As a member of the ST ScI's OPUS team, I examined the data and provided the following assessment. The guide star reacquisition for this exposure failed.
Additional information suggests the take data flag was down.
If that was the case, then the WFPC shutter simply toggled at the start of the exposure. Most of the exposure occurred while the shutter was closed. These observations were implemented as observation set U3815H in Science Mission Specification 970347E2. The exposure logsheet line that defined them are listed in the following table. The intention of this report is to provide you with information on problems with the execution of your observations.