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GCN Circular 32422

GRB 220715B: VIRT Optical Upper Limit
2022-07-24T02:17:46Z (2 years ago)
Priyadarshini Gokuldass at U. of the Virgin Islands <>
K. Noonan (UVI), P. Gokuldass (Florida Institute of Technology), N. Orange
(OrangeWave Innovative Science, LLC), K. Smith (UVI), R. Querrard (UVI), D.
Morris (UVI) report:

We observed the field of GRB220715B (Fermi GRB team, GCN 32404; and Troja
et al., GCN 32405) with the 0.5m Virgin Island Robotic Telescope (VIRT) at
the University of the Virgin Islands' Etelman Observatory on 07-16-2022
starting at 00:06:54 UT (T+1.7 hrs). We performed a series of exposures in
the R filter with a total exposure of 3910 s. The weather conditions were
partly cloudy during the hours of observation with an average airmass of

We detect no new source within the enhanced XRT position error circle
(Evans et al., GCNC 32406), consistent with other non-detections (Lipunov
et al. GCN 32407, Hu et al, GCN 33408; and Kuin et al., GCN 32410) and
report the following 5-sigma upper limit:

T_mid            ||Exposure     ||Filter      ||Limit

T+ 3.1  hrs     ||3910s          ||R            ||>19.1

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

We acknowledge financial support from NASA MUREP MIRO award 80NSSC21M0001,
NASA EPSCoR award 80NSSC19M0060, and NSF EiR award 1901296.This message can
be cited.
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