Taare Sadak Par is a collaborative project, where observations taken by students, general public and amateur astronomers are being combined together at this Taarewiki, to look at the emerging picture of light pollution in India. There are some sites that have been studied well by the professional astronomers, of course. Compiled here are references that discuss the sky conditions measured by astronomers, for some selected sites in India (and some locations elsewhere, for comparison).
Go here From online references and observations outside India ? - Just a few references are collected together, just for comparison with Indian locations
References to observations related to sky conditions, for locations in India
From the paper 'Visual observations of Geminid Meteor Shower 2004' by K. Chenna Reddy, D.V. Phanikumar and G. Yelliah, Bull. Astron. Soc. India (2006), 34, 223.
They obtain a limiting magnitude of 6.0 for the site of the observatory, for observations conducted from the 11th-14th December 2004.
Here at http://adsabs.harvard.edu/full/2000BASI...28..429S
Here at http://adsabs.harvard.edu/full/2000BASI...28..437P