[vsnet-grb-info 27338] GRB 210207B: Continued LCO Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29441
SUBJECT: GRB 210207B: Continued LCO Observations
DATE:    21/02/09 16:35:12 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh at uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We performed a second set of observations on Swift GRB 210207B (Lien, GCN 29420) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on February 9, from 11:19 to 11:24 UT (corresponding to 37.23 to 37.31 hours from the GRB trigger time) with the Bessel R filter.

We performed a second series of 4x60s exposures in R band. We no longer detect a source at the location consistent with other optical detections (Lien, GCN 29420; Kumar, GCN ; Zheng, GCN 29430; Strausbaugh, GCN 29431).  Using the USNO-B.1 catalog as reference, we calculate the following upper limit:

R > 21.42


These magnitudes are not corrected for galactic extinction.  This lack of a detection provides further evidence for the transient nature of this source.  As a correction to GCN 29431, the series of exposures in R and I bands were 4x60s, not the originally reported 5x60s.

R.S. is funded by NSF AST grant #1831682