Two scopes, 3 planets, and a bunch of DSOs

[davesellars]

After having a couple of hours sleep, I woke up at midnight refreshed with the plan to get a good session in mainly concentrating on the planets.

The sky was amazingly transparent (for the second night running!). The Milky Way already easily visible although a couple of lights from houses were still an annoyance until they shut off at around 1am. The seeing also seemed to be pretty good.

I set up the 102ED refractor on the Alt/Az and immediately got to work with Saturn after a short cool down with it being lower down had a much shorter window of opportunity to view it.

Saturn just seems to give more with further magnification and this refractor just continues to surprise me how well it handles high power without it going mushy at all. With the 5mm Pentax XW for 143x, the Cassini division was sharply defined, however at approx 220x with the 2.2(ish)x Barlow with the 7mm Pentax was spectacular and perhaps the sweet spot, with the Cassini division very clear and reasonble in size and also now more surface detail of the planet itself as the brightness was now brought down sufficiently. Using the barlow with the 5mm Pentax for approx 2.2mm and 325x I half expected the view to break-down somewhat however the view was still mainly good but too dependant on the seeing level and my ability to track suffiently with stability on the alt/az mount (not recommended for this level!). I would say though that the ideal contrast has been reached somewhere between the two powers of 220x and 325x though as with moments where I could get it stable enough at this high power the view was really quite something.

I was now "waiting" for Jupiter to come up sufficiently so I switched to doing the rounds of some DSOs.

M33 - After being able to see this easily with the binoculars the previous night, I chose the largest focal length I had (a 32mm Baader Plossl) to maximise exit pupil and this seemed to work well although M33 was a mere ghost on glimpsing into view and would be easily missed if you didn't know what you're looking for. Using higher power just made it worse.

M31 - Sufficiently large view with the 32mm Plossl to encompass the all three galaxies with a touch of structure of M31 coming through but very subtle.

Veil Nebula - Again with the 32mm Plossl to maximise exit pupil together with the Astronomik OIII. Conditions were considerably better that a previous week where I'd attempted this and not really got a good view of the Western Veil. However this time it was nice and obvious but with little detail. The Eastern Veil showed a touch more and came though as large bright arc of nebulosity in the eyepiece but without any definition.

North America nebula - With the 32mm Plossl and the Hbeta this was very diffuse and difficult to see such a large object.

M57 - The Ring Nebula was a lovely sharp view with the Pentax XW perfectly framed within the starfield. Further power trying the 5mm Pentax XW diminished it rather too much for my liking.

M102 - Small but the galaxy was reasonably bright.

NGC 5907 - Its extremely low surface brightness made this one very difficult to observe - it was on the edge of vision with averted vision necessary to bring it out.

Approaching 2am by this point it was time to view Jupiter as it had risen sufficiently, The GRS was just about on the edge of going out of view by this point and viewing through the 7mm Pentax I could just about make this out. With the 5mm Pentax giving 143x, this seemed to be a really good power still giving excellent contrast of the planet's subtle details. Trying with the barlow for 220x in my view was too much, although the main belts were larger the detail in and around was much more difficult to discern.

After a little while viewing Jupiter, my 12" dob started to call to me from the conservatory... :p I would probably be heading to bed with regret if I didn't go for it with the quality of the sky like this. Therefore, I did the only sensible thing at 2:30am and set it up. Fortunately, it doesn't take long and after collimation was good to go... I thought I'd let the scope settle down to ambient temperature before observing Jupiter with it and its lower position meant I needed to wait a little while for Jupiter to rise even more anyway.... So back to some DSOs to take advantage of the exceptional clarity.

Back to M33.. and with the 28mm Maxvision eyepiece this was now very obvious as a nebulous blob however I couldn't make out any structure.

M31 / M32 / M110 - This just blew me away with the 28mm eyepiece. I wouldn't normally use such a large exit pupil viewing galaxies sticking to the 17.3mm Delos for most observations and dropping down to 10mm for detail... but this was quite the revelation in a decently dark sky. M31 showed real structure for the first time with dark lanes easily discernable. The view just about got it M32 and M110 in the same field with M110 really showing brightly and extended. Best view I've ever had of this group!

