First microlensing candidate towards M 31 from the Nainital Microlensing Survey
Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai – 400 005, India e-mail: email@example.com
2 Aryabhatta Research Institute of Observational Sciences (ARIES), Manora peak Nainital – 263129, India
3 Astronomical Institute, Tohoku University, Sendai 980-8578, Japan
Accepted: 20 December 2004
We report our first microlensing candidate NMS-E1 towards M 31 from the data accumulated during the four years of Nainital Microlensing Survey. Cousin R and I band observations of ∼ field in the direction of M 31 have been carried out since 1998 and data is analysed using the pixel technique proposed by the AGAPE collaboration. NMS-E1 lies in the disk of M 31 at and , about 15.5 arcmin to the South-East direction of the center of M 31. The degenerate Paczyński fit gives a half intensity duration of ~59 days. The photometric analysis of the candidate shows that it reached mag at the time of maximum brightness and the colour of the source star was estimated to be mag. The microlensing candidate is blended by red variable stars; consequently the light curves do not strictly follow the characteristic Paczyński shape and achromatic nature. However its long period monitoring and similar behaviour in R and I bands supports its microlensing nature.
Key words: cosmology: dark matter / Galaxy: halo / galaxies: Local Group / gravitational lensing / methods: data analysis
© ESO, 2005