Quoting Bamm Gabriana <bamm@...>:

>> The methods used are those described in the "Explanatory Supplement
>> to the Astronomical Almanac". They are extremely good - contact
>> times should be correct to the nearest second.
>
> Does the elevation above sea level matter in computing the
> circumstances? I imagine it should, but changing the elevation in
> SkyMap does not have seem to change the results.
>

Yes, the user's elevation is used when computing local circumstances
but, unless the elevation is extreme, the effect will be extremely
small.

Regards,

Chris