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Optical follow up of the GRB 990123 source from UPSO, Nainital

R. Sagar·A. K. Pandey·V. Mohan·R. K. S. Yadav·Nilakshi·D. Bhattacharya·A. J. Castro-Tirado
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Abstract

The CCD magnitudes in Johnson $BV$ and Cousins $R$ photometric passbands are determined for the optical transient of GRB 990123. These observations have been taken approximately 12 hours after trigger of the gamma-ray burst. BVR photometric light curves are obtained by combining the published data with the present measurements. They indicate that the flux decay constants in $BV$ and $R$ passbands are almost the same. Its value is $1.1\pm 0.06$. Such decay is quite consistent with the fireball models for the optical transient.

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R. Sagar, A. K. Pandey, V. Mohan, R. K. S. Yadav, Nilakshi, D. Bhattacharya, A. J. Castro-Tirado. 1999-02-17. Optical follow up of the GRB 990123 source from UPSO, Nainital. https://arxiv.org/abs/astro-ph/9902196

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