Optical Photometric and Spectroscopic Observations of M31N 2008-12a during its 2025 eruption
ATel #17530; K. Taguchi (Kyoto University), H. Naito, Y. Sano (Nayoro Observatory), K. Matsumoto (Osaka Kyoiku University), H. Maehara, A. Arai (NAOJ), K. Itagaki (Itagaki Observatory), M. Kato (Keio University), S. Kiyota (VSOLJ), K. Nishiyama, F. Kabashima (Miyaki-Argenteus Observatory), A. Tajitsu (NAOJ), S. Takagi (Hokkaido University), F. Watanabe (Nayoro Observatory), for a larger collaboration
on 8 Dec 2025; 06:23 UT
Credential Certification: Keisuke Isogai (isogai@kusastro.kyoto-u.ac.jp)
Subjects: Optical, Cataclysmic Variable, Nova, Transient, Variables
We report additional multicolor photometry and spectroscopy of the 2025 eruption of the remarkable recurrent nova M31N 2008-12a (ATels #17511, #17514, #17520, #17521, #17524, #17526, also see Darnley et al. 2014, 2015, 2016, Henze et al. 2014, 2015a, 2015b, 2018 and Basu et al. 2024, for comprehensive multi-wavelength light curves of previous eruptions).
We obtained its spectrum by the fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2025, 2019) mounted on the 3.8 m Seimei telescope (Kurita et al. 2020) at Okayama Observatory of Kyoto University on 2025-11-30.49 UT using the VPH-blue grism (covering 4100 - 8500 Å, resolution ~ 500).
The magnitudes and upper limits (5 sigma) for the nova are given in the table below.
Date UT Exp. time Filter Magnitude Site
2025 Nov 28.433 300sec Ic >19.0 A
2025 Nov 30.390 180sec Rc 18.61 ± 0.24 B
2025 Nov 30.399 180sec Ic 17.92 ± 0.41 B
2025 Nov 30.404 300sec V 19.07 ± 0.12 B
2025 Nov 30.408 600sec B 19.41 ± 0.20 B
2025 Nov 30.411 300sec Ic 18.77 ± 0.38 A
2025 Nov 30.452 300sec Rc 18.45 ± 0.26 A
2025 Nov 30.483 100sec (10sec x 10) g2 18.352 ± 0.016 C
2025 Nov 30.483 100sec (10sec x 10) r2 18.587 ± 0.029 C
2025 Nov 30.483 50sec (10sec x 5) z 18.891 ± 0.070 C
2025 Nov 30.484 50sec (10sec x 5) i2 18.968 ± 0.059 C
2025 Nov 30.527 100sec (10sec x 10) g2 18.302 ± 0.017 C
2025 Nov 30.527 100sec (10sec x 10) r2 18.561 ± 0.029 C
2025 Nov 30.527 50sec (10sec x 5) i2 18.975 ± 0.066 C
2025 Nov 30.528 50sec (10sec x 5) z 19.090 ± 0.089 C
2025 Nov 30.544 400sec (50sec x 8) C 18.7 ± 0.1 D
2025 Dec 1.472 300sec Ic 18.64 ± 0.37 A
2025 Dec 1.483 300sec Rc 18.78 ± 0.38 A
2025 Dec 1.558 180sec Rc 18.79 ± 0.22 B
2025 Dec 1.561 180sec V 19.03 ± 0.21 B
2025 Dec 1.567 300sec Ic 18.69 ± 0.30 B
2025 Dec 1.662 180sec (10sec x 18) g2 18.676 ± 0.074 C
2025 Dec 1.662 80sec (10sec x 8) i2 >19.184 C
2025 Dec 1.662 100sec (10sec x 10) r 18.947 ± 0.114 C
2025 Dec 1.664 100sec (10sec x 10) r2 >19.214 C
2025 Dec 1.664 80sec (10sec x 8) z >18.841 C
2025 Dec 4.41 810sec (10sec x 81) g2 >19.88 C
2025 Dec 4.41 810sec (10sec x 81) r2 >19.51 C
2025 Dec 4.41 870sec (10sec x 87) i2 >19.41 C
2025 Dec 5.52 930sec (30sec x 31) g2 >21.68 C
2025 Dec 5.52 930sec (30sec x 31) r >21.70 C
2025 Dec 5.52 930sec (30sec x 31) i2 >21.26 C
Site information:
A. Osaka Kyoiku University, Japan, 0.51-m f/12 + SBIG STXL-6303E
B. Nayoro Observatory, Japan, 1.6-m Pirka telescope + MSI (Watanabe et al. 2012)
C. Okayama Observatory of Kyoto University, Japan, 3.8-m Seimei telescope (Kurita et al. 2020) + TriCCS
D. Nayoro, Hokkaido, Japan, 0.36-m f/11 + FLI-ML1001 CCD (unfiltered)
Our spectrum
