GRB 991208
GCN Circular 872
Subject
GRB 991208: HST Imaging of the Host Galaxy
Date
2000-11-01T20:05:21Z (25 years ago)
From
Andrew S. Fruchter at STScI <fruchter@stsci.edu>
A. Fruchter, (STScI), P. Vreeswijk (Amsterdam), V. Sokolov (SAO RAS)
and A. Casto-Tirado (IAA-Granada, INTA-Madrid) report on behalf of the
larger HST GRB collaboration report:
We observed the field of GRB 991208 with the HST STIS CCD on August 3,
2000, or approximately 8 months after outburst. A total exposure time
of 5210s was obtained in the (50CCD) clear aperture. At the position
of the burst we find a very compact galaxy with a magnitude of V= 24.6
+/- 0.15, where a conservative error bar is given due to the very wide
bandpass of the filter. The full-width at half-maximum (FWHM) of the
galaxy is measured as 0."095, only marginally larger than the intrinsic
0."08 of the STIS PSF. However, both curve-of-growth analysis and
direct subtaction of a STIS PSF indicate that the object is indeed
resolved. We estimate the intrinsic FWMH of the core of the galaxy is
less than 0."06.
Comparison of the HST image with ground-based images (Castro-Tirado et
al., A&A submitted, see also GCN 452) shows the position of the optical
transient to be offset from the center of the host by less than the
0."1 one-sigma uncertainty in the relative positions.
We believe the ellipticity and position angle reported for the host by
Bloom et al. (GCN 764) is due to the presence of a fainter, small
object located approximagely 1" to the ESE of the host. It is not clear
from the HST image whether these two objects are merely close due to a
projection effect or whether they are indeed physically related.
The wider (50") field of the STIS CCD shows a rich association of
spiral galaxies surrounding the position of the OT. While some of the
spirals show grand design or prominent bulges, and are up to 5" across,
we cannot rule out the possibility that the host of the GRB (which is
at a redshift of 0.7, Dodonov et al., GCN 475) is a member of this
apparent group of galaxies.
The images can be seen at http://www.stsci.edu/~fruchter/GRB/991208 .
This GCN may be cited.
GCN Circular 764
Subject
GRB 991208 Host Galaxy Imaging
Date
2000-08-01T23:17:28Z (25 years ago)
From
Josh Bloom at CIT <jsb@astro.caltech.edu>
GRB 991208 Host Galaxy Imaging
A. Diercks, J. S. Bloom, T. J. Galama, and S. R. Kulkarni report on
behalf of the larger Caltech-NRAO-CARA collaboration:
"We observed the field of GRB 991208 (Hurley et al. 1999, GCN #450) with
the with the Echellette Spectrograph and Imager (ESI) on the Keck II 10-m
Telescope on Mauna Kea at 4 April 2000 UT. A 1200-s Gunn r-band image
with 0.75 arsec seeing (FWHM) reveals a galaxy at the location (Frail et
al. 2000, GCN #451) of the afterglow. This galaxy, the putative host of
GRB 991208, is likely responsible for the nebular emission lines
previously observed spectra of the transient (Dodonov et al. 1999, GCN
475; Bloom et al. 1999, GCN 464). The galaxy appears extended with an
ellipticity of ~0.3 and PA= 106 +/- 6 degrees. Using differential
astrometry with respect to our early K-band image when the transient was
bright (Bloom et al. 1999, GCN #480), we find the GRB was 66 +/- 63 mas (1
sigma) from the center of the galaxy; i.e. the GRB location is consistent
with no offset from its host."
A 39" x 39" image of the field surrounding the host galaxy is posted at
http://astro.caltech.edu/~ad/grb991208-host.ps
This message may be cited.
GCN Circular 631
Subject
GRB 991208, UBVRI field photometry
Date
2000-04-10T16:13:39Z (26 years ago)
From
Arne A. Henden at USNO/USRA <aah@nofs.navy.mil>
A. Henden (USRA/USNO) reports on behalf of the USNO GRB team:
We have acquired UBVRcIc all-sky photometry for
the field of GRB 991208 with the USNOFS 1.0-m telescope
on two photometric nights. This 11x11arcmin field
covers the optical transient and extends a little
fainter than V=21. All stars brighter than V=14
are saturated and should be used with care. We have
placed the photometric data on our anonymous ftp site:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/grb/grb991208.dat
The astrometry in this file is based on linear plate
solutions with respect to USNO-A2.0; estimated errors
are +/- 0.1 arcsec on the brighter stars.
