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Polar alignment error

Piero
2022-02-01
2022-02-02
  • Piero

    Piero - 2022-02-01

    Hi Han,
    I recently discovered and am now playing a bit with the sky simulator and let me tell you this is another great and very useful piece of software from you!
    I don't know whether this is something not yet implemented or I am missing something, but when I set some PA error, without guiding shouldn't the objects in the FOV drift away, more or less slowly depending on the amount of PA error?
    I don't see it happen for now, is there anything I should configure?

    Thank you and keep up the great work!
    Piero

     
  • han.k

    han.k - 2022-02-01

    Hello Piero,

    It should. But the Ascom mount simulated mount has some limitations. The mount position and setpoint are coupled. I have to test it. For the Alpaca simulated mount (internal in the program) it should work. You should be able to access this mount via Ascom 6.5. You may try. I will test it after finishing some other work.

    Han

     
  • Piero

    Piero - 2022-02-01

    Hi Han and thanks for the info.

    I am using the simulator together with CCDciel under Linux, so I am using the Alpaca interface.
    Should it work already in this configuration?
    I am testing it right now, but even with a large PA error I can't see any drift.

    Thank you.
    Piero

     
  • han.k

    han.k - 2022-02-01

    Yes it should. Probably the problem is that is doesn't make a new sky image if the time changes. I think that isn't implemented yet. You can force an update by uncheck and check again the polar error check-mark. Can you try that?

    Han

     

    Last edit: han.k 2022-02-01
  • han.k

    han.k - 2022-02-01

    polar error check/uncheck.

     
  • Piero

    Piero - 2022-02-01

    It seems to work, I had to increase the PA error a lot to see some effects in a shorter time.
    Probably one thing that tricked me is the fact that even though I set CCDciel for a 300s exposure, the simulator returns the image after one second, and I guess the sky is updated accordingly.
    That is, the sky updates between two 300s exposures are actually the updates that occur in only two "real" seconds, correct?

    Thank you.

     
  • han.k

    han.k - 2022-02-01

    Yes the exposure duration is ignored. I'm working on Sky Simulator version 2 now. To demonstrate drift I have to wait the exposure time and update the image on the new time. I will not be possible to demonstrate elongated stars due to drift unless I combine an image from the beginning and the end of the exposure. Not a problem but it makes it all more complicated.

    I can upload a Linux version of V2 in one or two days. Feedback helps so please test it.

    Han

     
  • han.k

    han.k - 2022-02-01

    In the new version the exposure time and gain have an influence. Furthermore the images are 16 resolution. Now they are 8 bit resolution in 16 bit format.

     
  • Piero

    Piero - 2022-02-01

    That sounds great and will further improve an already outstanding project!
    Thanks a lot!

     
  • han.k

    han.k - 2022-02-01

    In about 5 minutes you can download v2 for Linux.

    Han

     
  • han.k

    han.k - 2022-02-01

    If polar alignment is checked then the image is every 10 seconds updated in the background. You can see that in the log. The stars will be drifting.

    For the moment I keep the immediate image ready even if you select 200 seconds exposure.

    Note that image will get saturated if you expose longer. 5 or 10 seconds are fine. A fast telescope is simulated.

    Han

     
  • Piero

    Piero - 2022-02-02

    Thanks Han, the drift is clearly visible now, if I check the "stack" checkbox in ccdciel and disable the star alignment function, I get nicely elongated stars without guiding :)
    The effects of exposure and gain are clearly visible as well.
    Are the produced images full 16 bit yet?

    Thanks a lot for your great work.

     

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