love my dob!

[Piero]

Finally clear sky!

The sky conditions were pretty good tonight. The air was steady and the sky reasonably transparent. Light pollution is always a bit of an issue in this area of Italy (NE). It was not too bad though. 

The views of M10 and M12 were really impressive I have to say, particularly after pushing the magnification above 150x (and up to about 230x). How many little stars just popped up! M107, M4, M80 and M71 were also interesting. M27 was just glorious at 60x without any filter. With the DGM NPB, the view was really enhanced. Shades in the "apple" were easily identifiable with direct vision. At 92x, the view was similar in detail, but just bigger. As I am used to observe with a 60mm refractor, observing through an 8" reflector is a WOW for nearly every target! The journey continued in Cygnus at 60x. M29, the cooling tower, revealed stars that I never saw..  NGC6910 near Sadr (Gamma Cyg) was also very impressive. Through the cygnus' neck at 40x with the NPB, I attempted NGC6888, the crescent nebula, buy just a minor sign of nebula was revealed. No shape was detected really, but just a timid confirmation that the location was correct due to the presence of a very very faint smudge where expected. A bit easier but still with poor detail due to light pollution, the Veil and the North America showed up too at 40x plus NPB filter. Then, I spent a lovely time between Scutum and Sagittarius: Sagittarius Star cloud, M8 (Lagoon nebula), M20 (Trifid nebula), M6 (Butterfly nebula), M7 (Ptolemy cluster). The Trifid and Lagoon nebulae were spectacular at 40x or 60x with NPB filter. I spend about 40 minutes just for these two targets.

Finally, it was the time for Saturn. Four moons were easily visible. I did my best to try to spot Enceladus but there was no chance. The Cassini division was constantly visible as well as a nicely coloured equatorial belt and the shadows between planets and rings. I got really great views between 250x and 330x. As the sky was steady, I pushed my HR 2.4mm in the focuser, getting a view of Saturn at 500x. Compared to my TV60, the view was slightly soft at this exit pupil. Still, there was no difficulty at all in observing the Cassini division and the other features visible at a lower magnification. In addition, at 500x the inner and outer sides of the rings somehow showed different colours. The inner side was more grey compared to the outer side. This was quite noticeable, especially on the ring portions placed to the left/right of the planet.

[nightfisher]

Nice session Piero, 

[Paul73]

You certainly had a busy time! Nice write up too.

Whilest whizzing around with a 60mm is fun (I'm always amazed at what these little guys can uncover), things really wake up once you get 200mm on them.

Paul

 

[estwing]

Fantastic report Piero,really feel your enthusiasm....clear skies!

[scarp15]

Lovely and engaging report Piero, interesting comparisons between your TV60 and 8" dob, they complement each other really well. Currently inactive in astronomy for the time being, to read this and others accounts retains the interest and enjoyment momentum.

[jetstream]

Great report Piero!

Once you get the OIII that Crescent will become more visible and once you are in dark skies more will open up here. You had some excellent seeing- we need Vixen to make those HR2's in a bit longer focal length!

[Piero]

59 minutes ago, jetstream said:

Great report Piero!

Once you get the OIII that Crescent will become more visible and once you are in dark skies more will open up here. You had some excellent seeing- we need Vixen to make those HR2's in a bit longer focal length!

That's very true! Looking forward to it!

[Richard Hather]

Lovely report piero, you certainly was whizzing around the sky with that list ?

I'm growing to love my dob also, I tried to observe the Veil last night but I was unsuccessful maybe next time, anyway very enthusiastic report good job ?

[John]

7 minutes ago, Richard Hather said:

Lovely report piero, you certainly was whizzing around the sky with that list ?

I'm growing to love my dob also, I tried to observe the Veil last night but I was unsuccessful maybe next time, anyway very enthusiastic report good job ?

The star 52 Cygni is the key to finding the Veil - the western portion (witches broom) runs right by it. The Eastern segment (bridal veil) is brighter and around 3 degrees away from the western part. Overall, the Veil is a huge object !

UHC filter will help see it. O-III filter for the best contrast and extent. Without a filter it's possible to completely overlook it even with a 12" scope.

 

[Richard Hather]

6 minutes ago, John said:

The star 52 Cygni is the key to finding the Veil - the western portion (witches broom) runs right by it. The Eastern segment (bridal veil) is brighter and around 3 degrees away from the western part. Overall, the Veil is a huge object !

UHC filter will help see it. O-III filter for the best contrast and extent. Without a filter it's possible to completely overlook it even with a 12" scope.

 

I was using my UHC filter but I think the skies aren't dark enough yet or is it possible to observe in these sort of skies?

[John]

5 minutes ago, Richard Hather said:

I was using my UHC filter but I think the skies aren't dark enough yet or is it possible to observe in these sort of skies?

