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Discovery of a Luminous Blue Variable Candidate in NGC925

ATEL # 1347; Mansi M Kasliwal, Brad Cenko, Varun Bhalerao, Arne Rau, Robert Quimby, Eran Ofek, Shri Kulkarni (Caltech)
on 3 Jan 2008; 23:17 UT
Password Certification: Mansi Manoj Kasliwal (mansi@astro.caltech.edu)

Subjects: Optical, Nova, Supernova, Transients, Variables

The automated Palomar 60-inch telescope found a flickering source on a spiral arm of NGC 925 on MJD 54388.3 at RA(J2000) = 02:27:36.25, Dec(J2000)= +33:34:26.7. P60-NGC925OT-071016 has been varying by approximately one magnitude in the range of g~20.0 and g~21.0 based on 75 images in the past year. Assuming a distance modulus of 29.84 (Saha et al 2006), this corresponds to an absolute magnitude range of -8.8 to -9.8. Follow-up spectroscopy with the Double Beam Spectrograph on the Palomar Hale telescope on MJD 54389.32 and Low Resolution Imaging Spectrometer on the Keck I telescope on MJD 54445.24 suggest that this is a luminous blue variable. The following emission lines are detected and the redshift of the line centers is consistent with the assumed distance to the galaxy:

   Line    | Center      | FWHM       | 
| (Angstrom) | (Angstrom) |
[O II] | 3733.2 | 5.4 |
H-delta | 4110.2 | 4.8 |
H-gamma | 4348.3 | 6.3 |
H-beta | 4869.5 | 8.4 |
[O III] | 5014.3 | 4.6 |
He I | 5885.6 | 5.6 |
H-alpha | 6573.5 | 10.2 |
He I | 7077.7 | 5.0 |
Light Curve, Spectrum and Finder Chart are available at http://www.astro.caltech.edu/~mansi/P60FasTING/Atel/


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