Sergey

13 hours ago, John said:

The brightest is 3C 273 in Virgo at magnitude 12.9. It depends how dark your skies are but while it might be theoretically possible with a 100mm aperture but practically 130mm would stand more of a chance.

Thank you very much, John. I will try it.

On 31/01/2020 at 00:44, John said:

Other interesting "point source" challenges include:

- spotting the central star in planetary nebulae. A few are relatively straightforward, many are rather difficult !

- spotting quasars. A few are possible with moderate aperture scopes and observing such distant objects is kind of fun.

- spotting supernovae when they occur. There is a bright one (relatively speaking) in NGC 4636 (Virgo) as I type.

- finding Barnards Star in Ophiuchus. The closest star (apart from the Sun) that we can see in the N. Hemisphere.

- spotting well known asteroids such as Ceres and 4 Vesta.

And many more ..... probably justifies a separate thread

 

John, are there quasars, achievable for moderat apertures (e.g. 100mm)?

Thank you, Mike!

On 06/09/2017 at 18:45, mikeDnight said:

Screwing on a 2" back to the DC focuser and using a low profile 2" to 1.25" adapter allows plenty of inward travel for a binoviewer, without the use of Barlow lens.

The advantage would be that short focal length eyepieces could be used for high power binoviewer observing, or low power viewing with longer fl eyepieces, though the latter may be of limited use in a 100mm scope, and vignetting may be a problem! Also, the scope becomes shorter to transport when the extension tubes are removed.

Mike, where can I get this low profile 2" to 1.25" adapter?

Thank you!