LONG-PERIOD VARIABLES IN THE LARGE-MAGELLANIC-CLOUD .4. A COMPENDIUM OF NORTHERN VARIABLES

We present new data for an extensive sample of candidate long-period variable stars in a 16-deg(2) field in the northern part of the LMC. Our data are derived from COSMOS scans of I-band UK Schmidt plates, and we have used two techniques to search for variables: first, an extension of the interactive methods employed by Reid, Glass and Catchpole; secondly, the semi-automatic methods of variable star detection used to identify long-period variables in the southern and central parts of the LMC by Hughes. We detect a total of 302 periodic variables, of which 258 (and 29 non-periodic variables) are identified through the former technique and 186 by the latter method. We compare the results from the two methods, and present positions and finding charts for all of the stars identified in our survey. We have also obtained near-infrared (JHK) data for 276 stars, most of which are AGE stars and at least 190 of which are LMC Miras. A further 34 variables are also likely to be Miras but currently lack JHK photometry. We discuss the period-luminosity relations defined by our observations of the shorter period Miras.