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diff --git a/pkg/images/imcoords/doc/imcctran.hlp b/pkg/images/imcoords/doc/imcctran.hlp new file mode 100644 index 00000000..760f3caf --- /dev/null +++ b/pkg/images/imcoords/doc/imcctran.hlp @@ -0,0 +1,598 @@ +.help imcctran Oct00 images.imcoords +.ih +NAME +imcctran -- convert between image celestial coordinate systems +.ih +USAGE +imcctran image outsystem +.ih +PARAMETERS +.ls image +The list of images whose celestial coordinate systems are to be converted. The +image celestial coordinate system must be one of the standard FITS celestial +coordinate systems: equatorial (FK4, FK4-NO-E, FK5, ICRS, or GAPPT), ecliptic, +galactic, or supergalactic. +.le +.ls outsystem +The input and output celestial coordinate systems. The options are +the following: +.ls <imagename> [wcs] +The celestial coordinate system is the world coordinate system of the image +<imagename> and the input or output pixel coordinates may be in the +"logical", "tv", "physical" or "world" coordinate systems. If wcs is not +specified "logical" is assumed, unless the input coordinates are read from the +image cursor, in which case "tv" is assumed. The image celestial coordinate +system must be one of the valid FITS celestial coordinate systems: +equatorial (FK4, FK4-NO-E, FK5, or GAPPT), ecliptic, galactic, or +supergalactic. +.le +.ls equinox [epoch] +The equatorial mean place post-IAU 1976 (FK5) system if equinox is a +Julian epoch, e.g. J2000.0 or 2000.0, or the equatorial mean place +pre-IAU 1976 system (FK4) if equinox is a Besselian epoch, e.g. B1950.0 +or 1950.0. Julian equinoxes are prefixed by a J or j, Besselian equinoxes +by a B or b. Equinoxes without the J / j or B / b prefix are treated as +Besselian epochs if they are < 1984.0, Julian epochs if they are >= 1984.0. +Epoch is the epoch of the observation and may be a Julian +epoch, a Besselian epoch, or a Julian date. Julian epochs +are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to the epoch type of +equinox if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. If undefined epoch defaults to equinox. +.le +.ls icrs [equinox] [epoch] +The International Celestial Reference System where equinox is +a Julian or Besselian epoch e.g. J2000.0 or B1980.0. +Equinoxes without the J / j or B / b prefix are treated as Julian epochs. +The default value of equinox is J2000.0. +Epoch is a Besselian epoch, a Julian epoch, or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Julian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. If undefined epoch defaults to equinox. +.le +.ls fk5 [equinox] [epoch] +The equatorial mean place post-IAU 1976 (FK5) system where equinox is +a Julian or Besselian epoch e.g. J2000.0 or B1980.0. +Equinoxes without the J / j or B / b prefix are treated as Julian epochs. +The default value of equinox is J2000.0. +Epoch is a Besselian epoch, a Julian epoch, or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Julian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. If undefined epoch defaults to equinox. +.le +.ls fk4 [equinox] [epoch] +The equatorial mean place pre-IAU 1976 (FK4) system where equinox is a +Besselian or Julian epoch e.g. B1950.0 or J2000.0, +and epoch is the Besselian epoch, the Julian epoch, or the Julian date of the +observation. +Equinoxes without the J / j or B / b prefix are treated +as Besselian epochs. The default value of equinox is B1950.0. Epoch +is a Besselian epoch, a Julian epoch, or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Besselian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. If undefined epoch defaults to equinox. +.le +.ls noefk4 [equinox] [epoch] +The equatorial mean place pre-IAU 1976 (FK4) system but without the E-terms +where equinox is a Besselian or Julian epoch e.g. B1950.0 or J2000.0, +and epoch is the Besselian epoch, the Julian epoch, or the Julian date of the +observation. +Equinoxes without the J / j or B / b prefix are treated +as Besselian epochs. The default value of equinox is B1950.0. +Epoch is a Besselian epoch, a Julian