Just for laffs, here's what I come up with:
Using VSOP87D, with deltaT = 79 seconds, taking into account all known
effects except refraction:
azimuth = 200.72354871227333
altitude = 39.1844374748319
with refraction 39.20512111866974
Using the simpler Sun model in Meuus which only gives the ecliptic
longitude, but includes the nutation and the aberration:
azimuth = 200.71774169672503
altitude = 39.18821032219071
with refraction 39.2088912042855
I agree with Gian.
Brad
On Wed, Mar 3, 2010 at 6:33 PM, Aimo Niemi <[email protected]> wrote:
> Hi
>
> 2010/3/3 [email protected] <[email protected]>
>
>> I think that no comparison can be made between different programs results
>> without knowing the value of DeltatT that has been used.
>>
>
>
> I again think that DeltaT is not needed if we calculate apparent places and
> use UT.
> Most accurate link capable for that (what I know) is at
> http://ssd.jpl.nasa.gov/horizons.cgi#results
> If refraction is not calculated, the link gives
> azimuth=200.7239 and altitude = 39.1824 (39.2031 if refraction is included)
> Regards
> Aimo
>
>
>
>
>
>> Ephemeris tables usually declare the value of DeltaT that was used.
>> It is also worthy to note that for gnomonic applications all these results
>> are more than correct :-)
>> Regards.
>> Gian
>>
>>
>>
>> ----Messaggio originale----
>> Da: [email protected]
>> Data: 03/03/2010 20.51
>> A: "John Goodman"<[email protected]>
>> Cc: "Sundial List"<[email protected]>
>> Ogg: Re: Solar position calculator
>>
>>
>> Hi
>> I got following results from the link
>> http://www.roman-britain.org/astronomy/astro.htm#
>> which I believe is trustworthy
>>
>> azimuth=200.7233 (20.7233 if south is the zeropoint)
>> altitude= 39.1827
>>
>> I also tested the results with my own semi-accurate PcAllakka
>> with following results
>> azimuth=200.715 and altitude=39.188
>> Anyone interested can load the program from
>> http://pc-calculator.110mb.com/allakka/
>>
>> or perhaps some of you is curious enough to visit my solar tracking
>> sundial pages at
>> http://pc-calculator.110mb.com/tracker/solartracker.html
>>
>> Greetings
>> Aimo Niemi
>>
>>
>> 2010/3/3 John Goodman <[email protected]>
>>
>>> If anyone needs to make precise solar position calculations, the
>>> following software may be useful. There are a few caveats. The software is
>>> not a stand-alone application, it's a software library. The software library
>>> needs to be used from the command line and it runs using the Python
>>> programming language.
>>>
>>>
>>> I'm a Mac user and this is one of those rare occasions when an arcane set
>>> of requirements actually favors the Mac. While Macintosh users tend to be
>>> allergic to the command line, it has existed in the OS for the past 10
>>> years. Python is there too, lurking under the surface.
>>>
>>> I don't know enough about the PC, but clearly the command line is there
>>> and Python is available too. ( http://www.python.org/download/windows/ )
>>>
>>> With all that preface, here's what the code can do. Once the necessary
>>> files are installed, you can type the following commands and see the
>>> following results:
>>>
>>> >>> import datetime, solar
>>> >>> d = datetime.datetime(2010, 3, 3, 18, 0, 0)
>>> >>> lat = 42.0
>>> >>> long = -71
>>> >>> solar.GetAltitude(lat, long, d)
>>> 39.203509044804704
>>> >>> solar.GetAzimuth(lat, long, d)
>>> -20.717667802423591
>>> >>>
>>>
>>> Someone with an ephemeris can check these results. The format for
>>> datetime is "yyyy, mm, dd, hh, mm, ss", optionally followed by a number of
>>> microseconds. The time value entered is for UTC.
>>>
>>> There are other functions for calculations that I haven't explored. You
>>> can read more about the software tools at http://pysolar.org/ Example
>>> uses are shown at http://wiki.github.com/pingswept/pysolar/examples The
>>> software itself is at http://github.com/pingswept/pysolar/downloads
>>>
>>> All of this software is the work of Brandon Stafford, who has generously
>>> offered his code free of charge to anyone who may find it useful. I have
>>> little experience with this software but, as much as I can, I'll be happy to
>>> help anyone trying to use it.
>>>
>>> If there are any questions, I can pass them on to Brandon. I hope this is
>>> helpful to some.
>>>
>>> ---------------------------------------------------
>>> https://lists.uni-koeln.de/mailman/listinfo/sundial
>>>
>>>
>>
>>
>>
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>>
>>
>>
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