GCN Circular 531
Subject
GRB 991208, radio observations
Date
2000-02-03T09:02:38Z (26 years ago)
From
Javier Gorosabel at LAEFF-INTA, Madrid <jgu@laeff.esa.es>
C. Garcia-Miro (LAEFF-INTA, Madrid and IAA-CSIC, Granada), J.
Gorosabel (DSRI, Copenhagen), J. Calvo (INSA, Madrid) and A.J.
Castro-Tirado (LAEFF-INTA, Madrid and IAA-CSIC, Granada) report:
We scanned at 8.42-GHz the position of the afterglow reported for
GRB 991208 (GCN 451) with the 70-m radio-telescope of the Madrid Deep
Space Communication Center (MDSCC, NASA-INTA) located at Robledo de
Chavela, Madrid. The observations were based on two observing runs
carried out on Dec 22.2491-22.6488 UT and Dec 23.3243-23.6095 UT 1999.
We derive a 1 sigma upper limit for the flux density of 3.5 mJy for
the afterglow. The authors wish to thank the MDSCC staff and the JPL
scheduler for their enthusiastic support.
This message may be cited.
GCN Circular 481
Subject
GRB 991208 Keck Spectroscopy
Date
1999-12-18T01:25:49Z (26 years ago)
From
George Djorgovski at Caltech/Palomar <george@oracle.caltech.edu>
GRB 991208 Keck Spectroscopy
S. G. Djorgovski, A. Dierks, J. S. Bloom, S. R. Kulkarni (Caltech),
A. V. Filippenko (UC Berkeley), L. A. Hillenbrand, and J. Carpenter
(Caltech), report on behalf of the Caltech-CARA-NRAO GRB collaboration:
We recalibrated and combined the Keck spectra of GRB 991208 obtained on
14 and 15 Dec 1999 UT, for which preliminary results were reported earlier
(GCN #460, GCN #464). Addition of the spectra improved the total S/N as
expected. We confirm the existence of emission lines at the observed
wavelengths 6356, 8454, and 8545 Ang, reported by Dodonov et al. (GCN #475).
We agree with their proposed identifications as [O II] 3727, and [O III]
4959, 5007, giving the redshift z = 0.7055 +- 0.0005. However, we note
that the proximity of the strong night sky lines (especially for the
tentative 8454 Ang line), and additional spectroscopic observations are
still needed in order to firm up this result.
Assuming z = 0.7055, and the standard Friedmann cosmology with h = 0.65,
Omega_0 = 0.2, and Lambda_0 = 0, the luminosity distance is 1.30E28 cm.
Assuming the integrated gamma-ray fluence of >~ 1.E-4 erg/cm2 (GCN #450),
the implied isotropic energy is ~ 1.3E53 erg, which of course may be
affected by beaming.
We also performed a power-law fit to the fully calibrated and extinction
corrected spectrum from UT Dec. 15.64. For F_nu ~ nu ** beta, we obtain
beta = -0.9 +- 0.15, in a good agreement with the photometric measurement
reported by Bloom et al. (GCN #480).
This message may be cited.
GCN Circular 480
Subject
GRB 991208 Infrared Detection
Date
1999-12-18T00:09:47Z (26 years ago)
From
Josh Bloom at CIT <jsb@astro.caltech.edu>
GRB 991208 Infrared Detection
J. S. Bloom, A. Diercks, S. R. Kulkarni, S. G. Djorgovski, N. Z. Scoville,
D. T. Frayer (Caltech) report on behalf of the Caltech-NRAO-CARA GRB
Collaboration:
"On 16 December 1999 UT N. Scoville and D. Frayer observed the field of
GRB 991208 with the slit-viewing camera of the Near-Infrared Echelle
Spectrograph (NIRSPEC; McLean et al. SPIE, 1998) at the Keck II 10-m
Telescope on Mauna Kea, Hawaii. In a stacked 1560-s imaging exposure we
detect a K-band source at the position of the transient afterglow (GCN
#450, GCN #451, GCN #452) of GRB 991208. We find no clear extension of
this presumed IR afterglow with respect to other stars in the field. We
note the presence of a faint extended galaxy ~8.3" W of the source.
