Dear colleagues,

I have been collecting unfiltered CCD observations of ASASSN-21tr over the past several nights at CBA Extremadura Observatory, using a 0.40-m f/5.1 telescope and SX-46 CCD camera under (mostly) clear skies.

The collected light curves did not show obvious periodic modulations, with the exception of last night Oct 25/26, 2021. Regular superhumps with an amplitude of 0.11 mag are clearly visible, establishing ASASSN-21tr 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 0.0647 +/- 0.0012d. The object was at mag CV = 15.4 on Oct 25th.

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