Discovery of an Apparent Nova in M81 and H-alpha Confirmation of Three M81 Nova Candidates

ATel #6276; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), O. Vaduvescu, V. Tudor (ING, La Palma, Spain)
on 27 Jun 2014; 05:21 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

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We report the discovery of an apparent nova in M81 on a co-added 2000-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma under ~1.6" seeing on 2014 Jun. 23.912 UT. The new object is easily visible on the co-added image (see the finding chart linked below), but is not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 22.3. On Jun. 23.930 UT we also obtained Sloan r'-band images which helped us to classify the object.

The new object designated PNV J09554805+6901248 = M81N 2014-06c? is located at R.A. = 9h55m48s.05, Decl. = +69o01'24".8 (equinox 2000.0), which is 79.8" east and 150.3" south of the center of M81.

The photometry obtained with the INT + WFC for the PNV J09554805+6901248 and for M81 nova candidates PNV J09554050+6904048 and PNV J09560098+6903513 (see ATel #6209), and PNV J09552936+6905474 (see ATel #6188) is summarized in the following table:

 
                         2014 06 23.912    2014 06 23.930 
 
       Object             H-alpha mag       Sloan r' mag 
 
PNV J09554805+6901248    19.30 +/- 0.08    20.35 +/- 0.10 
PNV J09554050+6904048    20.1 +/- 0.2         > 21.9 
PNV J09560098+6903513    21.0 +/- 0.3         > 22.3 
PNV J09552936+6905474    20.7 +/- 0.2      21.8 +/- 0.3 

Relatively weak H-alpha emission of the PNV J09554805+6901248 together with a non-detection of the object down to a limiting magnitude 21.6 on Jun. 9.882 UT (on unfiltered co-added image obtained by J. Vrastil using the 0.65-m telescope at Ondrejov), is consistent with a young nova discovered shortly after eruption. Strong H-alpha emission together with relative faintness in Sloan r'-band (both observed in the INT data) of the PNV J09554050+6904048 and the PNV J09560098+6903513 supports their classification as novae. Relatively weak Halpha emission (H-alpha-Sloan r' ~ 1.1 mag, evolved moderately fast/fast novae typically exhibit H-alpha-Sloan r' ~ 1.8 to 2.5 mag) observed for the PNV J09552936+6905474 in the INT data one month after eruption together with its faint maximum magnitude (Sloan r' ~ 21) is consistent with a slow nova in M81.

This work is based on observations made with the Isaac Newton Telescope operated on the island of La Palma by the ING in the Spanish Observatorio del Roque de los Muchachos. We thank J. Vrastil for getting M81 images at Ondrejov.

Finding chart