I was observing under mag 5 NELM skies (approx) on Saturday night and the Veil was nice through my ED120 refractor with the O-III filter. Clear enough to impress society colleagues who had not seen it before.  The 24mm Panoptic eyepiece was giving a 1.8 degree true field and the curved eastern segment of the Veil extended across much of the field of view.

[Chris]

Lovely report, Piero  

[niallk]

Smashing report Piero!! 500x on Saturn - nice 

[Piero]

32 minutes ago, niallk said:

Smashing report Piero!! 500x on Saturn - nice 

Thank you! 

The HR is a great eyepiece and doesn't break the view at high magnification.

The optics of my Skywatcher dobson 200 F6 are not premium. For instance my TV60 F6 holds the image with the HR 2.4mm better and even beyond (e.g. 2.4mm + VIP 1.5x => ~ 1.6mm or 0.26mm exit pupil, without any image breakdown). Nevertheless, it is amazing how a cheap commercial telescope can still manage 0.4mm exit pupil (500x) and maintain target details. If the TV60 has PV of 0.98 or 0.99, this skywatcher maybe has something around 0.96.  

One day I hope to get my hands a premium classic dob like yours or similar. Under the right sky conditions, these mags and beyond are feasible I reckon. 

[John]

14 minutes ago, Piero said:

... If the TV60 has PV of 0.98 or 0.99, this skywatcher maybe has something around 0.96.  

 

I suspect you mean strehl ratio here

I've found all the Skywatcher dobs I've owned seemed to have excellent mirrors in them.

As part of a long, long, long SGL thread nearly a decade ago, a Skywatcher F/5 200 mirror was tested by Orion Optics. Just one mirror of course but it came out at 1/5th wave PV and a strehl ratio of .96. Very decent for a mass produced mirror

I'm not sure how refractors and newtonian strehls and PV values can be directly compared though because the newt figure is (usually) just the primary rather than a whole system figure

Anyway, that whole area can be a "can of worms" so as long as we are happy with our scopes, thats what matters

[Piero]

7 minutes ago, John said:

I suspect you mean strehl ratio here

I've found all the Skywatcher dobs I've owned seemed to have excellent mirrors in them.

As part of a long, long, long SGL thread nearly a decade ago, a Skywatcher F/5 200 mirror was tested by Orion Optics. Just one mirror of course but it came out at 1/5th wave PV and a strehl ratio of .96. Very decent for a mass produced mirror

I'm not sure how refractors and newtonian strehls and PV values can be directly compared though because the newt figure is (usually) just the primary rather than a whole system figure

Anyway, that whole area can be a "can of worms" so as long as we are happy with our scopes, thats what matters

 

Yes, John, I meant strehl ratio. Thank you for the correction.

 And you are right again when you pointed out the potential meaningless in comparing refractors and newtons in the way I kind of did informally. Eventually, what matters is that we are happy with what we have. I completely agree with this. 

 

Mine was just a mere observation about how two F6 telescopes handled a very short exit pupil. To make things more explicit, aside from the numbers, my thought is that: 

1. these mass produced mirrors can be really good. It is great that amateur astronomers can get such a quality nowadays

2. although they are not premium optics, under average seeing conditions, the difference could be marginal (if any), simply because those seeing conditions don't enable one to really push the optics at the limit. (e.g. both a Fiat Punto and a Ferrari can travel at 140 km/h)

3. under good/excellent seeing conditions, the difference can be visible because the image using premium optics does not break in the same way as it can in mass produced optics at high mags in particular. 

 

Under dark transparent skies, these differences may be also noticeable at low magnifications on DSO, I guess. What do you think?

[niallk]

You must have a fine mirror there! I saw a Skywatcher mirror on Mr Rohr's website that was rated ~0.99 strehl I'm sure, and better than 1/10 PV on the wavefront, and it was commented that it was exceptionally smooth (I hope my memory is correct here!). I think it was on a thread comparing 3 mirrors: an OO (also excellent), and something else.

Fwiw, I have been very happy too with the mirror in my SW 250px

[alan potts]

Nice report Piero,can't say I have heard M29 called the cooling tower before.

 

[FenlandPaul]

Great report Piero! Interesting how the HR 2.4mm performed too. Come and use the 12" at some point!!

I'm looking forward to the return of dark skies at socially responsible times!'

Paul

[Piero]

16 minutes ago, FenlandPaul said:

Great report Piero! Interesting how the HR 2.4mm performed too. Come and use the 12" at some point!!

I'm looking forward to the return of dark skies at socially responsible times!'

Paul

Thanks Paul!

We need to get in touch this summer. It would be great to have a proper session out. If there is a cycle path to your place, I can cycle.  

[F15Rules]

Great report Piero ?. I really enjoyed reading it and I envy your more southerly location and being able to see objects clearly that we can't easily observe from the UK.

And that Vixen HR eyepiece sounds like a cracker!?

Dave