Comparison with standard star SJ 9162 (Persson, AJ, 1998) yields a
preliminary magnitude of the afterglow of K=19.31 +/- 0.15 mag (16.68 Dec
1999 UT).
Extrapolating the R-band light curve using the reported decay slope from
Masetti et al. (GCN #462), on 16.68 Dec 1999, we find R - K = 2.7
(including the small Galactic extinction) implying a spectral index beta =
-0.77 +/- 0.14 (statistical uncertainty). We note this optical-IR spectral
index is inconsistent with reports of an apparent blue spectrum from
preliminary reductions of optical spectroscopy (GCN #460, GCN #461)."
A K-band finding chart can be found at
http://astro.caltech.edu/~jsb/GRB/grb991208/
This message may be cited.
GCN Circular 475
Subject
GRB 991208 SAO-RAS Spectroscopy
Date
1999-12-17T20:52:14Z (26 years ago)
From
Vladimir Sokolov at SAO RAS <sokolov@sao.ru>
S.N. Dodonov, V.L. Afanasiev, V.V. Sokolov, A.V. Moiseev (SAO-RAS)
and Alberto J. Castro-Tirado (INTA, Madrid and IAA, Granada) report:
"A BTA/MPSF 4500-s spectrum of the optical transient of
GRB 991208 (GCN #452) was obtained on
14.14 Dec 1999 UT with the the SAO-RAS 6-m telescope.
The observational conditions on 14 Dec were already given in GCN #461.
The data were obtained with
the integral field spectrograph (Multi Pupil Fiber Spectrograph,
MPFS, http://www.sao.ru:8100/~gafan/devices/mpfs/mpfs_main.htm )
with 300 lines/mm grating blazed at 6000 A giving a spectral resolution
of about 5 A/pix and effective wavelength coverage of 4100 - 9200 A.
Emission lines at lambda = 6350 A, 8550 A and 8470 A are present,
with the most likely identifications of these emission lines being:
[OII] 3727 A, [OIII] 4959,5007 A at a redshift of z = 0.707 +/-0.002,
presumably that of the host galaxy.
This message may be cited."
GCN Circular 467
Subject
GRB 991208 optical observations
Date
1999-12-17T06:11:35Z (26 years ago)
From
Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct@iaa.es>
GRB 9901208
-----------
Vijay Mohan, Anil K. Pandey, Ram Sagar and S.B. Pandey (from UPSO,
Nainital) and Alberto J. Castro-Tirado (INTA, Madrid and IAA, Granada)
-on behalf of a larger European collaboration- report:
"We have imaged the field of GRB 991208 with the 2k x 2k CCD camera
mounted
on the UPSO 104-cm telescope on 1999 Dec 12.0 (UT); Dec 13.0 (UT) and
Dec 14.0
(UT) in I photometric passband during photometric sky conditions. The
optical
transient of the GRB 991208 (Castro-Tirado et al. GCN 452) is fading
rapidly
about 0.5 mag between Dec 12 and 13. This indicates a power decay index
of
-2.0. The object has become so faint for our telescope that it is barely
visible on the 1 hour CCD image. Thus flux decay in I is almost similar
to
that in R filter (Jensen et al. GCN 454; Garnavich et al. GCN 456).
Calibration of the field is in progress.
This message is citable."
