DIVA (Double Interferometer for Visual
Astrometry) is a Fizeau interferometer on a small
satellite. It will perform astrometric and
photometric observations of at least 4 million
stars. A launch in 2002 and a minimum mission
length of 24 months are aimed at. A detailed
description of the experiment can be obtained from
the DIVA homepage at
http://www.aip.de:8080/᷉dso/diva. An overview is
given by Röser et al.,
1997.
The limiting magnitude of DIVA is about V
= 15 for spectral types earlier than M0, but drops
to about V = 17.5 for stars later than M5. Table 1
gives a short overview on DIVA’s performance. DIVA
will carry out a skysurvey complete to V = 12.5.
For the first time this survey will comprise
precise photometry in at least 8 bands in the
wavelength range from 400 to 1000 nm.
DIVA will improve parallaxes by a factor
of 3 compared to Hipparcos; proper motions by at
least a factor of 2 and, in combination with the
Hipparcos observations, by a factor of 10 for
Hipparcos stars. At least 30 times asmany stars as
Hipparcos will be observed, and doing this DIVA
will fill the gap in observations between
Hipparcos and GAIA. DIVA’s combined astrometric
and photometric measurements of high precision
will have important impacts on astronomy and
astrophysics in the next decade.
Diva - A Small Satellite for Global
Astrometry and Photometry
