Quote:
Originally Posted by TR
Hello Peter,
I can see your ST-i guide camera in your photo. How hard is it to locate a guide star using the ST-i? Or, is there always a guide star in the field? If you were to perform a meridian flip, how likely is it that there would be a star in the field of view of the ST-i autoguider, or is the field to narrow and requires the human touch?
I am interested, but I have a feeling the FOV would be the same size as my guide chip on the STL, and I have to hunt for a suitable guide star. Can you share your experiences?
Terry
|
Hi Terry,
The nice feature about the ONAG is that you can find any star seen by the entire FOV of the telescope! Now, you won't see the whole field with the ST-i due to the CCD size, but the mechanical stage allows you to change where the ST-i is looking. Now, to specifically answer your question(s).
1. If the ST-i is exactly centered in the FOV (by centering the ST-i on the stage) doing a meridian flip should yield the same guide star but 180 degrees rotated in the FOV.
2. I often see stars! When you are using the full aperture as a guiding scope a lot of faint stars come into play. This is mitigated by the lower energy to some extent as only the IR signal is available to use.
3. I have never failed to find a star by just moving the guide camera on the stage of the ONAG. Also, I have never needed to rotate the imaging camera to find a guide star. You can frame your target exactly as you want and very very likely there will be a guide star!
4. Do I wish I had a guide camera with a large FOV. Yes. I don't love needed to sometimes hunt around with the stage given that my computer is indoors and I need to see whats going on with images when I'm outside. So, it's not a perfect solution for those trying remote imaging. I've been told that a motorized stage is in the works (but this was a year ago and there still is nothing like that).
Any more questions?
Peter