Dear colleagues,
The outburst of TCP J22571796+4707418 was discovered by the NMW-TexasTech survey team on 2026 Aug 09.3 UT at mag g = 14.4. The quiescent counterpart is a 21.4 g mag star, implying an outburst amplitude of ~7 mag.
I have completed the analysis of my unfiltered CCD time-series observations of TCP J22571796+4707418, obtained on 5 nights between 2026 Aug 09/10 and 13/14 at CBA Extremadura & CBA Belgium Observatories. The data were acquired under clear skies with 0.40-m telescopes equipped with Moravian G2-4000 CCD and QHY-268M CMOS cameras.
The last two nights of the combined light curve clearly show regular superhump modulations with an amplitude of 0.35 mag. A period analysis using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0669 +/- 0.0002d. The object was measured at mag CV = 14.7 on Aug 14th.
Over the course of those five nights, we see a stage A (low-amplitude onset) transition into stage B with growing and mature superhumps.
Image calibration and photometry were carried out using the latest release of Phoranso, which enabled simultaneous photometry of additional variable stars in the same field of view.
The detection of superhumps with a period of 0.0669 d securely establishes TCP J22571796+4707418 as an SU UMa-type dwarf nova.
Continued monitoring is strongly encouraged.
I will submit my observations to AAVSO, CBA and VSNET for further analysis.
With kind regards,
Tonny
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Tonny Vanmunster
CBA Belgium Observatory
CBA Extremadura Observatory