I have looked for months for any site capable of calculating solar altitude w.r.t an observer located on the surface of a generic celestial bodies, but with no luck as of now. Even NASA does not provide such information in its Horizons page/software, although technically Horizons contains all the needed data to calculate "local solar time"; indeed, Horizons allows asking for such an output... but currently output is jut "n/a" for bodies other than Earth:
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Date__(UT)__HR:MN, , , L_Ap_Sid_Time, L_Ap_SOL_Time, L_Ap_Hour_Ang,
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$$SOE
2020-Aug-09 10:51,*,x, n.a., n.a., n.a.,
2020-Aug-09 11:51,*,x, n.a., n.a., n.a.,
Url to ask for quantities 7, 34 and 42 (note: only 42 is declared as "Earth surface only").
So I tried to setup my own page ( http://win98.altervista.org/space/exploration/moon/moontime.html ), which makes its calculations starting from "colongitude" and moon terminator longitude, but it completely disregards observer latitude and altitude.
Any suggestion about pages which perform these calculations?
My GUI for NASA Horizons: http://win98.altervista.org/space/exploration/NHUGUI.html
To specify a location on another body, write "coord@body" in "CENTER" field, without changing "COMMAND" field, which will be ignored, and write the triplet "lon, lat, alt" in field SITE_COORD.
To find predefined sites on a body use *@body , for example *@301 will list Moon landing aites.