Quote:
Originally Posted by astro744
Just think of it in 24hr clock terms (24-19 = 5). The first 5hr brings you to 24/0hrs LST which = 00hrs RA on the meridian. Add another 5hr and Orion is up high.
LST is now just after 21hrs so add 3 to get to 24/00 and then add the RA of the object in question (approx 5 for Orion). In 3hrs time the LST is 24/00 so any objects with an RA of 00 will be on the meridian. Approx 5hrs later again will be Orion.
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Got it. I think. If we say directly overhead/transit is 24h on some local RA grid, 18h would be rise, 6h would be set.
To find transit time: 24h - LST + RA(object) + local time
eg LST is currently 22:00 or 22 in decimal for simplicity; RA of NGC1499 is 4h (nice round number); local time is 5:30pm or 17.5 in decimal.
NGC1499 should transit at 24-22+4+17.5=23.5 which is 11:30pm. Got it.
Thanks for sticking with me on that.