TITLE:   GCN CIRCULAR
NUMBER:  25769
SUBJECT: HAWC-190916A: DDOTI Optical Observations
DATE:    19/09/17 04:39:42 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Eleonora Troja (GSFC/UMD), Rosa L.
Becerra (UNAM), Simone Dichiara (GSFC/UMD), Diego Gonzalez (UNAM), Alexander
Kutyrev (GSFC/UMD), William H. Lee (UNAM), Margarita Pereyra
<mpereyra@astro.unam.mx> (UNAM), and Tanner Wolfram (ASU) report:

We observed the field of HAWC-190916A (Ayala, GCN Circ 25766, 25768) with the
DDOTI wide-field imager at the Observatorio Astronomico Nacional on Sierra San
Pedro Martir (http://ddoti.astroscu.unam.mx) from 2019-09-17 03:14 to 2019-09-17
04:17 UTC (2.0 to 3.1 hours after the trigger).

We obtained a total of 2340 seconds of exposure in the w filter. We calibrated
our images against the APASS catalog. Our 10-sigma limiting magnitude is w =
19.5.

Comparing our 10-sigma detections against the USNO-B1 catalog, we detect no
reliable uncataloged sources with significant fading within 1.7 degrees of the
nominal coordinates.

We thank the staff of the Observatorio Astronomico Nacional in San Pedro Martir.