| ccxymatch | images.imcoords | ccxymatch |
ccxymatch -- Match celestial and pixel coordinate lists using various methods
ccxymatch input reference output tolerance [ptolerance]
CCXYMATCH matches ra / dec or longitude / latitude coordinates in the celestial coordinate list reference to their corresponding x and y coordinates in the pixel coordinate list input using user specified tolerances in arcseconds tolerance and pixels ptolerance , and writes the matched coordinates to the output file output . The output file is suitable for input to the plate solution computation task CCMAP.
CCXYMATCH matches the coordinate lists by: 1) projecting the celestial coordinates onto a plane using the sky projection geometry projection and the reference point lngref and latref , 2) computing an initial guess for the linear transformation required to match the pixel coordinate system to the porjected celestial coordinate system, 3) applying the computed transformation to the pixel coordinates, 4) sorting the projected celestial and pixel coordinates lists, 5) removing points with a minimum separation specified by the parameters separation and pseparation from both lists, 6) matching the two lists using either the "triangles" or "tolerance" matching algorithms, and 7) writing the matched list to the output file.
An initial estimate for the linear transformation is computed in one of two ways. If refpoints is defined, the celestial and pixel coordinates of up to three tie points are read from succeeding lines in the refpoints file, and used to compute the linear transformation. The coordinates of the tie points can be typed in by hand if refpoints is "STDIN". The formats of two sample refpoints files are shown below.
# First sample refpoints file (1 reference file and N input files) ra1 dec1 [ra2 dec2 [ra3 dec3]] # tie points for reference coordinate file x1 y1 [ x2 y2 [ x3 y3]] # tie points for input coordinate file 1 x1 y1 [ x2 y2 [ x3 y3]] # tie points for input coordinate file 2 .. .. [ .. .. [ .. ..] x1 y1 [ x2 y2 [ x3 y3]] # tie points for input coordinate file N # Second sample refpoints file (N reference files and N input files) ra1 dec1 [ra2 dec2 [ra3 dec3]] # tie points for reference coordinate file 1 x1 y1 [ x2 y2 [ x3 y3]] # tie points for input coordinate file 1 ra1 dec1 [ra2 dec2 [ra3 dec3]] # tie points for reference coordinate file 2 x1 y1 [ x2 y2 [ x3 y3]] # tie points for input coordinate file 2 .. .. [ .. .. [ .. ..]] ra1 dec1 [ra2 dec2 [ra3 dec3]] # tie points for reference coordinate file N x1 y1 [ x2 y2 [ x3 y3]] # tie points for input coordinate file N
If the refpoints file is undefined the parameters xin , xin , xmag , ymag , xrotation , xrotation are used to compute a linear transformation from the pixel coordinates to the standard coordinates xi and eta as shown below. Orientation and skew are the orientation of the x and y axes and their deviation from perpendicularity respectively.
xi = a + b * x + c * y
eta = d + e * x + f * y
xrotation = orientation - skew / 2
yrotation = orientation + skew / 2
b = xmag * cos (xrotation)
c = -ymag * sin (yrotation)
e = xmag * sin (xrotation)
f = ymag * cos (yrotation)
a = 0.0 - b * xin - c * yin = xshift
d = 0.0 - e * xin - f * yin = yshift
Both methods of computing the initial linear transformation compute the standard coordinates xi and eta by projecting the celestial coordinates onto a plane using the sky projection geometry projection and the reference point lngref and latref . The celestial coordinates are assumed to be in units of lngunits and latunits and the standard coordinates are in arcseconds. The linear transformation and its geometric interpretation are shown below.
The celestial and pixel coordinates are read from columns lngcolumn and latcolumn in the celestial coordinate list, and xcolumn , and ycolumn in the pixel coordinate list respectively. The pixel coordinates are transformed using the linear transformation described above, the celestial coordinate in units of lngunits and latunits are projected to standard coordinates in arcseconds, and stars closer together than separation arcseconds and pseparation pixels are removed from the celestial and pixel coordinate lists respectively.
The coordinate lists are matched using the matching algorithm specified by matching . If matching is "tolerance", CCXYMATCH searches the transformed sorted pixel coordinate list for the coordinates that are within the matching tolerance tolerance and closest to the current standard coordinates. The major advantage of the "tolerance" algorithm is that it can handle x and y scale differences and axis skew in the coordinate transformation. The major disadvantage of the "tolerance" algorithm is that the user must supply tie point information in all but the simplest case of small x and y shifts between the pixel and celestial coordinate systems.