epoch, or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Besselian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian day. If undefined epoch defaults to equinox. +.le +.ls apparent epoch +The equatorial geocentric apparent place post-IAU 1976 system where +epoch is the epoch of observation. +Epoch is a Besselian epoch, a Julian epoch or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Besselian +epochs if the epoch value < 1984.0, Julian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. +.le +.ls ecliptic epoch +The ecliptic coordinate system where epoch is the epoch of observation. +Epoch is a Besselian epoch, a Julian epoch, or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Besselian epochs +if the epoch values < 1984.0, Julian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian day. +.le +.ls galactic [epoch] +The IAU 1958 galactic coordinate system. +Epoch is a Besselian epoch, a Julian epoch or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Besselian +epochs if the epoch value < 1984.0, Julian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. The default value of epoch is B1950.0. +.le +.ls supergalactic [epoch] +The deVaucouleurs supergalactic coordinate system. +Epoch is a Besselian epoch, a Julian epoch or a Julian date. +Julian epochs are prefixed by a J or j, Besselian epochs by a B or b. +Epochs without the J / j or B / b prefix default to Besselian +epochs if the epoch value < 1984.0, Julian epochs +if the epoch value <= 3000.0, otherwise epoch is interpreted as +a Julian date. The default value of epoch is B1950.0. +.le + +In all the above cases fields in [] are optional with the defaults as +described. The epoch field for the fk5, icrs, galactic, and supergalactic +coordinate systems is required only if the input coordinates are in the +equatorial fk4, noefk4, fk5, or icrs systems and proper motions are defined. +.le +.ls nx = 10, ny = 10 +The dimensions of the coordinate grid used to compute the rotation angle and, +optionally, the x and y magnification factors required to transform the input +image celestial coordinate system to the output celestial coordinate system. +.le +.ls longpole = no +If longpole = yes the zenithal projections ARC, SIN, STG, TAN, and ZEA +will be transformed by updating the longpole and latpole parameters instead +of rotating the CD matrix in the usual manner. +.le +.ls verbose = yes +Print messages about actions taken by the task on the standard output ? +.le +.ls update = yes +Update the image celestial coordinate system ? +.le + +.ih +DESCRIPTION + +IMCCTRAN converts the celestial coordinate system stored in the headers of the +input images \fIimage\fR to the celestial coordinate system specified by +\fIoutsystem\fR, and updates the input image header appropriately. The input +and output celestial coordinate systems must be one of the following: +equatorial, ecliptic, galactic, or supergalactic. The equatorial coordinate +systems must be one of: 1) FK4, the mean place pre-IAU 1976 system, 2) FK4-NO-E, +the same as FK4 but without the E-terms, 3) FK5, the mean place post-IAU 1976 +system, 4), ICRS, the International Celestial Reference System, 5) GAPPT, +the geocentric apparent place in the post-IAU 1976 system. + +The input celestial coordinate system is read from the input image header. +IMCCTRAN assumes that the celestial coordinate system is specified by the FITS +keywords CTYPE, CRPIX, CRVAL, CD (or alternatively CDELT / CROTA), RADECSYS, +EQUINOX (or EPOCH), MJD-WCS (or MJD-OBS, or DATE-OBS). USERS SHOULD TAKE NOTE +THAT MJD-WCS IS CURRENTLY NEITHER A STANDARD OR A PROPOSED FITS STANDARD +KEYWORD. HOWEVER IT OR SOMETHING SIMILAR, IS REQUIRED TO SPECIFY THE EPOCH OF +THE COORDINATE SYSTEM WHICH MAY BE DIFFERENT FROM THE EPOCH OF THE OBSERVATION. + +The first four characters of the values of the ra / longitude and dec / latitude +axis CTYPE keywords specify the celestial coordinate system. The currently +permitted values of CTYPE[1:4] are RA-- / DEC- for equatorial coordinate +systems, ELON / ELAT for the ecliptic coordinate system, GLON / GLAT for the +galactic coordinate system, and SLON / SLAT for the supergalactic