TITLE:   GCN CIRCULAR
NUMBER:  25376
SUBJECT: LIGO/Virgo S190814bv: no candidates from optical imaging of selected galaxies at the NOT
DATE:    19/08/17 00:32:54 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>

Kasper E. Heintz (Univ. Iceland), Daniele B. Malesani (DTU Space), 
Giorgos Leloudas (DTU Space), Darach J. Watson (DAWN/NBI), Jens Hjorth 
(DARK/NBI), Silvia Piranomonte (INAF/OAR), Nicholas E. Jannsen (NOT), 
report on behalf of a larger collaboration:

We observed the position of the 10 galaxies listed below, using the 
Nordic Optical Telescope equipped with the ALFOSC instrument. These 
targets were selected from the list of most probable host galaxies 
generated by the HOGWARTS code (https://gwtool.watchertelescope.ie/), 
consistent with the latest available 90% probability region of S190814bv 
(LIGO Scientific Collaboration and Virgo Collaboration, GCN 25333).

Each galaxy was observed for 5 minutes using the SDSS i filter. 
Observations started around 2019 August 16.15 UT (1.27 days after the GW 
event) and lasted about 1.5 hr. Conditions were unfortunately affected 
by the nearby bright Moon and the poor seeing (1.6-2.5") leading to 
shallower than expected images.

Visual inspection of the galaxies does not reveal any new candidate 
compared to the deeper archival images from the Pan-STARRS survey. The 
typical limiting magnitude is i ~ 19.5 AB (3 sigma), but we caution that 
the actual limit is shallower at locations superimposed on the brightest 
parts of the targeted galaxies. This limit corresponds to an absolute 
magnitude M_i > -17.5 at a distance of 276 Mpc, which would not have 
allowed us to detect an event as bright as AT 2017gfo.

List of targeted fields (RA, Dec, name)
00:47:07.527 -24:22:14.33 ESO474-026
00:48:43.287 -23:33:42.07 IC1587
00:48:21.859 -25:07:36.53
00:49:01.481 -23:48:40.74
00:52:41.582 -25:44:01.87 ESO474-035
00:47:28.948 -25:26:26.36
00:55:13.534 -26:19:16.51
00:46:10.416 -24:39:00.69
00:49:27.554 -26:32:17.88
00:51:29.863 -24:38:32.98