Recurrent Nova M31N 2008-12a: discovery of the 2021 eruption
ATel #15034; K. Itagaki (Itagaki Observatory), T. Vanmunster (AAVSO), F. Watanabe (Nayoro Observatory), J.-L. G. Carballo (Observadores de Supernovas, AAVSO, Cerro del Viento Observatory), K. Matsumoto (Osaka Kyoiku University), H. Naito (Nayoro Observatory), M. W. Healy (LJMU), M. J. Darnley (LJMU), S. C. Williams (Turku), S. Kafka (AAVSO), A. W. Shafter (SDSU), M. Henze (SDSU), on behalf of the 12a Collaboration
on 14 Nov 2021; 12:42 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)
Subjects: Optical, Nova, Transient
We report the discovery of the predicted 2021 eruption of the remarkable recurrent M31 nova M31N 2008-12a (see ATels #5607, #6527, #7964, #9848, #11116, #12177, #13269, #14130 for earlier detections as well as Darnley et al. 2014, 2015, 2016 and Henze et al. 2014, 2015a, 2015b, 2018, for comprehensive multi-wavelength studies of previous eruptions).
The nova was clearly detected on 2021 Nov 14.3784 (UT) with an unfiltered discovery magnitude of 18.7 at the Itagaki Observatory (Okayama, Japan). We will continue to monitor the nova light curve and strongly encourage additional follow-up observations. We have also triggered our pre-approved Swift campaign for UV/X-ray follow-up. It is likely that the nova was discovered during its one day rise to a peak magnitude of around 18.2 mag in the R-band.
Below we report a number of additional observations:
| Date UT | Exp. time | Filter | Magnitude | Observer | Site |
|---|
| 2021 Nov 7.50 | 240 sec | Rc | >19.3 | K. Matsumoto | (*1) |
| 2021 Nov 13.0134 | 1200 sec (120s x 10) | none | >20.5 | J.-L. G .Carballo | (*2)
|
| 2021 Nov 13.0238 | 300 sec | V+R | >21.1 | M. J. Darnley | (*3) |
| 2021 Nov 13.4501 | 1290 sec (30s x 43) | none | >18.0 | F. Watanabe | (*4) |
| 2021 Nov 13.7604 | 300 sec | V+R | >18.9 | T. Vanmunster | (*5) |
| 2021 Nov 14.378 | 60 sec | none | 18.7 | K. Itagaki | (*6) |
| 2021 Nov 14.390 | 60 sec | none | 18.5 | K. Itagaki | (*6) |
| 2021 Nov 14.475 | 60 sec | none | 18.5 | K. Itagaki | (*6) |
*1 Osaka Kyoiku University, Japan; 0.51-m f/12 telescope + SBIG STXL-6303E CCD
*2 Pla D'Arguines Observatory Castellón, Spain; LX200 16 ACF f7.3, CCD SBIG STL-1001
*3 Liverpool Telescope, La Palma; 2.0-m f/10 Ritchey-Chrétien + RISE, an Andor DW485 which houses an E2V CCD 47-20 frame transfer device
*4 Nayoro Observatory, Japan; 0.4-m f/10 Meili telescope + SBIG STL-1001E
*5 AAVSO VMT
*6 Itagaki Observatory (Okayama station), Japan; 0.35-m f/11 reflector + KAF-1001E
We strongly encourage observations particularly spectroscopic.
