GCN Circular 33263

Subject

GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate

Event

Date

2023-02-04T14:02:18Z (3 years ago)

From

Robert Strausbaugh at University of Minnesota <rstrausb@umn.edu>

R. Strausbaugh (University of Minnesota), A. Cucchiara (NASA) report on
behalf of a larger collaboration:

We observed the GRB 230204A/Swift J1552.8-5055 (D'Ai et al., GCN 33260Loading...
 
 )
field with the LCOGT 1-meter Sinistro instrument at the Cerro Tololo
Interamerican Observatory, Chile site, on February 4, from 07:24 to 7:57 UT
(corresponding to 4.47 to 5.02 hours after GRB trigger time) with the
Bessel R and I filters.

We performed a series of 3x300s exposures in both bands.  We detect a
source consistent with the XRT enhanced error position (Evens et al., GCN
33261Loading...
 
 ) that is not present in USNO, SkyMapper, or 2MASS catalogs.  The
coordinates for this candidate are: 238.19844d, -50.917039d.

As the field is near the galactic plane, the field is quite crowded.  It is
possible that this source is present in the catalogs mentioned, but was not
able to be resolved due to different plate scales.  Future observations are
planned to determine if the detected source is fading and other follow-up
efforts are encouraged.

The following magnitudes are calculated using the USNO-B1.0 catalog as
reference:

R = 17.75 +/- 0.02
I = 17.16 +/- 0.01

Due to the crowded field, these magnitudes may be contaminated by a nearby
bright star. These magnitudes are not corrected for galactic extinction.