coordinate +system. + +The second four characters of the values of the ra / longitude and dec / +latitude axis CTYPE keywords specify the sky projection geometry. IRAF +currently supports the AIT, ARC, CAR, CSC, GLS, MER, PAR, PCO, QSC, +SIN, STG, TAN, TSC, and ZEA geometries as well as two internal projection +geometries TNX, and ZPX. Consequently the currently permitted values of +CTYPE[5:8] are -AIT, -ARC, -CAR, -CSC, -GLS, -MER, -PAR, -PCO, -QSC, +-SIN, -STG, -TAN, -TSC, -ZEA as well as -ZPX and -TNX. + +If the input image celestial coordinate system is equatorial, the value of the +RADECSYS keyword specifies which fundamental equatorial system is to be +considered. The permitted values of RADECSYS are FK4, FK4-NO-E, FK5, ICRS, +and GAPPT. If the RADECSYS keyword is not present in the image header, the +values of the EQUINOX / EPOCH keywords (in that order of precedence) are used +to determine the fundamental equatorial coordinate system. EQUINOX or EPOCH +contain the epoch of the mean place and equinox for the FK4, FK4-NO-E, FK5, +and ICRS systems (e.g 1950.0 or 2000.0). The default equatorial system is +FK4 if EQUINOX or EPOCH < 1984.0, FK5 if EQUINOX or EPOCH >= 1984.0, and FK5 +if RADECSYS, EQUINOX, and EPOCH are undefined. If RADECSYS is defined but +EQUINOX and EPOCH are not, the equinox defaults to 1950.0 for the FK4 and +FK4-NO-E systems, and 2000.0 for the FK5 and ICRS systems. The equinox value is +interpreted as a Besselian epoch for the FK4 and FK4-NO-E systems, and as a +Julian epoch for the FK5 and ICRS systems. Users are +strongly urged to use the EQUINOX keyword in preference to the EPOCH keyword, +if they must enter their own equinox values into the image header. The FK4 and +FK4-NO-E systems are not inertial and therefore also require the epoch of the +observation (the time when the mean place was correct), in addition to the +equinox. The epoch is specified, in order of precedence, by the values of the +keywords MJD-WCS or MJD-OBS (which contain the modified Julian date, JD - +2400000.5, of the coordinate system), or the DATE-OBS keyword (which contains +the date of the observation in the form DD/MM/YY, CCYY-MM-DD, or +CCYY-MM-DDTHH:MM:SS.S). As the latter quantity may +only be accurate to a day, the MJD-WCS or MJD-OBS specification is preferred. +If all 3 keywords are absent the epoch defaults to the value of equinox. +Equatorial coordinates in the GAPPT system require only the specification +of the epoch of observation which is supplied via the MJD-WCS, MJD-OBS, +or DATE-OBS keywords (in that order of precedence) as for the FK4 and +FK4-NO-E system. + +If the input image celestial coordinate system is ecliptic the mean ecliptic +and equinox of date are required. These are supplied via the MJD-WCS, MJD-OBS, +or DATE-OBS keywords (in that order or precedence) as for the equatorial FK4, +FK4-NO-E, and GAPPT systems. + +The output coordinate system is specified by the \fIoutsystem\fR parameter +as described in the PARAMETERS section. + +If an error is encountered when decoding the input or output world coordinate +systems, an error message is printed on the standard output (if \fIverbose\fR +is "yes"), and the input image left unmodified. + +If the input projection is one of the zenithal projections TAN, SIN, STG, +ARC, or ZEA, then the header coordinate transformation can be preformed by +transforming the CRVAL parameters and rotating the CD matrix as described in +detail below. Otherwise the CRVAL values are transformed, the CD matrix is +left unmodified, and the LONGPOLE and LATPOLE parameters required to perform +the rotation are computed. If \fIlongpole\fR is yes then the zenithal +coordinate systems will also be transformed using LONGPOLE and LATPOLE. At +present IRAF looks for longpole and latpole parameters in the appropriate +WATN_* keywords. If these are undefined the appropriate default values for +each projection are assumed and new values are written to the WATN_* keywords. + +The new image celestial coordinate system is computed as follows. First a +grid of \fInx\fR by \fIny\fR pixel and celestial coordinates, evenly