2 LOTIS observation of GRB 971227

LOTIS received GCN coordinates derived from BATSE telemetry approximately 4 s after the start of the burst and obtained its first 10 s exposure, centered on the GCN coordinates 6 s later (10 s after the burst began: 27.3495 UT). LOTIS continued taking 10 s exposures at the rate of 1 image every 20 s for the next 20 minutes, then at the rate of once per minute for the rest of the night. Because of LOTIS's large, field-of-view, the recorded images fully contain the error box of the location of the associated X-ray transient detected by BeppoSAX's NFI despite the $6.7^\circ$ difference between the location of the BeppoSAX NFI position and the GCN BATSE-Original coordinates. We scanned the area of our images within the BeppoSAX error circle (8 arcmin radius) and found 10 objects brighter than an R equivalent magnitude of $R_{\rm eq}=12.3\pm0.3$; all of which were identified with known objects in the Guide Star Catalog and the Digital Sky Survey, and none showing variations in brightness in the other images. We calculate $R_{\rm eq}$ by scaling the ratio of R band to the entire CCD spectral band width.

We can improve our limiting magnitude by co-adding frames which reduces the background noise and enhances the signal. We added 60 frames which were taken during the first 20 min after the GRB and searched for any objects not in the catalog. We did not see any such objects at $R_{\rm eq}=14.2\pm0.2$. Details of our analysis method and comparisions of our limits with GRB models can be found in Williams et al. (1999).