spectro-aras.com

Hello,
This is a question about the guidance system in spectroscopy. Both, myself (with Alpy) and another colleague (with Lisa) used Atik Titan to guide. We have independently verified that using, for example, Artemis (Atik program) the guiding image is good enough, even with stars of magnitude 14, but it is not a system that allows automatic guiding. However, if we use the PhDGuiding 2 guiding program, the image is much blurrier. This is not a problem to guide with stars of intermediate magnitudes, but it is a problem to guide objects of low luminosity. Why the loss of image quality with PhDGuiding 2? This greatly limit us the objects to guide.
Juan José

perhaps you have not set the same exposure duration in phd2 as that which was apparently giving non blurry images in artemis? If phd2 is using a very short exposure, signal to noise of a mag 14 star might be too low?

alternatively, is artemis perhaps stacking several images?

since your guide image frequency should anyway not be too rapid (you just end up chasing the short term fluctuations due to seeing and guide image noise), perhaps try a longer guide image exposure in phd2 of say 4 seconds.

Hi Juan José,

I use Artemis and PHD2. The image that PHD2 shows on screen is continuously being adjusted for brightness and contrast so I find it difficult to see the true image quality. Have you tried saving an image in PHD and comparing it with the image from Artemis with the same exposure ? Do you see any difference then ?

Cheers
Robin

thanks Hamish and Robin,
It is a general impression that we have when comparing the images. When weather permits it I will do an exhaustive test.
Juan Jose

Hello.

I am having the same problem. I tried what Robin says with the same results as Juan.
Anyway i have opened a thread in PHD2 forum to see if somebody has the answer.

For me the same, i use a old version for 2.6.3 for good use !