spaced +over the input image, is generated using the input image celestial coordinate +system. Next these input celestial coordinates are transformed to coordinates +in the output celestial coordinate system. Next the input celestial coordinates +of the reference point (stored in degrees in the input image CRVAL keywords) +are transformed to coordinates in the output celestial coordinate system, +and new x and y pixel coordinates are computed using the transformed reference +point coordinates but the original input CD matrix. The differences +between the predicted and initial x and y pixel coordinates are used to +compute the x and y axis rotation angles and the x and y magnification factors +required to transform the original CD matrix to the correct new CD matrix. +The process is shown schematically below. + +.nf +1. x,y(input grid) -> ra,dec(input grid) + +2. ra,dec(input grid) -> ra,dec(output grid) + +3. ra_ref,dec_ref(input) -> ra_ref,dec_ref(output) + +4. ra,dec(output grid) -> x,y(predicted grid) + +5. x,y(input grid) -> F -> x,y(predicted grid) + +6. cd matrix(input) -> F -> cd matrix(output) +.fi + +F is the fitted function of the x and y axis rotation angles and the +x and y scaling factors required to match the input x and y values to the +predicted x and y values. + +For most celestial coordinate transformations the fitted x and y scale factors +will be very close to 1.0 and the x and y rotation angles will be almost +identical. However small deviations from unity scale factors and identical +x and y axis rotation angles do occur when transforming coordinates systems +with the skewed axes. + +The precision of the transformations is usually very high, on the order +of 10E-10 to 10E-11 in most cases. However conversions to and from the FK4 +equatorial system are less precise as these transformations +involve the addition and subtraction of the elliptical aberration +or E-terms. In this case the x and y scale factors correct for the first +order E-terms and do significantly improve the precision of the coordinate +transformation. The quadratic terms, i.e. terms in xy, x**2, and y**2 +however are not corrected for, and their absence does diminish the precision +of the transformation coordinate transformation. For most practical purposes +this loss of precision is insignificant. + +After the fit is completed, the celestial coordinates of the reference point +in dd:mm:ss.s in the old and new systems, the rotation angle in degrees, the x +and y scaling factors, and an estimate of the rms error of the x and y +coordinate transformation are printed on the standard output. + +If \fIupdate\fR is yes, then the image header parameters CRVAL, CD, +CTYPE, RADECSYS, EQUINOX, EPOCH, and MJD-WCS are modified, deleted, or +added as appropriate. The position of the reference pixel in the +image (stored in the CRPIX keywords), and the sky projection geometry, e.g. +TAN, SIN, ARC, ETC are unchanged. + +USERS NEED TO BE AWARE THAT THE IRAF IMAGE WORLD COORDINATE SYSTEM +CURRENTLY (IRAF VERSIONS 2.10.4 PATCH 2 AND EARLIER) SUPPORTS ONLY THE +EQUATORIAL SYSTEM (CTYPE (ra axis) = "RA--XXXX" CTYPE (dec axis) = "DEC-XXXX") +WHERE XXXX IS THE PROJECTION TYPE, EVEN THOUGH THE IMCCTRAN TASK +SUPPORTS GALACTIC, ECLIPTIC, AND SUPERGALACTIC COORDINATES. IMCCTRAN will +update the image correctly for non-equatorial systems, but IRAF will +not be able to read these transformed image coordinate systems correctly. + +USERS SHOULD ALSO REALIZE THAT IMAGE WORLD COORDINATE SYSTEM REPRESENTATION +IN FITS IS STILL IN THE DRAFT STAGE. ALTHOUGH IMCCTRAN TRIES TO CONFORM TO +THE CURRENT DRAFT PROPOSAL AS MUCH AS POSSIBLE, WHERE NO ADOPTED STANDARDS +CURRENTLY EXIST, THE FINAL FITS STANDARD MAY DIFFER FROM THE ONE ADOPTED HERE. + +.ih +REFERENCES + +Additional information on the IRAF world coordinate systems can be found in +the help pages for the WCSEDIT and WCRESET tasks. +Detailed documentation for the IRAF world coordinate system interface MWCS +can be found in the file "iraf$sys/mwcs/MWCS.hlp". This file can be +formatted and printed with the command "help iraf$sys/mwcs/MWCS.hlp