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Two more bright MPs on the way
Hi MP watchers. There are 2 more MPs visible now & coming closer. (4660) Nereus is currently 14.3 magnitude in Perseus with close approach on Dec 11. (163899) 2003 SD220 is currently 15.3 magnitude in Draco with close approach on Dec 17. Both objects are currently moving at several arcsec/min despite the present distance from earth.

Good hunting,

Phil S.
My notes on these two MP:

Interestingly, SD220 has a small window of opportunity (19:00CST) on two evenings (Dec 16 & 17) when up 57° in the west, with the near full Moon 80+ degrees away in the east but 30°-40° high. The rock may be hovering ~13th magnitude.

As for Nereus, the hours after midnight on December 10th & 11th make for good opportunities, with the close pass being in daylight on the morning of the 11th when it is placed in the same part of the sky as SD220 but a week earlier. It could be as bright as 12th magnitude just prior to astronomical twilight high in the north on both December 9th, 10th & 11th. I mentioned this rock on Nov. 3 - Elements for this rock are rock solid, so should get at least one day of favorable weather.
Looking back at some old posts on this topic, I noticed that (163899) 2003 SD220 also made a close approach in December 2018. It will be back in December 2024, but at a distance of 0.088 AU.

Phil S.
Phil, I know you already know this but for those that don't, Horizons has made it much easier today to hunt down that sort of information. Go to then put in the rock designation or number and scroll down and click "show" on the Close Approach Data. You can now look far back as well as at future dates for not only our home planet but the Moon, other planets and several of the larger asteroids. I've used stand-alone specialty software to do that for years but now find it easier to let Horizons show me the work they have already done.

You can even get data for recent discoveries, even though they may have only 1 day arcs with reasonably low uncertainty with a couple dozen observations. I'm not sure why JPL calls 4-8 days reasonably low uncertainty!

Take the small rock 2022 CJ5 that scrapped my horizon a couple days ago just 31,221Km from my yard. Punch it in at Horizons to see that it had a similar close approach almost exactly 12 years ago. Cool stuff!
Yes, that's how I discovered the 2018 close approach of 2003 SD 220. It's very impressive. 

JPL may be able to have high certainty in their position predictions, if the object isn't being perturbed by other planets. When it's close to earth, that would be the case. Also, the accuracy of the astrometry being done with digital sensors is much better than what was possible with photographic plates. 

I watched a presentation by Daniel Parrott, developer of Tycho, software for analysis of photometric & astrometric data that was put on by the iTelescope folks. His software is very impressive. I need to investigate it further. It looks like it would work well with SkyTools & the iTelescopes.

Here's the link to it:

Tycho Tracker (

I hope Greg doesn't mind me including the link here. He can delete it, if he likes.
Phil S.

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