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+--- Forum: Observing Close Approaching Asteroids (https://skyhound.com/forums/forumdisplay.php?fid=28)
+--- Thread: Late Discoveries (/showthread.php?tid=2160)
Late Discoveries - bigmasterdrago - 2021-07-12
It's sometimes interesting how we miss these small rocks until after closest approach. This appears to happen rather often. Take 2021 NU3 as an example, discovered just couple days ago, 1+ days after its close approach which occurred on July 8, 7:17UT (my location). The small (25') rock came in from the sun-ward side and directly over the north pole unseen at magnitude 15.7. It then continued outside our orbit and finally crossed the ecliptic a day later (9 July 3UT) at magnitude 17.6ish. At this point I think observations may have begun. It was actually a magnitude fainter when closest due to phase angle. At this point the orbit is still uncertain. Crazy stuff as sun-ward approaching rocks will surprise us.
Some useful tools for getting info on rocks your interested in can be found at https://minorplanetcenter.net/db_search
and https://minorplanetcenter.net/db_search/show_object?utf8=%E2%9C%93&object_id=2021+NU3
And there, you can get a geocentric flyby diagram if you don't have software to do detailed solar system simulations. https://minorplanetcenter.net/neo/view?date=2459403.805&label=2021%20NU3&packed_desig=K21N03U
RE: Late Discoveries - obrazell - 2021-07-12
Like the Chelyabinsk object? That came from the sunward side and caused a bit of an issue when it hit.
RE: Late Discoveries - PMSchu - 2021-07-12
Spotting these things after close approach is a fairly common occurrence, unfortunately. Anything coming from the sunward direction is naturally hard to spot. It usually misses & we can spot it, or it will never pass us again. If an asteroid explodes over the Pacific, does it make a sound? Sure does & sometimes our detectors can hear it.
The amazing ones are those that skip off the atmosphere & continue on.
Thanks for the web link BMD. It doesn't like the way I have MS Edge set up.
Phil S.