fi+ | +lprint". + +Details of the FITS header world coordinate system interface can +be found in the draft paper "World Coordinate Systems Representations Within the +FITS Format" by Hanisch and Wells, available from the iraf anonymous ftp +archive and the draft paper which supersedes it "Representations of Celestial +Coordinates in FITS" by Greisen and Calabretta available from the NRAO +anonymous ftp archives. + +The spherical astronomy routines employed here are derived from the Starlink +SLALIB library provided courtesy of Patrick Wallace. These routines +are very well documented internally with extensive references provided +where appropriate. Interested users are encouraged to examine the routines +for this information. Type "help slalib" to get a listing of the SLALIB +routines, "help slalib opt=sys" to get a concise summary of the library, +and "help <routine>" to get a description of each routine's calling sequence, +required input and output, etc. An overview of the library can be found in the +paper "SLALIB - A Library of Subprograms", Starlink User Note 67.7 +by P.T. Wallace, available from the Starlink archives. + +.ih +EXAMPLES + +[1]. Precess the equatorial FK5 J2000 celestial coordinate system of the +input 512 by 512 pixel square input image to J1975.0. + +.nf +cl> imcctran image j1975.0 + +INPUT IMAGE: image +Insystem: image logical Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J2000.000 + Epoch: J1987.25667351 MJD: 46890.00000 +Outsystem: j1975 Coordinates: equatorial FK5 + Equinox: J1975.000 Epoch: J1975.00000000 MJD: 42413.25000 +Crval1,2: 201:56:43.5, 47:27:16.0 -> 201:40:53.8, 47:35:01.2 dd:mm:ss.s + Scaling: Xmag: 1.000000 Ymag: 1.000000 Xrot: 359.923 Yrot: 359.923 degrees + Rms: X fit: 8.465123E-11 pixels Y fit: 5.204446E-11 pixels +.fi + +Before the transformation the image coordinate system looked like the following. + +.nf + ... + EPOCH = 2000 + DATE-OBS= '05/04/87' + CRPIX1 = 257.75 + CRPIX2 = 258.93 + CRVAL1 = 201.94541667302 + CRVAL2 = 47.45444 + CDELT1 = -2.1277777E-4 + CDELT2 = 2.1277777E-4 + CTYPE1 = 'RA---TAN' + CTYPE2 = 'DEC--TAN' + ... +.fi + +After the transformation the header looks like the following. + +.nf + ... + DATE-OBS= '05/04/87' + CRPIX1 = 257.75 + CRPIX2 = 258.93 + CRVAL1 = 201.681616387759 + CRVAL2 = 47.583668865029 + CTYPE1 = 'RA---TAN' + CTYPE2 = 'DEC--TAN' + RADECSYS= 'FK5 ' + EQUINOX = 1975. + MJD-WCS = 42413.25 + WCSDIM = 2 + CD1_1 = -2.1277757990523E-4 + CD1_2 = 2.84421945372844E-7 + CD2_1 = 2.84421945363011E-7 + CD2_2 = 2.12777579905235E-4 + LTM1_1 = 1. + LTM2_2 = 1. + WAT0_001= 'system=image' + WAT1_001= 'wtype=tan axtype=ra' + WAT2_001= 'wtype=tan axtype=dec' + ... +.fi + +Note the rms of the x and y fits is on the order 10.0e-10 to 10.0e-11 which +is the expected numerical precision of the transformation. + + +[2]. Convert the input image used in example 1 to the BFK4 1950.0 system. + +.nf +cl> imcctran image B1950.0 + +INPUT IMAGE: image +Insystem: image logical Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J2000.000 + Epoch: J1987.25667351 MJD: 46890.00000 +Outsystem: B1950 Coordinates: equatorial FK4 + Equinox: B1950.000 Epoch: B1950.00000000 MJD: 33281.92346 +Crval1,2: 201:56:43.5, 47:27:16.0 -> 201:25:02.3, 47:42:47.1 dd:mm:ss.s + Scaling: Xmag: 0.999999 Ymag: 0.999999 Xrot: 359.848 Yrot: 359.848 degrees + Rms: X fit: 1.302837E-7 pixels Y fit: 8.545616E-8 pixels + +.fi + +Note that precision of the transformation is still good but is significantly +less that the precision of the previous example. This is due to the fact +that the quadratic terms in the E-term computation are not included in the +transformation. + +The transformed image header in this case looks like the following. + +.nf + ... + DATE-OBS= '05/04/87' + CRPIX1 = 257.75 + CRPIX2 = 258.93 + CRVAL1 = 201.417300629944 + CRVAL2 = 47.7130749603847 + CTYPE1 = 'RA---TAN' + CTYPE2 = 'DEC--TAN' + RADECSYS= 'FK4 ' + EQUINOX = 1950. + MJD-WCS = 33281.92345905 + WCSDIM = 2 + CD1_1 = -2.1277680505752E-4 + CD1_2 = 5.66226465943254E-7 + CD2_1 = 5.66226470798410E-7 + CD2_2 = 2.12776805056766E-4 + LTM1_1 = 1. + LTM2_2 = 