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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

StarSense-alike functionality

  • Posts: 158
  • Thank you received: 2
Celestron users might know about one wonderful device - StarSense AutoAlign. It allows to perform completely automatic star alignment. Basically it does astrometry for achieving this. And here rises a question for users which doesn't own StarSense - what if I want to use for astrometry not the main telescope, which is doing the photography, but the guider? We run into a problem - optical axes of the main telescope and the guider can't get completely parallel even we try very hard. How this is solved with StarSense? Correction procedure! We need to tell StarSense what is the misalignment between optical axes. For this we align main telescope to a star and tell StarSense to calculate the difference.
This is the algorithm for getting the same functionality in Ekos:
1) User points main telescope to a star and position it to the center as precise as possible;
2) User replace eyepiece with camera. Focus and after that center it with the help of a cross-hair;
3) Tell Ekos to guide the star - it must remain in the center;
4) Sync to the centered star in the KStars;
5) Run astrometry on the camera attached to the guider;
6) After pressing a conventional button Ekos calculates the misalignment between optical axes of the main telescope and the guider. It will be used for further pointing of the objects (and alignment procedures in Ekos also).

Something like this... Very useful functionality for users with main telescope which have big focal length and cameras with small sensors (but even with big sensors it is indeed a problem, especially with poor polar alignment)!
8 years 10 months ago #4219

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No comments? It's only me struggling with Schmidt-Cassegrain?
8 years 10 months ago #4263

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What's wrong with solving using the main CCD?
8 years 10 months ago #4272

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Field of view is small, especially with small sensors (e.g. ATIK Titan). Because of this astrometry is impossible/failing. I tried also with ATIK 383L+ - field of view is bigger but still complicated, you need long exposures (more than 15 seconds. With poor polar alignment and focal length of 3950 mm you get into trouble, stars are becoming trails very fast...). In this situation astrometry accomplished with the guider can significantly help, especially if you are not an owner of big sensors cameras like 383L+.

P.S. May be guiding during the the exposures for astrometry shot can improve the situation? Because in this case exposure durations can be increased to the necessary length and necessity for second astrometry-device will disappear... Or I am missing some important point?
8 years 10 months ago #4275

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Replied by Terry on topic StarSense-alike functionality

I realize it's been a while since you posted but have you ever sought out or looked at any tutorials Jasem has placed on the Internet. He covers How to find the suggested FOV settings and how to use/copy them to the necessary window for Astrometry to use it correctly saving time on the process. I found 3 separate videos covering Astrometry alignment using Ekos. If you follow the tutorials within you should not have an issue. I was having similar problems I just wasn't using a guide camera I used the main ccd.
4 years 9 months ago #39729

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