Dropping down to Mirach and viewing Mirach's Ghost (NGC 404) with the same eyepiece showed a decent extension of the main core.

Back to the Veil... With the 28mm without any filter I could just about make out a touch of the Western Veil around 52 Cyg but it was very faint. I had to switch here to the 32mm Plossl as I only have 1.25" filters but once using the OIII , the nebula stood out immensely. The knotting / twisting nature of the Western Veil was very apparent and beautiful to follow along the entire length. The middle section of the Veil (NGC 6974) while much more difficult was just about visible. The Eastern Veil showed incredible structure with wisps of nebulosity all over the place with incredible contrast. The only shame was that with the Plossl, the view is not fully immersive like you get when jumping up to 68 degrees as with the Maxvision.

Now Jupiter had risen high enough it was time to back to this and leave the DSOs for another night perhaps for a dedicated session - astro dark has come to an end anyway.

So, the difference between the 12" dob and the 102ED on Jupiter... Surprisingly not as large as I'd expected. I used the 5mm Pentax in the 102ED for 143x and the 7mm Pentax in the Dob for 214x. Exit pupil was twice as much in the 12" dob as the 102ED, so in theory the contrast should be better(?) than in the 102ED.

Jupiter presented exceptionally well with the 12" dob in times of great seeing. Undulations in the main belts were quite obvious with darker / light regions becomeing visible with extended viewing at the eyepiece in one sitting. The lighter southern equatorial belt was obviously split halfway through by a long light patch. The NEB had multiple darker small blobs sitting in the belts. The fine northern temperate belts were very obvious. Colour not really distingishable though with the 12" dob. Using more power (5mm Pentax) for 300x was really too much for the seeing tonight although occasionally good I didn't feel that the view of any details improved any (actually worse if anything).

In the 102ED by comparison, even though the exit pupil was approx 1/2 that of the dob presented visually seemingly more contrast. Colour was still visible with a light shade of brown rather than grey. The image was obviously smaller but comparing the two images it wasn not difficult to see the main features. Those undulations seen in the dob were still there in the 4" refractor although a bit more time needed to be spent at the eyepiece to really capture them. Dark and lighter regions were very easy to distinguish particularly the large ones like the lighter "streak" through the SEB as seen in the 12" dob was very obvious. The much more subtle temperate belts are still present although finer. The 12" dob picked up more finer detail within the belts although it was necessary to stay at the eyepiece for 20 to 30 seconds to really get these and pick them up as subtle whorls within the main belts. That kind of detail was very difficult with the 102ED in my view. For pure sharpness and contrast the refractor killed it and probably gave 90% of the detail of the 12" dob, however that extra 10% that the dob gave was quite spectacular to see those extra little details that occasionally popped in to view.

Finishing with Mars... I used the 5mm Pentax for 300x which gave a nice decent sized scale. I really had to stay at the eyepiece for extended amounts of time to get the best from this as its brightness and suspetibility to seeing made it difficult, however at 300x the brightness was tamed enough for it to show large darker regions on the surface although I could not see any polar caps.

It was now getting on for 4:30am and the sky was now quite light so it was time to call it a night and get some well earned rest...

Looking good for another session tonight - I think purely on DSOs if the transparency is anything like it has been for the last couple of nights!

[John Baars]

A great report! I was very pleased to read it. The detailed shootout between the two instruments was very nice to read and correspond to my experiences with this type of instruments. I think this is certainly worth a VROD!

[kt4hx]

A very fine report Dave. Lots of excellent targets for sure, with nice descriptions. It sounds like you had both pretty good seeing and transparency for the night which is always a pleasure. I would suggest that if you return to the N.A. Nebula that you try your O-III rather than the HaB filter. The nebula is more responsive to either a narrow-band nebula filter or O-III line filter.

