TITLE:   GCN CIRCULAR
NUMBER:  24631
SUBJECT: LIGO/Virgo S190517h : No counterpart candidate in TAROT-GRANDMA observations.
DATE:    19/05/21 08:27:55 GMT
FROM:    Nicolas Leroy at LAL  <leroy@lal.in2p3.fr>

N.Leroy (LAL), Jicheng Zhang (THU), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), K. Noysena (Artemis, IRAP), M. Boer (Artemis),
N. Christensen (Artemis), L. Eymar (Artemis), A. Klotz (IRAP),
S. Antier (APC), S. Basa (LAM), D. Corre (LAL), M. Coughlin (Caltech),
D.Coward (OzGrav-UWA), J.G. Ducoin (LAL), B. Gendre (OzGrav-UWA),
P. Hello (LAL), C. Lachaud (APC), N. Leroy (LAL), D. Turpin (NAOC),
X. Wang (THU)

Report on behalf of the TAROT network and GRANDMA collaborations.

We performed tiled observations of LIGO/Virgo S190517h event with the
TAROT-Chili (TCH) telescope operating in the visible located at La
Silla ESO observatory (LaS/ESO).
The observation started on 05/17/19
10:04:53 UTC which corresponds approximately to 254 minutes after the
GW trigger time.

We performed the following tiled observations :

+------------+------------+---------+---------+---------+
| TStart     | TEnd       | RA      | DEC     |   Proba |
| [UTC]      | [UTC]      | [deg]   | [deg]   |     [%] |
|------------+------------+---------+---------+---------|
| 2019-05-17 | 2019-05-17 | 227.368 | -48.182 |     3.2 |
| 10:04:53   | 10:11:24   |         |         |         |
| 2019-05-17 | 2019-05-17 | 230.075 | -48.182 |     3.2 |
| 10:11:43   | 10:18:13   |         |         |         |
| 2019-05-17 | 2019-05-18 | 227.812 | -50     |     2.9 |
| 10:18:31   | 03:18:40   |         |         |         |
+------------+------------+---------+---------+---------+

TStart and TEnd refers respectively to the time of the first and last
exposure for a given tile. Observations are not necessarily continuous
  in this interval.
The Probability refers to the 2D spatial
probability of the GW skymap enclosed in a given tile. Each tile is
1.9x1.9 degrees. These observations cover about 9% of the cumulative
probability of the skymap.
The typical limiting magnitude is 18.0 for a 60.0 s exposure.

The coverage map is available at: 
https://grandma-owncloud.lal.in2p3.fr/index.php/s/j8EDTsfDQUDq1D4

According to our data analysis, no serious optical transient candidates
were found

GRANDMA (Global Rapid Advanced Network Devoted to the Multi-messenger
Addicts) is a network of robotic telescopes connected all over the
world with both photometry and spectrometry capabilities for Time-
domain Astronomy (https://grandma.lal.in2p3.fr/).
Details on the TCH telescope  are available on the GRANDMA web pages
or on  http://tarot.obs-hp.fr/.

  This circular is citable.