Dear colleagues,

I have just finished analysing my unfiltered observations of ASASSN-19ax, obtained on 2021, September 17/18 at CBA Belgium Observatory (0.40-m f/10.0 telescope, QHY-268M CMOS, clear then clouds) and at CBA Extremadura Observatory (0.40-m f/5.1 telescope, SX-46 CCD, clear then clouds).

The combined lightcurve covers a time span of 7.2h and clearly shows the presence of superhumps with an amplitude of 0.26 mag, establishing ASASSN-19ax 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 0.1015 +/- 0.0024d, well above the period gap (as suspected by Taichi Kato in vsnet-alert 26256). The object was at mag CV = 13.5 on Sep 18th.

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