Aql X-1 at stage of fading after current flare

ATel #17720; V. V. Vlasyuk, O. I. Spiridonova (Special Astrophysical Observatory of the Rus. Ac. Sci.)
on 12 Mar 2026; 09:03 UT
Credential Certification: Alexander Moskvitin (mosk@sao.ru)

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Within a course of optical monitoring campaign of Soft X-ray Transient (SXT) Aql X-1 performed with the 1-m and 0.5-m SAO RAS optical telescopes we have detected the fading phase after its new outburst. Our preliminary estimates of brightness of Aql X-1 optical counterpart in R-band in last decade of December were between 18.2 and 18.3 mag. The observations of transient were impossible in epoch of invisibility and inconvenient morning conditions in last February. Meanwhile, R-magnitude for epochs in March revealed Aql X-1 at maximum brightness stage, as seen in Table.

Typical errors of individual brightness estimates are about 0.02 mag and should be decreased after more accurate data reduction. Further observations of Aql X-1 in X-ray, UV, Optical, IR and Radio ranges are highly encouraged.