gcat -- get catalog at location gimages -- get images at location gstar -- get star statistics extract -- extract average vectors from catalogs mextract -- extract measurement vectors from catalogs imstats -- plot image statistics imextract -- extract image vectors from database lcat -- list catalogs in display region cmatch -- match two catalogs
There are a variety of other commands which directly refer to the photometry database. Some of these functions extract data of various types from the database, others perform more complex plotting operations. The commands listed above are those which simply extract data from the database. The first three list information relevant to a specific RA, DEC location on the sky: gcat (RA) (DEC) lists the catalog at the specified location and places the name in the variable $CATNAME, gimages (RA) (DEC) lists all images which overlap the specified location, gstars (RA) (DEC) (RADIUS) lists data about the stars within a specified radius of the specified location (all numbers above are given in decimal degrees). Similarly, lcat lists the catalogs in the region. Imstats lists statistics about each image
The next three commands extract a specific piece of information from the photometry database and places it in a vector. First, extract will extract average values for each star and place it in a vector. Next, mextract will extract measurement values for each star and place it in a vector: as a result a single star may have multiple entries in the measurement vectors. Finally, imextract will extract image statistics into vectors (not yet implemented).
catalog -- plot catalog stars cgrid -- plot sky coordinate grid cplot -- plot vectors in sky coordinates czplot -- plot scaled vectors in sky coordinates images -- plot image boxes imdense -- image density plot lcurve -- plot lightcurve for a star pcat -- plot catalog boundaries region -- define sky region for plot resid -- plot residuals simage -- plot stars in an image
There are two types of database plotting functions: those that display or refer to the spatial charateristics of the data and those that refer to other types of charatersitics, such as the time domain. The graphics window 0 is reserved for all plots of objects on the sky. The command region defines the current sky coordinates for plots in graphic window 0. The command pcat plots the outline of all photometry database files which are within the currently defined region (and by default, only those with data). images plots the outline of the images in the image database, while imdense shows the number of images at a location by randomly spacing dots within the boundary of the images. The command cgrid draws a grid in celestial coordinates on the for the current region.
The most complex, but also one of the most useful command is catalog, which plots the positions of stars in the photometry database (and others) on the sky. There are many options to this command. One set allows the user to plot stars from the photometry database (the default), from the HST GSC, or from an ASCII text file with RA, DEC, and Mag in specified columns. If the ASCII file has a fixed number of bytes per line, the data can be more quickly loaded. The size of the points may be scaled by the star magnitude, by the number of observations of the star, or by the number of missing datapoints for the star. In addition, points may be plotted only if they land in specified magnitude ranges, or with specified numbers of measurements, or missed measurements. Also, objects may be plotted only if they have a specified Average.code, so that only asteroids or only perfect stars may be plotted. The plotted vectors may be saved, if desired, and the source catalog epoch may be specified as different from J2000 (only valid for ASCII data).
Several other commands relate to non-spatial charateristics of images and stars. lcurve will plot a light curve for all stars within some radius of a point. resid plots the photometry residuals for a particular region file.
Some Examples
we need some better and more relevant examples
Fig. 1 shows a map of the entire sky, and the location
of the images currently in the database. This picture was made with
the following commands: (output is not shown)
status: region 0 0 90 gls status: cgrid status: style -lw 2 -c red status: images status: psIn this example, on the graphics window, the image boxes are shown in red. The user now has the possiblitiy of using the cursor command to narrow in on a specific region, and so forth.
Fig. 1 shows a map of the entire sky, and the location of
the images currently in the database from a polar project. This
picture was made with the following commands: (output is not shown)
status: region 0 0 90 zea status: cgrid status: style -lw 2 -c red status: images status: psIn this example, on the graphics window, the image boxes are shown in red. The user now has the possiblitiy of using the cursor command to narrow in on a specific region, and so forth.
Fig. 3 shows an example comparison of the photometry database star positions and the HST Guide Star Catalog star positions. The crosses are all objects in the photometry database, while the boxes are only the stars identified as USNO stars. The circles are the stars from the HST GSC. The size of both points is a function of brightness. This plot was made with the following commands (starting from the previous image):
status: cursor (typed 1 on region of interest) 1 137.097858 22.698305 q 137.097858 22.698305 status: region $R1 $D1 0.2 TAN status: cgrid status: box status: style -pt 0 status: gcat $R1 $D1 0 n2230/1951.cpt * status: style -pt 2; cat -all -m 12 18 status: style -pt 1; cat -all -m 12 18 -ID $USNO status: style -pt 7; cat -all -m 12 18 -g