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Title: Optical photometry of the GRB 010222 afterglow
Authors: Cowsik, R
Prabhu, T. P
Anupama, G. C
Bhatt, B. C
Sahu, D. K
Ambika, S
Bhargavi, S. G
Keywords: Optical photometry;GRB 010222
Issue Date: 2001
Publisher: Astronomical Society of India
Citation: BASI, Vol. 29, No. 2, pp. 157 - 168
Abstract: The optical afterglow of GRB 010222 was observed using the recently installed 2-m telescope at the Indian Astronomical Observatory, Hanle, and the telescopes at the Vainu Bappu Observatory, Kavalur, beginning ~ 0.6 day after the detection of the event. The results based on these photometric observations combined with others reported in the literature are presented in this paper. The R band light curve shows an initial decline of intensities proportional to t-0.542 which steepens, after 10.3 hours, to t-1.263. Following the model of collimated outflow, the early break in the light curve implies a very narrow beam angle (~ 2 deg - 3 deg). The two decay rates are consistent with the standard jet model in a uniform density ambient medium, but require a hard spectrum of electron power density with p ~ 1.5. The R band light between 14 and 17 hours since outburst departs from the power law fit by 0.1 mag and shows some evidence for fluctuations over timescales of an hour in the observer's frame. Such deviations are expected due to density inhomogeneities if the ambient medium is similar to the local interstellar medium. GRB 010222 is thus an example of a highly collimated outflow with a hard spectrum of electron energy distribution in normal interstellar environment.
Appears in Collections:Publications based on data from IAO, Hanle
BASI Publications

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