At 07:21 2001-03-23 -0600, Axel wrote:
>Is there a way to manually match images with charon ?
>Whatever the settings I use, it never finds the stars to align my CCD
>image with.
>Is there a limitation in the star's sizes. Mine are about 10 pixels
>in diameter (binning 1x1).
>
>It finds noise within the galaxies, but never finds the stars !
Axel.
There several things you could try:
1. Set the centroid size in the Charon menu to 10 or 12. That should take
care of your large star images and may also improve the accuracy of the
reduction.
2. Since charon is picking up noise in the image and marking it as a star
image set the cutoff point in the Charon menu to 0.990 or higher. Look at
Bill's warning about this so that you don't cut off too many stars.
3. Charon looks at the brightest stars first when choosing stars for the
match and there are two related things to change here: the magnitude limit
in the menu selections and the number of stars Charon will look at which is
in the "Charon Dat" file. Edit the "charon dat" file, located in the Guide
directory, to a smaller number of stars. See an example of this file below.
0.174533 0.980000 C:\cdguide\ -1.592993 0.782184 1
400 20 0.250000 1.010000 259 0.000000 50000 0.000000
2 0 1 1.000000 dummy 0 9 c110P 1
mpc.log 750
C:\IMAGES\APOGEE\DISK4\2001\FEB\DATA\19FEB.002 4 0 0 0
1 38.900000 9.00 9.00 0 1919 0 0R
2 2 2 2
Change the "400" in this example to a smaller number like 100 or 50.
4. Lastly, try to work on an image that just has stars in it. I think
that a galaxy is much too busy for Charon to work with as a start.
I hope all of this helps.
Bob Elliott
750 Fall Creek