TITLE:   GCN CIRCULAR
NUMBER:  24661
SUBJECT: LIGO/Virgo S190521r: Kanata optical/NIR follow-up observations of the CNEOST Transient
DATE:    19/05/24 23:02:01 GMT
FROM:    Mahito Sasada at Hiroshima University  <sasadam@hiroshima-u.ac.jp>

Sasada, M., Nakaoka, T., Akitaya, H., Imazato, F. (Hiroshima U.) on behalf
of J-GEM collaboration


We observed the optical transient identified by CNEOST (Li et al., GCN
Circ. 24647) at two epochs using the 1.5-m Kanata telescope at
Higashi-Hiroshima Observatory with HONIR (Akitaya et al. 2014, Proc SPIE,
9147, 91474O) and HOWPol (Kawabata, K. S., et al. 2008, Proc. SPIE, 7014,
151).

We confirmed that the transient existed at the position where Li et al.
reported. We derived following magnitudes for the transient based on the
magnitudes of the field stars taken in the same frames (in AB system;
PanSTARRS and 2MASS catalogs):

MJD 58625.66

B = 18.19 +/- 0.06

V = 17.83 +/- 0.04

R = 17.87 +/- 0.02

J = 18.41 +/- 0.04

MJD 58627.59

B = 18.45 +/- 0.05

V = 18.11 +/- 0.03

R = 18.04 +/- 0.02

J = 18.72 +/- 0.10

The Galactic extinction has not corrected for. These suggest that the
transient faded by about 0.3 mag in 2 days.



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Name: Mahito Sasada
Affiliation: Hiroshima University
E-mail address: sasadam@hiroshima-u.ac.jp <sasada.mahito@naoj.ac.jp>
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