From planetaryscience at yahoo.com Thu Dec 24 19:32:29 2020 From: planetaryscience at yahoo.com (Sam Deen) Date: Fri, 25 Dec 2020 00:32:29 +0000 (UTC) Subject: [neo_followup] ST20L43 = very low relative velocity, might be old space debris. References: <1242744438.4272001.1608856349324.ref@mail.yahoo.com> Message-ID: <1242744438.4272001.1608856349324@mail.yahoo.com> Hi all, Recommending followup of this object ASAP, but with a bit of healthy hesitation as it seems like the sort of object surveys should have recovered by now. Either way, worth a shot. Discovered a few days ago by the JPL robotic observatory in california and recovered later from Naples, ST20L43 has a very surprisingly earthlike orbit: ?? Perihelion 2020 Sep 25.257218 +/- 881 TT =? 6:10:23 (JD 2459117.757218) Epoch 2020 Dec 21.0 TT = JDT 2459204.5?? Earth MOID: 0.0105?? Find_Orb M? 84.62237264 +/- 800????????????? (J2000 ecliptic) n?? 0.97555520 +/- 0.00227????????? Peri.?? 68.95364 +/- 800 a?? 1.00685782 +/- 0.00156????????? Node?? 295.40901 +/- 10 e?? 0.0030126 +/- 0.00877?????????? Incl.??? 1.48337 +/- 0.54 P?? 1.01/369.01d?????????? H 26.3?? G? 0.15?? U? 8.8 ? q 1.00382447 +/- 0.00734??? Q 1.00989117 +/- 0.0103 >From 6 observations 2020 Dec. 20 (14.6 hr); mean residual 1".10 In fact, just based on eyeballing it, it might have the lowest geocentric velocity of any asteroid ever discovered, even beating out 2000 SG344! The incredibly low eccentricity and similar semimajor axis does it some great favors in this regard. Still, despite it supposedly being magnitude 19 (and some change) nobody's recovered it in the four days since. According to the NEOCP blog, I52 has hunted for it on the mornings of the 21st, 22nd, and 24th with no luck. Currently, its position uncertainty is around 800 arcseconds and growing at a generous elongation of 157 degrees. To anyone having a go at it, it seems your main obstacle will be the fairly large uncertainty. It moves reliably enough around 2 arcseconds per minute to show up against background stars. I suggest people expect it to be a couple magnitudes dimmer too, though. With these low velocities, there's always the chance of it being some old space debris, and that combined with nobody spotting it yet looks a whole lot like we've got a satellite flaring up, and you might need to get lucky if you hope to spot it again. ~Sam -------------- next part -------------- An HTML attachment was scrubbed... URL: