Dear colleagues,

I have just finished analysing my time-series observations of ASASSN-21sb, obtained on 2021, Sep 25/26 and Sep 26/27 at resp. CBA Extremadura Observatory and CBA Belgium observatory, using 0.40-m telescopes with SX-46 CCD and QHY-268M CMOS camera's.

Regular superhumps with an amplitude of 0.32 mag are clearly visible in the resulting light curve, establishing ASASSN-21sb as a new SU UMa-type dwarf nova. A period analysis using the ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.0), yields a combined superhump period of 0.0589 +/- 0.0003d. The object was at mag CV = 16.2 on Sep 27th.

I will send my observations to AAVSO, CBA and VSNET for further analysis.

Best regards Tonny

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Tonny Vanmunster CBA Belgium Observatory CBA Extremadura Observatory http://www.cbabelgium.com

PERANSO : The Light Curve and Period Analysis Software http://www.peranso.com