TITLE:   GCN CIRCULAR
NUMBER:  30451
SUBJECT: GRB 210704A: Lowell Discovery Telescope Optical Observations
DATE:    21/07/12 13:02:36 GMT
FROM:    Brendan O'Connor at UMD  <oconnorb@umd.edu>

B. O'Connor (GWU, UMD), E. Troja (UMD, NASA-GSFC), E. Zack (UMD),
S.Dichiara (UMD, NASA-GSFC), P. Gatkine (Caltech), J.M. Durbak (UMD),
S.B. Cenko (NASA-GSFC), A. Kutyrev (UMD, NASA-GSFC), S. Veilleux (UMD)
report:

We observed the field of GRB 210704A (Ursi et al., GCN 30372;
Berretta et al., GCN 30375; Prasad et al., GCN 30378; D'Ai et al.,
GCN 30379; Malacaria et al., GCN 30380; Ridnaia et al., GCN 30388)
with the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations started on July 11, 2021
at 3:57:51 UT (about 6.4 days after the GRB trigger) in the SDSS r filter.
The observations were taken at airmass 1.8 and seeing 2.0" for 1500 s.

We detect the optical afterglow (Kim et al., GCN 30384)
with magnitude r ~ 23.4 +/- 0.2 AB mag. This indicates a
negligible decay of the transient between 4.1 and 6.4 days
(Watson et al., GCN 30436).

Magnitudes are calibrated against the SDSS catalog and are not
corrected for Galactic extinction.

We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.