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whatzdaname |
07/19/2007 01:37AM (Read 3095 times)
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Status: offline
Registered: 03/29/2006
Posts: 1
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Hi,I'm using the TFINDER task in the FINDER package to get astrometric solutions for my CCD frames. I pull out the reference stars from the USNO-B1 catalog, convert the ASCII RA and DEC to IRAF table format using MKGSCTAB task, and then use TFINDER to get a solution. Everything is working fine except for one thing. When I use the "e" keystroke in TFINDER to get a "rough" solution (after matching a few stars that are spread out over the entire field) and hit "q" from the graphic terminal, only the stars that I've selected in the previous step (using either "l" or "k" keystrokes) appears on the display. As I understand, the stars I did NOT selected are supposed be marked with red circles with the X/Y coordinates calculated from the rough solution.I tried to track down what may be the problem by looking at the overwritten table file, and figured out that the calculated coordinates (X_CENTER and Y_CENTER in terms of table column names) are nowhere near the actual stars -- they are >60000 and >100000 in pixel coordinates! which doesn't make sense.I wonder if anyone else has experienced the same problem?Thanks.
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seaman |
07/19/2007 01:37AM
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Status: offline
Registered: 11/11/2005
Posts: 3
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1) Do you have the RA units right in mkgsctab?2) Perhaps tfinder parameters like scale, north or east are wrong?3) How many stars is a "few"? You might try a few more. Note that nothing requires that you fit a solution to every source from the catalog.4) Are you convinced your eyeball matching of sources is correct? If the pixel coordinates are that far off you likely wouldn't be able to find any to match in the first place.5) Note that the catalog may contain sources that don't lie within the field of view of your image.
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