What's this? a clear night? Well I never!
Clear, cold and dryer than normal out tonight. Hauled my 10" dob outside just before sundown and checked both primary and secondary collimation. Secondary looked good and I gave the primary a quick tweak using a cheshire. Switched on the cooling fan for about 40 minutes, then switched it off and left the scope to cool for another 10 or 15 while I watched "Deadliest catch".
Telescope: 250mm (10") Newtonian
Seeing: 5-7/10
Transparency: 4/5
Checked collimation again, and it seemed to have shifted a bit as the mirror cooled (I always thought that was a myth and didn't believe the guys on Cloudy Nights lol). A quick turn of the screw and I'm set. During an earlier session I noticed the scope had a bit of astigmatism, so before tonight's session I loosened the primary mirror clips so they sit a paper's width above the mirror. I decided to check on this and glad I did, as two of the clips were quite firmly clamped down.
Observing Jupiter at 138x, I believe I could see an improvement in image quality! I had a clean, sharply defined disk. Seeing was good but not great and often would blur the whole image. At 138x, the rift in the SEB was most obvious, infact the SEB appears as two narrow brownish belts entirely seperated by the much wider rift. The South Temperate Belt was obvious, as was the North Temperate belt in good seeing. The NEB appeared to have a narrow, white rift running about 1/3 of the way across the diameter of the planet.This was intriguing as it was the first time I saw this. I could hint at streamers in the EQ zone and ruffling in the NEB during moments of good seeing. During rare very moments of excellent seeing, more belts would pop into view as would a couple of ovals in the SEB and other white features nestled beneath the NEB. Now, Jupiter was only about 10º above my rooftop so the average seeing was probably confined entirely within my backyard!!
Pumping it up to 166x, which is about as high as I like to go on Jupiter, (on my 4.5", 121x was the clincher
) the image held up quite well, with everything that was evident at 138x visible. But ofcourse, I had to be more patient with the seeing! At 227x, Jupiter's disk started to go a bit 'soft' but seemed cleaner than before my mirror clip adjustment. By now, it was 8.30pm and Jupiter was flirting with my TV antenna. In very good seeing, I reckon I could get decent views at 227x, and definately great views with my 166x and 208x eyepieces.
I then aimed for the moon. At 166x, 4 craters in Plato were resolved, including the "double craterlet".
Next, I went for the globular M4. At 83x, despite moonlight, it was well resolved with the central bar a collection of stars, unlike the "pricks in haze" effect in my 4.5". I upped it to 227x and the 60º field of the plossl nicely took in what was now an intergalactic swarm of bees! Nice! The bar was now well and truly resolved. Until now I could never fully appreciate the spectacularity of a globular cluster hence I always went for galaxies, Nebulae and Open clusters instead with my 4.5". The 4.5" did do justice on the larger globulars but the 10" cleans the smaller scope up in everyway! Can't wait for the day when Omega Centauri is straddling the zenith....
Just for kicks, I then tried the Double Double in Lyra. At perhaps barely 10º altitude, the star images at 166x were completed mangled. Plus I think my garden fence was in the way as I was seeing 6 diffraction spikes instead of 4! Despite this, I could see that each star was decidedly elongated even though it was flaring and jumping in the seeing and it was obvious that there was *something there*.
It's cold out so I came in while I wait for 47 TUC to rise
Hope my scope is still dry and hasn't been pissed on by the dog or cat like before lmao
Now when in storage, I lean small bits of carpet against the sides of the base so when Mr Kitty decides to go on a territory marking rampage, it's the carpet that takes it head-on!