occulting bar

occulting bar

[ə′kəlt·iŋ ‚bär]
(astronomy)
A bar placed in the focal plane of a telescope eyepiece to cover part of the field of view, usually to cover a bright object in order to permit observation of a nearby faint object.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Try putting an occulting bar across the field stop of your highest-power eyepiece--a bit of aluminum foil across the field stop works --or just move Uranus slightly outside the edge of the view.
It is best to try and keep the star just out of the field of view, or use an occulting bar. Also the nebula is rather small, just a 4' notch--a careful balance of magnification and field size will help.
The club member running the telescope at the time employed an occulting bar eyepiece to help defeat Mars's glare.
After totality, noticing that a southing Sirius was barely twinkling, I tried for the Pup at only 244 using a lunar filter and no occulting bar. To my surprise I succeeded, though the separation was only 8.1" at the time.
Observe when Sirius is highest in the south, use your highest magnification, hide Sirius's dazzle behind an occulting bar or the sharp edge of your eyepiece's field stop, and wait patiently for moments of good seeing--but you know that already.
An occulting bar should help, so here is an approximate separation and position angle I worked out based on measuring the photo and the cataloged proper motion of 61 Cyg:
I had placed Saturn behind an occulting bar in my eyepiece to hide its glare, leaving just the ringtip visible so that I know where Mimas should be.
The trick would be to observe Earth at its thinnest crescent phase and block the crescent's glare with an occulting bar in the eyepiece.
I made an occulting bar for my 10.4-mm eyepiece (212x) to block the glare of Merope.
To reduce the star's glare, you can add an occulting bar to your eyepiece by taping a tiny strip of aluminum foil to the field stop so it sticks out into the view.
Narrow-field eyepieces aren't common any more, but it's still possible to heed Hall's advice and "get rid of the dazzling light of the planet." Use an eyepiece that contains an occulting bar, a narrow metallic strip across the center of its focal plane.
In near-perfect seeing the dark side of Saturn's rings is feebly visible to us while using averted vision and an occulting bar made from a section of a drill bit.