BUGS · SEE_ALSO
eqxy -- Get pixel coordinates from equatorial positions.
eqxy iminfo image eqfile
This task will compute the pixel coordinates for a given set of equatorial (i.e., right ascension, declination) coordinates based on the plate solution coefficients. The pixel origin convention is set by the pixel_center parameter value. Usually this plate solution is in the input image header which is created by the Guide Star Selection System (the source of the image). The coefficients can be read from an ASCII file (coeffile)---see the help for task xyeq.
Output is sent to the terminal screen and consists of:
* The RA,DEC input coordinates * The 'X_nsol','Y_nsol' from the new plate solution * The 'X_osol','Y_osol' from the original plate solution or the 'X_cd','Y_cd' from the CD matrix values.
If you have an image one of these special headers, and you would like to create the information for your subimage, run the task makewcs which will generate the CRPIX, CRVAL, and CD values.
- iminfo [boolean]
- Is there an input image with plate solution coefficients in the header file?
- image [file name]
- Name of the image that has a set of coefficients with plate solution values in the image header. The keyword names for these values are AMDX1, AMDX2, AMDY1, AMDY2, etc., also, if pltsol was run it will contain NAMDX1, NAMDY1, etc. Values are in units of arcseconds per millimeter.
- rdfile [file name]
- Name of the input file containing equatorial coordinates
Right ascension is in hours (hh:mm:ss.dd) and declination is in degrees. This file can be an ASCII file in column form (there should be at least one blank between columns and the row length should not exceed 162 characters). You can define the input file to be STDIN, in which case you will be able to enter values directly from the keyboard; at least two values per input line. If you use STDIN, then press CTRL-Z to end the input session.
- pixel_center ("iraf") [string]
- Which convention your X,Y will have? If iraf then the center of the
lower left pixel is (1,1). If dss (Digital Scan Survey) then the
center of the lower left pixel is (1.5,1.5). If cos, then you
are using the COSMOS convention which is (0.5,0.5).
- rcolnum [integer]
- Column number in the ASCII file where right ascension values can be found.
- dcolnum [integer]
- Column number in the ASCII file where declination values can be found.
- nskip [integer]
- Number of lines to skip at the beginning of the ASCII file.
- coeffile [string]
- Name of the astrometric solution file.
- (cdmatx = no) [boolean]
- Use CD matrix values?
- (new = yes) [boolean]
- Use a new plate solution?
- (original = no) [boolean]
- Use original plate solution?
- xformat = "", yformat = ""
- The default output format for the output X and Y. If xformat or yformat
are undefined, then eqxy uses a default format of %8.2f.
A format specification has the form "%w.dCn", where w is the field width, d is the number of decimal places or the number of digits of precision, C is the format code, and n is radix character for format code "r" only. The w and d fields are optional. The format codes C are as follows:
b boolean (YES or NO) c single character (c or '\c' or '\0nnn') d decimal integer e exponential format (D specifies the precision) f fixed format (D specifies the number of decimal places) g general format (D specifies the precision) h hms format (hh:mm:ss.ss, D = no. decimal places) m minutes, seconds (or hours, minutes) (mm:ss.ss) o octal integer rN convert integer in any radix N s string (D field specifies max chars to print) t advance To column given as field W u unsigned decimal integer w output the number of spaces given by field W x hexadecimal integer z complex format (r,r) (D = precision) Conventions for w (field width) specification: W = n right justify in field of N characters, blank fill -n left justify in field of N characters, blank fill 0n zero fill at left (only if right justified) absent, 0 use as much space as needed (D field sets precision) Escape sequences (e.g. "\n" for newline): \b backspace (not implemented) \f formfeed \n newline (crlf) \r carriage return \t tab \" string delimiter character \' character constant delimiter character \\ backslash character \nnn octal value of character Examples %s format a string using as much space as required %-10s left justify a string in a field of 10 characters %-10.10s left justify and truncate a string in a field of 10 characters %10s right justify a string in a field of 10 characters %10.10s right justify and truncate a string in a field of 10 characters %7.3f print a real number right justified in floating point format %-7.3f same as above but left justified %15.7e print a real number right justified in exponential format %-15.7e same as above but left justified %12.5g print a real number right justified in general format %-12.5g same as above but left justified %h format as nn:nn:nn.n %15h right justify nn:nn:nn.n in field of 15 characters %-15h left justify nn:nn:nn.n in a field of 15 characters %12.2h right justify nn:nn:nn.nn %-12.2h left justify nn:nn:nn.nn %H / by 15 and format as nn:nn:nn.n %15H / by 15 and right justify nn:nn:nn.n in field of 15 characters %-15H / by 15 and left justify nn:nn:nn.n in field of 15 characters %12.2H / by 15 and right justify nn:nn:nn.nn %-12.2H / by 15 and left justify nn:nn:nn.nn \n insert a newline