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+--- Thread: Missed a real screamer 2021 TX (/showthread.php?tid=2271)
Missed a real screamer 2021 TX - PMSchu - 2021-10-05
I missed a really fast one - 2021 TX that hit 61"/sec motion ~midnight on Oct 2 in Spain!! Minimum Re was 57.96k km. It reached 15.9 mag, too. I've never found one moving this fast. I only noticed it because I misread 2021 TK as 2021 TX in the results of today's MP DBPS. It passed so fast that the searches for Sep 29, & Oct 1&3 didn't find it. It may have been discovered after close approach. According to the entry in the JPL Small Body Database, the first data used was from Oct 2 so it had already passed us.
Win some, lose some.
Phil S.
RE: Missed a real screamer 2021 TX - razvan - 2021-10-06
Obligatory Expanse joke: it must have been covered in Martian stealth tech, like the others thrown towards Earth
JPL says the closest approach was at 0.00028 AU, that's 41,887km, quite close. And that's Earth center to asteroid center, that's 35,516km from the Earth surface!
RE: Missed a real screamer 2021 TX - PMSchu - 2021-10-06
Close for sure, almost to the geosynchronous satellites. That Martian tech is good stuff.
Phil S.
RE: Missed a real screamer 2021 TX - razvan - 2021-10-06
I subscribed to ESA's NEO Coordination Centre | Planetary Defence Office (this must be the coolest employer name to put on LinkedIn for those people) and there is an interesting note in their October issue: "of the almost 27 000 discovered NEOs, about 25% have an observed arc of less than a week, and 50% have been seen for less than a month. Many of these objects will likely be already unrecoverable at their next favourable apparition, and will have to be rediscovered in the future."
RE: Missed a real screamer 2021 TX - PMSchu - 2021-10-06
Talk about assured employment! Even when they find 'em they lose 'em again. These little motes become so faint after close approach I suppose they're impossible to track even with professional equipment. According to Shefer's paper his method provided ~3x better accuracy than the older methods even for short arcs. I guess many of the subsequent passes aren't as favorable as the ones when they get discovered. 2010 CA261 seems to be an excellent example of a 'lost' object.
I wonder what kind of orbit accuracy the MPC gets with a week or a month of observations. Current techniques yield much better accuracy than the photographic methods used in the past. Shefer stated that photographic methods had accuracies of ~1.6 arcsec, while CCD imagers are 10 or more times better.
If you've run any of the ephemerides for these things, it's amazing how fast they brighten & fade in a week or two.
Phil S.
RE: Missed a real screamer 2021 TX - bigmasterdrago - 2021-10-07
(2021-10-06, 06:48 PM)razvan Wrote: I subscribed to ESA's NEO Coordination Centre | Planetary Defence Office (this must be the coolest employer name to put on LinkedIn for those people) and there is an interesting note in their October issue: "of the almost 27 000 discovered NEOs, about 25% have an observed arc of less than a week, and 50% have been seen for less than a month. Many of these objects will likely be already unrecoverable at their next favourable apparition, and will have to be rediscovered in the future."
I tried to search for that office and mostly found only this: https://dart.jhuapl.edu/
(2021-10-06, 12:32 AM)razvan Wrote: Obligatory Expanse joke: it must have been covered in Martian stealth tech, like the others thrown towards EarthWhen that rock screamed by me on On Oct 1 16:27CDT (daylight), it came whipping by my yard, moving 1.5°/min at a distance of 38,841Km!! Yikes! Talk about ruffle the short hairs. I always use topo centric distances. Even when using Horizons.
JPL says the closest approach was at 0.00028 AU, that's 41,887km, quite close. And that's Earth center to asteroid center, that's 35,516km from the Earth surface!
RE: Missed a real screamer 2021 TX - PMSchu - 2021-10-07
And we were all none the wiser because it wasn't detected until it went past. Assured employment = Job Security
I found this link to the ESO NEA Coordination Centre Planetary Defense Office:
ESA - Risky asteroids
Phil S.
RE: Missed a real screamer 2021 TX - bigmasterdrago - 2021-10-07
Thanks Phil