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Astron. Astrophys. 317, 925-928 (1997)

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1. Introduction

Solar irradiance measurements were carried out with the DIFOS experiment aboard the Russian-Ukrainian solar satellite CORONAS-I. The DIFOS photometer measured solar intensity integrated over the whole solar disk in three wavelength ranges. Detectors are silicon photodiodes. First of all DIFOS should measure global solar oscillations between 1 and 10 mHz. In 1991 Oraevsky and Zhugzhda published a description of the CORONAS-I satellite. In 1995 Lebedev et al. published an overview about the DIFOS-photometer and first results concerning solar irradiance oscillations.

In the present paper we use DIFOS observations for an estimate of short term solar irradiance variations between fractions of a day up to two solar rotations. In these time spans several authors investigated relations between solar irradiance variations and phenomena of activity. Mostly total irradiance measurements with ACRIM radiometers (Pap 1985, Pap et al. 1994) were used. It was found that generally sunspots cause a decrease and facula areas give an enhancement of solar luminosity. But details are complicated and an analysis of the DIFOS period between 1994, March 16 and May 7 is justified.

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© European Southern Observatory (ESO) 1997

Online publication: July 8, 1998