The data/+cats package
in the MATLAB Astronomy & Astrophysics Toolbox
Description
The +cats package contains astronomical catalogs, maps, spectra, and auxiliary files. Its main function is to allow easy access, search and cross-match of astronomical catalogs. This package is optimize for catalogs which size (number of rows) is smaller than about 10^5-10^6. For larger catalogs see catsHTM.
Credit
If you are using this code or products in your scientific publication please give a reference to Ofek (2014; ascl.soft 07005).
License
Unless specified otherwise this code and products are released under the GNU general public license version 3.
Installation
See http://weizmann.ac.il/home/eofek/matlab/doc/install.html for installation instruction and additional documentation.
The instellation of the +cats package requires running the command: VO.search_prep_data_dir.
You have to run this command once after you instaled the MATLAB Astronomy & Astrophysics Toolbox.
Structure and methodlogy
The package contains subpacakes of catalogs. The catalosg are saved in either mat files, hdf5 files, or FITS files. When a new catalof is added, it is important to execute the VO.search.prep_data_dir command (see also VO documentation).
Most catalogs are stored as AstCat object (a catalog container). However, other formats are supported too.
The interface function to the catalogs is called VO.search.catalog_interface.
Content and subpacakges
To view the contents of the cats directory, type from the matlab command prompt "cats." followed by <tab>.
Content
Currently the following subpackages are available:
- binaries - Binary stars catalogs.
- bright - Bright stars and object catalogs.
- compact - Compact objects - White Dwarfs, Neutron Stars, and Black Holes.
- galaxies - Galaxy and galaxy cluster catalogs.
- gamma - gamma-rays catalogs.
- maps - Maps (e.g., FIRST coverage map, SFD Galactic extinction).
- radio - Radio catalogs.
- SDSS - SDSS related catalogs.
- SN - Supernovae related catalogs.
- sources - UV/Visible/IR catalogs.
- spec - Spectroscopy related catalogs (e.g., Astronomical filters - see AstFilter; spectral lines).
- stars - Stellar evolutionary tracks.
- X - X-Ray catalogs.
Instellation
Before using the cats package, you need to generate the interface functions. This is done using the VO.search.prep_data_dir command. This command will generate an interface function for each catalog.
VO.search.prep_data_dir
% or if you want to install in a different location:
VO.search.prep_data_dir('Dir','/home/myname/matlab/data/+cats');
Examples
% load the FIRST catalog
F = cats.radio.FIRST
Important: when you load a catalog, it is uploaded to your output variable (F in the example) and also is being uploaded to the MATLAB session under the catalog name (FIRST in the example). In the next time you run this command, the function will identify the file in the matlab session and will not re-upload the file (saves times). If from some reason you need to delete the file or upload it again you have to clear the variable name (e.g., "clear FIRST").
You can search the catalogs directly using the upload command. For example, search the FIRST catalog around RA=180 deg, Dec=10 deg with search radius of 1800 arcsec:
F=cats.radio.FIRST(180,10,3600)
Note this command returns an AstCat object with the objects found in the search radius. However, in addition, the full catalog is uploaded into a session variable named in this example FIRST.
In order to view the help for additional options:
cats.radio.FIRST('h')
To see the catalog available colums and units:
cats.radio.FIRST('c');
You can also execute a query on the catalog columns
cats.radio.FIRST('q','RA>pi & Dec<1 & Fpeak>Fint & Fpeak>100')