LIGO/Virgo S191110af: Evryscope observation report, no counterpart candidates

The contact person for this circular is Hank Corbett (htc@unc.edu). Evryscope-South, located at Cerro Tololo Inter-American Observatory, (Ratzloff et al. 2019, Law et al. 2015) began observing the error region of LIGO/Virgo S191110af at 2019-11-11 01:00:05 UT during regular science operations. Evryscope-South has an instantaneous field of view of 8520 sq. degrees and observes at a continuous 2-minute cadence in Sloan g'. Evryscope-North, located at Mount Laguna Observatory, California, began observing the error region of LIGO/Virgo S191110af at 2019-11-11 01:35:30 UT during regular science operations. Evryscope-North has an instantaneous field of view of 7409 sq. degrees and observes at a continuous 2-minute cadence in Sloan g'. Under current full-moon conditions, single-exposure limiting magnitudes ranged from 12.5 to 14.5 as a function of moon elongation and airmass, averaging 13.7, calibrated to the ATLAS All-Sky Stellar Reference Catalog (Tonry 2018). We performed an automated search for optical transients over all Evryscope-South images within 5 hours of the alert, selecting candidates that appeared in multiple frames and were not associated with previously-detected variable sources. During this interval, Evryscope-South observed 93% of the LIGO/Virgo skymap and Evryscope-North observed 2% of the skymap. We found no candidates within the visible 90% probability containment region for S191110af. Evryscope-North data analysis is ongoing.