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Discovery of Two Probable Novae in M81

ATel #4462; K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), L. Patrick (ING, La Palma, Spain & University of Sheffield, UK), D. Arnold, L. Dominguez, A. Gonzalez Fernandez, L. Hardy, M. Hrudkova, P. van Oers, Y. Ramanjooloo, R. Karjalainen (ING, La Palma, Spain), O. Vaduvescu (ING, La Palma & IAC, Tenerife, Spain)
on 8 Oct 2012; 01:29 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

Subjects: Optical, Nova, Transient

We report the discovery of two probable novae in the M81 galaxy on a co-added 1600-s narrow-band H-alpha CCD image taken with the 2.5-m Isaac Newton Telescope (INT) + WFC at La Palma on Sep. 28.233 UT. The new objects are well visible on the co-added image (see the finding chart linked below) and faintly visible on individual 400-s frames, but are not present on numerous narrow-band H-alpha archival images from the INT down to limiting magnitude as faint as H-alpha = 22.3. We also obtained Sloan r'-band images that helped us to classify the objects. Strong H-alpha emission together with relative faintness in the Sloan r' band supports the classification of the objects as novae.

Designations, positions, and offsets of the new objects from the center of M81 are summarized in the following table:

 
 
  TOCP designation    CBAT designation  R.A. (J2000)  Dec. (J2000)  Offset R.A.  Offset Dec. 
 
PNV J09551009+6903254  M81N 2012-09a?   09 55 10.09   +69 03 25.4    123.7" W      29.7" S 
PNV J09553556+6904271  M81N 2012-09b?   09 55 35.56   +69 04 27.1     12.8" E      32.0" N 
 
The photometry obtained with the INT + WFC is summarized here:
 
 
                       PNV J09551009+6903254              PNV J09553556+6904271 
 
   Date UT         H-alpha mag      Sloan r' mag      H-alpha mag      Sloan r' mag 
 
2012 05 22.901       > 22.0                             > 21.9 
2012 05 22.919                        > 22.5                             > 22.4 
2012 09 28.233    19.0 +/- 0.15                      20.1 +/- 0.3 
2012 09 29.233    18.9 +/- 0.1                       20.0 +/- 0.15 
2012 09 29.249                     20.8 +/- 0.3                          > 21.2 
2012 09 30.241    19.0 +/- 0.1                       20.0 +/- 0.2 
2012 09 30.254                     20.9 +/- 0.25                         > 21.3 
2012 10 02.230    19.1 +/- 0.15                      20.2 +/- 0.3 
 
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.

Finding chart