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 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.