3 LOTIS observation of GRB 980703

LOTIS obtained images in the field of GRB 980703 5.03 hours (July 3.39 UT) after the burst began. Even though LOTIS is capable of responding to GRB events as soon as 10 s after a burst, the GRB 980703 trigger came at 9:20 PM local time while there was still day light at the LOTIS site. In fact, the reported radio/optical transient location (Frail 1998) was below the horizon at the time. Therefore, LOTIS could not cover this event in real-time. However, our all-sky patrol program eventually imaged the GRB 980703 field 5 hours after the burst. The GRB 980703 field was imaged 2 times the first night after rising above the horizon. We also have sky patrol data from the previous and the following nights. The integration time used for these images was 30 s. We have analyzed the images taken at July 2.39, 2.47, 3.39, 3.47, 4.39, 4.47 and 6.47 UTC by comparing them to each other and with Digital Sky Survey images.

No flaring sources were observed at brighter than $R_{\rm eq}=15.0~\pm~0.3$.Figure 1 shows the LOTIS limit with respect to H, I and R band follow-up observations made by other telescopes (Bloom 1998). A linear extrapolation of the R band observation to earlier times predicts bright signals easily detectable by LOTIS within the first 10 s of seconds after the start of the GRB.

  

Figure 1: Optical light curve of the H, I, and R band transients associated with GRB 980703