GCN Circular 21680

T. Callister (Caltech), J. Dowell (U New Mexico), J. Kanner (Caltech),
M. Kavic (LIU Brooklyn), C. League (LIU Brooklyn), P. Shawhan (U
Maryland), J. Simonetti (Virginia Tech), G. Taylor (U New Mexico), J.
Tsai, C. Yancey (U Maryland)

The Long Wavelength Array (LWA1, located west of Socorro, New Mexico)
[S.W. Ellingson, et al. http://lanl.arxiv.org/abs/1204.4816] made
observations on June 17 following the LIGO trigger G298048. The first
observation began at 2017-08-17 13:09:51 UTC (28 minutes after the
trigger) and ran for approximately 1.1 hours.

All observations were centered at frequencies 25.85 MHz and 45.45 MHz,
each with a bandwidth of 19.6 MHz. The FWHM is 15.499 degrees at 25.85
MHz, and 6.648 degrees at 45.45 MHz.

The beam centers for the first observation were: Beam 1: RA 2.391h, Dec
41.810deg; Beam 2: RA 2.431h, Dec 46.572deg; Beam 3: RA 2.803h, Dec
44.202deg; and Beam 4: RA 2.660h, Dec 50.480deg. These were chosen to
observe the maximum of the LIGO skymap available with the initial
notice.

The next observation, using an updated skymap, began at 2017-08-17
19:15:00 UTC (6.6 hours after the trigger) and ran for 4 hours.

The beam centers for the second observation were Beam 1: RA 12.814h, Dec
-13.862deg; Beam 2: RA 12.955h, Dec -17.896deg; Beam 3: RA 13.096h, Dec
-22.024deg; and Beam 4: RA 11.786h, Dec -39.840deg. These coordinates
include the position of the observed transient, as reported by D.A.
Coulter, et al., [GCN 21529], as well as nearby regions.

We plan to continue follow-up observations at the second set of
coordinates over the next few weeks. Data analysis is proceeding.