AstroCatalog

Description

Class Hierarchy: Base -> Component -> AstroTable -> AstroCatalog

The AstroCatalog class is a container for storing and manipulating astronomical catalogs (i.e., tables with two-dimensional coordinates like X, Y or RA, Dec). This class inherits from AstroTable. The class includes the basic functionality needed for catalog manipulation. Additional help is available using:

help AstroCatalog
help AstroCatalog.AstroCatalog
% to see this file
open +manuals.AstroCatalog
AstroCatalog.help

% while a list of properties and methods is available by typing AstroCatalog followed by <tab>, or using
methods(AstroCatalog)

Class properties

This class inherits from AstroTable inherits from Component that inherits from Base. Additional properties for this class are:

• ColX - X/RA/Lon column index or column name.
• ColY - Y/Dec/Lat column index or column name.
• CooType - Indicating the main coordinate type 'pix' | 'sphere'.
• CooUnits - Indicating the spherical coordinate units - 'deg'|'rad'|'pix'.

In addition, the following are inherited from AstroTable:

• JD - A scalar representing the time (or mean epoch) of the catalog.
• Catalog - Containing the table data. This can be either a matrix, or a table.
• ColNames - A cell array of column names.
• ColUnits - A cell array of column units.
• ColDesc - A cell array of column descriptions.
• SortByCol - An array of column indices, or a cell array of column names by which the catalog is sorted.
• IsSorted - A logical indicating if the catalog is sorted.

In addition, the following hidden constant properties are available in Astrocatalog:

• DefNamesX = {'X','X_IMAGE','XWIN_IMAGE','X1','X_PEAK','XPEAK'};
• DefNamesY = {'Y','Y_IMAGE','YWIN_IMAGE','Y1','Y_PEAK','YPEAK'};
• DefNamesRA = {'RA','ALPHA','ALPHAWIN_J2000','ALPHA_J2000','RA_J2000','RAJ2000','RightAsc'};
• DefNamesDec = {'Dec','DELTA','DELTAWIN_J2000','DELTA_J2000','DEC_J2000','DEJ2000','Declination'};
• DefNamesPMRA = {'PMRA'};
• DefNamesPMDec = {'PMDec'};
• DefNamesRV = {'RV'};
• DefNamesPlx = {'Plx'};
• DefNamesMag = {'Mag','PSF_MAG','MAG_PSF','Mag_BP','Mag_G','Mag_RP'};

Constructor

The AstroCatalog constructor can be used to generate empty objects, or load tables into an AstroTable object. A few examples:

% create a single element AstroTable with an empty Catalog.
AC = AstroCatalog
% Create a 2x2 AstroTable with an empty Catalog
AC = AstroCatalog([2 2])
% Created a 1x2 AstroTable. In each catalog store a rand(10,2) matrix
AC = AstroCatalog({rand(10,2),rand(10,2)})
% THe same as the previous line + set the Column names to 'a' and 'b'
AC = AstroCatalog({rand(10,2),rand(10,2)},'ColNames',{'X','Y'});
% store tables
AC=AstroCatalog({array2table(rand(10,2))});
% Create an AstCat object (an old version of AstroTable)
A = AstCat;
A(1).Cat=rand(10,2);
A(2).Cat=rand(10,2); A(1).ColCell={'RA','Dec'};
A(1).ColUnits={'rad','rad'};
% read the AstCat object and convert it to AstroTable
AC = AstroCatalog(A);
% read from a FITS table
AC=AstroCatalog('asu.fit','HDU',2);

Setters and getters

The setters and getters will set the IsSorted to false when a Catalog is changed. Furthermore, when the ColNames is modified, if the Catalog property contains a table, it will be updated accordingly. In Addition getter for CooUnits - if empty, attempt to obtain from the catalog. Note this is not cleared when the catalog is changed.

