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L OTIS obtained images in the field of GRB980703 within 5.03 hours after the burst began (July 3.39 UT). LOTIS resumed its automatic observation program after a recent upgrade incorporating thermoelectric cooling to its four CCD cameras. The upgrade increased the sensitivity from the non-cooled apparatus by at least three magnitudes.

LOTIS is capable of responding to GRB events as soon as 10 s after a burst localization by utilizing the BATSE real-time trigger to initiate the fast slewing mount. The telescope has a 17.4 x 17.4 degree wide field-of-view which can cover a large portion of the BATSE error box for real-time triggers.

The GRB980703 trigger came at 9:20 PM local time while there was still day light in California. In addition, the reported OT location (GCN #128) was below the horizon when the sky monitoring began that night. Therefore, LOTIS could not cover this event in real-time. However, our all-sky patrol program eventually imaged the GRB980703 field 5 hours after the burst. We also have the 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 UT by comparing them to each other and with the Digital Sky Survey images.

No flaring or fading sources were observed at mV~15 with a 5 sigma detection threshold.

GRB 980703 Images

To see the full size image choose here

The figure above shows the LOTIS coverage of the final RXTE/BeppoSAX error for GRB 980703. Each image covers an area of 10' x 10'. The images were obtained prior to the burst on July 2.39 and 2.47 and beginning 5.03 hours after the burst on July 3.39, 3.47, 4.39, 4.47 and 6.47. Two 30 s exposures were obtained at each epoch. The circle in the first image is the 50" BeppoSAX/NFI error radius.

The chart below illustrates the field shown in the images above. The number next to each star indicates the stellar magnitude.

GRB 980703 Finder Chart

To view a full finder chart choose here

To obtain a postscript finder chart choose here

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