GCN Circular 21236
Subject
LIGO/Virgo G288732: GWFUNC/NOWT observations of the skymap and follow-up of the Fermi/LAT candidate
Date
2017-06-09T17:34:53Z (7 years ago)
From
Dong Xu at NAO/CAS <dxu@nao.cas.cn>
D. Xu (NAO/CAS), J.Z. Liu, H.B. Niu, S.G. Ma, Y. Zhang, X. Zhang, G.X.
Pu,T.Z. Yang, F.F. Song (XAO/CAS), H.B. Zhao, B. Li, G.T. Zhaori, H. Lu,
R.Q. Hong, L.F. Hu (PMO/CAS), H.X. Feng, Z.P. Zhu, T.M. Zhang, X. Zhou,
H.X. Feng, Z.P. Zhu (NAO/CAS), J. Mao, J.M. Bai (YNAO/CAS) report on
behalf of the Gravitational Wave Follow-Up Network by NAO-PMO-XAO-YNAO
in China (GWFUNC):
We have performed tiled observations of LIGO/Virgo G288732 (LVC, GCN
21221) using the Nanshan One-meter Wide field Telescope (NOWT) with a
FOV of 1.3 x 1.3 deg^2, located in Xinjiang, China. Observations started
at 18:21:44 UT and ended at 21:31:17 UT on 2017-06-08, covering a total
area of ~337 deg^2 and with each exposure of 150s in the R-band. Data
analysis is still underway. We note that the Fermi/LAT error circle
(Omodei et al., GCN 21227) was not covered in the tiled observations,
because the LAT altitude was too low since the starting of the observations.
However, the NOWT manged to image the Fermi/LAT error circle at the very
beginning of the following night, and we obtained 3x150s and 2x200s
R-band images around 15:30:19 UT on 2017-06-09. Five uncatalogued X-ray
sources by Swift/XRT have been reported, which might be the X-ray
counterpart candidates of the Fermi/LAT transient (Evans et al. GCN
21233). These five sources, i.e., sources #1, 2, 3, 6, and 7, are within
the FOV of each Nanshan exposure. Comparison with DSS-II, SDSS, and
PanSTARRS reveals that sources #1, 3, 6, and 7 have known optical
counterparts already, and no apparent strong variation in brightness for
the optical counterparts. Source #2 doesn't have any optical counterpart
in the DSS-II, SDSS, and PanSTARRS surveys. No optical transient is
detected at the source #2 position in the Nanshan images, down to a
limiting magnitude of R>19.2 mag. Therefore, deeper photometry at this
position is encouraged.