DB_OVER

COMMAND TYPE : GRAPHIC

PURPOSE:

Prepares an overlay map.

DESCRIPTION:

This task produces a file of stars and objects positions to get sky maps in the same scale of the astronomical plates (or prints), that can be plotted with the DB_OVPLOT command. The maps can be plotted on transparent films and overlapped to the plates for objects identification.

For each map the user defines the center field, the scale factor and the name of a reference stars catalogue. The center field generally coincides with the position of the object that must be identified. Otherwise when there are many close objects on the same plate, these can be plotted on the same map giving a suitable center field. Many maps can be produced at a time with different sets of objects coordinates in a PDB catalogue.

This program was developed, in the first version, to identify objects on the Palomar Sky Survey plates (1973 A. Ficarra, L.Padrielli). The transformations of the coordinates in the tangent plane use the method developped for the Schmidt camera (1962 Dixon).

The task evaluates the overlay position using the coordinates of the center of the plates. In the DIRA public data base the catalogues of the center field coordinates of the Palomar Sky Survey and of ESO Sky Survey are available.

INPUT FIELDS of the command:

Target center plate from PDB ?

When the user wants to produce overlay for plates he must have in the PDB a catalogue that contains the coordinates of the center fields of the plates. In this case he must enter Y here to use this catalogue.

Example : N

Catalogue

The name of the catalogue that contains the center field coordinates of the plates. Typically this catalogue is PSSCL for Palomar Sky Survey (North) or ESOSPL for Eso Sky Survey (South). These catalogues are in public database. Otherwise a private catalogue of plates center field can be used.

Example : PSSCL

Arcsec/mm.

Plate scale in arcsec/mm.. This value is 67.14 for Palomar Sky Survey and 67.20 for Eso Sky Survey.

Example : 67.14

Half width in arcmin

The user must enter here the half width size of the plates in arcmin. The values for Palomar and Eso Sky Surveys is 180.

Example : 180

Print

The user can obtain overlays for prints or for plates. He must enter Y when he works with prints.

Example : Y

Right Ascension

The user must enter here the name of the field that contains the Right Ascension in the catalogue of the center fields of the plates.

Example : RA

Declination

The user must enter here the name of the field that contains the Declination in the catalogue of the center fields of the plates.

Example : RA

Year

The user must enter here the year of the plates. This value can be a number or the name of a field in the plates center field catalogues. This value is used in the computation of the proper motion of the stars.

Example : 1950.

Target stars from PDB ?

The command uses a catalogue of star positions to plot the reference stars. Usually this catalogue is a public one, but the user can also work with a personal catalogue in his own PDB

Example : N

Catalogue

The name of the star positions catalogue. AGK3 (for North) or SAO are the catalogues used for the reference stars. The user can have a personal catalogue too, but the coordinates must be at equinox 1950.00 (Use DB_COCO to precess data) and have the proper motion values (PMRA, PMDEC fields)

Example : SAO

Right Ascension

The user must enter here the name of the field that contains the Right Ascension in the catalogue of star positions.

Example : RA

Declination

The user must enter here the name of the field that contains the declination in the catalogue of star positions.

Example : DEC

Magnitude

The star magnitudes are used by the task to plot different symbols in the overlay map. The user must enter here the name of the field that contains the magnitude in the catalogue of star positions.

Example : PHOTMAG

Superimposed objects from PDB ?

When the user has many objects near to an appropriate center field he can plot objects in an overlay map in different runs. The object file must be in the Personal Data Base and this flag must be set to Y. Else the user can choose to plot in the overlay maps other reference objects (qsos, galaxies and so on) selected from an existing catalogue. In a standard identification job, superimposed objects are not used.

Example : Y

Catalogue

The name of the catalogue of superimposed objects, that can be the objects to identify or other reference objects that will be plotted on the overlay map. When this field is empty no catalogue is used.

Example : MYCAT

Right Ascension

The user must enter here the name of the field that contains the Right Ascension in the catalogue of superimposed objects

Example : RA

Declination

The user must enter here the name of the field that contains the declination in the catalogue of superimposed objects

Example : DEC

Magnitude

The magnitudes of the superimposed objects are used by the task to plot different symbols in the overlay map. The user must enter here the name of the field that contains the magnitude in the catalogue of superimposed objects.

Example : MAG

Output file name:

The name of the output file that will contain overlay data and will be read by DB_OVPLOT to plot the map.

Example : FOR012.DAT

Center field from file ?

The center fields of the overlay maps to plot can be entered in an interactive way or can be read from a PDB catalogue. After this answer the program opens a window on the screen to ask for more input data. When the user has a catalogue of center fields in the PDB he can answer Y.

Example : Y

FILE OF CENTER FIELD, input:

Catalogue of center field

The name of the catalogue of the center fields. The center fields of the overlay maps frequently are the coordinates of the objects to identify. The catalogue must be in the PDB.

Example : MYOBJEC

Right Ascension

The user must enter here the name of the field that contains the Right Ascension in the catalogue of center fields.

Example : RA

Declination

The user must enter here the name of the field that contains the declination in the catalogue of center fields.

Example : DEC

Identif.

The user must enter here the name of the field that contains an identifier of the center field coordinate. This will be printed in the overlay map header to identify the map.

Example : NUMBER

Half width in arcmin

The size of the overlay map in arcmin.

Example : 45 45

Otherwise the task requires an INTERACTIVE input:

Identifier.

The user must enter here a name (or a number) that identifies the overlay. This will be plotted in the map.

Example : AN33

Center field RA

The user must enter here the value of the Right Ascension of the center field.

Example : 10 25 37.30

DEC

The user must enter here the value of the declination of the center field.

Example : -17 23 50.25

Half width in arcmin

The size of the overlay map in arcmin.

Example : 45 45

NOTE:

The program starts reading the input catalogues and type on the screen the number of stars and superimposed objects found in the fields.

The user must call DB_OVPLOT command to draw the overlay maps.



Previous: DB_MERGE
Up: Commands
Next: DB_OVPLOT
Previous Page: DB_MERGE
Next Page: DB_OVPLOT