TCP J16271026-1030020: a new WZ Sge-type dwarf nova candidate possibly with large-amplitude early superhump

TCP J16271026-1030020 was discovered by T. Kojima on 2025-07-25.52 UTC at 13.8 mag (unfiltered). ATLAS force photometry and ASASSN also detect this outburst since 2025-07-22.3 UTC, peaking around g~12.6 mag. The Pan-STARRS1 counterpart is g=22.1(2) mag, giving the outburst amplitude of ~9.5 mag.

http://www.cbat.eps.harvard.edu/unconf/followups/J16271026-1030020.html 

I have obtained the low-resolution spectrum with the Lesedi telescope at the SAAO Sutherland. This spectrum shows prominent Balmer, He II 4686, and other He I emission lines with no absorption features. Itoh-san also reported the time-resolved observations for ~45 min. The light curve shows a modulation of ~0.2 mag.

These overall features suggest that TCP J16271026-1030020 is a new large-amplitude dwarf nova, most likely a WZ Sge-type, showing relatively large early superhump amplitude.

Further time-resolved observations (with multiple bands, if possible) and time-resolved spectroscopy are encouraged.

Best regards,

Yusuke