I should get a detailed star atlas. A deep Map 600 is the recommended
book. Can you give me a quick hint where I can order one? If it will
assist me in hunting down these objects then I'll order one up today.
2. I'll check the audubon guide for 39 & 41 and will follow the line.
3. Can you explain what an "O-III filter" is and how it works?
peace,
cherokee
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Hi Cherokee, Yes, some sort of decent Star Atlas is a must. After
awhile, folks learn generally where the brighter, more popular Deep Sky
Objects are.

The Sky Atlas I use, and many others do, but it's not a cheap Atlas, is
Wil Tirion's Sky Atlas 2000. Mine is the laminated large size desk
version with Black Stars on a White background, and if memory serves me
correctly, this Atlas set me back $90.00

There are less expensive versions, which are usually unlaminated. Some
laminate them themselves, and some draw in constellation lines
beforehand to aid in helping them be more familar.

An O-III filter is a Oxygen Filter, which is a specialized, very narrow
bandpass filter.

By this, it means that it rejects most wavelengths of light, and only
permits certain portions of the light spectrum to pass through it.
Typically with an O-III, it lets the light emitted by gaseous nebulae
through (such as the Veil Nebula), thus darkening the sky background,
sodium, and mercury vapor lamps emittance, and increases the contrast of
these objects by permitting the wavelengths of light these objects to
pass through the filter.

The problem is not so much with Zarkovic's scope that he cannot detect
certain dimmer objects, as an 8" reflector is large enough.

The problem is perhaps Zarkovic's somewhat lack of astro-experience,
that he never has personally seen these objects, and doesn't know what
to look for, and also, he may not be viewing under really dark sky
conditions.

Zarkovic could own a 25" Obsession Reflector, but if he lived in the
heart of the city of Chicago for instance, even with all the aperture in
the world, he will not see much of the dimmer objects listed in the NCG
Catalog. Mark