Nothing at all wrong with using a larger exit pupil for M31/32/110, as the size of the overall field is better suited for it. However, if one wishes to see more detail, then tightening that exit pupil will certainly help. I am sure you also saw the star cloud NGC 206 within the disk of M31. When you do have another excellent night, you might wish to try for the brightest globular in M31, Mayall II, otherwise known as G1. At mag 13.7 it is within reach of your 12 inch. The key is finding the field and identifying it as a tiny non-stellar mote. Second John's nomination for the daily VROD!

[Bigzmey]

Excellent! Your experience with 102ED vs light bucket on the planets matches my to the letter. For most nights the level of details will be quite similar. However, there are a few nights per year with excellent seeing, when larger aperture really shines resolving fine details unreachable by small scopes.

[davesellars]

Many thanks John & Alan!

@kt4hx That's a great tip for the OIII on the N.A nebula, many thanks - I hadn't though of using this...

Normally I would not go for such a large exit pupil which is why my 28mm normally goes un-used during a session. As you say, restricting the exit pupil to a more reasonable amount between 2 to 3mm I've found much more conducive to observing detail as otherwise the lighter sky background that I normally get from my Bortle 5(ish) skies wash out the object. The transparency last was such this didn't seem to represent much a problem which hardly ever happens here (unfortunately).

I'd actually forgotten about the glob G1 within M31! I'll definitely have to give this a go hopefully tonight as the sky is looking pristine at the moment (6pm)...

[davesellars]

Excellent! Your experience with 102ED vs light bucket on the planets matches my to the letter. For most nights the level of details will be quite similar. However, there are a few nights per year with excellent seeing, when larger aperture really shines resolving fine details unreachable by small scopes.

Many thanks Andrey! Yes, I'm definitely happy that I invested in the 4" refractor as it's so easy to get out for the windows of opportunity to observe (that can be small), when lugging out the 12" is not suitable - so knowing that generally the performance for lunar and planetary is not that big (unless, as you say seeing is exceptional) - the 4" refractor will get a whole load of use.

[davesellars]

I'd actually forgotten to mention that a couple of nights previously, I'd used the 102ED on Jupiter and Mars between 4am and 5am - For Mars I used the barlow with the 5mm Pentax for over 300x which it just took with ease showing a perfect image and great surface detail (considering the size).. I actually preferred the view to the 12" dob's observation last night!

[Bigzmey]

I am a big planets aficionado and usually spend many hours during oppositions, trying to squeeze as much fine details as I can. Yet there were whole seasons when large scope (in my case 9.25" SCT) would not offer any advantage over 102ED because of the prevailing mediocre viewing conditions. So on many occasions I would not bother with big guns and just deploy 102ED grab and go setup.

As you I have also discovered that 102ED can handle 200-300x confidently and on most nights use 2.5-3.5mm EPs for planets, Moon and to split tight doubles. Did I mention that 102ED is also great doubles splitter?

Having slow motion or tracking is a big help at high powers. Another trick is to use EP turret. Although unfortunately one can't use it with XWs or Delos.

[Lady Fraktor]

A great report Dave, thank you for sharing it.

[Unitron48]

Great session...and report, Dave! Certainly VROD worthy! Enjoyed your review/comparison of the two scopes with respect to the different targets. While I'm mostly a "Frac Head", I appreciate having access to observatory based large aperture Dob's!! Best of all worlds :smile:

Dave

[Makuser]

Hi Dave. A very nice observing report with your 1-2 punch of the Starfield ED102 f/7 and SW Flextube 12" Dobsonian telescopes. Saturn, Jupiter, Mars, and several fine DSO objects in your session. Thanks for your fun read and well written report Dave and I agree too that it is certainly VROD worthy.

[davesellars]

Thanks Marshall!

Just got in from yet another 4 hour session... :p The transparency was a bit variable and not on the scale of last night but was still fun nonetheless!!!

[helicon]

Great report Dave and congrats on winning the VROD for today through the nomination of your readers!

[Unitron48]

Congrats on your VROD recognition!

Dave

[davesellars]

Many thanks Michael!!!

[John Baars]

Congratulations on the VROD!