GCN Circular 464
Subject
GRB 991208 Keck Spectroscopy
Date
1999-12-17T02:52:34Z (26 years ago)
From
Josh Bloom at CIT <jsb@astro.caltech.edu>
GRB 991208 Keck Spectroscopy
J. S. Bloom, A. Diercks, S. G. Djorgovski, S. R. Kulkarni (Caltech), A. V.
Filippenko (UCB), on behalf of the Caltech-NRAO-CARA GRB Collaboration
report:
"On 15.638 December 1999 UT, A. Filippenko obtained a 900-s spectrum using
the Low-Resolution Imaging Spectrometer (LRIS; Oke et al. 1995) on the
Keck II 10-m telescope of the transient associated with GRB 991208 (GCN
#450; GCN #451; GCN #452). The grating was 300 l/mm giving an effective
wavelength coverage of 3850 Ang to 8850 Ang with a dispersion of ~2.47
Ang/pixel. The optical transient is better detected in this spectrum
compared to the observations of December 14, 1999 and reported earlier
(GCN #460). Reductions of the December 15 data reveal an emission line at
lambda=8541 Ang (preliminary wavelength calibration). The presence of
continuum emission blueward of this line effectively rules out a Ly-alpha
origin.
The two most likely candidate identifications of this emission line are
[OII] 3727 Ang or H-alpha 6563 Ang. If the former, then the redshift
implied, presumably that of the host galaxy, is z=1.29. Coupled with the
bright fluence above 25 keV (10^-4 erg cm^-2; GCN #450) this implies an
isotropic emission (restframe 30-2000 keV) of ~4 x 10^{53} erg (Omega=0.2,
Lambda=0, H_0 = 65 km/s/Mpc). Such high energetics could be
relaxed by collimated emission as suggested by the steep decay in the
optical light curve.
If instead we associate the emission line with H-alpha 6563 Ang, then the
implied redshift is z=0.30, making it the lowest redshift of all
cosmological GRBs. The associated isotropic energy loss would be ~2 x
10^{52} erg (Omega=0.2, Lambda=0, H_0 = 65 km/s/Mpc), consistent with the
energies of GRB 970508, 970228, and GRB 980613. We disfavor this
low-redshift hypothesis since the [OIII] 4959,5007 lines should be present
in our spectrum but we have not detected these lines. Nevertheless, if the
low redshift proves correct, then GRB 991208 would be an excellent
candidate for a detectable supernova component in the the coming month."
This message may be cited.
GCN Circular 462
Subject
R-band Observations of GRB991208 at TNG
Date
1999-12-16T15:46:06Z (26 years ago)
From
Nicola Masetti at ITeSRE,CNR,Bologna <masetti@tesre.bo.cnr.it>
N. Masetti, E. Palazzi, E. Pian, F. Frontera (ITESRE, CNR, Bologna),
S. Benetti, A. Magazzu' (TNG), A.J. Castro-Tirado (LAEFF-INTA and
IAA-CSIC) and B.L. Jensen (Univ. of Copenhagen), on behalf of a
larger collaboration, report:
"R images of the optical afterglow of GRB991208 (GCN #452 and #453) were
obtained between Dec. 12.29 and Dec. 15.29 UT at Roque de Los Muchachos
(Canary Islands, Spain) with the 3.58-meter Telescopio Nazionale Galileo
(TNG) + OIG CCD camera. We clearly detected the optical transient in all
R images. The following table shows the results of these observations:
Date (UT) Exptime Magnitude Seeing
1999 Dec 12.29 500 sec 20.25 +- 0.15 1".8
1999 Dec 13.29 360 sec 20.3 +- 0.2 1".6
1999 Dec 14.29 600 sec 21.25 +- 0.15 1".5
1999 Dec 15.29 900 sec 21.6 +- 0.3 1".5 (clouds)
Photometric calibration was tied to the USNO A2.0 star 1350-08916561
(R = 15.85 +- 0.1 was assumed).
Preliminary analysis of R data shows that these are consistent with a
power-law decay with index alpha = -2.15 (GCN #454 and #456) with the
exception of the observation of Dec. 13.29, which may however be affected
by uncertainties associated with the observing conditions and with the
shorter exposure time."
This message can be cited.
