Originally Posted by richardda1st
Thanks Gary, just logged in and found your post.
Wasn't aware that CdC adjusted the time for local time according to the co-ordinates.
Another good example of "why do the calculations when a computer can do it".
What will be important to the program is the UTC time and your lat/long.
The UTC time it will derive simply from your current local time setting
and time zone (+10 hours for AEST and +11 for AEDT).
So getting the time zone and local time right then allows it to perform
the arithmetic to obtain UTC.
But even then UTC is just used to help derive other time scales.
Internally, planetarium programs are mainly computing using sidereal time rather
than civil time. For example, during the course of a year, the Earth rotates
one more time with respect to the stars than it does to the Sun. This makes a solar
day about 3 minutes and 56.4 seconds longer than a sidereal day. In other words, a
sidereal second is not the same as a regular civil time second. Subtleties
such as this are again taken into account by the program but conveniently
all you have to do is enter your own civil time, time zone offset and lat/long
and the program will do all the tedious calculations.
ps Maybe my next upgrade will be an Argo navis, any comments.
Pity you can't be at the IceInSpace AstroCamp this weekend where some lucky
soul will walk away with a discount voucher as one of the sponsored prizes.
Anyway, hope the weather is good this weekend in Snake Valley!