GCN Circular 21759
Subject
LIGO/Virgo G299232: HAWC follow-up
Date
2017-08-30T02:03:26Z (8 years ago)
From
Israel Martinez-Castellanos at UMD/HAWC <imc@umd.edu>
I. Martinez-Castellanos (University of Maryland, College Park) and A.J.
Smith (University of Maryland, College Park) on behalf of the HAWC
Collaboration:
The HAWC Collaboration performed a follow-up of LIGO trigger G299232. At
the time of the trigger the HAWC local zenith was oriented toward (��, ��) =
(75.0��, 19.0��), so the LV contour had just set in our field of view and no
prompt follow-up was possible.
We searched for long time scale emission during the following transit. The
observations ranged from T0+28ks to T0+87ks. In total 70% of the
probability space was covered. There were no >5 sigma points observed. For
a single transit, the 5 sigma sensitivity to a power law spectrum with a
-2.5 index ranges from ~1.9e-11 >1TeV cm^-2 s^-1 (~1 Crab unit) at dec=-19
to about 10 times higher at the edge of our FOV (45�� from zenith).
At the point of the source reported by Swift/UVOT (RA=01h40m08.55s
DEC=+34d34'03.6", LVC GCN 21733) we obtain an 95% confidence level upper
limit for >1TeV assuming a -2.5 spectrum of 4.3e-12 cm^-2 s^-1. These
observations were made from T0+62ks to T0+85ks.
We found no significant excess on the error radius corresponding to the
neutrino reported by IceCube (RA=28.2�� DEC= 44.8��, LVC GCN 21698). For the
location of maximum excess in the error radius we obtain an 95% confidence
level upper limit for >1TeV assuming a -2.5 spectrum of 2.8e-11 cm^-2 s^-1.
These observations were made from T0+64ks to T0+86ks.
HAWC is a TeV gamma ray water Cherenkov array located in the state of
Puebla, Mexico. It is sensitive to the energy range ~0.5-100TeV, and
monitors 2/3 of the sky every day with an instantaneous field-of-view of ~2
sr.