Optical imaging of M31N 2008-12a during its 2025 eruption from IAO

ATel #17524; Judhajeet Basu (IIA), Shatakshi Chamoli (IIA), Aditya Pawan Saikia (IIT Bombay), Vishwajeet Swain (IIT Bombay), Sudhanshu Barway (IIA), G. C. Anupama (IIA), Varun Bhalerao (IIT Bombay)
on 3 Dec 2025; 09:22 UT
Credential Certification: Judhajeet Basu (judhajeet.basu@iiap.res.in)

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We report the optical imaging observations of M31N 2008-12a using the GROWTH-India Telescope (GIT) and the Himalayan Chandra Telescope (HCT) located at IAO, Hanle. The 2025 eruption was discovered by K. Itagaki et al. (ATel #17511) on 2025 Nov 30.3634 UT at a magnitude of 18.7 in clear filter. F. Diaz-Segado et al. (ATel #17514) reported detection in an image taken 6 hours prior to discovery on 2025 Nov 30.1130 UT at g′ = 19.39 ± 0.22. The spectroscopic confirmations were reported by S. Chamoli et al (ATel #17520) and D.P.K. Banerjee et al (ATel #17521).

GIT daily monitoring of M31 did not detect the source on 2025 Nov 29.6393 UT up to a 3 sigma limiting mag of 20.367 in g′ filter. This constrains the eruption time to be within 2025 Nov 29.8761 ± 0.2368 UT

We triggered ToO observations with HCT on 30th Nov, when it was detected in g′ (∼18.5), r′ (∼18.4) and i′ (∼18.7) filters, approximately 17 hrs after the first detection. Follow-up observations with GIT on 1st December revealed that the nova has faded by approximately 0.5 mags in g′ and r′ filters and by 0.2 mags in i′ filter within 24 hrs

We are continuing to monitor this object. Follow-up photometric and spectroscopic observations are highly encouraged.

GIT is a 70 cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/. We thank the HCT staff for their support during the observations. We thank the HCT observers for giving us time to carry out the ToO observations. The Indian Astronomical Observatory is operated by the Indian Institute of Astrophysics, Bengaluru, India.