What ultimately became of the 2011 efforts to find Snoopy?
It was left in the hands of the Faulkes Telescope Project:
"Imagers with Registered Faulkes telescope accounts will be able to get the latest coordinate data on areas we'd like searching on this web-page. If you do wish to use any of your allocated telescope time on this project, please adopt the following naming style for your observations.
Eg: SNOOP1108231400 - would be 2011, 23rd of the 8th at 14:00UT. This will make data searches for our team and for anyone who wishes to assist in the hunt much easier.".
Apollo 10: Where's Snoopy?
Where would one start if one were attempting to find it?
The Smithsonian National Air and Space Museum gives it's location as:
"Apollo 10 'Snoopy' (LM-4) - In heliocentric orbit".
See this space.SE question: "Where were the various Apollo Lunar Modules (LMs) discarded?"
Why is the search area so large if the starting conditions are known?
Looking for a known object, WT1190F, at a specific location is expensive and difficult, see:
"The observing campaign on the deep-space debris WT1190F as a test case for short-warning NEO impacts" (Oct 20 2017), by Marco Micheli, Alberto Buzzoni, Detlef Koschny, Gerhard Drolshagen, Ettore Perozzi, Olivier Hainaut, Stijn Lemmens, Giuseppe Altavilla, Italo Foppiani, Jaime Nomen, Noelia Sánchez-Ortiz, Wladimiro Marinello, Gianpaolo Pizzetti, Andrea Soffiantini, Siwei Fan, and Carolin Frueh, on page 4 they explain:
The observations obtained in this campaign prove that, to
achieve complete observational coverage of an incoming object
on short notice, it is necessary to develop a network of instruments of different classes, each of which is capable of providing a given type observation covering a specific niche in the overall observational strategy.
In particular, it is often necessary to have access to:
At least one large telescope (e.g. VLT), which allows for cutting-edge observations (such as spectroscopy at very faint magnitude levels) early in the approach phase. At the same time, being an expensive resource, a telescope of this class can only be obtained on short notice for a limited
amount of time.
One or two mid-class telescopes (e.g. Loiano), which can be used with much more flexibility, for multiple nights, but may not be sensitive enough at large distances.
A network of small telescopes (e.g. Lumezzane), which can be triggered even on very short notice and made available for extended period of time, and are ideal to cover the last phases of the impact trajectory from multiple locations.
If you know where to look this is what you would see, can you spot the object?
Figure 1: An illustrative astrometric image, taken along the night of 2015 November 12, just a few hours before the WT1190F atmosphere entry, with the 1.52 m “Cassini” telescope of the Loiano Observatory (Italy). The telescope was tracking non-sidereally at the apparent angular motion of the target (which appears as a point source near the center of the field), therefore all astrometric reference stars in the frame are severely trailed (approximately 10 in this example). A correct astrometric reduction of a frame like this requires to fit every reference star with a trailed model, to properly determine their centroid.