From planetaryscience at yahoo.com Fri Jan 17 13:29:29 2020 From: planetaryscience at yahoo.com (Sam Deen) Date: Fri, 17 Jan 2020 18:29:29 +0000 (UTC) Subject: [neo_followup] ZTF09p2 5% chance of Earth impact yesterday References: <205965588.349242.1579285769993.ref@mail.yahoo.com> Message-ID: <205965588.349242.1579285769993@mail.yahoo.com> Hi all, Usually, reporting potential impact chances comes after a bit more than 4 observations over a period of 30 seconds, but this object that ZTF found yesterday, and reported far too late yesterday, seems to be a decent exception. The object was observed moving around 200 arcminutes per hour over the observation time, which really doesn't leave much room for it to be further away than a few lunar distances at the observation time. The timing of the 4 observations gives some cause for suspicion, with pairs of observations each only 0.9 seconds apart, but considering there's a multi-arcsecond difference between said observations, I expect it could very well just be measurement of a streak caused by the high motion. According to CNEOS, 5% of the virtual orbit solutions give impacting solutions, and fitting the observations to an impact in find_orb seems to fall somewhere on the west coast of the US (I invite others to double check that) with an absolute magnitude of around 34 +/- 1. Normally, I would discount something with that tiny an absolute magnitude as unprovable for an impact, but considering the well-observed region of the west coast, I imagine getting some accurate impact times, trajectories, and locations should allow it to be checked against the AMS's prolific US fireball logs from 2020/01/16. ~Sam -------------- next part -------------- An HTML attachment was scrubbed... URL: From pluto at projectpluto.com Fri Jan 31 09:25:38 2020 From: pluto at projectpluto.com (Bill Gray) Date: Fri, 31 Jan 2020 09:25:38 -0500 Subject: [neo_followup] C21E3U2 = interesting object Message-ID: <361bc692-0d07-ce46-ca5c-0dff2acb6ac8@projectpluto.com> Hello all, If you can follow this object up in the next few hours, I'd strongly urge you to do so. It looks as if it could make a very close approach sometime around 19:00 UTC today. (It also may turn out to be much less interesting than that. We have four observations covering 20.1 minutes; sweeping claims are difficult.) If you look at the MPC's uncertainty maps, you'll see that the nominal position is for the "uninteresting" case. Down to the southwest end of the uncertainty region, you start to get the close-approach cases. I'd suggest looking there first, because if it's in that region, time is of the essence. If it's really more distant, you can look in the nominal region later, in a more leisurely manner. It's that possibility of a close-in shot that ought to get the attention right now. It's quite faint and the uncertainty will grow fairly quickly, so I'm not really optimistic here... but it should definitely be a priority object if you can go to mag 21.5 or so. -- Bill From pluto at projectpluto.com Fri Jan 31 11:11:20 2020 From: pluto at projectpluto.com (Bill Gray) Date: Fri, 31 Jan 2020 11:11:20 -0500 Subject: [neo_followup] {MPML} C21E3U2 = interesting object Message-ID: <6cf5d9f2-dc71-6fc7-c1ad-89a5cea6c2a7@projectpluto.com> Hi David, Got it. Never mind; looks as if it's going away from us, not toward us, after a really close pass. In fact, I can actually exclude a lot of otherwise possible orbits for this particular object on the grounds that they'd have had to tunnel underground at perigee. (*) That constraint usually wouldn't eliminate enough possibilities to be worth thinking about. Hope the ATLAS follow-up works, though it seems a bit fainter than they usually go. -- Bill (*) Underground, gravity drops linearly as you reach the center of the planet; dig a third of the way to the earth's center, and you're at 2/3 of the surface gravity. (**) Find_Orb actually handles that correctly. But I did that only to keep the math and software simpler. Unless you're a black hole, orbiting inside or through the earth is a theoretical concept only. (**) OK, OK... assuming uniform density. Much of the mass is in the earth's core. So it wouldn't drop quite that much. On 1/31/20 10:01 AM, David Rankin wrote: > There was a mixup with the follow up. There should be 3 discovery obs and only the 4 follow up obs. > > C21E3M2 C2020 01 31.55461 14 25 30.20 +31 56 50.4 20.4 ?G G96 > C21E3M2 C2020 01 31.55514 14 25 28.86 +31 56 51.8 20.3 ?G G96 > C21E3M2 C2020 01 31.55566 14 25 27.56 +31 56 53.6 20.0 ?G G96 > C21E3M2 C2020 01 31.55618 14 25 26.26 +31 56 54.5 ?G96 > > Notified MPC. > > -------- Original message -------- > From: "Bill J. Gray" > Date: 1/31/20 7:25 AM (GMT-07:00) > To: "MPML Groups.io" , neo_followup at projectpluto.com > Subject: {MPML} C21E3U2 = interesting object > > Hello all, > > ??? If you can follow this object up in the next few hours, > I'd strongly urge you to do so.? It looks as if it could > make a very close approach sometime around 19:00 UTC today. > (It also may turn out to be much less interesting than > that.? We have four observations covering 20.1 minutes; > sweeping claims are difficult.) > > ??? If you look at the MPC's uncertainty maps,? you'll see > that the nominal position is for the "uninteresting" case. > Down to the southwest end of the uncertainty region,? you > start to get the close-approach cases.? I'd suggest looking > there first,? because if it's in that region,? time is of > the essence.? If it's really more distant,? you can look > in the nominal region later,? in a more leisurely manner. > It's that possibility of a close-in shot that ought to get > the attention right now. > > ??? It's quite faint and the uncertainty will grow fairly > quickly,? so I'm not really optimistic here... but it > should definitely be a priority object if you can go to > mag 21.5 or so. > > -- Bill > > -=-=-=-=-=-=-=-=-=-=-=- > Groups.io Links: You receive all messages sent to this group. > > View/Reply Online (#35281): https://groups.io/g/mpml/message/35281 > Mute This Topic: https://groups.io/mt/70789862/917999 > -=-=- > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > Posts to this list or information found within may be freely used, with the stipulation that MPML and the originating author are cited as the source of the information. > -=-=- > Group Owner: mpml+owner at groups.io > Unsubscribe: https://groups.io/g/mpml/unsub? [david at rankinstudio.com] > -=-=-=-=-=-=-=-=-=-=-=- >