GCN Circular 461
Subject
GRB991208, optical observations
Date
1999-12-15T19:42:33Z (26 years ago)
From
Vladimir Sokolov at SAO RAS <sokolov@sao.ru>
GRB 991208 SAO RAS follow-up observations
S. Dodonov, V. Afanasiev, V. Sokolov, V. Komarova, T. Fatkhullin, A.
Moiseev report:
"One 2700-sec spectrum and one 4500-sec spectrum of the optical
transient of GRB 991208 detected by A.Castro-Tirado et al., (GCN
#452) were obtained on the nights of the 13th and 14th Dec
1999 UT respectfully with the SAO RAS 6-meter telescope at the Northern
Caucasus. Observational conditions on the night of the 13th of December
were poor. The seeing was 3 arcsec and the transparency was not good.
On the 14th of December the observational conditions were good:
the seeing ~1.5 arcsec (at a zenithal distance of 60 degrees),
a good transparency. So, the first spectrum is with a poor S/N ratio,
the second one is much better. The observations were carried out with
the integral field spectrograph (Multi Pupil Fiber Spectrograph,
MPFS http://www.sao.ru:8100/~gafan/devices/mpfs/mpfs_main.htm)
with 300 lines/mm grating blazed at 6000 A giving a spectral resolution
of about FWHM=14A/px and effective wavelength coverage of 4100 - 9200 A.
A spectrophotometric standards HZ44 and BD+75d325 (Oke et al. 1995)
were used for the flux calibration. The spectra show a blue continuum and
in the second one with better S/N there are possible two emission lines.
The data are being processed.
On the second night (on Dec 14.14 UT) simultaneously with spectroscopic
observations at the 6-meter telescope we imaged the field of GRB991208
in the R_c band (Cousins) with the SAO RAS 1-m telescope (Zeiss-1000).
Two 10-minute exposures were obtained at an airmass of ~1.6 in good
photometric conditions. The seeing was of ~2 arcseconds. The brightness
estimate was made for optical counterpart of GRB 991208:
R_c = 21.6 +/- 0.3. For photometric calibration Landolt standards
were used.
This message may be cited."
-Vladimir Sokolov, on behalf of the RAS Special Astrophysical Observatory
GRB followup team.
GCN Circular 460
Subject
GRB 991208 Keck Spectroscopy
Date
1999-12-15T06:37:17Z (26 years ago)
From
Josh Bloom at CIT <jsb@astro.caltech.edu>
GRB 991208 Keck Spectroscopy
A. Diercks, J. S. Bloom, S. G. Djorgovski, L. Hillenbrand, and J.
Carpenter (Caltech) report on behalf of the Caltech-NRAO-CARA GRB
collaboration:
"A 1500-s spectrum of the afterglow of GRB 991208 (GCN #450; GCN #451; GCN
#452) was obtained on the night of 14 Dec 1999 UT at the Keck II 10-m
Telescope on Mauna Kea by L. Hillenbrand and J. Carpenter (Caltech). The
observations were conducted using the Low-Resolution Imaging Spectrometer
(LRIS; Oke et al. 1995) with a 400 line/mm grating blazed at ~8500 Ang
giving an effective wavelength coverage of ~6250 - 9050 Ang. A
previously-measured instrument response function was used for an
approximate flux calibration.
Interestingly, the spectrum appears very blue, in contrast with
theoretical expectations for an afterglow. Though the spectrograph slit
was aligned close to the parallactic angle, the observations were
performed at an airmass of ~3.6 and with a bright dawn sky foreground.
However, we do not think that the observed spectral slope can be entirely
explained by the differential slit losses. The extreme blueness is so
puzzling that we strongly encourage multiband photometric or additional
spectrophotometric observations to check this potentially interesting
result.
This message may be cited."
GCN Circular 459
Subject
GRB991208 - millimeter detection
Date
1999-12-15T00:18:32Z (26 years ago)
From
Frank Bertoldi at MPIFR/Bonn <bertoldi@mpifr-bonn.mpg.de>
Michael Bremer (IRAM Grenoble), Frank Bertoldi (MPIfR Bonn),
Ute Lisenfeld (IRAM Granada), Alberto Castro-Tirado (LAEFF-INTA Madrid and
IAA-CSIC Granada), Titus Galama (Caltech, Pasadena),
and Ernst Kreysa (MPIfR) report:
The afterglow of GRB 991208 was detected at 240 GHz with the Max-Planck
Millimeter Bolometer (MAMBO) array (80 GHz bandwidth, 10.7 arcsec HPBW) at
the IRAM 30 m telescope on Pico Veleta, at the position reported by Frail
et al. (GCN 451). Three on-off integrations yield the following flux
densities:
UT December 11.77, 1999 2.6 +/- 0.8 mJy
UT December 12.38, 1999 1.9 +/- 0.6 mJy
UT December 14.35, 1999 2.2 +/- 0.7 mJy
Combining all data we obtain a flux density 2.4 +/- 0.5 mJy. The source
intensity appears to remain nearly constant. We will continue to monitor
its flux.
