Several messages have been published on sci.astro and other places announcing that a Saturn-like companion was orbiting around Hale-Bopp, "proving that Hale-Bopp is an alien spacecraft heading toward the Earth".
Here is the famous picture (on the left, image obtained and sent on the net by Chuck Shramek). It is a decent picture of Hale Bopp, nicely showing its jets. I rotated the original image to set North up and East left, to compare it to a portion of the Digital Sky Survey (right, a scan of an old plate take at the Palomar observatory in 1954). I marked a few common stars, and plotted the path of the comet.
The "mysterious object", marked by "1", is a commons 9th magnitude star, as there are MANY in the sky! (SAO 141894 = PPM 180171 = gsc 5086 361, Spectral type M, Coordinates: 17h 49min 33.3sec -2deg 13' 45.4" (eqx 2000)). Some people have remarked that the star looks brighter in the amateur image than on the Palomar survey: this reflects the fact that this star is a cold M type, emitting most of its light in the red and infrared, where the CCD used for the "UFO" image is much more sensitive than the plates used at Palomar.
Mr.Shramek claims that the software he used to obtain a map of that region of the sky did not show that star. The problem is that he did not set up his software properly. Moreover, that close approach between the comet and this star was predicted: Ovidiu VADUVESCU, from the Astronomical Institute of the Romanian Academy Bucharest, publishes a list of "Appulses by PPM Stars of the Comet C/1995 O1 (Hale-Bopp)", that can be found on various WWW servers (e.g. at University of Maryland"; a local copy is available here).
While an error like this one can happen to the best observer, it seems that Ch.Shramek refuses to admit that he made a mistake and keeps claiming that SAO 141894 is following the comet (c.f. discussion on going on sci.astro). (update - Dec.24, 1996: Ch.Shramek's home page is working again; see for yourself...)
More details about this story, including the original messages posted on the net, can be found on The SLO Files of the www.haleBopp.com site.
(updated Thu Jan 16 18:55:22 1997)