If matching is "triangles", CCXYMATCH constructs a list of triangles using up to nmatch celestial coordinates and transformed pixel coordinates and performs a pattern matching operation on the resulting triangle lists. If the number of coordinates in both lists is less than nmatch the entire list is matched using the "triangles" algorithm directly, otherwise the "triangles" algorithm is used to estimate a new linear transformation, the input coordinate list is transformed using the new transformation, and the entire list is matched using the "tolerance" algorithm. The major advantage of the "triangles" algorithm is that it requires no tie point information from the user. The major disadvantages of the algorithm are that, it is sensitive to x and y scale differences and axis skew between the celestial and pixel coordinate systems, and can be computationally expensive.
The matched celestial and pixel coordinates are written to columns 1, 2, 3, and 4 of the ouput file, in the formats specified by the lngformat , latformat , xformat and yformat parameters. The original line numbers in the celestial and pixels coordinate files are written to columns 5 and 6.
If verbose is yes, detailed messages about actions taken by the task are written to the terminal as the task executes.
The "triangles" algorithm uses a sophisticated pattern matching technique which requires no tie point information from the user. It is expensive computationally and is therefore restricted to a maximum of nmatch objects from the celestial and pixel coordinate lists.
The "triangles" algorithm first generates a list of all the possible triangles that can be formed from the points in each list. For a list of nmatch points this number is the combinatorial factor nmatch! / [(nmatch-3)! * 3!] or nmatch * (nmatch-1) * (nmatch-2) / 6. The length of the perimeter, ratio of longest to shortest side, cosine of the angle between the longest and shortest side, the tolerances in the latter two quantities and the direction of the arrangement of the vertices of each triangle are computed and stored in a table. Triangles with vertices closer together than tolerance and ptolerance , or with a ratio of the longest to shortest side greater than ratio are discarded. The remaining triangles are sorted in order of increasing ratio. A sort merge algorithm is used to match the triangles using the ratio and cosine information, the tolerances in these quantities, and the maximum tolerances for both lists. The ratios of the perimeters of the matched triangles are compared to the most common ratio for the entire list, and triangles which deviate too widely from this number are discarded. The number of triangles remaining are divided into the number which match in the clockwise sense and the number which match int the counter-clockwise sense. Those in the minority category are eliminated. The rejection step can be repeated up to nreject times or until no more rejections occur, whichever comes first. The last step in the algorithm is a voting procedure in which each remaining matched triangle casts three votes, one for eached matched pair of vertices. Points which have fewer than half the maximum number of votes are discarded. The final set of matches are written to the output file.
The "triangles" algorithm functions well when the celestial and pixel coordinate lists have a sufficient number of objects (50%, in some cases as low as 25%) of their objects in common, any distortions including x and y scale differences and skew between the two systems are small, and the random errors in the coordinates are small. Increasing the value of the tolerance parameter will increase the ability to deal with distortions but will also produce more false matches which after some point will swamp the true matches.
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
A detailed description of the "triangles" pattern matching algorithm used here can be found in the article "A Pattern-Matching Algorithm for Two- Dimensional Coordinate Lists" by E.J. Groth, A.J. 91, 1244 (1986).
1. Compute the plate solution for a 1528 by 2288 B band image of M51 by matching a list of reference stars extracted from the Guide Star Catalog with the regions task against a list of bright stars detected with the daofind task. The approximate image center is RA = 13:29:52.8 and DEC = +47:11:41 (J2000) and the image scale is 0.43 arcseconds / pixel.
... Get the guide stars (see stsdas.analysis.gasp package).
cl> regions 13:29:52.8 47:11:41 0.27 m51b.gsc.tab
... Convert the binary table to a text file (see package tables.ttools).
cl> tprint m51b.gsc.tab > m51b.gsc
... Examine the guide star list.
