August 2026 - vsnet-campaign-dn - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-campaign-dn 17595] TCP J18030904+1218140= ZTF18absdcuk: large-amplitude CV outburst, possibly AM CVn-type?
by Yusuke Tampo 31 Aug '26

31 Aug '26

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 -- ---------------------------------------------- Yusuke TAMPO / 反保雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-campaign-dn 17594] ASASSN-26ew: new SU UMa-type dwarf nova, possibly WZ Sge-type
by Yusuke Tampo 24 Aug '26

24 Aug '26

ASASSN-26ew: new SU UMa-type dwarf nova, possibly WZ Sge-type ASASSN reported the discovery of ASASSN-26ew at 14.73 mag on 2026-08-13.82 UT. The archival ASASSN light curve shows that this had the outburst maximum on 2026-08-07.9 UT around 13.7 mag. The likely counterpart is the Bj=22.2 mag star in the GSC v2.4.2 catalogue; thus the outburst amplitude is ~8.5 mag. https://vsx.aavso.org/index.php?view=detail.top&oid=10875981 The SAAO Lesedi telescope observed ASASSN-26ew on 2026-08-18 and 2026-08-19. The light curve shows clear ordinary superhumps with a period of 0.05677(3) d and an amplitude of 0.15 mag. Thus ASASSN-26ew is a new SU UMa-type dwarf nova. Given its short superhump period and large outburst amplitude, this is a good candidate for a WZ Sge-type dwarf nova. The optical spectrum, also observed with the Lesedi telescope on 2026-08-18 UT, shows the Balmer absorption lines and superposed narrow emission core in Hα. Follow-up observations are encouraged. Best regards, Yusuke -- ---------------------------------------------- Yusuke TAMPO / 反保雄介 Postdoc fellow South African Astronomical Observatory / University of Cape Town EMAIL: tampo(a)kusastro.kyoto-u.ac.jp ALT. EMAIL: yusuke(a)saao.ac.za ----------------------------------------------

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[vsnet-campaign-dn 17590] TCP J22571796+4707418: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 16 Aug '26

16 Aug '26

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 --- Tonny Vanmunster CBA Belgium Observatory CBA Extremadura Observatory http://www.cbabelgium.co <http://www.cbabelgium.com/> m

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[vsnet-campaign-dn 17589] ASASSN-26ev: new SU UMa-type dwarf nova
by Gianluca Masi 16 Aug '26

16 Aug '26

Dear colleagues, I report time-resolved photometry for the ASASSN-26ev transient, discovered in outburst by the ASAS-SN team on 2026-08-2.15. The brightest mag. of the transient from ASAS-SN data is g=13.2 on 2026-07-29.30; assuming the quiescence magnitude from PS1 (g=21.2), we get an outburst amplitude of about 8 mags. My run covered about 2.6 hours, around 14.86 Aug. 2026 UTC; the transient was found at mag. 15.2 (unfiltered, R-mags for the reference stars from GAIA DR2). Observations were remotely performed using the 14" OTA + ST-10XME unit available at the Virtual Telescope Project facility in Manciano, Italy. Data clearly show 0.12 mags full amplitude superhumps; period analysis using PDM with Peranso 3.0 yields a superhump period of 0.055 +/- 0.012 days. This reveals that ASAS-SN-26ev is a SU UMa-type dwarf nova. Further observations are encouraged. All the best Gianluca Masi

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[vsnet-campaign-dn 17588] TCP J14515140+6613240: new SU UMa-type dwarf nova
by tonny.vanmunster＠gmail.com 14 Aug '26

14 Aug '26

Dear colleagues, The outburst of TCP J14515140+6613240 was discovered by the NMW-TexasTech survey team on 2026 Jul 29.3 UT at mag g = 13.2. The quiescent counterpart is a 21.2 g mag Pan-STARRS1 star, implying an outburst amplitude of ~8 mag. I have completed the analysis of my unfiltered CCD time-series observations of TCP J14515140+6613240, obtained on 10 out of 11 nights between 2026 Aug 03/04 and 13/14 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD camera. The combined light curve clearly shows regular superhump modulations with an amplitude of 0.34 mag. A period analysis using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0566 +/- 0.0002d. The object was measured at mag CV = 15.7 on Aug 14th. Superhumps were absent till 2026 Aug 08/09, when they first started to appear. No early superhumps were detected with sufficient evidence. 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 0.0566 d securely establishes TCP J14515140+6613240 as an SU UMa-type dwarf nova. The large outburst amplitude (~8 mag) might be consistent with a WZ Sge-type classification, but the absence of early superhumps does not (yet) support such classification. Continued monitoring is strongly encouraged. I will submit my observations to AAVSO, CBA and VSNET for further analysis. With kind regards, Tonny --- Tonny Vanmunster CBA Belgium Observatory CBA Extremadura Observatory http://www.cbabelgium.co <http://www.cbabelgium.com/> m

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[vsnet-campaign-dn 17587] ASASSN-26eq: new SU UMa-type dwarf nova; WZ Sge-type classification not excluded
by tonny.vanmunster＠gmail.com 09 Aug '26

09 Aug '26

Dear colleagues, The outburst of ASASSN-26eq was discovered by the ASAS-SN team on 2026 Jul 21.4 UT at mag g = 15.3. The quiescent counterpart is a 22.8 g mag Pan-STARRS1 star, implying an outburst amplitude of ~8 mag. I have completed the analysis of my unfiltered CCD time-series observations of ASASSN-26eq, obtained on 4 nights between 2026 Aug 04/05 and 08/09 at CBA Extremadura Observatory. The data were acquired under clear skies with a 0.40-m f/5.1 telescope and a Moravian G2-4000 CCD camera. The combined light curve clearly shows regular superhump modulations with an amplitude of 0.14 mag. A period analysis using ANOVA, Lomb-Scargle, Generalized-Lomb-Scargle and PDM methods (Peranso 3.1) yields a combined superhump period of 0.0622 +/- 0.0020d. The object was measured at mag CV = 16.6 on Aug 09th. 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 0.0622 d securely establishes ASASSN-26eq as an SU UMa-type dwarf nova. The large outburst amplitude (~8 mag) is consistent with the WZ Sge subclass of dwarf novae. As our coverage began 14 days after the discovery, the presence of early superhumps prior to Aug 04/05 could not be assessed from our data, so a WZ Sge-type classification cannot be excluded. Continued monitoring for possible post-outburst rebrightenings would help to further support a WZ Sge-type classification, should one occur. I will submit my observations to AAVSO, CBA and VSNET for further analysis. With kind regards, Tonny --- Tonny Vanmunster CBA Belgium Observatory CBA Extremadura Observatory http://www.cbabelgium.co <http://www.cbabelgium.com/> m

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