W. E. Pereira

Super‐LOTIS and LOTIS for HETE2 GRB Triggers

LOTIS (Livermore Optical Transient Imaging System) and Super‐LOTIS are automatic telescope systems that search for prompt optical emission from gamma‐ray bursts (GRBs). Both systems are capable of responding to the Gamma‐ray burst Coordinate Network (GCN) triggers within seconds. These systems have been monitoring the GCN real‐time data for automatic HETE2 GRB triggers since HETE2’s launch. In this paper, we present the systems’ capability and current status. We also present the result of the GRB010921 afterglow detection that was localized by HETE2 and the IPN.

Super-LOTIS/LOTIS/LITE: Prompt GRB followup experiments

LOTIS (Livermore Optical Transient Imaging System) and Super-LOTIS are automatic telescope systems that measure very prompt optical emission occurring within seconds of the gamma-ray energy release during a Gamma Ray Burst (GRB). Unlike hour-to-days delayed afterglow measurements, very early measurements will contain information about the GRB progenitor. To accomplish this, we developed and have been operating automated telescopes that rapidly image GRB coordinate error boxes in response to triggers distributed by the GRB Coordinate Distribution Network (GCN). LOTIS, located in California, consists of 4 cameras each with a different astronomical filter (B, V, R, open) that can respond to GRB triggers within 5 s. Super-LOTIS can point to any part of the sky within 30 s upon receipt of a GCN trigger and its sensitivity is as deep as V = 17-19 depending on the integration times. Since the shutdown of the CGRO, there has been no real-time GRE3 triggers that enable the LOTIS systems to measure real-time GRE3 counterpart fluxes as of May 2001. This paper describes performance of these systems. We also present our plan to replace the current optical CCD camera on the Super-LOTIS to a near infrared camera to be able to probe dusty GRB environment.

Super-LOTIS early time optical counterpart measurements

We present an update on our ongoing effort to establish a dedicated observation program with an automated 0.6 meter telescope system that can detect GRB optical signals from 30 s to many hours after the start of the burst. The Super-LOTIS telescope has a 0.8°×0.8° field-of-view, is sensitive to V 17∼19 objects, depending on the integration times, and will be placed at the Kitt Peak National Observatory. This paper presents technical aspects of this telescope and first results from initial operations at LLNL. Utilizing real-time coordinates from BATSE, BeppoSAX, XTE, IPN, HETE-2 and INTEGRAL, our LOTIS and SLOTIS systems will measure prompt GRB optical light curves that will enhance our understanding of GRBs.

Prompt GRB optical follow-up experiments

Gamma Ray Bursts (GRBs) are brief, randomly located, releases of gamma-ray energy from unknown celestial sources that occur almost daily. The study of GRBs has undergone a revolution in the past three years due to an international effort of follow-up observations of coordinates provided by Beppo/SAX and IPN GRB. These follow-up observations have shown that GRBs are at cosmological distances and interact with surrounding material as described by the fireball model. However, prompt optical counterparts have only been seen in one case and are therefore very rare or much dimmer than the sensitivity of the current instruments. Unlike later time afterglows, prompt optical measurements would provide information on the GRB progenitor. LOTIS is the very first automated and dedicated telescope system that actively utilizes the GRB Coordinates Network (GCN) and it attempts to measure simultaneous optical light curve associated with GRBs. After 3 years of running, LOTIS has responded to 75 GRB triggers. The lack of a...