Recurrent Nova M31N 2008-12a: Pre-Discovery upper limit and multi-colour follow-up observations with NEXT-XMO

ATel #12200; H. Tan (National Central University), X. Gao (Xinjiang Astronomical Observatory)
on 10 Nov 2018; 19:23 UT
Credential Certification: Martin Henze (henze@ice.cat)

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We report the prediscovery non-detection and multi-colour follow-up of the recurrent nova M31N 2008-12a (see ATels #12177, #12179, #12181, #12182, #12189, #12190, #12195) using the 0.60-m Ningbo bureau of Education and Xinjiang observatory Telescope (NEXT) located at Xingming Observatory (IAU Code C42), Mt.Nanshan, Xinjiang, China. All photometric observations listed below were obtained in the B, V, R, I filters between 2018-11-07.5 UT and 2018-11-10.5 UT and calibrated using secondary standards in the field (cf. Darnley et al. 2016).

Nothing was detected at the nova position on 2018-11-06.53 UT with an upper limit of V > 21.2 mag. Together with the discovery at Liverpool Telescope on 2018-11-06.80 (ATel #12177), our non-detection constrains the outburst time with an uncertainty of only 0.27 days.

 
     T_mid       Filter    Exp(s)      Photometry(mag) 
2018-11-06.537    Clear    300*2        >21.2 
 
2018-11-07.580      B      300*2        18.97±0.04 
2018-11-07.563      V      300*2        18.87±0.04 
2018-11-07.554      R      300*2        18.81±0.05 
2018-11-07.572      I      300*2        18.78±0.11 
 
2018-11-09.635      B      300*2        20.49±0.26 
2018-11-09.643      V      300*2        20.50±0.13 
2018-11-09.676      R      300*2        20.29±0.18 
2018-11-09.665      I      300*2        >19.2 
 
2018-11-10.593      B      300*5        20.90±0.09 
2018-11-10.612      V      300*5        21.16±0.18 
2018-11-10.631      R      300*5        20.72±0.13 
2018-11-10.724      R      300*5        20.73±0.15 
2018-11-10.705      I      300*3        19.69±0.30