9cm) Merz and Mahler refractor at Pulkovo Observatory, Otto Struve (1819-1905) came to the conclusion that certain aspects they had observed at the ansae
, which he termed appendices lumineux, were independent of the ansae
it has ansae
, which probably indicate a surrounding nebulous ring seen edgeways.
In deep images, NGC 6886 resembles the planet Saturn, but even with my 15-inch reflector at high power, I can't see the ansae
that elongate it southeast-northwest.
Despite a modest reduction in image brightness, the crepe ring is visible at a glance in the ansae
of the rings through all of the dielectric filters; the denser Wratten 12 filter doesn't fare as well in this respect.
So was the Cassini Division (at the rings' "tips," or ansae
, where it is most conspicuous).
Over the years only a handful of observers have made it a point to routinely examine Saturn's rings through color filters, but there are a few simultaneous sightings of the phenomenon, invariably at the ansae
of the rings (from the Latin for "handles"; the extremities of the major axis of the ellipse seen by earthbound observers).
It extended almost halfway to the rings' extremities (the ansae
, Latin for "handles") before becoming lost in their glare.
Observers with access to a stopwatch and an accurate time source can make timings of the various stages: the preceding ansae
(tips) of rings A and B, preceding limb of disk, center of disk, following limb of disk, and following ring ansae
4-inch) aperture, he could detect the Cassini Division only in the ansae
(tips) of the rings, but with the aperture reduced to 50 mm he could no longer make it out with certainty.
The faint extensions or ansae
that give NGC 7009 its Saturn-like appearance are not easily visible in scopes less than 10 inches in aperture.
While the rings were easily seen as a thin black silhouette against the planet, I was surprised to see that they were also visible as a thin gray line extending all the way out to the ring's ansae
Sharp extensions, known as ansae
, protrude from the object, creating a major axis nearly 30 arcseconds long.