[vsnet-grb-info 23570] LIGO/Virgo S190814bv: GRAWITA VST-ESO PARANAL observations and independent transient candidates discovery.

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25669
SUBJECT: LIGO/Virgo S190814bv: GRAWITA VST-ESO PARANAL observations and independent transient candidates discovery.
DATE:    19/09/05 19:31:31 GMT
FROM:    Aniello Grado at INAF-OAC  <aniello.grado at gmail.com>

AUTHORS: A. Grado (INAF-Napoli), E. Cappellaro (INAF-Padova), E. Brocato
(INAF-Abruzzo),
S. Covino (INAF-Brera), F. Getman (INAF-Napoli), G. Greco (University
Urbino) , P. D'avanzo
(INAF-Brera), A. Rossi (INAF-OAS), E. Palazzi (INAF-OAS), S. Yang
(INAF-Padova) on behalf of GRAWITA.

We observed the field of S190814bv (GCN 25324 and updated GCN 25333) in r'
band with the VLT Survey
Telescope (VST) equipped with Omegacam (1 sqdeg FOV) (Proposal ID ESO
0103.D-0070 ).
The field was observed for a total of 5 epochs distributed as reported in
the following table.

epoch 1 2019-08-15 from 08:50:26.860 to 10:13:47.602
epoch 2 2019-08-16 from 05:29:37.904 to  07:20:36.231
epoch 3 2019-08-19 from 04:55:59.697 to 06:08:28.809
epoch 3 2019-09-20 from 03:45:54.370 to 04:39:27.598
epoch 4 2019-8-22 from 03:01:00.585 to 05:41:44.089
epoch 5 2019-08-29 from 09:07:41.251 to 09:36:29.055
epoch 5 2019-08-30 from 07:49:42.449 to 09:34:10.334
all time are in UTC.

In the first night we imaged 18 sqdeg covering 65% of the localization
probability region.
Starting from the second epoch we modified the pointings to improve the
updated skymap coverage.
The area imaged is 23 sqdeg covering 87% of the localization region.
Each 1 sqdeg pointing was observed three times for a total exposure time of
135 seconds.

Images were analized using the our photometric pipelines (Brocato et al.
2018 MNRAS, 474,1).
The final vetting was done via visual inspection. The candidates were
matched against the Minor
Planet Center to further filter against slow moving asteroids. The three
most outstanding candidates,
already reported in TNS, and visible in at least three epochs are:

Name       | TNS Name |    RA | Dec   | Night | Mag   | MAGERR

VST J004656.70-252236.7 | AT2019npd   | 00:46:56.711 |  -25:22:36.43    |
2019-08-21 | 19.874 +/- 0.062
VST J004847.88-251823.5 | AT2019noq   | 00:48:47.882 |  -25:18:23.46    |
2019-08-15 | 19.962 +/- 0.033
VST J005605.55-243826.4 | AT2019nve   | 00:56:05.510  | -24:38:26.40    |
2019-08-14 | 20.531 +/- 0.083
VST J004659.45-230559.5 | AT2019nyv   | 00:46:59.451  | -23:05:59.50    |
2019-8-15   | 21.200 +/- 0.087

where the magnitude and night refers to the peak value.

Automatic VST data processing was done with the VSTTube pipeline (Grado et
al. 2012 Mem.SAIt 19, 362).
The pointing sequence was generated using the GWsky script (
https://github.com/ggreco77/GWsky).
We acknowledge excellent support from the ESO User Support Department and
from ESO observing staff
in Paranal.