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Optical counterpart of
GRB 971214
Discovered with the 2.4 m telescope at MDM Observatory
| IAU Circular #6788: GRB 971214 |
J. Halpern, J. Thorstensen, D. Helfand, E. Costa, and the
BeppoSAX team have detected a fading optical transient within the
error circle of GRB 971214 (IAUC 6787) in a series of I-band images
taken on the MDM Observatory 2.4-m telescope on Kitt Peak. The
position is R.A. = 11h56m26s.40, Decl. = +65o12'00".5 (equinox
2000.0). The I magnitude was 21.2 +/- 0.3 on Dec. 15.47 UT, and
near the detection limit of 22.6 on Dec. 16.47. Images will be
made available at http://www.astro.columbia.edu/~cba/mdm/.
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These I band images revealing the
counterpart of the BeppoSAX gamma-ray burst GRB 971214 were obtained
by John Thorstensen on the MDM Observatory's 2.4m Hiltner telescope in
subarcsecond seeing. They were obtained 12 hours and 36 hours after
the burst, respectively, and reveal a pointlike transient within the
BeppoSAX error circle that faded from approximately I=21.2 on the
first night to near the limiting magnitude of approximately I=22.6 on
the second night. Conditions were photometric, and the magnitudes
were calibrated using Landolt standards. In addition to full moon,
background light from the 6.7 mag star SAO 15663 made this a
challenging observation. The images displayed are the nightly
averages.
The position of the optical transient is (J2000) 11 56 26.40, +65 12 00.5. It was measured with respect to a fit of five stars that appear in the USNO-A1.0 astrometric catalog of the POSS plates (Monet et al. 1996). There are several galaxies in the neighborhood of the optical transient, including one that is clearly visible only 5" to the southwest. GRB 971214 is the third gamma-ray burst for which an optical counterpart has been found. Its magnitude and rate of decay are similar to the two others, GRB 970228 and GRB 970508, for which power-law decays of slope 1.3 and 1.2, respectively, were fitted to the time-dependent optical flux. The 2.4m Hiltner telescope is the larger of two telescopes that comprise the MDM Observatory on Kitt Peak. Its mirror is fitted with an air-bag support, and an air-conditioning system that keeps the mirror temperature just below the ambient for better seeing. Heat sources in the dome are kept to a minimum, with the result that seeing of 0.8 arc seconds is routinely obtained on this telescope. |
Other GRB 971214 web sites:
BATSE Rapid Burst Response Page
grb971214.gif
ARC 3.5m Detects GRB 971214 Optical Transient
Gamma Ray Burst 971214 observations at NOAO
