[vsnet-grb-info 23048] LIGO/Virgo S190720a: Thacher Observatory follow-up observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25147
SUBJECT: LIGO/Virgo S190720a: Thacher Observatory follow-up observations
DATE:    19/07/25 03:03:29 GMT
FROM:    Charles Kilpatrick at UC Santa Cruz  <cdkilpat at ucsc.edu>

J. Swift, Y. Yin (Thacher School Observatory), C. D. Kilpatrick, J. S. Brown, D. A. Coulter, G. Dimitriadis, R. J. Foley, T. Hung, D. O. Jones, C. Rojas-Bravo, M. R. Siebert, K. Siellez (UCSC)

report on behalf of the One-Meter Two Hemisphere (1M2H) collaboration:

in the process of following up the localization region of LIGO/Virgo event S190720a (GCN 25138), we observed the following fields for 300s each in r-band with the 0.7-m Thacher telescope at the Thacher School Observatory. The localization region was provided by the LIGO/Virgo collaboration in the LALinference map of July 22 17:43:30. All Thacher observations were performed on UT 2019 Jul 23.  The approximate center of each image is noted in the table below, and the field of view is a 21 arcmin x 21 arcmin rectangle.  We note the approximate 3-sigma limiting magnitude of each image.

Comparing our images to PS1 r-band images of the same fields, we did not detect any transient sources.

RA (J2000)  | Dec (J2000) | MJD         | Limiting Magnitude
19:45:50.18 | +35:28:46.2 | 58687.34652 |    20.4
19:55:39.26 | +37:12:37.4 | 58687.35060 |    20.1
19:54:27.91 | +37:33:24.8 | 58687.35459 |    19.8
19:52:21.53 | +38:14:58.9 | 58687.35855 |    20.2
19:55:01.25 | +37:54:12.6 | 58687.36250 |    20.0
19:56:12.58 | +37:33:26.6 | 58687.36645 |    18.8
19:53:15.86 | +37:54:13.0 | 58687.37039 |    19.0
19:57:23.21 | +37:12:40.3 | 58687.37435 |    20.1
19:56:49.44 | +36:51:54.7 | 58687.37831 |    20.5
19:50:35.76 | +38:15:01.4 | 58687.38227 |    20.7
19:51:30.55 | +37:54:15.1 | 58687.38623 |    20.6
19:52:42.91 | +37:33:27.7 | 58687.39022 |    20.6
19:53:54.65 | +37:12:41.8 | 58687.39418 |    20.6
19:55:05.59 | +36:51:56.2 | 58687.39814 |    20.3
19:48:50.04 | +38:15:02.2 | 58687.40209 |    20.2
19:49:45.19 | +37:54:15.8 | 58687.40606 |    19.7
19:50:58.03 | +37:33:29.5 | 58687.41002 |    18.5
19:52:10.22 | +37:12:43.6 | 58687.41397 |    18.9
19:53:21.70 | +36:51:57.2 | 58687.41792 |    17.1
19:54:32.47 | +36:31:12.0 | 58687.42186 |    16.9

Please direct all communication related to this circular to Charlie Kilpatrick (cdkilpat at ucsc.edu).