(Email from Cattle Point Dark Sky Urban Star Park volunteer William Smith)
Dear Gerhard Drolshagen : On the Orbit of WT1190F (aka Snoopy)
Does object get captured weeks before and go into earth’s orbit, slowly losing speed and descending? OR does it come shooting directly into the earth’s atmosphere – almost perpendicular to a tangent ie pointing at the earth’s centre? This is important because if it orbits the earth one or two times as it slows down, then we might see it in the dark of the late evening where we are on West Coast of North America..
Look here : https://www.pinterest.com/pin/564357397034893195/
If you look at the ISS paths then focus in on the one which crosses southern India, this might indicate that SNOOPY (coming also NW-> SE) would pass over Panana, Bahamas, Northern Spain , Mediterranean and then IRAN . No luck for west coast of USA/Canada where I am.
Hello Bill,
Gerhard Drolshagen forwarded your message to me. Here is some of the info we have on WT1190F.
The object has been in Earth’s orbit at least since 2009. It has been moving in an elongated orbit with apogee at about twice the distance of the Moon, and perigee getting closer and closer to the Earth, until the upcoming re-entry. Since 2009, it has completed dozens of orbits around the Earth, and each orbit is about a month long.
The impact trajectory is not very vertical, but still much steeper than the typical re-entry of a low-orbiting satellite. It will come in with an angle of about 20° from the horizontal (=70° from vertical).
Given the fact that the orbit is so long, the geometry is totally different from a pass of the ISS. The latter orbits the Earth in about 90 minutes, while WT1190F takes weeks. So the current pass is actually the last part of the last orbit for this object.
Anyway, from a geometry point of view, it will definitely be observable from north America in the morning hours of November 12. However, it will be very faint, magnitude 19 or so, invisible by eye even with a large telescope. A CCD camera and at least a moderate-size telescope will be needed to get an image of it at that time.
Even for Europe and Northern Africa, which are the countries best-placed to observe it just hours before impact, it will only reach magnitude 15 or so, too faint for anything but images with a good telescope.
If you want to get an ephemeris for a specific site, I suggest you use this page from the Minor Planet Center: http://www.minorplanetcenter.net/iau/artsats/artsats.html. Just select WT1190F, enter the required information, and you will get your specific ephemeris based on the latest data.
Let us know if you need any additional info, and thanks for contacting us.
Marco
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