On Sun, 11 Apr 2021 23:23:11 +0000 (UTC), R Kym Horsell
wrote:

B R Sitaram wrote:
Hi,
I am a physicist/model designer from Ahmedabad, India. Recently, I designed a model called the Sub-solar point model, which shows the point on the earth's surface where the sun is exactly overhead at that instant. This point changes from east to west during the course of the day and from the tropic of cancer to capricorn and back during the course of the year. The model is very useful in looking at the apparent motion, especially the north-south motion.

So your program calculates the RA and Dec of the sun and subtracts
Greenwich siderial time from the RA?

Does it need updating every "epoch" or have you found some trick
to make the calculation "perpetual".
test 7