cl> type m51b.gsc
# Table m51b.gsc.tab Tue 10:39:55 22-Oct-96
# row RA_HRS RA_DEG DEC_DEG MAG
# hours degrees degrees magnitudes
1 13:29:13.33 202:18:19.9 47:14:16.3 12.3
2 13:29:05.51 202:16:22.6 47:10:44.7 14.8
3 13:29:48.60 202:27:09.0 47:07:42.5 15.0
4 13:29:47.30 202:26:49.4 47:13:37.5 10.9
5 13:29:31.65 202:22:54.7 47:18:54.7 15.0
6 13:29:06.16 202:16:32.4 47:04:53.1 14.9
7 13:29:37.40 202:24:21.1 47:09:09.2 15.1
8 13:29:38.70 202:24:40.5 47:13:36.2 15.0
9 13:29:55.42 202:28:51.3 47:10:05.2 15.4
10 13:29:06.91 202:16:43.7 47:04:07.9 12.4
11 13:29:29.73 202:22:25.9 47:12:04.1 15.1
12 13:30:07.96 202:31:59.4 47:05:18.3 14.7
13 13:30:01.82 202:30:27.2 47:12:58.8 11.8
14 13:30:36.75 202:39:11.2 47:04:05.9 14.9
15 13:30:34.04 202:38:30.6 47:16:44.8 13.2
16 13:30:14.95 202:33:44.3 47:10:27.6 13.4
... Locate bright stars in the image (see noao.digiphot.daophot package).
... Suitable values for fwhmpsf, sigma, ... and threshold can be determined
... using the imstatistics and imexamine tasks. Some experimentation may be
... necessary to determine optimal values.
cl> daofind m51b "default" fwhmpsf=4.0 sigma=5.0 threshold=20.0
... Examine the star list.
cl> type m51b.coo.1
...
#N XCENTER YCENTER MAG SHARPNESS SROUND GROUND ID
...
401.034 147.262 -2.315 0.473 -0.075 -0.170 1
261.137 453.696 -1.180 0.481 -0.373 -0.135 2
860.002 480.061 -1.397 0.373 -0.218 -0.178 3
69.342 675.895 -0.955 0.368 -0.294 -0.133 4
1127.791 680.033 -1.166 0.449 -0.515 -0.326 5
972.435 691.544 -1.722 0.449 -0.327 -0.060 6
1348.891 715.084 -1.069 0.389 -0.242 -0.145 7
946.114 797.067 -0.543 0.406 -0.198 -0.069 8
698.455 811.407 -1.620 0.437 -0.038 -0.028 9
964.566 853.201 -0.317 0.382 0.031 -0.086 10
236.088 864.817 -3.515 0.429 -0.164 -0.035 11
919.703 909.835 -3.775 0.447 0.051 0.007 12
406.592 985.807 -0.715 0.424 -0.307 -0.068 13
920.790 986.083 -0.600 0.364 -0.047 0.021 14
761.403 1037.795 -1.944 0.383 -0.023 0.120 15
692.012 1050.603 -0.508 0.339 -0.365 -0.164 16
1023.330 1060.144 -1.897 0.381 -0.246 -0.288 17
681.864 1066.937 -0.059 0.467 -0.175 0.135 18
1307.802 1085.564 -1.173 0.435 0.032 -0.207 19
716.494 1094.800 -0.389 0.421 -0.412 -0.032 20
715.935 1106.616 -3.747 0.649 0.271 0.245 21
1093.813 1300.189 -1.557 0.377 -0.309 -0.078 22
596.406 1353.798 -0.461 0.383 0.029 -0.103 23
1212.117 1362.636 -0.362 0.369 -0.180 0.043 24
251.355 1488.048 -0.909 0.357 -0.390 0.077 25
600.659 1630.261 -1.392 0.423 0.013 -0.312 26
329.448 2179.233 -0.824 0.442 -0.463 0.325 27
... Match the two lists using the "triangles" algorithm and tolerances of
... 1.0 arcseconds and 3.0 pixels respectively.
cl> ccxymatch m51b.coo.1 m51b.gsc m51b.mat.1 1.0 3.0 lngcolumn=2 latcolumn=4
... Examine the matched file.
cl> type m51b.mat.1
# Input: m51b.coo.1 Reference: m51b.gsc Number of tie points: 0
# Initial linear transformation
# xref[tie] = 0. + 1. * x[tie] + 0. * y[tie]
# yref[tie] = 0. + 0. * x[tie] + 1. * y[tie]
# dx: 0.00 dy: 0.00 xmag: 1.000 ymag: 1.000 xrot: 0.0 yrot: 0.0
#
# Column definitions
# Column 1: Reference Ra / Longitude coordinate
# Column 2: Reference Dec / Latitude coordinate
# Column 3: Input X coordinate
# Column 4: Input Y coordinate
# Column 5: Reference line number
# Column 6: Input line number
13:29:48.600 47:07:42.50 860.002 480.061 8 44
13:29:38.700 47:13:36.20 1093.813 1300.189 13 63
13:29:55.420 47:10:05.20 698.455 811.407 14 50
13:29:29.730 47:12:04.10 1307.802 1085.564 16 60
13:30:07.960 47:05:18.30 401.034 147.262 17 42
13:30:14.950 47:10:27.60 236.088 864.817 21 52
... Compute the plate solution.
