fuzzy guiding images

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fuzzy guiding images

Postby Juan Jose Pueyo » Thu Jan 28, 2021 2:36 pm

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
Juan José Pueyo
Azara Obs.
Azara (Huesca)
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Re: fuzzy guiding images

Postby Hamish Barker » Thu Jan 28, 2021 10:14 pm

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.
Hamish Barker
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Re: fuzzy guiding images

Postby Robin Leadbeater » Fri Jan 29, 2021 12:06 am

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 ?

LHIRES III #29 ATIK314 ALPY 600/200 ATIK428 Star Analyser 100/200 C11 EQ6
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Re: fuzzy guiding images

Postby Juan Jose Pueyo » Sat Jan 30, 2021 2:26 pm

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
Juan José Pueyo
Azara Obs.
Azara (Huesca)
Juan Jose Pueyo
Posts: 15
Joined: Thu Nov 12, 2020 4:35 pm

Re: fuzzy guiding images

Postby David Cejudo » Tue Feb 02, 2021 8:57 am


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.
David Cejudo.
Observatorio El gallinero.
El berrueco, Madrid.
David Cejudo
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Re: fuzzy guiding images

Postby etienne bertrand » Tue Feb 02, 2021 3:13 pm

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