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This queue is for tickets about the Astro-satpass CPAN distribution.

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The Basics
Id: 78866
Status: resolved
Priority: 0/
Queue: Astro-satpass
People
Owner: Nobody in particular
Requestors: balt [...] inside.net
Cc:
AdminCc:
Bug Information
Severity: Wishlist
Broken in: (no value)
Fixed in: (no value)

History Show all quoted text
  Thu Aug 09 11:15:42 2012 balt [...] inside.net - Ticket created
Subject: sunrise/set almanac data not taking height into account
Date: Fri, 10 Aug 2012 01:08:20 +1000
To: bug-Astro-satpass [...] rt.cpan.org
From: Balthasar Indermuehle <balt [...] inside.net>
While checking almanac data for an observatory site in the high chilean andes today I noticed that the almanac data doesn't seem to correct for altitude of the observer. Here's how to reproduce it: Version info: satpass 0.041 - Satellite pass predictor based on Astro::Coord::ECI 0.041 Perl 5.10.0 on linux Show quoted text
satpass> almanac today
Location: ATCA Latitude -30.3128, longitude 149.5500, height 205 m Fri 10-Aug-2012 00:07:16 Local midnight 00:21:18 Moon rise 04:55:18 Last quarter Moon 05:47:45 Moon transits meridian 06:15:43 Begin civil twilight (-6 degrees) 06:40:36 Sunrise 11:11:23 Moon set 12:07:11 Local noon 17:34:07 Sunset 17:59:00 End civil twilight (-6 degrees) Show quoted text
satpass> set height 5000 satpass> almanac today
Location: ATCA Latitude -30.3128, longitude 149.5500, height 5000 m Fri 10-Aug-2012 00:07:16 Local midnight 00:21:19 Moon rise 04:55:18 Last quarter Moon 05:47:45 Moon transits meridian 06:15:43 Begin civil twilight (-6 degrees) 06:40:36 Sunrise 11:11:23 Moon set 12:07:11 Local noon 17:34:07 Sunset 17:59:00 End civil twilight (-6 degrees) Show quoted text
satpass>
  Thu Aug 09 23:31:22 2012 wyant [...] cpan.org - Correspondence added
On Thu Aug 09 11:15:42 2012, balt@inside.net wrote: Show quoted text
> While checking almanac data for an observatory site in the high chilean > andes today I noticed that the almanac data doesn't seem to correct for > altitude of the observer.
You are exactly right. I believe the usual almanac definitions of sunrise and sunset involve the the upper limb of the Sun passing above or below altitude 0 (or elevation 0 in aviation-speak) and that is what is implemented. It sounds like you want something closer to a "true" horizon. Actual horizon modelling (with peaks and valleys) is on the wish list, but it has been there for quite a while, and I would not hold my breath if I were you. There is actually a user who could use this (a satellite communications company) but they did their own. I think I would prefer not to actually depress the nominal horizon for elevation above sea level, since that would be inconsistent with the way my code handles satellite passes (you make the horizon setting something less than zero if you are on top of a mountain). A horizon other than 0 for almanac calculations is a possibility, but I will have to think how to implement. Possibilities at the moment include * An almanac_horizon setting; * A setting (which I do not have a good name for yet) that says "use the horizon setting for almanac calculations as well as satellite visibility calculations." I am currently leaning toward the first, but that may change after I sleep on it. Maybe almanac_horizon could be a hybrid (that's the polite term!) like the twilight setting, and take codes for special behaviors as well as number of degrees. If you have any words about what you would like the satpass script to do, please let me know. I won't guarantee to grant your every wish, but I think the more I know about your needs, the more likely you are to get something you can actually use. Tom
  Thu Aug 09 23:31:22 2012 The RT System itself - Status changed from 'new' to 'open'
  Thu Aug 09 23:31:34 2012 wyant [...] cpan.org - Severity Wishlist added
  Sat Aug 18 13:39:53 2012 wyant [...] cpan.org - Correspondence added
Astro-satpass 0.051_01 just went to PAUSE, and should be available on a CPAN mirror near you Real Soon Now. This development release involves (among other things) a new setting, 'almanac_horizon', which defaults to 0. Its value is degrees above the horizontal (negative for below), but it also takes the strings 'horizon' to make it follow the 'horizon' attribute, or 'height' to depress it for height above sea level. Obviously there is no way to specify, for example, "10 degrees above the true horizon depressed to compensate for my height above sea level" other than to compute the desired setting yourself and plug the value in.
  Sat Aug 18 13:39:53 2012 wyant [...] cpan.org - Status changed from 'open' to 'patched'
  Mon Aug 27 15:00:21 2012 wyant [...] cpan.org - Correspondence added
On Sat Aug 18 13:39:53 2012, WYANT wrote: Show quoted text
> Astro-satpass 0.051_01 just went to PAUSE, and should be available on a > CPAN mirror near you Real Soon Now. > > This development release involves (among other things) a new setting, > 'almanac_horizon', which defaults to 0. Its value is degrees above the > horizontal (negative for below), but it also takes the strings 'horizon' > to make it follow the 'horizon' attribute, or 'height' to depress it for > height above sea level. > > Obviously there is no way to specify, for example, "10 degrees above the > true horizon depressed to compensate for my height above sea level" > other than to compute the desired setting yourself and plug the value in.
I'm having second thoughts about allowing the 'almanac_horizon' attribute to take on the value 'horizon', meaning "use the value of the 'horizon' attribute, following it if it changes". I think allowing this will make it harder to enhance 'horizon' to be a real horizon, with mountains and valleys. I still plan to allow the 'almanac_horizon' attribute to take on special value 'height', tying it to the observer's height above sea level in the manner you originally suggested -- at least, as I understood your request.
  Mon Aug 27 15:00:21 2012 The RT System itself - Status changed from 'patched' to 'open'
  Sat Oct 13 21:59:56 2012 wyant [...] cpan.org - Correspondence added
Since version 0.052 has been out for a month, and there has been no activity on this ticket, or related to it in my inbox, I'm going to call this resolved.
  Sat Oct 13 21:59:57 2012 wyant [...] cpan.org - Status changed from 'open' to 'resolved'