GCN Circular 458
Subject
GRB 991208, Optical Observation
Date
1999-12-13T15:25:48Z (26 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern & D. J. Helfand (Columbia U.) report on behalf of the
MDM Observatory GRB follow-up team:
"We imaged the field of GRB 991208 in the R band on Dec. 13.53 UT
using the MDM 2.4m telescope. A single 10 minute exposure was
obtained in non-photometric conditions. The seeing was 1.1 arcseconds.
The afterglow was detected at R = 20.92 +/- 0.06, referenced to the
comparsion star quoted in GCNs 454 and 456 as having R = 15.9.
The decay index between our measurement and that of Garnavich &
Noriega-Crespo one day earlier (GCN 456) is -1.9 +/- 0.4.
This message may be cited."
GCN Circular 457
Subject
GRB991208 15-GHz observations
Date
1999-12-13T10:51:37Z (26 years ago)
From
Guy Pooley at MRAO, Cambridge, UK <ggp1@cam.ac.uk>
From guy Mon Dec 13 10:26:01 1999
Subject: Re: GRB991208
To: dfrail@aoc.nrao.edu (Dale Frail)
Date: Mon, 13 Dec 1999 10:26:01 +0000 (GMT)
From: Guy Pooley <guy@mrao.cam.ac.uk>
Guy Pooley, MRAO, University of Cambridge, reports two observations
of GRB991208 (first detected by Frail, GCN 451, with the VLA), using
the Ryle Telescope at 15 GHZ:
99 Dec 11.6 UT 2.1 +- 0.3 mJy (sigma)
99 Dec 12.5 UT 2.1 +- 0.4 mJy
More observations are planned.
GCN Circular 456
Subject
GRB991208, optical observations
Date
1999-12-12T17:52:41Z (26 years ago)
From
Peter Garnavich at Center for Astrophysics <peterg@mars.harvard.edu>
Peter Garnavich (CfA/Notre Dame) and
Alberto Noriega-Crespo (IPAC/CalTech)
We imaged the field of GRB991208 with the Vatican Advanced Technology
Telescope (VATT) on 1999 Dec 12.52 (UT) in an R filter. The optical
afterglow (GCN 452 & 453) was detected in 3x600s exposures and using a single
set of Landolt standards we estimate the R-band brightness to be 20.5+/-0.1
mag. This is consistent with the brightness predicted by Jensen et al.
(GCN 454) for the steeper of their two suggested decay rates, that
is a decay index of -2.15. A bright star 43" West and 24" South of the
optical transient is estimated to have R=15.9+/-0.1.
[GCN OPS NOTE: This circular was delayed in distribution by 2 hours
due to the use of a different account domain than by prior arrangement.]
[GCN ED NOTE (12Dec99): The line "...afterglow (GCN 453) was detected"
was changed to "...afterglow (GCN 452 & 453) was detected".]
GCN Circular 455
Subject
GRB 991208 - OVRO detection
Date
1999-12-12T05:09:41Z (26 years ago)
From
Shri Kulkarni at Caltech <srk@astro.caltech.edu>
D. S. Shepherd, S. Jogee, S. R. Kulkarni and D. A. Frail on behalf of
the Caltech-NRAO-Keck GRB effort report the detection of the radio
afterglow of GRB 991208 at millimeter wavelengths.
