We present multi-instrument optical observations of the High Energy Transient Explorer ( HETE-2 ) /Interplanetary Network ( IPN ) error box of GRB 010921 .
This event was the first gamma ray burst ( GRB ) localized by HETE-2 which has resulted in the detection of an optical afterglow .
In this paper we report the earliest known observations of the GRB010921 field , taken with the 0.11-m Livermore Optical Transient Imaging System ( LOTIS ) telescope , and the earliest known detection of the GRB010921 optical afterglow , using the 0.5-m Sloan Digital Sky Survey Photometric Telescope ( SDSS PT ) .
Observations with the LOTIS telescope began during a routine sky patrol 52 minutes after the burst .
Observations were made with the SDSS PT , the 0.6-m Super-LOTIS telescope , and the 1.34-m Tautenburg Schmidt telescope at 21.3 , 21.8 , and 37.5 hours after the GRB , respectively .
In addition , the host galaxy was observed with the USNOFS 1.0-m telescope 56 days after the burst .
We find that at later times ( t ¿ 1 day after the burst ) , the optical afterglow exhibited a power-law decline with a slope of \alpha = 1.75 \pm 0.28 .
However , our earliest observations show that this power-law decline can not have extended to early times ( t ¡ 0.035 day ) .