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The Optical Afterglow of GRB 971214: R and J Photometry
We present an R- and J-band photometry of an optical transient that islikely to be associated with the gamma-ray burst event GRB 971214. Ourfirst measurement took place 13 hr after the gamma-ray event. Thebrightness decayed with a power-law exponent alpha =-1.20+/-0.02 , whichis similar to those of GRB 970228 andGRB 970508, which had exponents ofalpha =-1.10+/-0.04 and alpha =-1.141+/-0.014 , respectively. Thetransient decayed monotonically during the first 4 days following thegamma-ray event in contrast with the optical transient associated withGRB 970508, which increased in brightness, peaking 2 days after theburst, before settling to a power-law decay.
| Detection of the near-infrared counterpart of GRB 971214 3.2 hours after the gamma-ray event
We report the detection of the GRB 971214 counterpart in thenear-infrared by means of two images in the K(') -band taken at CalarAlto only ~ 3.5 and ~ 5 hours after the gamma-ray event. We detect thetransient at K(') =18.03+/-0.18 and K(') =18.00+/-0.22 respectively. Ourdata seem to indicate the existence of a plateau with duration 1.5 <=T <= 6.7 hours (between 3.5 and 10.2 hours after the high-energyevent). Moreover the power-law decline should be steeper than the onegiven by the index alpha_K (') =0.45. There is also a change in theslope of the broad-band spectrum at some wavelength between the J andK(') bands (possibly around the H-band). Based on observations carriedout at the German-Spanish Astronomical Center, Calar-Alto, operated bythe Max-Planck-Institut für Astronomie, Heidelberg, jointly withthe Spanish National Commission for Astronomy.
| Identification of a host galaxy at redshift z = 3.42 for the γ-ray burst of 14 December 1997
Knowledge of the properties of γ-ray bursts has increasedsubstantially following recent detections of counterparts at X-ray,optical and radio wavelengths. But the nature of the underlying physicalmechanism that powers these sources remains unclear. In this context, animportant question is the total energy in the burst, for which anaccurate estimate of the distance is required. Possible host galaxieshave been identified for the first two optical counterparts discovered,and a lower limit obtained for the redshift of one of them, indicatingthat the bursts lie at cosmological distances. A host galaxy of thethird optically detected burst has now been identified and its redshiftdetermined to be z = 3.42. When combined with the measured flux ofγ-rays from the burst, this large redshift implies an energy of3× 1053erg in the γ-rays alone, if the emissionis isotropic. This is much larger than the energies hitherto considered,and it poses a challenge for theoretical models of the bursts.
| GRB 971214
IAUC 6792 available at Central Bureau for Astronomical Telegrams.
| GRB 971214
IAUC 6791 available at Central Bureau for Astronomical Telegrams.
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Osservazione e dati astrometrici
| Costellazione: | Orsa Maggiore |
| Ascensione retta: | 11h56m37.69s |
| Declinazione: | +65°14'34.5" |
| Magnitudine apparente: | 6.52 |
| Distanza: | 152.672 parsec |
| Moto proprio RA: | 57.9 |
| Moto proprio Dec: | -18.7 |
| B-T magnitude: | 7.8 |
| V-T magnitude: | 6.626 |
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