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    USNO Web App End Year 2035
    From: Frank Reed
    Date: 2019 Sep 23, 09:51 -0700

    Many of us regularly use the USNO website and the "Celestial Navigation Data for Assumed Position and Time" web app. Ten years ago, Gary LaPook noticed that "the Naval Observatory website only goes to 2035". That's still true today, except that the end date is ten years closer than it was. I think it's clear that the web app is just displaying output from some underlying stand-alone piece of software, quite possibly running as a console app or even an old-fashionaed DOS app. I consider this a "good idea" in general because it means that the output is very stable. No one is messing with the underlying code. And if you look at the code on each displayed output web page, it's plain text, e.g.:

    ANTARES 113 54.3 S26 28.4 + 6 44.6 226.7 | -7.6 0.0 0.0 -7.6
    ARCTURUS 147 25.3 N19 05.1 +14 02.9 283.3 | -3.9 0.0 0.0 -3.9
    CAPELLA 282 01.2 N46 00.8 + 3 51.4 27.8 | -11.6 0.0 0.0 -11.6
    DENEB 51 01.5 N45 21.3 +81 30.6 48.0 | -0.1 0.0 0.0 -0.1
    DIPHDA 350 24.4 S17 52.7 + 3 15.6 116.7 | -13.0 0.0 0.0 -13.0

    Does anyone recognize the output style of this data, with some degree of certainty, from another USNO software package? I ask because I'm wondering what will be required down the road to extend this tool beyond the year 2035. Can it be re-compiled easily with a later end year, or are the ephemeris algorithms themselves inadequate after that year? Back when Gary wrote the comment above, that "end year" was 26 years in the future, but now it's only 16 years. I was doing some error checking for a project today and needed data for 2036. There is none from the USNO tool; it returns a blank page. Of course, there are alternatives, but it's nice to have this USNO source.

    Frank Reed

       
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