SkyMap Online | Professional edition

About the Sky Map Online, professional edition

The professional version of the Sky Map Online was reflected as the tool for amateure astronomers and for professional astronomers It provides the creation of maps with the magnitude limit for stars up to 21-st magnitude (limit of the First POSS) and field size from several arcmins to 80 by 60 degrees, what makes possible to use it for the following goals:

• Creation of pointing maps and preliminary star field identifying on the telescopes of any size. Guiding stars selection. Palomar Observatory Sky Survey map usage, what is widely used for such goals all over the world, is not always a good solution, especially if you need to identify rich field on the TV-camera view on the large telescope, where the magnitude limit is about 17th-18th. USNO A2.0 contains an information about the bad quality of stellar magnitude measurement for some objects, which usually (when you are not near the Milky Way) specifies a galaxy or some kind of nebula. Such objects are not recommended to use as guiding stars.
• Creation of maps for identifying of photographic plates from small astrographs (less than 1 meter in the diameter) or CCD-images from small telescopes. It may be hard to identify such images with POSS maps, if the magnitude limit on them is less than 17-th magnitude. Using this program you are able to select magnitude limit for stars, what will suppress stars fainter than your limit.
• Creation of "maps of background stars", which are usable for the amateur astronomers to make drawings of different types of deep-sky objects.

The main advantage of this Internet-version with a comparison to the widely used astronomical software is the fast creation of the map of any part of the sky with any magnitude limit, what is hard to realize on PC because of distribution problems of such amount of data (data size is about 7 Gigabytes). One more advantage is possibility of individual object labelling and adding from the WEB-browser.

The data used in the project

• Combination of 2 catalogs of stars: TYCHO and USNO A2.0. The USNO A2.0 catalogue has very poor quality of both astrometrical and photometrical data for stars brighter than 10-th stellar magnitude, which is compensated by TYCHO catalogue, which is almost full up to 10.5 in the V filter, and contains more then million of stars up to 12.5 magnitude with high precision coordinates and photometry in B and V bands. The USNO A2.0 is used only if you specify magnitude limit deeper than 10.5 and field size less than 10 degrees.
• RC3 catalogue of galaxies. The program is able to display RC3 galaxies on the maps. RC3 catalogues includes information about 23000 objects. Galaxies, which large axis exceeds 4 pixels in the scale of the map are displayed with their real positional angles and sizes by 25m isophote. Other galaxies are displayed as standard-size 5x8 pixels ellipses. In the nearest future LEDA database, which contains information about approximately 1.3 millions of objects will be used in the sky map.

Technology:

• WEB-interface and multilingual support is based on the ZLine software technological platform developed in Delta-Soft LLC. Mod_perl is used as the main development tool, what provides a significant performance gain compared to the usual CGI applications, because of the deep integration with Apache WEB-server.
• Object relational DBMS PostgreSQL with a special pgSphere module is used to provide an access to the HyperLEDA data. psSphere adds the native support for datatypes describing geometrical objects in the spherical coordinate system. The indexed data access methods are provided. pgSphere project has been created the basis for the pgAstro project, which main goal is to provide necessary functionality (data types and data access methods) to work with heterogeneous astronomical data and databases.

Main features of the program

• Displaying of about 530 millions of stars up to 21-st stellar magnitude, contained in the USNO A2.0 and TYCHO catalogues and 23023 galaxies up to 18-th integral stellar magnitude from RC3 catalogue.
• Identification of any object on the map after mouse click on it with a possibility of adding its description to the mark list.
• Labelling of the any objects on the map, new objects adding from the WEB-form.
• Printable copy creation in PDF format. This feature provide the map creation in the vector PDF format, which can be scaled without quality loosing and edited using the corresponding software (Adobe Acrobat). It is hardly recommended to use Adobe Acrobat Reader v3.0 or higher for viewing and printing of Sky Map PDF files. This software can be freely downloaded from Adobe FTP Server. USAGE OF Ghost View IS NOT RECOMMENDED. YOU MAY GET INCORRECT RESULTS FOR PRINTING.

Project is based on GD Library 1.2 (author Tom Boutell) for GIF-image creation and CPDF Library 2.0.2 ( FastIO Systems) for printable copy creation.

Project is being developed with a financial support of RFBR (project MAC #02-07-06096, MAC #03-07-06116, #02-07-90222)

If you have any comments, or bug reports, you may send them to the author: chil@astronet.ru

Igor Chilingarian
2003, January, 12-th

modified: 2004, January, 19-th