cl> ccmap m51b.mat.1 ccmap.db results=STDOUT xcolumn=3 ycolumn=4 lngcolumn=1 \
latcolumn=2 refpoint=user lngref=13:29:52.8 latref=47:11:41 interactive=no
Coords File: m51b.mat.1 Image:
Database: ccmap.db Record: m51b.mat.1
Refsystem: j2000 Coordinates: equatorial FK5
Equinox: J2000.000 Epoch: J2000.000 MJD: 51544.50000
Insystem: j2000 Coordinates: equatorial FK5
Equinox: J2000.000 Epoch: J2000.000 MJD: 51544.50000
Coordinate mapping status
XI fit ok. ETA fit ok.
Ra/Dec or Long/Lat fit rms: 0.206 0.103 (arcsec arcsec)
Coordinate mapping parameters
Sky projection geometry: tan
Reference point: 13:29:52.800 47:11:41.00 (hours degrees)
Reference point: 760.656 1033.450 (pixels pixels)
X and Y scale: 0.430 0.431 (arcsec/pixel arcsec/pixel)
X and Y axis rotation: 180.158 359.991 (degrees degrees)
Input Coordinate Listing
X Y Ra Dec Ra(fit) Dec(fit) Dra Ddec
860.0 480.1 13:29:48.60 47:07:42.5 13:29:48.62 47:07:42.5 -0.153 0.017
1093.8 1300.2 13:29:38.70 47:13:36.2 13:29:38.73 47:13:36.4 -0.258 -0.164
698.5 811.4 13:29:55.42 47:10:05.2 13:29:55.43 47:10:05.2 -0.062 0.024
1307.8 1085.6 13:29:29.73 47:12:04.1 13:29:29.70 47:12:04.0 0.318 0.123
401.0 147.3 13:30:07.96 47:05:18.3 13:30:07.96 47:05:18.4 0.028 -0.073
236.1 864.8 13:30:14.95 47:10:27.6 13:30:14.94 47:10:27.5 0.127 0.073
2. Repeat example 1 but replace the daofind pixel list with one generated using the center task and a finder chart created with the skymap task.
... Get the guide stars. (see stsdas.analysis.gasp package)
cl> regions 13:29:52.8 47:11:41 0.27 m51b.gsc.tab
... Create the finder chart (see stsdas.analysis.gasp package)
cl> gasp.skymap m51b.gsc.tab 13:29:52.8 47:11:41 INDEF 0.27 \
objstyle=square racol=RA_HRS deccol=DEC_DEG magcol=MAG interactive- \
dev=stdplot
... Convert the binary table to a text file. (see tables.ttools package)
cl> tprint m51b.gsc.tab > m51b.gsc
... Mark and center the guide stars on the image display using the finder
... chart produced by the skymap task and the center task (see the
... digiphot.apphot package).
cl> display m51b 1 fi+
cl> center m51b cbox=7.0 ...
cl> pdump m51b.ctr.1 xcenter,ycenter yes > m51b.pix
... Display the pixel coordinate list.
cl> type m51b.pix
401.022 147.183
236.044 864.882
698.368 811.329
860.003 480.051
1127.754 680.020
1307.819 1085.615
1093.464 1289.595
1212.001 1362.594
1348.963 715.085
... Match the two lists using the "triangles" algorithm and tolerances of
... 1.0 arcseconds and 3.0 pixels respectively.
cl> ccxymatch m51b.pix m51b.gsc m51b.mat.2 1.0 3.0 lngcolumn=2 latcolumn=4
... Examine the matched file.
