Herschell 400 with binoculars

[astroeddie]

Guys,

Just wondering, how many of the Herschell 400 are visible in large binoculars ?

[BinocularSky]

Depends how large. O'Meara has seen the lot with a 4" apo so, if you have his ability (rare!), you would expect to be able to see the lot with a 100mm binocular at around x40. However, in less than ideal skies, that would be pushing it -- the Fujinon FMT 40x150 would give you a better chance, but an "average" observer would probably want at least 200mm. Most people who bag the H400 use a 10" or larger.

[astroeddie]

Cheers Steve.

It'll be interesting to see just how many I can get whilst away. I have the O'Meara "400" book. Its a fantastic book, my DSO bible so to speak. O'Meara has quite a few extraordinary astronomical claims, including banding around Uranus.

Not knocking him, he's a great author and astronomer.

[michael.h.f.wilkinson]

I must say getting the whole Herschel 400 in a 4" scope is quite a claim, as NGC 6540 is listed as a mag 14.6 globular, and was beyond me in with an 8" SCT under very good conditions (got a 13.6 planetary), and I am no slouch at observing really faint stuff. Assuming a mag 7 naked-eye limit even for 5mm fully dilated pupil (rather generous), a 4" delivers just 6.5 mag gain, or a limit of 13.5 (which is rather better than the usual limit of 11.9 or so). Even so, it would require another 1.1 magnitude, or factor 2.75 more light to be able to pick out a mag 14.6 star (a C8 might pull that off). A mag 14.6 globular with radius of 1.5 arc minutes is a lot harder still.

I would say I might perhaps with some effort under ideal circumstances get a glimpse of NGC 6540 in my C8, but I would need a 10" scope to get it, especially in the midst of a crowded star field.

[andrew63]

Hi Eddie

I know your travels take you to the southern hemisphere often. This forthcoming book make be of interest .Deep-Sky Companions: Southern Gems: Amazon.co.uk: Stephen James O'Meara: Books

andrew