This is the README file for the Hipparcos and Tycho Multiparameter
Search Tool (version 1)
Created: April 12, 2000
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Introduction:
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The Hipparcos and Tycho Multiparameter Search Tool is an online search
facility which allows users to query the Hipparcos and Tycho Catalogues
and the Tycho-2 Catalogue. The tool is available on the Hipparcos web
site at http://www.rssd.esa.int/hipparcos

A list of explanatory documents is given at the end of this README
note. These documents give details of the catalogues and their
contents.

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Background Information:
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The user can request all entries from any of these catalogues which
satisfy a range of criteria. (A maximum of 1000 entries per search can
be retrieved at one time.) Below we list the parameters which can be
selected (for the users convenience we note also the range of values
which the parameters span; the search tool will only accept values
within these ranges):

From the Hipparcos and Tycho Catalogues: 

Right ascension (epoch J1991.25, ICRS): Field H8/T8 from the Hipparcos
and Tycho Catalogues, range [0,360];

Declination (epoch J1991.25, ICRS): Field H9/T9 from the Hipparcos and
Tycho Catalogues, range [-90,90];

Trigonometric parallax (in milliarcseconds): Field H11/T11 from the
Hipparcos and Tycho Catalogues, Hipparcos range [-55, 772.33], Tycho
range [-919, 701.5];

V magnitude (in the Johnson UBV photometric system): Field H5/T5 from
the Hipparcos and Tycho Catalogues, Hipparcos range [-1.44, 14.08],
Tycho range [-1.44, 15.2];

B-V (colour index): Field H37/T37 from the Hipparcos and Tycho
Catalogues, Hipparcos range [-0.4, 5.46], Tycho range [-1.037, 4.353];

From the Tycho-2 Catalogue:

Mean right ascension (epoch J2000, ICRS): bytes 16-28 from the Tycho-2
Catalogue, range [0, 360];

Mean declination (epoch J2000, ICRS): bytes 29-41 from the Tycho-2
Catalogue, range [-90, 90];

Tycho-2 V_T magnitude: bytes 124-130 from the Tycho-2 Catalogue, range
[1.905, 15.193];

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How to use the search tool:
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1) Select the catalogue which you wish to query;

2) Select the parameter(s) in the Field column (Turn on the selection
   button), and fill in the minimum and maximum values for your search
   range - the minimum and maximum values are included;

3) Press "Submit" to activate the search or "Clear" to clear all
   entries and to start again.

The entries from the selected catalogue which satisfy your search
criteria will be returned to the browser window. A maximum of 1000
entries can be returned; if your search results in more than this then
you will be told how many entries satisfy the criteria but they will
not appear in the browser window.

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Further Reading:
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The following documents contain useful information on the Catalogues
and their contents:

Guide to the Hipparcos fields (pdf format) available at:
http://www.rssd.esa.int/Hipparcos/pstex/sect2_01.pdf

Guide to the Tycho fields (pdf format) available at:
http://www.rssd.esa.int/Hipparcos/pstex/sect2_02.pdf

Guide to the Tycho-2 Catalogue (pdf format) available at:
http://www.astro.ku.dk/~cf/CD/docs/guide.pdf

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Related Web Sites:
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Further information about the Hipparcos and Tycho Catalogues can be
found on the Hipparcos web site at http://www.rssd.esa.int/hipparcos


More details on the Tycho-2 Catalogue are available on the Tycho-2
website at http://www.astro.ku.dk/~erik/Tycho-2/

The Hipparcos and Tycho Catalogues are available for ftp download from 
the CDS, Strasbourg. See http://vizier.u-strasbg.fr/viz-bin/Cat?I/239
for further details.

The Tycho-2 Catalogue is also available for ftp download from the CDS,
Strasbourg. See http://cdsweb.u-strasbg.fr/viz-bin/Cat?I/259 for
further details.

The CDS also provide some possibilities for searching the catalogues.
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