TITLE:   GCN CIRCULAR
NUMBER:  25737
SUBJECT: LIGO/Virgo S190910d: No Counterparts in DDOTI/OAN Optical Observations
DATE:    19/09/13 06:02:44 GMT
FROM:    Emma Margarita Pereyra Talamantes at IA-UNAM Ensenada  <mpereyra@astro.unam.mx>

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

We observed LIGO/Virgo S190910d event (Badaracco F; LVC et al.; GCN #25695)
with the DDOTI/OAN wide-field imager at the Observatorio Astronomico
Nacional on Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) from
2019-09-10 04:25 to 2019-09-10 08:15 UTC ( ~ 3.0 to 7.8 hours after the
event).

We observed approximately 289 square degrees of the sky, with 5 pointings
centered on 17:30:00.089 +19:08:01.30, 17:49:53.330 +17:34:38.58,
17:49:53.330 +24:35:33.03, 18:09:04.387 +22:40:56.15 and 18:09:46.574
+30:03:26.65. We obtained about 18, 36, 18, 30 and 18 minutes total
exposure on each pointing, respectively. These regions include about 6% of
the 2D probability in the current BAYESTAR map and 5% of the 2D probability
in the LALInference map.

We calibrated our images against the APASS catalog. Our 10-sigma limiting
magnitude are typically between w = 18.04 and w = 18.96.

Comparing our 10-sigma detections against the USNO-B1 catalog, we detect no
uncataloged sources with significant fading.

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