TITLE: GCN CIRCULAR NUMBER: 25781 SUBJECT: LIGO/Virgo S190915ak: No significant candidates in TAROT-GRANDMA observations DATE: 19/09/19 14:22:52 GMT FROM: Alexander Kann at IAA-CSIC D. A. Kann (HETH/IAA-CSIC), A. Simon (ASPD TSNUK), Z. Vidadi (Shao), S. Antier (APC), M. Boer (Artemis), N. Christensen (Artemis), L. Eymar (Artemis), A. Klotz (IRAP), S. Alishov (SHAO), K. Barynova (Kyiv Univ), D. Coward (OzGrav-UWA), K. Noysena (Artemis, IRAP), S. Basa (LAM), D. Corre (LAL), M. Coughlin (Caltech), J.G. Ducoin (LAL), B. Gendre (OzGrav-UWA), P. Hello (LAL), C. Lachaud (APC), N. Leroy (LAL), D. Turpin (NAOC) and X. Wang (THU) report on behalf of the TAROT network and GRANDMA collaborations: We performed tiled observations of LIGO/Virgo S190915ak event (GCN #25753) with the TAROT-Calern (TCA) telescope operating in the visible located at Calern site at the Cote d'Azur observatory. The observation started on 09/16/19 00:12:27 UTC which corresponds approximately to 16 minutes after the GW trigger time. We performed the following tiled observations : +------------+------------+---------+---------+---------+ | TStart | TEnd | RA | DEC | Proba | | [UTC] | [UTC] | [deg] | [deg] | [%] | |------------+------------+---------+---------+---------| | 2019-09-16 | 2019-09-16 | 195.545 | 68.682 | 1.0 | | 00:12:27 | 23:06:42 | | | | | 2019-09-16 | 2019-09-16 | 187.785 | 66.826 | 0.7 | | 00:19:13 | 23:13:29 | | | | | 2019-09-16 | 2019-09-18 | 190.68 | 68.682 | 1.1 | | 00:54:58 | 01:52:26 | | | | | 2019-09-16 | 2019-09-17 | 185.815 | 68.682 | 0.5 | | 01:20:35 | 01:17:26 | | | | | 2019-09-16 | 2019-09-18 | 192.342 | 66.826 | 1.6 | | 01:27:23 | 03:10:13 | | | | | 2019-09-16 | 2019-09-16 | 186.244 | 70.538 | 0.4 | | 01:34:07 | 22:57:41 | | | | | 2019-09-16 | 2019-09-17 | 191.538 | 70.538 | 0.8 | | 02:51:43 | 01:10:45 | | | | | 2019-09-16 | 2019-09-17 | 168.392 | 77.96 | 0.2 | | 23:58:22 | 00:04:42 | | | | | 2019-09-17 | 2019-09-18 | 195.774 | 64.971 | 1.9 | | 00:05:13 | 02:57:21 | | | | | 2019-09-17 | 2019-09-17 | 161.664 | 74.249 | 0.1 | | 00:17:49 | 02:54:26 | | | | | 2019-09-17 | 2019-09-17 | 196.899 | 66.826 | 1.3 | | 00:24:37 | 21:01:18 | | | | | 2019-09-17 | 2019-09-17 | 191.538 | 64.971 | 1.5 | | 02:15:22 | 20:54:35 | | | | | 2019-09-17 | 2019-09-17 | 180.95 | 68.682 | 0.4 | | 02:41:18 | 02:47:37 | | | | | 2019-09-17 | 2019-09-17 | 196.541 | 50.125 | 5.3 | | 19:19:28 | 21:40:15 | | | | | 2019-09-17 | 2019-09-17 | 195.704 | 51.981 | 4.9 | | 19:30:30 | 19:34:40 | | | | | 2019-09-17 | 2019-09-17 | 193.706 | 50.125 | 2.1 | | 20:16:20 | 20:22:40 | | | | | 2019-09-17 | 2019-09-17 | 196.832 | 46.414 | 1.7 | | 20:28:50 | 20:35:09 | | | | | 2019-09-17 | 2019-09-17 | 194.796 | 63.115 | 1.5 | | 20:41:28 | 20:47:47 | | | | | 2019-09-17 | 2019-09-17 | 197.021 | 55.692 | 1.3 | | 21:01:43 | 21:08:03 | | | | | 2019-09-17 | 2019-09-17 | 192.753 | 51.981 | 1.1 | | 21:13:51 | 21:20:10 | | | | | 2019-09-17 | 2019-09-17 | 200.95 | 53.837 | 1.1 | | 21:20:24 | 21:26:44 | | | | | 2019-09-17 | 2019-09-17 | 198.655 | 51.981 | 4.2 | | 21:46:35 | 21:52:54 | | | | | 2019-09-17 | 2019-09-17 | 197.873 | 53.837 | 3.3 | | 21:53:19 | 21:59:38 | | | | +------------+------------+---------+---------+---------+ 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 36% the cumulative probability of the LALInference skymap available on Sep 17, 2019 14:16:39 UTC. 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/55vKDfmLJzbHyBn No significant transient candidates were found during our low latency 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 spectroscopy capabilities for Time-domain Astronomy (https://grandma.lal.in2p3.fr/). Details on the TCA telescope are available on the GRANDMA web pages or on http://tarot.obs-hp.fr/.