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Astron. Astrophys. 351, 945-953 (1999)

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New surveys of UBV photometry and absolute proper motions at intermediate latitude *

D.K. Ojha 1, O. Bienaymé 2, V. Mohan 3 and A.C. Robin 2,4

1 Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai - 400 005, India
2 Observatoire de Strasbourg, CNRS URA 1280, 11 rue de l'Université, 67000 Strasbourg, France
3 Uttar Pradesh State Observatory, Manora Peak, Nainital, 263 129, India
4 Observatoire de Besançon, 41 bis Av. de l'Observatoire, B.P. 1615, 25010 Besançon Cedex, France

Received 15 July 1997 / Accepted 29 September 1999


A photometric and proper motion survey has been obtained in 2 directions at intermediate latitude: ([FORMULA], [FORMULA]; [FORMULA],[FORMULA]) and ([FORMULA], [FORMULA]; [FORMULA], [FORMULA]). The survey covers 7.13 and 20.84 square degrees, respectively. The limiting magnitude is about 18.5 in V for both directions.

We have derived the density laws for stars (MV [FORMULA] 3.5) as a function of distance from the galactic plane. The density laws for stars follow a sum of two exponentials with scale heights of 240 pc (thin disk) and 790 pc (thick disk), respectively. The local density of thick disk is found to be 6.1[FORMULA]3% relative to the thin disk. The kinematical distribution of stars has been probed to distances up to 3.5 kpc above the galactic plane. New estimates of the parameters of velocity ellipsoid have been derived for the thick disk of the Galaxy. A comparison of our data sets with the Besançon model star count predictions has been performed, giving a good agreement in the magnitude range V = 13 to 18.

Key words: techniques: photometric – surveys – Galaxy: halo – Galaxy: kinematics and dynamics – Galaxy: stellar content – Galaxy: structure

* Based on observations made on photographic plates obtained with the Tautenburg, ESO and Palomar Schmidt telescopes and on CCD observations made at UPSO, Nainital (India) and OHP, France. Digitizations made with the MAMA measuring machine. MAMA is developed and operated by INSU (Institut National des Sciences de l'Univers, Paris).

Send offprint requests to: D.K. Ojha (ojha@tifr.res.in)

© European Southern Observatory (ESO) 1999

Online publication: November 16, 1999