cl> type m51b.mat.2
# Input: m51b.pix Reference: m51b.gsc Number of tie points: 0
# Initial linear transformation
# xi[tie] = 0. + 1. * x[tie] + 0. * y[tie]
# eta[tie] = 0. + 0. * x[tie] + 1. * y[tie]
# dx: 0.00 dy: 0.00 xmag: 1.000 ymag: 1.000 xrot: 0.0 yrot: 0.0
#
# Column definitions
# Column 1: Reference Ra / Longitude coordinate
# Column 2: Reference Dec / Latitude coordinate
# Column 3: Input X coordinate
# Column 4: Input Y coordinate
# Column 5: Reference line number
# Column 6: Input line number
13:29:48.600 47:07:42.50 860.003 480.051 8 4
13:29:37.400 47:09:09.20 1127.754 680.020 12 5
13:29:55.420 47:10:05.20 698.368 811.329 14 3
13:29:29.730 47:12:04.10 1307.819 1085.615 16 6
13:30:07.960 47:05:18.30 401.022 147.183 17 1
13:30:14.950 47:10:27.60 236.044 864.882 21 2
... Compute the plate solution.
cl> ccmap m51b.mat.2 ccmap.db results=STDOUT xcolumn=3 ycolumn=4 lngcolumn=1 \
latcolumn=2 refpoint=user lngref=13:29:52.8 latref=47:11:41 interactive=no
Coords File: m51b.mat.2 Image:
Database: junk.db Record: m51b.mat.2
Refsystem: j2000 Coordinates: equatorial FK5
Equinox: J2000.000 Epoch: J2000.000 MJD: 51544.50000
Insystem: j2000 Coordinates: equatorial FK5
Equinox: J2000.000 Epoch: J2000.000 MJD: 51544.50000
Coordinate mapping status
XI fit ok. ETA fit ok.
Ra/Dec or Long/Lat fit rms: 0.312 0.0664 (arcsec arcsec)
Coordinate mapping parameters
Sky projection geometry: tan
Reference point: 13:29:52.800 47:11:41.00 (hours degrees)
Reference point: 761.093 1033.230 (pixels pixels)
X and Y scale: 0.430 0.431 (arcsec/pixel arcsec/pixel)
X and Y axis rotation: 180.175 359.998 (degrees degrees)
Input Coordinate Listing
X Y Ra Dec Ra(fit) Dec(fit) Dra Ddec
3. Repeat example 1 but use the "tolerance" matching algorithm and apriori knowledge of the celestial and pixel coordinates of the nucleus of M51, the x and y image scales, and the orientation of the detector on the telescope to match the two lists.
... Match the two lists using the ccxymatch "tolerance" algorithm and
... a matching tolerance of 2.0 arcseconds. Note the negative and positive
... signs on the xmag and ymag parameters and lack of any rotation,
... indicating that north is up and east is to the left.
cl> ccxymatch m51b.coo.1 m51b.gsc m51b.mat.3 2.0 lngcolumn=2 latcolumn=4 \
matching=tolerance xin=761.40 yin=1037.80 xmag=-0.43 ymag=0.43 xrot=0.0 \
yrot=0.0 lngref=13:29:52.80 latref=47:11:42.9
... Examine the matched file.
cl> type m51b.mat.3
# Input: m51b.coo.1 Reference: m51b.gsc Number of tie points: 0
# Initial linear transformation
# xref[tie] = 327.402 + -0.43 * x[tie] + 0. * y[tie]
# yref[tie] = -446.254 + 0. * x[tie] + 0.43 * y[tie]
# dx: 327.40 dy: -446.25 xmag: 0.430 ymag: 0.430 xrot: 180.0 yrot: 0.0
#
# Column definitions
# Column 1: Reference Ra / Longitude coordinate
# Column 2: Reference Dec / Latitude coordinate
# Column 3: Input X coordinate
# Column 4: Input Y coordinate
# Column 5: Reference line number
# Column 6: Input line number
13:30:07.960 47:05:18.30 401.034 147.262 17 42
13:29:48.600 47:07:42.50 860.002 480.061 8 44
13:29:37.400 47:09:09.20 1127.791 680.033 12 46
13:29:55.420 47:10:05.20 698.455 811.407 14 50
13:30:14.950 47:10:27.60 236.088 864.817 21 52
13:29:29.730 47:12:04.10 1307.802 1085.564 16 60
13:29:38.700 47:13:36.20 1093.813 1300.189 13 63
... Compute the plate solution.
cl> ccmap m51b.mat.3 ccmap.db results=STDOUT xcolumn=3 ycolumn=4 lngcolumn=1 \
latcolumn=2 refpoint=user lngref=13:29:52.8 latref=47:11:41 interactive=no
Coords File: m51b.mat.3 Image:
Database: ccmap.db Record: m51.mat.3
Refsystem: j2000 Coordinates: equatorial FK5
Equinox: J2000.000 Epoch: J2000.000 MJD: 51544.50000
Insystem: j2000 Coordinates: equatorial FK5
Equinox: J2000.000 Epoch: J2000.000 MJD: 51544.50000
Coordinate mapping status
XI fit ok. ETA fit ok.