1. + WAT0_001= 'system=image' + WAT1_001= 'wtype=tan axtype=ra' + WAT2_001= 'wtype=tan axtype=dec' + ... +.fi + + +[3]. Transform the celestial coordinate system of the input image used in +examples 1 and 2 to the galactic coordinate system. + +.nf +cl> imcctran image galactic + +INPUT IMAGE: image +Insystem: image logical Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J2000.000 + Epoch: J1987.25667351 MJD: 46890.00000 +Outsystem: galactic Coordinates: galactic + MJD: 33281.92346 Epoch: J1949.99979044 B1950.00000000 +rval1,2: 201:56:43.5, 47:27:16.0 -> 106:01:19.4, 68:27:46.1 dd:mm:ss.s + Scaling: Xmag: 1.000000 Ymag: 1.000000 Xrot: 202.510 Yrot: 202.510 degrees + Rms: X fit: 9.087450E-11 pixels Y fit: 3.815443E-11 pixels +.fi + +The transformed header looks like the following. + +.nf + ... + DATE-OBS= '05/04/87' + CRPIX1 = 257.75 + CRPIX2 = 258.93 + CRVAL1 = 106.022047915293 + CRVAL2 = 68.4627934475432 + CTYPE1 = 'GLON-TAN' + CTYPE2 = 'GLAT-TAN' + MJD-WCS = 33281.92345905 + WCSDIM = 2 + CD1_1 = 1.96567112095654E-4 + CD1_2 = 8.14601120181094E-5 + CD2_1 = 8.14601120174619E-5 + CD2_2 = -1.9656711209802E-4 + LTM1_1 = 1. + LTM2_2 = 1. + WAT0_001= 'system=image' + WAT1_001= 'wtype=tan axtype=glon' + WAT2_001= 'wtype=tan axtype=glat' + ... +.fi + +Users should not that although imcctran can write a legal galactic coordinate +system to the image header, it and other iraf tasks cannot currently +read this coordinate system. + +[4]. Repeat the previous example but don't update the image header. + +.nf +cl> imcctran image galactic update- + +INPUT IMAGE: image +Insystem: image logical Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J2000.000 + Epoch: J1987.25667351 MJD: 46890.00000 +Outsystem: galactic Coordinates: galactic + MJD: 33281.92346 Epoch: J1949.99979044 B1950.00000000 + +Current wcs + Axis 1 2 + Crval 201.9454 47.4544 + Crpix 257.75 258.93 + Cd 1 -2.128E-4 0. + Cd 2 0. 2.128E-4 + +New wcs + Axis 1 2 + Crval 106.0220 68.4628 + Crpix 257.75 258.93 + Cd 1 1.966E-4 8.146E-5 + Cd 2 8.146E-5 -1.966E-4 + +Crval1,2: 201:56:43.5, 47:27:16.0 -> 106:01:19.4, 68:27:46.1 dd:mm:ss.s + Scaling: Xmag: 1.000000 Ymag: 1.000000 Xrot: 202.510 Yrot: 202.510 degrees + Rms: X fit: 9.087450E-11 pixels Y fit: 3.815443E-11 pixels +.fi + +[5]. Repeat example 1 and check the accuracy of the results by using the +skyctran task on the original image and on the transformed image. + +.nf +cl> type coords + 1.0 1.0 +512.0 1.0 +512.0 512.0 + 1.0 512.0 + +cl> skyctran coords STDOUT "image logical" J1975.0 + +Insystem: image logical Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J2000.000 + Epoch: J1987.25667351 MJD: 46890.00000 +Outsystem: j1975 Coordinates: equatorial FK5 + Equinox: J1975.000 Epoch: J1975.00000000 MJD: 42413.25000 + +Input file: coords Output file: STDOUT + + 1.0 1.0 13:27:02.9797 47:31:43.269 +512.0 1.0 13:26:24.3330 47:31:43.793 +512.0 512.0 13:26:24.3448 47:38:15.219 + 1.0 512.0 13:27:03.0718 47:38:14.693 + +cl> imcctran image j1975.0 + +cl> skyctran coords STDOUT "image logical" "image world" + +Insystem: image logical Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J1975.000 + Epoch: J1975.00000000 MJD: 42413.25000 +Outsystem: image world Projection: TAN Ra/Dec axes: 1/2 + Coordinates: equatorial FK5 Equinox: J1975.000 + Epoch: J1975.00000000 MJD: 42413.25000 + +Input file: coords Output file: STDOUT + + 1.0 1.0 13:27:02.9797 47:31:43.269 +512.0 1.0 13:26:24.3330 47:31:43.793 +512.0 512.0 13:26:24.3448 47:38:15.219 + 1.0 512.0 13:27:03.0718 47:38:14.693 +.fi + +.ih +TIME REQUIREMENTS + +.ih +BUGS + +At present IRAF requires that the LONGPOLE and or LATPOLE keywords be +defined in the appropriate WAT_* keywords, e.g. WAT1_* and WAT2_* for +a 2D image. If these are not present then default values are assumed. +The new values are computed and added to the WAT1_* and WAT2_* keywords. + +At present the experimental TNX and ZPX projections cannot be transformed +with precision. Users should use the SKYCTRAN task to transform individual +coordinate pairs. + +.ih +SEE ALSO +setjd,precess,galactic,xray.xspatial.skypix,stsdas.toolbox.tools.tprecess +.endhelp |