TITLE:   GCN CIRCULAR
NUMBER:  38299
SUBJECT: GRB 241026A: VIRT Optical Upper Limit
DATE:    24/11/22 16:35:54 GMT
FROM:    Priya Gokuldass at ERAU <gokuldap@my.erau.edu>

R. Querrard (UVI), P. Gokuldass (ERAU), N. Orange (OrangeWave Innovative Science, LLC), D. Morris (NASA), T. Lombardi (Eckerd College), F. George (ERAU), K. Noonan (UVI), D. Smith (UVI), K. Smith (UVI), C. Watson (UVI) report:

We observed the field of GRB241026A (Fermi GBM Team, GCN 37894; Melandri et al., GCN 37896; Li et al., GCN 37909; Zhang et al., GCN 37921) with the 0.5m Virgin Island Robotic Telescope (VIRT) at the University of the Virgin Islands' Etelman Observatory on 2024-10-27 starting at 22:49:52.275 (T-mid ~T0+24 hrs). We performed a series of exposures in an R filter with a total exposure of 1100s. The weather conditions were partly cloudy during the hours of observation with an average airmass of 1.48. 

We do not detect any source within the enhanced XRT position (Osborne et al. GCN 37904). This non-detection is consistent with reported detections (Moskvitin et al. GCN 37899; Watson et al. GCN 37900; Zheng et al. GCN 37903; Shrestha et al. GCN 37913; Mohan et al. GCN 37918; Moskvitin et al. GCN 37922; Wang et al. GCN 37928; Moskvitin et al. GCN 37953; Rossi et al. GCN 37969; Moskvitin et al. GCN 38028; and Wang et al. GCN 38035;) and upper limits  (Lipunov et al. GCN 37898; Mo et al. GCN 37915 and Siegel et al. GCN 37947). We report the following 3-sigma upper limit:

T_mid                ||Exposure   ||Filter   ||Limit 
T+24  hrs            || 1100s     || R       || >20.5

The limit is estimated from comparison to nearby USNO B1 stars and is not corrected for Galactic extinction. The VIRT is still in the commissioning phase. 

We acknowledge financial support from NASA EPSCoR award 80NNSC22M0063, NSF PAARE award 2319415, and NASA EPSCoR award 80NSSC24M0112. This message can be cited.