GCN Circular 24309

B. J. Shappee (IfA-Hawaii), C. S. Kochanek (OSU), K. Z. Stanek (OSU),
S. Holmbo (Aarhus), A. Franckowiak (DESY), T. W.-S. Holoien (Carnegie
Observatories),
J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU),  T. A. Thompson
(OSU), J. F. Beacom (OSU)

ASAS-SN covered 10% of the probability region in the 1 hour preceding the
LIGO/Virgo Alert GCN #24168 of a BNS merger through normal operations.
Following, the LIGO/VIRGO alert optical follow-up was triggered with the
All-Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014;
Kochanek et al. 2017).   ASAS-SN covered 67% of the probability region in
the 24 hours after the LIGO/VIRGO alert through a combination of normal
operations and triggered observations.  The majority of the remaining
probability region was Sun constrained.  We obtained 6 epochs on the
highest probability regions during that time. Candidates were scanned in
near real time. No obvious candidates were discovered. Given the lunation,
our depth was typically between g~18-18.5 mag.

Our coverage is shown here:
http://www.astronomy.ohio-state.edu/~assassin/LIGO/S190425z_coverage.png

We would like to thank Las Cumbres Observatory and its staff for their
continued support of ASAS-SN. ASAS-SN is funded in part by the Gordon and
Betty Moore Foundation through grant GBMF5490 to the Ohio State University,
NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for
Cosmology and AstroParticle Physics (CCAPP) at OSU, the Chinese Academy of
Sciences South America Center for Astronomy (CASSACA), and the Villum
Fonden (Denmark). For more information about the ASAS-SN project, see
http://www.astronomy.ohio-state.edu/asassn/index.shtml