TITLE:   GCN CIRCULAR
NUMBER:  25212
SUBJECT: LIGO/Virgo S190728q: ZTF19abjethn TShAO and NUTTelA-TAO optical observations / classification
DATE:    19/07/29 01:03:07 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), I. Reva (AFIF), M. Krugov (AFIF), A. Pozanenko (IKI), 
B. Grossan (ECL) report on behalf of larger GRB IKI FuN collaboration:

We observed  the    optical  transient  AT2019lvs/ZTF19abjethn 
discovered by ZTF (Kasliwal et al. GCN 25199) with TShAO Zeiss-1000 and 
CDK700  telescope (NUTTelA-TAO) of Assy-Turgen observatory. Observations 
started earlier than Update on Sky-Localization (LVC, GCN 25208).   We 
observed the transient in B,R - filters.   The transient photometry is 
following.

Date, UTC, MJD, Filter, Exposure, OT, Err, Uplim, FWHM Obs., Telescope

2019-07-28 16:04:19 58692.65864 R 23*120 16.63  0.02 21.5 2.1 TSHAO 
Zeiss-1000

2019-07-28 17:15:10 58692.72234 R 5*120 16.49 0.03 21.3 1.8 Assy-Turgen 
CDK700

2019-07-28 17:17:18 58692.72729 B 10*120 16.35 0.07 21.0 1.8 Assy-Turgen 
CDK700


2019-07-28 20:29:12 58692.86056 B 10*120 15.51 0.09 21.0 2.8 Assy-Turgen 
CDK700

The photometry is based on the nearby USNO-B1  (R2) stars.
The extremely blue color of the transient (B-R) = -0.15 is fully agreed 
with classification of  the transient as CV (Magee et al., GCN 25209).