From erik Tue Jan 12 12:55:09 1999
Subject: CUO_53, 54 Survey; Supernovae
To: erik (Erik Hoeg)
Date: Tue, 12 Jan 1999 12:55:09 +0100 (MET)
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SAG_CUO_53 and _54 are are summarized hereafter and are available on:
http://www.astro.ku.dk/~erik/gaia/

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CUO_53:

Sky survey and photometry by the GAIA satellite

E. H{\o}g, C. Fabricius, J. Knude, V.V. Makarov 
11 Jan. 1999 -- SAG\_CUO\_53
submitted to {\em Baltic Astronomy}

{abstract}
GAIA is designed as a scanning satellite to collect data for 
high-precision astrometry with standard errors of 10$~\mu$arcsec 
of positions, parallaxes and annual proper motions for stars 
brighter than $V=15$~mag, and sub-milliarcsec precision for all 
stars brighter than $V=20$~mag.  Multi-colour photometry will 
be obtained for these about one billion stars.
 
An overview of the GAIA mission with respect to multi-colour 
photometry of stars is given. The detection of supernovae and 
solar system objects, and the possiblity for surface photometry 
are mentioned.  An appendix on GAIA mapping and photometry contains 
the three sections: samples and patches, precision of aperture 
photometry, mapping and photometry.

NB:
This report is an update of CUO_50 which should no more be used.
The new number _53 shall facilitate referencing.

Essential news:
1. PSF photometry is described in a new section 7.3.3 with formulae and
discussion. This could help resolve some of the issues raized in
GG-011.  A 'corrected' aperture photometry is defined as a special case
of PSF photometry.

2. Several improvemenents of terminology and description are made in
Sections 7.2 and 7.3, e.g. the units for S, b, r etc are simplified to
[e-] instead of [e-/sample].

3. In Sect.4: 
More recently, Knude \& Kaltcheva~(1998) have obtained an accuracy
in $M_V$ of $\pm$ 0.3 - 0.4 mag for A-F supergiants by means 
only of $uvby$ photometry and no $H\beta$, and using Hipparcos 
parallaxes for calibration.
 
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CUO_54:

The velocity field and 3-D structure of the Universe

E. H{\o}g , C. Fabricius, V.V. Makarov
12 Jan. 1999 -- SAG\_CUO\_54
submitted to {\em Baltic Astronomy} 
 
 
{abstract}
The velocity field of matter in the Universe is dominated by the Hubble
expansion, and the 3-D structure is characterized by sheets with high
density of visible matter separated by large voids. A superposed
large-scale streaming of the luminous matter is only poorly indicated
because distance determination independent of the Hubble law is too
uncertain. Very accurate distance tracers, $\pm 5\%$, are available
in the Type Ia Supernovae, but they have been too sparsely observed to
be useful in this context. Detection with GAIA followed by
ground-based monitoring can give distances of about
$50\,000$ supernovae out to 500~Mpc or $z=0.10$. This will
greatly enhance our knowledge of the structure and velocities of the
Universe. The underlying dark matter and dark energy will emerge
from obscurity.