Session 6 for 2022

[Davesellars]

Session Date: 16th Jan, 2022
Time: 10pm - 12
Scope: 120ST

So, 99% moon but it was beautifully clear and thankfully the extreme humidity seemed to have gone that had plagued previous sessions - it was, in fact, nice and dry and just above above 0C. Of course, having recently got back into this this I couldn't resist the 4th session of the week to finish off the Sunday.  I didn't feel quite like lugging out the dob though so I quickly setup the 120ST with a plan to just to see what Messier objects and to what level could still be observed and also of course , the Moon.

First off, I could at least see that the transparency was pretty good. Seeing was so-so (nowhere near as good as the previous session) where the stars were rock solid steady.  I would estimate that the sky was approx bortle 7 bordering on 8, whereas usually it's 5.  Naked eye I could still see Orion's sword and M42.

Uranus -  Quite a bright very small disc with the 4mm (150x), with the BCO 10mm could not discern any real colour.  While this is still reasonably positioned on a darker night I want to see if I can observe any its moons - should be a reasonable challenge!

M42 - Well, the nebula was still quite obvious with the 10mm BCO - but only the brighter central region and any real structure was lost only seeing a very faint amount with concentration.

M31/ M32 - With the 32mm BCO, only a the very brightest part of the core could be seen.  This improved massively with the 10mm BCO which darkens the background considerably and with the extra boost in contrast I could see more of the core region again, but nothing more - I would say that it was 10-20% of what I can normally see without the moon presence.  M32 never seems to change much anyway as it's very small and bright!

M45 Plieades - OK, the 120ST F/5 refractor was built for this type of cluster.  Even with the 32mm BCO giving quite a bright sky background, the view is outstanding.

M35 - Nothing except the brightest 7/8 stars visible with the 32mm BCO.  The 10mm however gave the boost in contrast required to view this in a half-decent form but still needing some averted vision.

M36 Pinwheel Cluster - With the 10mm BCO this is still quite bright despite the moon - The pinwheel shape still quite distinct and some minor stars giving a good appearance to the cluster.

M37 - While this is normally a magnificent cluster to view with some power and darkness. the lower magnitude of the stars that really make the cluster shine were pretty much obliterated by the brightness of the sky.  While the cluster was visible direct vision, averted vision needed really to get much of anything out of this with the 10mm BCO.

M67 Open Cluster - Most difficult target of the night! Only a few stars were initially visible and needing some extra dark adaption and work with averted vision for the cluster to finally appear like a wisp in the eyepiece.

M44 Behive - Like M45, this still showed marvellously in the 120ST with the 10mm BCO giving extra contrast.

Sirius - Something I've not tried before (or can't remember doing it) - I had a very very optimistic go at splitting the pup however, I think the 120ST is definitely not the scope to do this with... Sirius looked like it was on fire.  Later i had the idea to stop down the aperture which did control the CA at least to make the star less violent however there was still no sign of the pup (probably no-where near enough aperture to do this then after this).

Moon - There was a considerable difference in brightness from a few nights ago!  Anything but the 4mm at 150x was unbearably bright.  Fortunately, the seeing was just about good enough for this to be used but it a little wavy.  I went over most of the features from my previous observation with the 12" dob - but most were very indistinct now with the extra brightness seemingly obliterating the detail.  The terminator at least had some interesting features around Grimaldi and also Pythagoras really nicely partly illuminated with deep shadows.  To the south, the Schickard craters were nicely pronounced  with a series of smaller craters seperating it from Phocylides.

It has reached midnight already - 2 hours had done by in a shot!  An added bonus was getting out and returning without sopping wet scopes and accessories! It had been an interesting "experiment" in how light pollution really affected these DSOs although I was pleasantly surprised by still being able to see them despite 99% moon affected skies.

 

[F15Rules]

Nice report Dave👍.

The bright moon is a real game changer, isn't it?

These days I tend to concentrate on doubles etc when it's so bright, but you did well to cover so many varied objects in less than ideal conditions!

..and the moon is going to be much less of an "intrusion" over the next few nights..😊

Dave

[Davesellars]

Thanks Dave! , the Moon will not be intrusive until around 7ish so may have an hour or so of decently dark skies to start off at least.

[wookie1965]

I got the pup in my 127 but I did put Sirius right at the edge of FOV to block out most of the glare. 

[Davesellars]

Just now, wookie1965 said:

I got the pup in my 127 but I did put Sirius right at the edge of FOV to block out most of the glare. 

Ah, good to know it's possible - I suspect though your 127mm at f9.3 shows considerably less CA to content with than my 120ST at f/5,  However, I shall have to give it another when the seeing is very good!

[Mr Spock]

It's a good session. The moon does tend to interfere with just about everything though.

I do think with an achro you are going to struggle with the pup. Sirius already has a lot of flare without adding CA into the mix.

[Davesellars]

Just now, Mr Spock said:

It's a good session. The moon does tend to interfere with just about everything though.

I do think with an achro you are going to struggle with the pup. Sirius already has a lot of flare without adding CA into the mix.

Agreed.  Unfortunately I sold my Skywatcher 120ED a few years ago (had excellent optics as well!) - I regret doing that now...