GCN Circular 28270
Subject
GRB 200729A: Lowell Discovery Telescope observations
Date
2020-08-20T02:43:52Z (4 years ago)
From
Simone Dichiara at UMCP/NASA/GSFC <dichiara@umd.edu>
S.Dichiara (UMD, NASA-GSFC), P. Gatkine (UMD), J. Durbak (UMD),
S.B. Cenko (NASA-GSFC), E. Troja (UMD, NASA-GSFC), A. Kutyrev (UMD,
NASA-GSFC), S. Veilleux (UMD), report on behalf of a larger
collaboration:
We observed the field of GRB 200729A (Evans et al., GCN Circ. 28165)
using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations started on August 17,
03:52:06 UT (18.34 days after the Swift trigger) taking 6 exposures of
150 s each with SDSS i filter. Observations were taken at an airmass of
about 2.4 and seeing of 1.9".
We do not find any source inside the enhanced XRT position (Osborne et
al., GCN Circ. 28168) down to a 3-sigma limiting magnitude of i>21.8
AB mag.
Magnitudes are calibrated against the SDSS catalog and not corrected for
Galactic extinction.
The time of our observation corresponds to the typical peak time for an
associated supernova. Therefore, our upper limit on the supernova
component strengthens the hypothesis of a chance alignment of the GRB
with the foreground galaxy NGC 4242, which is at a distance of ~ 7.5 Mpc
(Anand et al., GCN Circ. 28175). In particular we note that our limit is
about 11.6 magnitudes deeper than the one expected from a SN1998bw-like
supernova at the same distance (without correcting for the large but
uncertain extinction; Tohuvavohu et al., GCN Circ. 28176).
We thank the staff of the Lowell Discovery Telescope for assistance with
these observations.