1 Introduction

The program for solar CCD observations with a Danjon astrolabe, aiming to monitoring variations of the apparent diameter, has been pursued since January 1997 at the Observatório Nacional (ON), Rio de Janeiro ( $\varphi = -22^\circ 54'$). First results and analysis of the observations through June 1998 were reported in Jilinski et al. (1998, 1999).

Here the results of the campaign from July 1998 to June 1999 are presented. Analogous studies have been made by Noël (1995, 1998) and Laclare (1996).

The observations have been made with a reflecting variable angle prism, between 27$^\circ$ and 58$^\circ$ of zenith distance. A description of the observational method used is given in Chollet & Sinceac (1999).

The images of the Sun are acquired by a CCD camera COHU $\char93$ 4710. The camera is IR sensitive ( 4000 - 10000 Å). The effective wavelength is 6400 Å and the bandpass is 3000 Å.