2021-09-28, 10:23 PM
(This post was last modified: 2021-09-28, 10:52 PM by bigmasterdrago.)
A similar and not outdated list can be found at https://spaceweather.com/ and by clicking on the name, it's easy to quickly run a fast ephemeris for your location spanning the 48 hours (1 hour steps) near close approach. I use that info to best determine the time and interval to run an ephem in ST, etc. to get best times. And discover that the best apparition for 2021 RG19 is not at closest (Sep 28, 17:01 CDT moving 3.9'/min) but in dark time on the 27th between 20:00 and 23:45 CST for me. Moving ~1.5'/min, alt 31°-57° at NE azimuth moving from Andromeda into Cassiopeia. And very little difference in apparent magnitude due to the phase angle change 84% vs 56%@closest approach. At closest approach it is actually 8° below my NW horizon! I did not even know of this rock as I was out of town. good for those with imaging 4"-6" but too faint for my visual 13".
In the produced ephemeris at Horizons, use the column deldot to determine when the object is changing from coming to going and then look at the illu% for % phase angle.
In the produced ephemeris at Horizons, use the column deldot to determine when the object is changing from coming to going and then look at the illu% for % phase angle.