Recurrent Nova M31N 2008-12a: Pre-detection upper limit and multicolor follow-up observations of 2021 eruption with XMO-NEXT

ATel #15037; Hanjie Tan (Astronomical Institute of Charles University), Mi Zhang, Jingyuan Zhao, Jiangao Ruan, Guoyou Sun (Xingming Observatory), Xing Gao (Urumqi No. 1 Senior High School)
on 15 Nov 2021; 10:10 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)

Tweet

We report the pre-detection upper limit and multicolor follow-up of the recurrent nova M31N 2008-12a using the 0.60-m Ningbo Bureau of Education and Xinjiang Observatory Telescope (NEXT) at Xingming Observatory, China.

All multicolor observations listed below were obtained in the B, V, g, r, i, z filters between 2021-11-14 15h UT and 20h UT, and calibrated by secondary standards in the field (cf. Darnley et al. 2016). The unfiltered observations were calibrated by same standard stars in V band.

Nothing was visible at this nova position on 2021-11-13.9641 UT with an upper limit of V > 19.0 mag. Together with the discovery on 2021-11-04.378 (ATel #15034), our non-detection constrains the outburst time with an uncertainty of 0.41 days.

Our observations show the nova with a significant decay since its peak, especially in B band. The rising in i-band, and B-V color changes from 0.05 mag to 0.30 mag, indicating the nova is turning redder.

 
Date (UT) Filter Exp(s) mag 
2021-11-13.6090 Clear 300*2 >20.5  
2021-11-13.9641 Clear 300*2 >19.0  
  
2021-11-14.6519 B 300 18.44±0.05 
2021-11-14.6557 V 300 18.39±0.06 
2021-11-14.6333 r 300 18.28±0.06 
2021-11-14.6442 i 300 18.89±0.12 
2021-11-14.6481 z 300 19.66±0.40 
 
2021-11-14.8440 B 300 18.71±0.13 
2021-11-14.8477 V 300 18.41±0.12 
2021-11-14.8290 g 300 18.39±0.08 
2021-11-14.8327 r 300 18.35±0.08 
2021-11-14.8365 i 300 18.36±0.17 
2021-11-14.8402 z 300 >18.5