TITLE:   GCN CIRCULAR
NUMBER:  27003
SUBJECT: GRB 200205A = Swift J0840.7-3516: optical photometry in Chilescope observatory
DATE:    20/02/06 18:31:31 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

E. Mazaeva (IKI), A. Pozanenko (IKI), M. Krugov (AFIF),  A. Volnova 
(IKI), S. Belkin (IKI) report on behalf of IKI-FuN follow-up collaboration:

We observed  the newly discovered transient X-ray pulsar  Swift 
J0840.7-3516 (Kennea et al., GCN 27000) initially classified as GRB 
200205A (Evans et al., GCN   26982; Niwano etal., GCN   26987;  Osborne 
et al., GCN  26996). Observation of Chilescope RC-1000 started on Feb. 6 
(UT) 02:13:56 in r'-filter. We detect optical transient (Evans et al., 
GCN 26982; Lipunov et al., GCN 26984; Melandri et al., GCN 26986; 
Malesani et al., GCN 26989).

Preliminary photometry is following.

Date       UT start MJD_mid     Filter Exp.  OT(AB) Err. UL
                     (mid, days)    (s)

2020-02-06 02:13:56 58885.11255 r'     5*600 19.70  0.06 22.1

The photometry is based on nearby stars of APASS catalog
Ref.stars
APASS_id r’        err
45257574 15.130    0.014
45257540 14.807    0.061