Constraints on the optical precursor to the naked-eye burst GRB080319B from Pi of the Sky observations

TL;DR

This study searched for an optical precursor to the extremely bright GRB080319B using Pi of the Sky data, but found no precursor signal within the observational limits, setting a new upper brightness limit.

Contribution

It provides the first robust upper limit on the optical precursor brightness for GRB080319B based on pre-burst observations.

Findings

No precursor detected within 3 sigma limit.

Set a 12m (V-band) upper limit on precursor brightness.

Provided the most stringent limit to date for this event.

Abstract

I present the results of the search for an optical precursor to the naked-eye burst - GRB080319B, which reached 5.87m optical peak luminosity in the "Pi of the Sky" data. A burst of such a high brightness could have been preceded by an optical precursor luminous enough to be in detection range of our experiment. The "Pi of the Sky" cameras observed the coordinates of the GRB for about 20 minutes prior to the explosion, thus provided crucial data for the precursor search. No signal within 3 sigma limit was found. A limit of 12m (V-band equivalent) was set based on the data combined from two cameras, the most robust limit to my knowledge for this precursor.