TITLE: GCN CIRCULAR NUMBER: 14919 SUBJECT: Swift Trigger 558631: AAO optical observations DATE: 13/06/22 13:42:50 GMT FROM: Alexei Pozanenko at IKI, Moscow A. Volnova (IKI), R.Inasaridze (AAO), O. Kvaratskhelia (AAO), V. Ayvazian(AAO), Yu. Krugly (IA KhNU), I. Molotov (KIAM), A. Pozanenko (IKI) report on behalf of larger GRB follow-up collaboration: Following trigger Swift #558631 (Barlow et al., GCN 14917) we imaged the region of the trigger with starting on June 21 (UT) 19:54:46. We obtained 50 unfiltered images of 50 s exposure. We investigated a combined image (mid time after the Swift trigger 0.75693 days) and within BAT error circle (Barlow et al., GCN 14917) found one bright source which is not catalogued in USNO-B1.0 but barely visible in DSS2 Red image. Coordinates of the source is (J2000) 18:07:13.13 -22:17:14.4. It is apparent that the source is not coincident with known X-ray source SAX_J1806.5-221. Brightness of the source is 17.09 +/- 0.03 calibrating against nearby USNO-B1.0 stars (R2). At present time it is not clear if the source is related to the Swift #558631 trigger. The source also can be a new cataclysmic variable with magnitude of the outburst of ~3m. A finding cahart can be found in http://grb.rssi.ru/Swift_558631/Swift_558631_chart.png