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GCN Circular 35110

GRB 231118A: LCOGT Optical Observations
2023-11-18T22:32:28Z (5 months ago)
Robert Strausbaugh at Eastern Illinois University <>
R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:

We observed the Swift/Fermi GRB 231118A field (Fermi GBM Team, GCN 35100; Laha et al., GCN 35101)  with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on November 18, from 21:20 to 21:52 UT (corresponding to 4.07 to 4.60 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 3x300s exposures in each band.  We detect an uncataloged source consistent with the Skynet afterglow candidate (Dutton et al., GCN 35103) in both bands.  This result is consistent with fading detected in continued Skynet observations (Dutton et al., GCN 35108) and MASTER observations (Lipunov, et al., GCN 35109)

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

R = 19.08 +/- 0.04
I = 18.67 +/- 0.03

These magnitudes are not corrected for galactic extinction.

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