STUDY OF CORONAL HOLES AND BRIGHT POINTS USING SOHO AND NANCAY RADIOHELIOGRAPH (NRH) OBSERVATIONS. JOP-Leaders: Barbara Thompson (EIT), Monique Pick (Nancay) We propose a joint study of coronal holes and bright points using simultaneous X/UV and radio observations. This proposal has two different aims which are: 1.) To analyze the physical conditions (mostly the temperature) at different levels in a coronal hole, which appear to be different when seen in radio and X/UV. 2.) To analyze possible pecularities in the magnetic field structure in regions where bright points appear, inside and outside coronal holes and compare radio and X/UV intensity and time profiles. The scientific objectives of these two studies are the following: 1.) To check a possible difference between the ion and electron temperature in coronal holes. In fact the electron temperature can be derived straightforward from radio observations since atomic constants, atomic aboundances, ionization equilibria, etc... are not involved in the calculations. On the other hand the width of the X/UV lines can supply the ion temperature. 2.) The time profiles of the bright points in the two different range of wavelengths could be us ed to probe the type of mechanisms involved in this phenomenon. These observations should be done in the period May 15 - June 30 1997, because we have the best resolution of the NRH during this period of the year. Since in the first study we want to have quantitative values of the brightness temperature, the observations should be dedicated to coronal holes located near the center of the disc avoiding problems related to transfer radiation. In point two we are interested in the morphology and time profiles of the bright points, therefore observations can also be performed on polar coronal holes. The instruments required for these studies are the Soft X-ray Telescope aboard Yohkoh and the following instruments aboard SOHO: EIT MDI CDS SUMER Since the CDS and SUMER instruments have a small field-of-view we would like that the pointing of these instruments is on the bright points or coronal holes selected for this study. As far as SUMER is concerned this would be possible only on the central meridian passage of the selected region.