Sun, 10/20/2019 - 05:35
Hi
I have a small and not well populated field. Target star is about mag 9, one comparison star is about 9.7 and one about 11.0. Ther is one more star about magnitude 10.5. in the field. There are no other stars brighter than 15th magnitude.
In order to fit the comp stars the target is off center
Vphot will solve about 1 in 10 images even though they have the same exposure and taken within a few seconds of earch other. Is there a way to to predefine a sequence for the non resolved images to do a time series or would each have to be done individually? Is there a way to force the resolution of one image as standard for the unresolved images?
Thanks in advance
S
Hello!
It is even kind of easy if you can use wcstools package, which runs well under Linux and MacOSX. Maybe there are ports for Windows, too. Or can be used in Linux environment of Windows 10.
Look at the description and examples of command cphead (http://tdc-www.harvard.edu/wcstools/cphead.html).
E.g. a copy of linear part of WCS (NB! all of it is one line) from real image to a FITS file with absolutely minimal header:
cphead SXCAS-20190825-230351-I-BIN1-E-003-00.fits test.fits ra dec epoch radecsys ctype1 ctype2 crpix1 crpix2 crval1 crval2 cd1_1 cd1_2 cd2_1 cd2_2
There can be many files instead of one target - test.fits here - either named on command line, or a text file containing filenames line by line. The same about FITS keywords.
Best wishes,
Tõnis
Serge:
Apparently PinPoint (used by VPhot) is having a hard time solving your sparse images. IF you are able to get one solved, you can use it to solve your other images. Use the "more" button to select only the images of interest. Select the solved image in your image list. Click on the Update WCS link and it can be applied to all the other unsolved images. Effectively, the correct WCS headers get applied to all the other unsolved images. If your images have significant movement, this may not work but otherwise it should be successful.
The WCS link has some help info but it may be a bit obscure. Advise if you do not get it to work. I do this so infrequently, that I am recalling the steps poorly. If you share this set of images with me at MZK, I can help with more info? I don't have such a set right now.
Ken
Hi
Sharing 17 images with you. None plate solved on first upload. I did a plate solve on astrometry.net for one of them (successful) and used the center co-ordinates from it rather than the center co-ordinates of the target star which as I mentioned had to be moved off center to include the two comparison stars.
Using the astrometry co-ordinates about 1/3 of the images are successfully plate solved however following your WCS steps did not improve the situation.
Thanks Ken
I will try your solution once the log in issues are resolved
You could try local installation of astrometry.net, too.