Ra/Dec or Long/Lat fit rms: 0.342 0.121 (arcsec arcsec)
Coordinate mapping parameters
Sky projection geometry: tan
Reference point: 13:29:52.800 47:11:41.00 (hours degrees)
Reference point: 760.687 1033.441 (pixels pixels)
X and Y scale: 0.430 0.431 (arcsec/pixel arcsec/pixel)
X and Y axis rotation: 180.174 359.949 (degrees degrees)
Input Coordinate Listing
X Y Ra Dec Ra(fit) Dec(fit) Dra Ddec
401.0 147.3 13:30:07.96 47:05:18.3 13:30:07.97 47:05:18.4 -0.109 -0.109
860.0 480.1 13:29:48.60 47:07:42.5 13:29:48.64 47:07:42.5 -0.385 -0.045
1127.8 680.0 13:29:37.40 47:09:09.2 13:29:37.34 47:09:09.0 0.572 0.152
698.5 811.4 13:29:55.42 47:10:05.2 13:29:55.43 47:10:05.2 -0.118 0.009
236.1 864.8 13:30:14.95 47:10:27.6 13:30:14.92 47:10:27.5 0.290 0.116
1307.8 1085.6 13:29:29.73 47:12:04.1 13:29:29.72 47:12:04.0 0.082 0.060
1093.8 1300.2 13:29:38.70 47:13:36.2 13:29:38.73 47:13:36.4 -0.332 -0.184
4. Repeat example 3 but input the appropriate linear transformation via a list of tie points, rather than setting the transformation parameters directly.
... Display the tie points.
cl> type refpts
13:29:55.42 47:10:05.2 13:29:38.70 47:13:36.2 13:30:14.95 47:10:27.6
698.5 811.4 1093.8 1300.2 236.1 864.8
... Match the lists using the ccxymatch "tolerance" algorithm and a matching
... tolerance of 2.0 arcseconds. Note the negative and positive signs on the
... xmag and ymag parameters and lack of any rotation, indicating that north
... is up and east is to the left.
cl> ccxymatch m51b.coo.1 m51b.gsc m51b.mat.4 2.0 refpoints=refpts \
lngcolumn=2 latcolumn=4 matching=tolerance lngref=13:29:52.80 \
latref=47:11:42.9
... Examine the matched list.
cl> type m51b.mat.4
# Input: m51b.coo.1 Reference: m51b.gsc Number of tie points: 3
# tie point: 1 ref: 26.718 -97.698 input: 698.500 811.400
# tie point: 2 ref: -143.629 113.354 input: 1093.800 1300.200
# tie point: 3 ref: 225.854 -75.167 input: 236.100 864.800
#
# Initial linear transformation
# xi[tie] = 327.7137 + -0.4306799 * x[tie] + -2.0406E-4 * y[tie]
# eta[tie] = -448.0854 + 0.00103896 * x[tie] + 0.430936 * y[tie]
# dx: 327.71 dy: -448.09 xmag: 0.431 ymag: 0.431 xrot: 179.9 yrot: 0.0
#
# Column definitions
# Column 1: Reference Ra / Longitude coordinate
# Column 2: Reference Dec / Latitude coordinate
# Column 3: Input X coordinate
# Column 4: Input Y coordinate
# Column 5: Reference line number
# Column 6: Input line number
13:30:07.960 47:05:18.30 401.034 147.262 17 42
13:29:48.600 47:07:42.50 860.002 480.061 8 44
13:29:37.400 47:09:09.20 1127.791 680.033 12 46
13:29:55.420 47:10:05.20 698.455 811.407 14 50
13:30:14.950 47:10:27.60 236.088 864.817 21 52
13:29:29.730 47:12:04.10 1307.802 1085.564 16 60
13:29:38.700 47:13:36.20 1093.813 1300.189 13 63
... Compute the plate solution which is identical to the solution computed
... in example 2.
cl> ccmap m51b.mat.4 ccmap.db results=STDOUT xcolumn=3 ycolumn=4 lngcolumn=1 \
latcolumn=2 refpoint=user lngref=13:29:52.8 latref=47:11:41 interactive=no
stsdas.gasp.regions, stsdas.gasp.skymap,tables.ttools.tprint,daophot.daofind,ccmap