2024-10-08, 08:13 PM
Hi smockdonner,
Welcome to the forum. Actually 2024 RJ2 made its close approach on 2024 Sep 5, but the peak brightness occurred one day later on 2024 Sep 6. It's quite common for the close approach and peak brightness to occur at different times unless the NEO passes very close by, then the peak brightness coincides with the time of close approach. The brightness is a function of NEO diameter, distance from earth and the phase angle between the earth, sun and NEO. For very close approaches the distance becomes the dominant factor.
The orbital motion calculations in SkyTools are very accurate. The calculations solve for the motion of the NEO around the sun using orbital elements downloaded from the Minor Planet Center (MPC) by SkyTools under the Data>Minor Planets Menu option. Click the 'Download/Import' button, then Chose the 'MPC NEA Today' to download the orbital elements for ~35,000 NEOs at today's epoch of osculation. Refer to the Help for more information about orbital elements and calculating the positions of minor planets and comets (the 'Ephemerides' tab).
Because the orbit is known the position of the NEO can be calculated at any time. The uncertainty of the time of close approach of 2024 RJ2 was <1 minute. You're right that the NEO will move ~40"/minute at peak brightness and ~50"/minute at close approach. Some recently discovered NEOs were moving much faster, but were discovered after close approach, so I didn't report them here.
Hope this helps,
Phil S.
Welcome to the forum. Actually 2024 RJ2 made its close approach on 2024 Sep 5, but the peak brightness occurred one day later on 2024 Sep 6. It's quite common for the close approach and peak brightness to occur at different times unless the NEO passes very close by, then the peak brightness coincides with the time of close approach. The brightness is a function of NEO diameter, distance from earth and the phase angle between the earth, sun and NEO. For very close approaches the distance becomes the dominant factor.
The orbital motion calculations in SkyTools are very accurate. The calculations solve for the motion of the NEO around the sun using orbital elements downloaded from the Minor Planet Center (MPC) by SkyTools under the Data>Minor Planets Menu option. Click the 'Download/Import' button, then Chose the 'MPC NEA Today' to download the orbital elements for ~35,000 NEOs at today's epoch of osculation. Refer to the Help for more information about orbital elements and calculating the positions of minor planets and comets (the 'Ephemerides' tab).
Because the orbit is known the position of the NEO can be calculated at any time. The uncertainty of the time of close approach of 2024 RJ2 was <1 minute. You're right that the NEO will move ~40"/minute at peak brightness and ~50"/minute at close approach. Some recently discovered NEOs were moving much faster, but were discovered after close approach, so I didn't report them here.
Hope this helps,
Phil S.