[vsnet-grb-info 25112] LIGO/Virgo S200224ca: No Counterparts in DDOTI/OAN Optical Observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27212
SUBJECT: LIGO/Virgo S200224ca: No Counterparts in DDOTI/OAN Optical Observations
DATE:    20/02/25 22:12:02 GMT
FROM:    Simone Dichiara at UMCP/NASA/GSFC  <dichiara at umd.edu>

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

We observed LIGO/Virgo S200224ca (Valsan et al, GCN Circ. 27184) with the
DDOTI/OAN wide-field imager at the Observatorio Astronomico Nacional on
Sierra San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of
2020-02-25 UTC.

We tiled the LVC localization with two pointings centered on 11:35:23.26
-6:08:15.3 and 11:42:35.81 -11:48:03.3 (J2000). The combined
field covers about 135 square degrees and includes about 83% of the
probability in the current BAYESTAR map.

We observed from 2020-02-25 05:32 UTC to 2020-02-25 11:55 UTC (from 7.17 to
13.55 hours after the event) obtaining exposures of 123 to 155 minutes
across the field in the w filter. We calibrate our images against the APASS
catalog. The 10-sigma limiting magnitude is w = 20.0

Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogs we
detect no uncatalogued sources within the observed field to our 10-sigma
limit.

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