Optical Observations of the February 2018 Outburst of Aql X-1: the Peak and Fading Stages.

ATel #11382; O. I. Spiridonova, A. S. Moskvitin, V. V. Vlasyuk (Special Astrophysical Observatory ot the Rus. Ac. Sci.)
on 8 Mar 2018; 12:20 UT
Credential Certification: Alexander Moskvitin (mosk@sao.ru)

Tweet

Just after end of the invisibility period of Aql X-1 we had started photometrical observations of this object in R passband. All data were taken using by the CCD-photometer of 1-meter Zeiss-1000 telescope of Special Astrophysical Observatory of Rus.Ac.Sci. Despite on inconvenient observations conditions (object airmass was about 2.0) we have measured brightness of Aql X-1 within three nights in February-March on the twilight sky. As the atmospheric conditions were mediocre we observed it only in R-passband. Results of preliminary data reduction are presented in the table. We can conclude that this transient is passing now it's peak phase and probably should begin the fading stage. Relatively large errors are explaining by high background level and 3-4 arcsec. atmospheric seeing. More precise data are in preparation. Further observations at all wavelengths are encouraged.

Date	JD	R_mag	R_err
2018.02.28	2457177.61	16.23	0.05
2018.02.29	2457178.59	15.75	0.05
2018.03.06	2457183.61	16.57	0.05