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Alpaca Telescope Position Display, How To Make It Disappear When Position Is Unavailable? (Answer: Read On!)

Steven R.

December 11, 2023 07:26

Answered

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I am making a telescope aiming aid using a camera and plate solving. I am using Alpaca to create a Telescope server that reports the plate-solved ra/dec to Sky Safari. I have this working-- Sky Safari connects to my Telescope server and puts up a bullseye at the ra/dec reported by the telescope, updating it as the telescope moves. Great!

Sometimes plate solving fails-- the telescope is moving too quickly, or the camera is out of focus. When this happens, I want the Sky Safari telescope position indicator to disappear (or change appearance); when the ra/dec becomes available again I want the telescope position indicator to re-appear.

I tried returning errors from the declination() and right_ascension() functions in my Telescope server, but Sky Safari continues to display the most recent non-error telescope position. How do I arrange to have the Alpaca telescope server signal the Sky Safari indicator to be disable and re-enabled?

Thanks,

-Steven

 

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5 comments

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  Keiron Smith January 08, 2024 23:57 Official comment

  DevOps reference: https://starrynight.unfuddle.com/a#/projects/7965/tickets/by_number/2872

   

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  Keiron Smith December 11, 2023 14:54

  Steven,

  I've checked with our developers, Ros, and she said SkySafari doesn't visually show position read errors.

  Forcing a disconnection is probably the only way to hide the crosshairs.

  Great project!  Please keep us updated on your success.

  Thanks!

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  Steven R. December 11, 2023 17:07

  Thanks for the quick response!

  Would forcing a disconnect imply that the Sky Safari user would need to re-initiate the connection? That would be unfortunate for a momentary position data dropout.

  Responding to a ValueNotSet error return from declination() and/or right_ascension(), by blanking, dimming, or changing the color of the telescope position indicator would be much better and would be in line with the ASCOM Alpaca API guidelines.

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  Steven R. December 25, 2023 06:15

  So I've come up with a workaround. When my position data is stale, I'll report the last-known position, and "wiggle" the declination by a degree or so to indicate the data is not valid. Not the best solution, but better than nothing.

  Still, it would be great if Sky Safari were to render an error return on the declination() and right_ascension() calls in some suitable fashion (dim the crosshair, change its color, something).

   

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  Keiron Smith January 08, 2024 23:57

  Developers will review your info when working on the telescope controls in the future.

  Thanks!