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Astrometry and photometry with IDL

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Astrometry and photometry with IDL

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    1. Astrometry and photometry with IDL ASTROLIB http://idlastro.gsfc.nasa.gov/

    2. Astrometry and photometry with IDL First of all we have to read FITS-image into IDL data and header variable:

    3. Astrometry and photometry with IDL FIND sources on image

    4. Astrometry and photometry with IDL Centering Compute the centroid of a star using a derivative search CNTRD, image, x, y, xcen, ycen, [ fwhm] 2. Compute the stellar centroid by Gaussian fits to marginal X,Y, sums GCNTRD, image, x, y, xcen, ycen, [ fwhm ] 3. Fit a gaussian, lorentzian or Moffat model to data yfit = MPFIT2DPEAK(Z, A [, X, Y, /gaussian,/lorenzian,/moffat] )

    5. Astrometry and photometry with IDL Compute concentric aperture photometry: APER, image, xc, yc, [ mags, errap, sky, skyerr, phpadu, apr, skyrad, badpix, /FLUX, PRINT = , READNOISE = readnoise ]

    6. Astrometry and photometry with IDL Very useful function - queryvizier! Query any catalog in the Vizier database by position: info = QueryVizier (catalog, targetname_or_coords, [ dis, /ALLCOLUMNS, /CANADA, CONSTRAINT= ,/VERBOSE ]) 'II/282' - Sloan SDSS photometric catalog Release 6 (2007) 'USNO-B1' - Verson B1 of the US Naval Observatory catalog (2003) 'I/259/TYC2' - Tycho-2 main catalog (2000) 'I/239/HIP_MAIN' - Hipparcos main catalog (1997)

    7. Astrometry and photometry with IDL Identification of image stars with catalogue stars MAKE_ASTR - Build an astrometry structure from input parameter values: MAKE_ASTR, astr, CD = , DELT =, CRPIX =, CRVAL =, CTYPE =,LATPOLE = , LONGPOLE = AD2XY - Compute X and Y from WCS coordinates and a FITS astrometry structure: AD2XY, RA ,DEC, astr, x, y SRCOR - Correlate the source positions found on two lists: srcor,x1in,y1in,x2in,y2in,dcr,ind1,ind2,/spherical

    8. Astrometry and photometry with IDL STARAST - Compute astrometric solution using positions of 2 or 3 reference stars starast, ra, dec, x, y, cd, [/Righthanded, HDR = header, PROJECTION=] For computing more precise astrometric solution using position of all reference stars in frame you can use: astrom, RAref, DECref, idgs, ximg, yimg, astr, err astr – astrometry structure containing the initial guess of plate solution

    9. Astrometry and photometry with IDL PUTAST - Put WCS astrometry parameters into a given FITS header: PUTAST, header, astr EXTAST - Extract Astrometry parameters from a FITS image header: EXTAST, header, astr

    10. Astrometry and photometry with IDL Finally we have to write astrometric solution to FITS-image: writefits,filename,image,header

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