1 Introduction

The recent discoveries of fading multiwavelength afterglows ([Costa et al. 1997]; [van Paradijs et al. 1997]; [Frail et al. 1997]) to a number of $\gamma$-ray bursts (GRBs) have been precipitated by the accurate and prompt localisation capability of the two Wide Field Cameras (WFC) aboard the Italian-Dutch BeppoSAX X-ray satellite ([Boella et al. 1997]). The shrinking of GRB error circles by BeppoSAX also made it feasible to study the content of these regions at far-infrared wavelengths with the European Space Agency's Infrared Space Observatory (ISO) which flew between November 1995 and April 1998 ([Kessler et al. 1996]).

A search for quiescent far-infrared emission from 23 well-localised GRBs using the IRAS faint source catalogue identified no quiescent counterparts ([Schaefer et al. 1987]). Compared to IRAS, ISO had broader wavelength coverage, better spatial resolution, greater sensitivity and a longer lifetime. ISO also had the added bonus that its operational lifetime serendipitously overlapped with that of BeppoSAX. In early 1997 a TOO program was awarded to make rapid follow-up observations of well-localised BeppoSAX GRBs with ISO. The objectives of the program were to observe infrared afterglow emission from GRBs for the first time and to place constraints on the underlying hosts which may be actively star-forming regions ([Bloom et al. 1998]; [Paczynski 1998]).