Static methods

see AstroTable. unitTest - unitTest for the class

% test the class
AstroTable.unitTest

Methods

For many more methods see AstroTable. Note that AstroTable contains most of the useful functions for this class. General coordinates type and conversion

• convertCooUnits - Convert all coordinates Units for multiple element object
• isCooSphere - Check if RA/Dec (units) coordinates exist in an AstroCatalog.
• getCooType - Return the Coordinate type of an AstroCatalog.
• getCommonCooType - get common CooType for two AstroCatalog objects.
• getColCooForCooType - Get the X/RA and Y/Dec column indices for a specific CooType.

A few examples

% convert the units in the coordinate columns from 'rad' to 'deg'
AC=AstroCatalog({'asu.fit','asu.fit'},'HDU',2)
AC.convertCooUnits('deg')
Obj.convertCooUnits('deg')

Methods for retrieving coordinate columns

• getLonLat - Get Lon/Lat columns from AstroCatalog.
• getRADecPM - Get RA/Dec/PM/Plx/RV from astrometric catalog.
• getXY - Get X/Y columns from AstroCatalog.

Examples

% Get RA/Dec columns
AC=AstroCatalog({'asu.fit'},'HDU',2);
% get RA, Dec, or X, Y (according to CooType) in deg in seperate variables
[RA, Dec] = AC.getLonLat('deg');
% get RA, Dec in rad in a single two column array
[RADec]   = AC.getLonLat('rad');

AC=AstroCatalog({'asu.fit'},'HDU',2);
% get RA, Dec
[Lon,Lat] = getLonLat(AC);
[Lon,Lat] = getLonLat(AC,'rad');

% get proper motion information:
C=catsHTM.cone_search('GAIADR2',1,1,100,'OutType','astrocatalog');
[RA, Dec, PM_RA, PM_Dec, Plx, RV] = getRADecPM(C)

% get X, Y coordinates
AC=AstroCatalog({rand(100,2)},'ColNames',{'XWIN_IMAGE','YWIN_IMAGE'});
[X,Y] = getXY(AC);

Special coordinates related functions

• boundingCircle - Fit a bounding circle position and radius to a catalog
• sphere_dist - Calculate the spherical distance and PA between Lon,Lat in Astrocatalog and a Lon, Lat in array.
• cropXY - crop AstroCatalog object by X/Y coordinates. Examples
• interpCoo - Interpolate all elements in catalog, and treat Lon/Lat columns taking into account zero crossing (convert to cosine direction prior to interpolation).

% crop AstroCatalog by X,Y coordinates
AC = AstroCatalog({rand(100,3).*100}, 'ColNames',{'XWIN','YWIN','Flux'});
Result = cropXY(AC, [1 50 1 50])
Result = cropXY(AC, [81 100 41 70],'AddX',{'Flux'})
Result = cropXY(AC, [81 100 41 70; 1 50 1 50]); % multiple crops of a single catalog

% Calculate spherical distance between Lon,Lat and celestial coordinates in
% AstroCatalog
AC=AstroCatalog({'asu.fit'},'HDU',2);
[Dist, PA] = sphere_dist(AC,1,1);

Interpolation example:

[Cat]=celestial.SolarSys.jpl_horizons('ObjectInd','9804','StartJD',celestial.time.julday([14 6 2018]),'StopJD',  celestial.time.julday([20 6 2018]));
Res = Cat.interpCoo(celestial.time.julday([15 6 2018])+(0:0.01:1).');

Conversion to other formats:

• writeCSV - save the headers and source entries from an AstroCatalog object (or a vector of AC objects) to a single .csv file

% make a list of Catalog files in the current directory:
Files  = dir ( fullfile('./', '**', '*Cat*') );
NData  = numel(Files); Data   = repmat({''}, NData, 1);
       for IData = 1:1:NData
              Data{IData} = fullfile(Files(IData).folder, Files(IData).name);
        end
% make an AstroCatalog object from all the catalog FITS files:
AC = AstroCatalog(Data);
% save all the source entries from all the data files as a single .csv file with default delimiter (,):
AC.writeCSV('/home/ocs/cat.csv');