The X-ray, optical and infrared counterpart to GRB 980703
Astronomical Institute "Anton Pannekoek”, University of Amsterdam, & Center for High Energy Astrophysics, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
2 Astrophysics Division, Space Science Department of ESA, European Space Research and Technology Centre, 2200 AG Noordwijk, The Netherlands
3 Joint Astronomy Centre, 660 N. A'ohoku Place, Hilo, Hawaii 9672 0, U.S.A.
4 Physics Department, University of Alabama in Huntsville, Huntsville AL 35899, U.S.A.
5 Universities Space Research Association
6 NASA/MSFC, Code ES-84, Huntsville AL 35812, U.S.A.
7 Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
8 Istituto Tecnologie e Studio Radiazioni Extraterrestri (TESRE), CNR, Via P. Gobetti 101, 40 129 Bologna, Italy
Accepted: 10 March 1999
We report on X-ray, optical and infrared follow-up observations of GRB 980703. We detect a previously unknown X-ray source in the GRB error box; assuming a power law decline we find for its decay index . We invoke host galaxy extinction to match the observed spectral slope with the slope expected from "fireball” models. We find no evidence for a spectral break in the infrared to X-ray spectral range on 1998 July 4.4, and determine a lower limit of the cooling break frequency: Hz. For this epoch we obtain an extinction of . From the X-ray data we estimate the optical extinction to be AV =, inconsistent with the former value. Following Wijers & Galama (1998), we determine intrinsic fireball properties for this burst.
Key words: gamma-rays: bursts / radiation mechanisms: non-thermal
© European Southern Observatory (ESO), 1999