Data Set Overview                                                         
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	CARA Data

This data set contains tables of information on a variety of comets 
observed and analyzed the the CARA Project to find the Afrho quantity.

CARA stands for Cometary ARchive for Afrho.

The goal of the project is to develop a standardized observing and 
reduction method devoted to perform CCD comet imaging and photometry
of comets with small and medium size telescopes, which is more suited
for amateur astronomers. 

Comets are a typical targets for amateur astronomers imaging, astrometry
and photometry. Since traditional photometry is mainly devoted to visual
total magnitude estimates and now complented by CCD digital techniques,
CARA chooses to run a more specialized program to extract more information
from CCD digital images. The collected data eventually are archived in a 
database in a format ready for a scientific analysis.

Amateur astronomers data are on an average less accurate than the ones 
obtained with professional equipments fron high quality sites, however 
non-professional data can allow longer term monitoring of specific targets.

The approach used in photometry differs from the classical visual technique.
Observations are taken using photometric filters with pass-bands are usually 
dominated by reflected sunlight (red and near infrared wavelenghts). Instead
of classical total magnitude  the Afrho quantity is calculated by means of 
differential aperture photometry.

The CARA Project is a consortium of amateur astronomers with support from some
profesional specialists.

Parameters                                                                
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The data is presented as an ASCII table with 18 columns. We list
them in order and give a brief description here.

    1. The first column is the MPC Comet Designation.

    2. The second column is the Julian Date of the observation.

    3. The third column is the Geocentric Distance in AU.

    4. The fourth column is the Heliocentric Distance in AU.

    5. The fifth column is the Phase Angle in degrees.

    6. The sixth column is the Photometric Filter Band.

    7. The seventh column is the Measured Magnitude of the comet.

    8. The eighth column is the Radius of the Coma in km.

    9. The ninth column is the Afrho quantity in cm.

    10. The tenth column is the Estimated Error in the Afrho quantity.

    11. The eleventh column is the Reference Catalog used for the 
        reference star.

    12. The twelfth column credits the Analyst that worked with the data.
        Note that CARA analysts often have codes which are tabulated in
        the cara_documents collection.

    13. The thirteenth column credits the Observer that worked with the 
        data. Note that CARA observers often have codes which are 
        tabulated in the cara_documents collection.

    14. The fourteenth column contains the Catalog Number of the 
        Reference Star.

    15. The fifteenth column contains an optional remark.

    16. The sixteenth column gives the Reference Star's Spectral Class.

    17. The seventeenth column give the Original File Name.

    18. The eighteenth column is the second optional remark.

Processing                                                                
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The data is dark frame subtracted and flat field corrected.

Data                                                                      
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The data consist of ASCII tables for several different comets. The
filenames tell which comet the table is for. A reference star with
known quantities is selected in order to compare with the comet 
and obtain necessary information to obtain the Afrho quantity.

If a value of 999.999 is given for a numerical value then it means
that entry is a null value.

Media/Format                                                              
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The data tables are given in the form of ASCII files.  These tables
do not use any sub- or super-script characters, and so are readable
in any format.

Spectra                                                                   
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The individual observations used to create the tables have not been 
submitted to PDS for archiving.

Review                                                                    
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This data has not yet been peer reviewed by PDS yet.