My scope simulator is pointing to the celestial north pole. My position is 41º 27' lat and 2º 15' long.

At 12h 43m local time (11h 43m UTC) the coordinates read from the scope are:
RA: 16h 14m 25s
DE: 90º 00'00"

There seems to be a constant 4h 31m difference between North pole RA and UTC time.

What the relation is between UTC, my location and celestial North Pole Right Ascension ?

I am making all kind of operations trying to relate these numbers to no avail.

Sorry if it's too stupid a question. I try to create a model in my brain of how celestial movements work and at the moment I only manage to explode a few neurons. Getting a clear answer will help me get the puzzle together


1 Answer 1


The north celestial pole doesn't have a right ascension. It's like the north terrestrial pole not having a longitude. Asking for it creates an exception. In any case, the RA of a point, other than the poles, isn't dependent on time or the observer's location. Your simulator has an error in its error handling.

  • $\begingroup$ Thanks. Crystal clear. $\endgroup$
    – joaquin
    Feb 25, 2021 at 15:49

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