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Why is the deep-sky and stellar database different in Deep-Sky Planner 6?
The data catalogs that compose the database are taken from professional, peer-reviewed results (see exceptions below.) Catalogs are viewed as different research results because the goals of the studies that produce each catalog differ. Researchers use differing techniques to study various aspects of the objects that appear in their catalog(s). This accounts for the difference in data between catalogs, even for the same object. That is why you can click on an object in a report and view data for the object as it appears in other catalogs.
Catalogs may also contain a type of data not found in others. For this reason, Deep-Sky Planner treats data for each cataloged object uniquely. If an object in a catalog includes cross references for the object in other catalogs, these other object designations appear in Deep-Sky Planner reports as cross references. Currently there are over 1,250,000 objects in the database (841,000 deep-sky and 411,000 stellar objects.) There are over 361,500 common names and over 324,000 cross-references included.
Exceptions: The term 'catalog' is not accurate for the Caldwell, Herschel 400, Herschel 2, and Messier objects; however, they are treated as catalogs within Deep-Sky Planner because they are in extensive use by astronomers. The data for these objects is taken primarily from the Revised NGC/IC (Steinicke, 2012) catalog.
Multiple catalog searching
Deep-Sky Planner has always offered the advantages of searching single catalogs as described below. By user request, Deep-Sky Planner 6 also has the ability to select multiple catalogs for one report. A multi-catalog search omits the catalog specific information but includes the type of information common to all selected catalogs.
Better data presentation
Reports on single catalogs contain the essential data present in all catalogs (RA, Declination, constellation, star atlas cross references, etc), but importantly, the database remains true to original catalog contents so that reports contain the additional data unique to each catalog. For example, a report of Abell Galaxy Clusters includes the number of member galaxies and the Bautz-Morgan type, and a report of Monella's Globular Clusters includes the Shapley-Sawyer concentration class.
Making catalog data easier to use
Professional data catalogs are readily available via the Internet and those available change constantly, but placing a catalog in Deep-Sky Planner's database is not at all trivial. The data is formatted for the database and extensively cross referenced. Helpful features in the user interface and reports are also updated when a new catalog is added to the product.
For example, most deep-sky object catalogs contain angular size data though some don't. The original catalogs use different units of measure for angular size data and different precision - planetary nebulae in the PNG catalog are measured in arc seconds while Zwicky galaxy clusters are measured in hundredths of square degrees. The range of angular size values present in a catalog also varies greatly. The user interface helps you to search by:
- permitting you to select a range of angular sizes only for catalogs that contain that data
- permitting you to select a range of angular sizes within the limits of the catalog (limits are shown for the catalog)
- permitting entry in the appropriate unit of measure and precision for the selected catalog (both are shown)
In addition, the report generated from the search only shows angular size if it is present in the catalog, and size data is shown in the appropriate unit of measure and precision for the catalog. Other types of data are treated similarly (magnitude, angular separation of double stars, etc.) Taken together, these features help to make the catalog data more useful to the end-user.
If you would like to request the addition of a catalog to the Deep-Sky Planner database, please send your request to Knightware.
This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France
The NASA/IPAC Extragalactic Database (NED) is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
We acknowledge the usage of the HyperLeda database (http://leda.univ-lyon1.fr).
Revised NGC/IC data are compiled by Dr. Wolfgang Steinicke and subject to copyright. The Revised NGC/IC is used under license from Dr. Steinicke.