Kurt (canopus56) wrote:
Since Barnard was working with 10" aperature astrophotography and the
catalogue lists nothing analogous to a magnitude (perhaps a contrast
index?), my current interest is which Barnard objects are visual and
which require astrophotography to bring out the contrast you describe.
The Tau-Per cloud is an example of region where an obscuring object is
visually detected by being an unusually star poor region.

Barnard's catalogue contains no magnitude because there can't be one.
At best, one could list the extinction. But that wouldn't necessarily
tell you how well the object stands out from the background, because
it depends on the background.

Do those dark nebulae glow prominently enough in other wavelengths?

--
Brian Tung
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