We undertook observations of the afterglow of GRB 991208 (Frail, GCN
451) with the Owens Valley Millimeter Array. The mean epoch of the
observations is UT 1999 December 11.58. We detected a source with a
flux of 3.8 +/- 0.8 mJy at position alpha(J)=16:33:53.5 and delta(J) =
+46:27:21.2. This is coincident (within errors) with the radio
afterglow of GRB 991208 first discovered at the VLA (GCN 451). This the
brightest afterglow detected at millimeter wavelengths to date. We urge
observations at higher frequencies.
GCN Circular 454
Subject
GRB 991208 Optical Decay
Date
1999-12-12T04:19:33Z (26 years ago)
From
Brian Lindgren Jensen at U.of Copenhagen <brian_j@astro.ku.dk>
GRB 991208 Optical Decay
B. L. Jensen, J. Hjorth, H. Pedersen (University of Copenhagen),
H. E. Kristen (CfA), L. Tomassi (Universita di Milano),
E. Pian (ITESRE, Bologna) and K. Hurley (UCB SSL) report on behalf of a
larger European collaboration:
"We have imaged a significant fraction of the errorbox of GRB 991208
(Hurley & Cline GCN #450) with the 2.5-m Nordic Optical Telescope. Three
5-min R-band exposures were obtained with ALFOSC on 10.27 December 1999
UT and three 3-min R-band exposures were obtained with StanCam on 11.85
December 1999 UT. On both occasions the data were obtained during
twilight, at high (3 - 4) airmass and in bad seeing (2.5" - 3" FWHM). At
the location of the new radio (Frail GCN #451) and optical
(Castro-Tirado et al. GCN #452) source we detect a transient optical
source [at RA(J2000) = 16:33:53.52, Dec = +46:27:21.0 (+- 0.4")], thus
confirming its proposed identification with the afterglow of GRB 991208.
We have performed PSF photometry on the images using DAOPHOT II/ALLSTAR
and tied our photometric zeropoint to the USNO-A2.0 star 1350-08916561
which has R = 15.8. On this system we find that the magnitudes of the
optical transient were R = 18.7 +- 0.1 on 10.27 Dec and 20.0 +- 0.2 on
11.85 Dec. We caution however that the latter data point may be affected
by systematic uncertainties due to the difficult observing conditions.
If the optical transient follows a power law decay, the decay index is
-2.15 and the predicted magnitude on 12.25 Dec is R = 20.2 +- 0.3. If we
discard the 11.85 Dec data point and use R = 19.1 +- 0.1 on 11.25 Dec
(GCN #452), the decay index is -0.98 and the predicted magnitude on
12.25 Dec is R = 19.4 +- 0.2.
The NOT images will be posted at
http://www.astro.ku.dk/~brian_j/grb991208/ ."
GCN Circular 453
Subject
GRB 991208 optical observations
Date
1999-12-12T03:46:38Z (26 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
GRB 991208, optical observations
--------------------------------------
B. Stecklum, S. Klose (Thueringer Landessternwarte Tautenburg),
O. Fischer (Universitaets-Sternwarte Jena),
F. J. Vrba, A. A. Henden, C. B. Luginbuhl, B. Canzian, S. E. Levine, H. H. Guetter, J. A. Munn (U.S. Naval Observatory,
Flagstaff),
A. Castro-Tirado (LAEFF-INTA, Madrid, and IAA-CSIC, Granada),
J. Greiner (AIP Potsdam),
J. Gorosabel (LAEFF-INTA, Madrid, and University of Amsterdam), and
A. Riffeser (Universitaets-Sternwarte Muenchen)
report:
"The error box of GRB 991208 (Hurley et al., GCN 450) was observed with the
Tautenburg Schmidt telescope on 1999 Dec. 11.21 UT in the I band. An object was
found whose position corresponds to that of the VLA radio source which is a
strong candidate for the afterglow from GRB 991208 (Frail et al. 1999, GCN 451).
This optical source is not visible in the Digitized Sky Survey. The detection of
the radio and optical sources which coincide in their positions within the
astrometric errors strongly supports the view that their origin is the afterglow
of the GRB. Photometric calibration of the I-band image is in progress. The
comparison of the brightness of the newly found object with nearby USNO stars
indicates an I magnitude of about 19...19.5 mag. The presence of the optical
source is confirmed by independent observations of Castro-Tirado et al. (GCN
452). The image can be found at
http://www.tls-tautenburg.de/research/grb991208.html"
This message is quotable.
