Stellarium

For Ocular Plug-In, increase input size limit of Diameter and Focal Length

Asked by R Rieffel

Feature request (very low importance) for the Ocular Plug-In:
Would it be possible to increase the input size limit of the "Diameter" and "Focal Length" values of the Telescopes?

I like to have fun with Stellarium and try to replicate the large telescopes around the globe (and in space!). However, when it comes to the Extremely Large Telescope observatories, I am unable to enter the extremely large sizes of these telescopes.

Currently, the Diameter's limit is 9999.0 mm, and the Focal Length's limit is 99999.0 mm.

I was thinking perhaps both parameters could have a limit of 9999999.0 mm. (7 digits with an additional tenth digit.) This would allow for something as ridiculously large as the cancelled Overwhelmingly Large Telescope with a diameter of about 100 meters.

I acknowledge there is probably something I do not understand about telescopes and/or Stellarium that might make this request nonsensical. But, I thought I ask anyway.

Thank you for your work!

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gzotti (georg-zotti) said : 		#1

Do you also know OLT's focal length?

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R Rieffel (rif-austin-tx) said : 		#2

It took some research to find an answer to your question. I am not sure if I am correct, but I believe the focal length is around 650 meters.

I found a number of design papers (links below) for the OLT (the European Southern Observatory actually refers to it as "OWL"). If I read them correctly, it was proposed to have a focal ratio between f/6 and f/7. If I apply the simple telescope equation, (Focal Length = Aperture * F-ratio), and take the f-ratio average of f/6.5 then I get 650 meters (100m * 6.5).

The papers are written well above my knowledge of telescopes, so could I be reading the data wrong. I also do not know if the simple telescope equation above is appropriate to use in this situation due to the added complexity of the telescope's optics.

For what it's worth, the ever-unreliable Wikipedia page for this telescope lists a focal length of 175 meters, but it provides no reference. So, I do not know where this number came from.

Thanks!

REFERENCES:
Got focal length from first paragraph here: http://www.eso.org/sci/facilities/eelt/owl/Blue_Book/6_Telescope_optics.pdf
This PDF is actually just one chapter of a large paper that may be found here: http://www.eso.org/sci/facilities/eelt/owl/Phase_A_Review.html

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Launchpad Janitor (janitor) said : 		#3

This question was expired because it remained in the 'Open' state without activity for the last 15 days.