TCP J18030904+1218140: brightening from the dip, probably the second superoutburst The Lesedi telescope observations on 26 August show that the system is now brightening after the dip. The latest observation in ZTF is g=15.9 on 28 August. https://alerce.online/object/ZTF18absdcuk Ordinary superhumps are expected to appear at this phase. Time-resolved observations are strongly encouraged. Best regards, Yusuke 2026年8月24日(月) 13:27 Yusuke Tampo <tampo@kusastro.kyoto-u.ac.jp>:
TCP J18030904+1218140: entering the dip
Sano-san, Itoh-san, Pavol A. Dubovsky, and the SAAO Lesedi telescope have reported the time-resolved observations, as well as snapshot observations by Funada-san and Moriyama-san. The latest observations on 2028-08-23 by Itoh-san and the Lesedi telescope show that this system is currently entering the dip around 17.5 mag.
Given its large outburst amplitude, it is expected that the system will be back in outburst soon, most likely with ordinary superhumps, regardless of whether it is an AM CVn star or a normal hydrogen-rich CV. Continuous monitoring is highly encouraged to catch the next brightening.
Best regards, Yusuke
2026年8月21日(金) 11:36 Yusuke Tampo <tampo@kusastro.kyoto-u.ac.jp>:
TCP J18030904+1218140= ZTF18absdcuk: large-amplitude CV outburst, possibly AM CVn-type?
TCP J18030904+1218140 was discovered by Yuji Nakamura on 2026-08-19.5199 UT at 14.9 mag. Its previous outburst and log decline in 2018 were detected as ZTF18absdcuk. The VSX lists the r=21.1 mag star as the quiescent counterpart; thus the outburst amplitude is ~6 mag. https://alerce.online/object/ZTF18absdcuk https://vsx.aavso.org/index.php?view=detail.top&oid=10875986
Sano-san has reported the time-resolved observations for ~1.5 hours on 2026-08-20 UT. The light curve shows possible modulations with a period of 0.0288 d (41.5 min) with a double-peaked profile (early superhumps?).
The optical spectrum obtained by the SAAO Lesedi telescope on 2026-08-19 UT shows a blue continuum with no prominent emission or absorption lines.
Time-resolved photometry is strongly encouraged to confirm the periodicity and determine whether this is an AM CVn star or not.
Best regards, Yusuke
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Yusuke TAMPO / 反保 雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo@kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke@saao.ac.za
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Yusuke TAMPO / 反保 雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo@kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke@saao.ac.za
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-- ---------------------------------------------- Yusuke TAMPO / 反保 雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo@kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke@saao.ac.za ----------------------------------------------