NavList:

John Howard, you wrote:
"nobody seems to use the JPL Horizons system to get Almanac data."

Well... I can think of several reasons for that:

• That resource is for astronomers, not navigators.
• It's quite a bit more technically challenging to use than other resources, and more than half of practitioners of celestial navigation are "all thumbs" when it comes to technology.
• There's far more precision in the usual data output than required for celestial navigation.
• Most navigators have no clue what to do with "right ascension" and as far as I know there is no option for GHA though it might be possible to "hack" that.
• Stars? Horizons has no data for the navigation stars.
• There are numerous online resources that provide the almanac data for celestial navigation in just the formats required with the right precision and data entries.

If you're doing almost any "normal" type of celestial navigation, the data you can get from the standard USNO almanac service is usually superior: http://aa.usno.navy.mil/data/docs/celnavtable.php. Of course, I don't want to imply that there's anything wrong with the Horizons service, and if you can handle its options, and you like its output, then it's great.

Frank Reed