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On February 23, 1997 at 08:26:17.67 UTC (00:26:17.67 PST) BATSE detected GRB 970223 (Trig. 6100). LOTIS received the Original GCN coordinates of RA=144.85°, Dec=36.13° at 08:26:23.5 UTC, approximately 5.8 seconds after the trigger. After slewing to the coordinates (~5.7 s) LOTIS began imaging the Original GRB position at 08:26:29.2 UTC, just 11.5 seconds after the BATSE trigger.

GRB 970223 Light Curve

The plot above illustrates the LOTIS response time to GRB 970223. The BATSE light curve ( > 20 keV) shows the burst with a duration of ~30 s. The grey area represents the integration time (10.0 s) of the first LOTIS image. LOTIS began imaging approximately 11.5 seconds after gamma-ray emission began resulting in an optical image simultaneous with the gamma-ray burst. LOTIS continued to image the area for the next 20 minutes.

GRB 970223 Coverage Plot

The plot above illustrates the LOTIS coverage of the Final BATSE error circle centered at RA=142.48°, Dec=35.43°, approximately 2.0° from the Original coordinates. The inner and outer ellipses represent the BATSE 1-sigma (0.73° statistical and 1.9° systematic errors) and 3-sigma error circles. The narrow arc represents the IPN annulus calculated using data from the BATSE and Ulysses instruments. The annulus is centered at RA=167.407°, Dec=36.399° and has a radius and width of 18.813° and ±0.029° respectively. The pseudo-rectangles represent the area covered by the LOTIS cameras and each of the dots is a star detected by the system.

Click here for a postscript plot of the light curve.

Click here for a postscript LOTIS coverage plot.

Click here for both the light curve and coverage plot in a single postscript file.

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