GCN Circular 24227

M. Blazek (HETH/IAA-CSIC), N. Christensen (Artemis),
E. Howell (OzGrav-UWA), M. Vardosanidze (Iliauni), M. Boer (Artemis),
L. Eymar (Artemis), A. Klotz (IRAP), R. Laugier (Artemis),
K. Noysena (Artemis, 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 event S190425z (GCN #24168)
with the TAROT-Reunion (Les Makes Observatory, La R��union Island, France)
telescope operating in clear filter.

The observation started on 04/25/19 14:56:19 UTC which corresponds
approximately to 6.65 hours after the GW trigger time.

We performed the following tiled observations :

+------------+------------+---------+---------+---------+
| TStart     | TEnd       | RA      | DEC     |   Proba |
| [UTC]      | [UTC]      | [deg]   | [deg]   |     [%] |
|------------+------------+---------+---------+---------|
| 2019-04-25 | 2019-04-25 | 194.595 | 30      |     0.2 |
| 14:56:19   | 22:29:56   |         |         |         |
| 2019-04-25 | 2019-04-25 | 182.338 | 25.714  |     0.2 |
| 17:03:57   | 17:55:18   |         |         |         |
| 2019-04-25 | 2019-04-25 | 189.73  | 30      |     0.3 |
| 17:16:58   | 21:51:14   |         |         |         |
| 2019-04-25 | 2019-04-26 | 243.117 | 25.714  |     0.6 |
| 18:07:39   | 01:40:56   |         |         |         |
| 2019-04-25 | 2019-04-26 | 246.076 | 21.429  |     0.7 |
| 18:20:49   | 01:09:32   |         |         |         |
| 2019-04-25 | 2019-04-25 | 238.442 | 25.714  |     0.9 |
| 19:11:40   | 22:16:40   |         |         |         |
| 2019-04-25 | 2019-04-26 | 241.519 | 21.429  |     0.7 |
| 19:43:51   | 00:18:12   |         |         |         |
+------------+------------+---------+---------+---------+


The Probability refers to the 2D spatial probability of the GW skymap
enclosed in a given tile. Each tile is 4.2x4.2 degrees. These observations
cover about 3% of the cumulative probability of the skymap. The typical
3-sigma limiting magnitude for a two minutes exposure is 17 mag.

The coverage map is available at:
https://grandma-owncloud.lal.in2p3.fr/index.php/s/tZTxGSoCEMc4fwG

Optical transient candidates will be sent through another GCN
circular depending on our data analysis.

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 TAROT
telescopes are available on the GRANDMA web pages or on
http://tarot.obs-hp.fr/