GCN Circular 452
Subject
GRB 991208 optical observations
Date
1999-12-11T13:27:36Z (26 years ago)
From
Alberto Castro-Tirado at Inst.de Astrofisica de Andalucia <ajct@iaa.es>
GRB 991208, optical observations
--------------------------------------
Alberto Castro-Tirado, LAEFF-INTA (Madrid) and IAA-CSIC (Granada)
Javier Gorosabel, LAEFF-INTA (Madrid) and Univ of Amsterdam (UoA)
Jochen Greiner, AIP (Potsdam)
Holger Pedersen, KUO (Copenhagen)
Elena Pian, ITESRE (Bologna)
Paul Vreeswijk (UoA)
on behalf of a larger European Collaboration
Chris Blake and Jasper Wall (Univ. of Oxford)
Georg Feulner and Ulrich Hopp, Universitaets Sternwarte (Muenchen)
Nick Rattenbury (Univ. of Auckland, New Zealand)
report:
"We have obtained several exposures of the IPN error box for
GRB 991208 (Hurley et al. GCN 450) with the 2.5-m Isaac Newton
telescope at La Palma and with the 2.2-m telescope at the German-
Spanish Calar Alto Observatory. The images were taken on Dec 10.27
(I-band) and Dec 11.25 UT (R- and I-band filters).
After a visual comparison with the Digital Sky Survey, a new source
is clearly detected with R = 19.1 +/- 0.1 (Dec 11.27). Its position
is AR(2000) = 16h 33m 53.51s, Dec(2000) = +46 27 21.5 (+/- 1"). We note
that this object coincides with the radio source reported by Frail et al.
(GCN 451) and therefore is the optical afterglow to GRB 991208. Further
multiwavelength imaging and spectroscopy are encouraged. A finding
chart will be posted at http://www.laeff.esa.es/~ajct/GRBs/GRB991208"
This message is quotable.
GCN Circular 451
Subject
GRB 991208: Radio Observations
Date
1999-12-11T02:42:10Z (26 years ago)
From
Dale A. Frail at NRAO <dfrail@nrao.edu>
D. A. Frail (NRAO) reports on behalf of a larger collaboration:
"Beginning 1999 December 10.92 UT we imaged the IPN error box (Hurley
et al. GCN #450) of GRB 991208 with the Very Large Array (VLA) at 4.86
GHz and 8.46 GHz. Near the center of the IPN box, at R.A.=16 33 53.50,
dec.=+46 27 20.9 (J2000), there is a previously uncataloged source.
The source is unresolved at a resolution of 0.8 arcsec and has a
spectral index of +1.4. Based on the source location, its inverted
spectrum and compactness we consider this to be a strong candidate for
the afterglow from GRB 991208. This GRB is located in the daytime sky,
making optical observations all but impossible at this time. We urge
further radio observations to determine whether the source is variable."
This message is citeable.
GCN Circular 450
Subject
IPN localization of GRB991208
Date
1999-12-10T00:42:16Z (26 years ago)
From
Kevin Hurley at UCBerkeley/SSL <khurley@sunspot.ssl.berkeley.edu>
K. Hurley (UCB SSL), on behalf of the Ulysses GRB team, and
T. Cline (NASA GSFC), on behalf of the KONUS and NEAR GRB teams,
report:
Ulysses, KONUS, and NEAR observed an extremely intense, 60 s long
gamma-ray burst on December 8, 1999, at 04:36:52 UT. Preliminary
estimates indicate a fluence >25 keV of ~10^-4 erg/cm^2, and
considerable flux was observed by NEAR >100 keV. We have localized
this burst to a 14 sq. arcmin. error box whose corners are:
RA(2000) Decl.(2000)
16 h 33 m 47 s +46 o 27 ' 43 "
16 h 34 m 08 s +46 o 20 ' 19 "
16 h 33 m 43 s +46 o 32 ' 52 "
16 h 34 m 04 s +46 o 25 ' 29 "
This error box can be refined considerably.