circular 3271
Subject
GRB 050416,optical observation
Date
2005-04-16T15:53:23Z (21 years ago)
From
Eri Sonoda at U of Miyazaki/Japan <sonoda@astro.miyazaki-u.ac.jp>
E.Sonoda,S.Maeno,Y.Tokunaga,M.Yamauchi
(University of Miyazaki)
"We have observed the field covering the error circle of
GRB 050416 (GCN3264 ; Swift-BAT Trigger time is 11:04:57 UT)
with the unfiltered CCD camera on the 30-cm telescope
at University of Miyazaki.
The observation was started 11:09:18 UT on Apr.16.
After co-adding a set of 5 images (11:09:18 - 11:14:52 UT)
of 30 sec exposures, we have compared with the USNO A2.0 catalog.
Preliminary analysis shows there is no new source brighter than
16.7 mag. at the reported position by S.Bradley Cenko et al.
(GCN3265) and J.A.Kennea et al.(GCN3268)."
GCN Circular 3270
Subject
GRB 050416: KAIT observations
Date
2005-04-16T15:30:38Z (21 years ago)
From
Weidong Li at UC Berkeley KAIT/LOSS <weidong@astron.berkeley.edu>
W. Li, R. Chornock, S. Jha, and A. V. Filippenko (University of
California, Berkeley) report:
"The Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory
robotically observed Swift GRB 050416 (Trigger #114753; Sakamoto et
al., GCN 3264). The first 3x15s R-band grid image started at 11:05:25
UT (40.5s after the burst), which did not detect the afterglow as
observed by Cenko and Fox (GCN 3265) to a limiting magnitude of about
16.5 when compared to the USNO A2.0 catalog. Our subsequent images
have varying exposure times from 15s to 360s, and were observed with
R, I, V, and z filters. Due to the depth of the images, only a 60s
I-band image started 11:12:09 UT (444.5s after the burst) has a
marginal detection of the afterglow. Further analysis is in progress."
GCN Circular 3269
Subject
GRB050416: P200 NIR Observations
Date
2005-04-16T14:58:48Z (21 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
S. Bradley Cenko, Derek B. Fox, and Avishay Gal-Yam (Caltech) report on
behalf of the Caltech-NRAO-Carnegie GRB Collaboration:
We have imaged the field of GRB050416 with the Wide-Field Infrared
Camera (WIRC) mounted on the Palomar 200-inch Hale Telescope. Images
were taken in Ks-band and began approximately 6 minutes after the burst.
The afterglow candidate reported in GCN 3265 is clearly detected. The
object fades by 0.8 mag from approximately 11:15 UT to 12:05 UT (10 - 50
minutes after the burst), confirming the results of Anderson et al. (GCN
3266).
GCN Circular 3268
Subject
GRB 050416: Swift XRT Position
Date
2005-04-16T13:55:53Z (21 years ago)
From
Jamie A. Kennea at PSU/Swift-XRT <kennea@astro.psu.edu>
J. A. Kennea, J. L. Racusin, D. N. Burrows (PSU), V. Mangano
(IASF/Palermo), T. Sakamoto (GSFC/NRC), N. Gehrels (NASA/GSFC) report on
behalf of the Swift XRT team:
The Swift BAT instrument detected a GRB at 11:04:45 UT on 16th April 2005
(GCN Circ 3264). The observatory executed an automated slew to the BAT
position and the XRT began taking data at 11:06:03 UT. The XRT was in
Auto state but was not able to centroid on the afterglow due to low source
brightness. From downlinked data we find a uncataloged fading X-ray source
located at:
RA(J2000) = 12:33:54.6,
Dec(J2000) = +21:03:24.
We estimate an uncertainty of about 5 arcseconds radius (90% containment). This
position is 49 arcseconds from the BAT position reported in GCN 3264, and
2.7 arcseconds from the P60 optical afterglow candidate reported in GCN
3265.
GCN Circular 3267
Subject
GRB 050416: Radio observations
Date
2005-04-16T13:17:22Z (21 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
D. A. Frail (NRAO) and A. M. Soderberg (Caltech) report on behalf of
the Caltech-NRAO-Carnegie GRB Collaboration:
"We observed the field centered on the BAT position of the Swift burst
GRB 050416 (GCN#3264) using the VLA at a frequency of 8.46 GHz and
starting at 11:42 UT, about 37 minutes after the burst. There are no
bright radio sources (> 260 microJy) within 1 arcminute of the BAT
position. At the position of the afterglow candidate of Cenko and Fox
(GCN#3265), the peak radio flux is 20 +/- 51 microJy.
Further observations are planned."
GCN Circular 3266
Subject
Confirmation of OT for GRB050416
Date
2005-04-16T13:01:18Z (21 years ago)
From
Brian Schmidt at RSAA, ANU (MSSSO) <brian@mso.anu.edu.au>
Gemma Anderson, Marilena Salvo, Josh Rich and Brian P Schmidt
(Australian National University) report on behalf of a larger collaboration
"We observed a 6' region covering the BAT position of the SWIFT burst
GRB 050416
using the ANU 2.3m telescope on April 12.51 UT in R band. The object
identified by Cenko and Fox is mvisible and clearly has faded in
comparison with their image. This indicate that this object is likely
the afterglow of GRB 050416
GCN Circular 3265
Subject
GRB050416: P60 Afterglow Candidate
Date
2005-04-16T12:06:54Z (21 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 error circle of the Swift GRB050416 with the
automated Palomar 60-inch Telescope. We find the presence of a bright,
stationary source not present in the DSS at the location:
RA: 12:33:54.6
Dec: +21:03:26.7
J2000.0
We tentatively identify this object as the afterglow of GRB050416
GCN Circular 3264
Subject
Swift BAT/XRT Detection of GRB 050416
Date
2005-04-16T11:50:53Z (21 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
T. Sakamoto (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC),
D. Burrows (PSU), M. Chester (PSU), J. Cummings (GSFC/NRC),
E. Fenimore (LANL), N. Gehrels (GSFC), D. Hullinger (UMD),
J. Kennea (PSU) , H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), M. Suzuki (Saitama),
M. Tripicco (GSFC-SSAI), J. Tueller (GSFC), D. Burrows (PSU),
on behalf of the Swift team:
At 11:04:44.5 UT, the Swift Burst Alert Telescope (BAT) triggered and
located on-board GRB050416 (trigger #114753). The BAT on-board
calculated location is RA, dec 188.478, 21.043 (J2000) with an
uncertainty of 3.00 arcmin (radius, 3-sigma, including estimated
systematic uncertainty). The BAT light curve shows double
structures with a duration of about three seconds. The peak
count rate measured by BAT was about 3000 counts/sec in the 15 -
350 keV band. The burst signal is mostly seen in 15-50 keV.
The XRT observed the target field at 11:06:12 UT and detected 17 counts in
a single CCD frame, just under the number needed for a reliable on-board
centroid. Initial indications based on the raw spectra and lightcurve
transmitted via TDRSS suggest that there is a real X-ray source in the
field. We will issue an update following the next ground station pass at
12:18 UT.