A large area near-infrared (IR) survey of the galactic plane (GPS) will be beneficial to many areas of stellar astrophysics, e.g. Star Formation, X-ray Binaries, AGB-stars, Protoplanetary Nebulae and Brown Dwarfs. In addition, the proposed GPS is conceived as a Legacy database and Atlas, with the long term goal of complete coverage of the Galactic Plane, which will require the addition of data from VISTA. The Atlas will lead to a major advance in understanding of the structure of the galaxy. The science described below is not intended to be a complete list but merely an indication of the most important science drivers presently identified by the UKIDSS consortium. The UKIDSS GPS will cover the entire northern plane in JHK up to 60o Declination, with two repeat scans at K band to provide the data needed to identify variability in the 108-109 sources detected. The variability data on so many sources will also detect phases of stellar evolution which are rarely or never observed, such as ignition of helium or carbon in the core or envelope of evolved stars. The database will be an invaluable resource for future science in all wavebands both for statistical studies and for baseline infrared photometry of newly discovered sources. The Atlas will locate all bright stellar populations (main sequence types O-F and giant stars) throughout the galaxy by virtue of the low galactic extinction in the K band. The fainter stellar populations (main sequence types G-M) will also be detected at distances of several kiloparsecs. Distances will be determined by dereddening in a two-colour diagram and kinematically via follow up in the radio waveband.
Figure 3.1. True colour JHK mosaic of the Galactic
Centre, taken in July 1999 with UFTI on UKIRT, and covering a region
approximately 7.5 X 4.5 arcmin. The exposure was 30 seconds per
filter. Image taken from the UKIRT web page. Data obtained and reduced
by Ant Chrysostomou.