7 hours ago, Littleguy80 said:

The Interstellarum Deep Sky Guide

Where did you buy it Neil, it seems very expensive here...

7 hours ago, Littleguy80 said:

The Interstellarum Deep Sky Guide

Thanks Neil, I need resources such as this- I'm a bit lacking in the info dept.. had a great night last night and the ortho worked! M57 central star easy with the 10mm BCO at 249x, among other things. Hickson 55 was behind the trees though unfortunately.

18 minutes ago, mdstuart said:

I am going to really enjoy this scope and my journey with it.

Great first light Mark and I await your reports!

4 hours ago, Piero said:

Last night the new dobson saw its first light! 

In summary, I really enjoyed using it, it surpassed my expectations, and I will have a learning curve with it due to many new variables to me.

Awesome Piero!

Great first light, this scope will give many fine obs sessions for years to come!

1 hour ago, MSammon said:

This article has just blown my mind. Right I tried a 9mm eyepiece tonight (X 133, 1.9mm exit pupil) and I got my best view of the bands. It was just very small. I will try a 7mm eyepiece when I get one.

anyway so it seems that exit pupil is a lot more important than I realised. So if I had a 12 inch F5 dob instead I could see the same detail perhaps with a 1.8mm exit pupil but it would be at X 166. 

But people are still getting better views with a 100mm apochromatic refractor?

 https://medium.com/@phpdevster/how-telescope-aperture-affects-your-view-24507147d7fc

Your path will lead to the discovery of this: from Peach and thats why I started posting MTF graphs...

"115/Aperture (mm.) For example, a 254mm aperture telescope has a dawes limit of 0.45" arc seconds. The dawes limit is really of little use the Planetary observer, as it applies to stellar images. Planetary detail behaves quite differently, and the resolution that can be achieved is directly related to the contrast of the objects we are looking at. A great example that can be used from modern images is Saturn's very fine Encke division in ring A. The narrow gap has an actual width of just 325km - which converts to an apparent angular width at the ring ansae of just 0.05" arc seconds - well below the Dawes criterion of even at 50cm telescope. In `fact, the division can be recorded in a 20cm telescope under excellent seeing, exceeding the Dawes limit by a factor of 11 times!. How is this possible?."

Seriously read and understand this article . Your 10" is a super planetary scope.

http://www.damianpeach.com/simulation.htm

ps I can see the Enke division on Saturn when the planet is high and the seeing good, in my 10" dob.

Do I ever like that Mewlon Stu, what a scope! Great observing with some nice detail

2 hours ago, estwing said:

One of the best and challenging books for big dob owners is the peculiar galaxies book available from FLO. very interesting articles and gives descriptions from observers using 18,20,22,24 even 26 and bigger scopes.

I highly recommend it Gerry.

Thanks Calvin, I'm going to get it. Tonight looks very good! Possibly better than the last couple of night, we'll see. Maybe I'll dust off the 10mm BCO and try Hickson 55 its nice and high.

10 minutes ago, estwing said:

15 occasionally...Mapstar has had success with higsons 55.

Thanks so much Calvin, the voice of experience means a lot. I just looked up Hickson on Vogels site- I can see where magnitudes get confusing- Vogel lists blue and red magnitudes and judging from the red I can see an opportunity for 4 of them-"a" and"b" should be do able here with luck, maybe more. Simbad lists UGC 6514 (Hickson 55) as 15.2 mag-maybe for the object as a whole.

If you guys have any suggestions for me pass them on will you? Thanks, Gerry

6 minutes ago, estwing said:

Lovely read Gerry....I feel the ap fever is upon me!

Thanks Calvin!

Just curious for reference, how faint of galaxies can you guys go on dark sites?  Has anyone gone over 16mag on one?

15 minutes ago, Stu said:

That's good news.

A bit of experimenting needed perhaps to see what works best. I assume you have dimmed it as far as it goes in the settings?

yes, its on the lowest setting and I love this thing already. Even with all my ducks in a row I'm not so sure I'll exceed 16mag on an extended object by much... with the 15" I don't think I exceeded Moores magnitude in the chart on an extended object.

1 minute ago, Stu said:

Keep them coming Gerry! Great to have you posting regularly again.

I'm sure there is plenty more to come. I wonder if it is worth using some neutral density film over the Skycommander display if it is too bright?

Thanks Stu, the weather is finally co operating.

I must do something, including shutting it off if needed- maybe an orange film over it to turn red? Another no no for me is the computer screen with its polarized light- this wrecks my eyes for a very long time, as well as the LED TV.

29 minutes ago, Piero said:

Thanks Gerry!

what is the CO of your 24" dobson?

I'm at 19% with the 24" and if I remember 21% with the 15". My playing around tells me 37% I don't like, 30% is better but 25% and less is where its at , for me anyway.

Yes, the Docter and orthos will be used as well as the 10mm BCO which is a good copy. I was out in the sun yesterday and had issues dark adapting- it took me much longer than normal. These computer screens don't help and neither does the Sky Commander 's green screen...

The Nikon HW/barlow at 14mm is acceptable but not optimum and the 10mm BCO will go a hair deeper than the Docter as tested in the 15" .  One thing is for certain, the size of the galaxy impacts its viewability and much higher mag is needed, where the f4 allows for a nice increase here. I have an excellent copy of the 7mm KK ortho for 357x. This one got me the central star in the ring nicely in the 15".

As far as magnitude limits what are the thoughts about point sources vs extended objects vs limiting magnitude?

Moore has a more conservative rating for point sources as shown in the chart.

"

6 hours ago, Piero said:

here are more accurate measurements. 

Piero, here is the 24"- opticians including Mel tell me that as long as bit of the field is fully illuminated and the edge is above 70% all is good espc if it allows low central obstruction- the trade off is worth it. In my experience this is very true. I'm not a fan of central obstructions over 30% for sure, less than 25% is better and yet some highly obstructed SCT's give super views...

thoughts?

" Remember that illumination may drop to 70 % for visual use.

Off-Axis	Illum.	Light Loss
0.00 in	100.0%	0.00 mag
0.10 in	100.0%	0.00 mag
0.20 in	100.0%	0.00 mag
0.30 in	99.93%	0.00 mag
0.40 in	98.42%	0.01 mag
0.50 in	96.29%	0.04 mag
0.60 in	93.93%	0.06 mag
0.70 in	91.44%	0.09 mag
0.80 in	88.89%	0.12 mag
0.90 in	86.30%	0.15 mag
1.00 in	83.69%	0.19 mag"

Excellent!

These true numbers give a fantastic illumination:

" Remember that illumination may drop to 70 % for visual use.

Off-Axis	Illum.	Light Loss
0.00 mm	100.0%	0.00 mag
2.00 mm	100.0%	0.00 mag
4.00 mm	100.0%	0.00 mag
6.00 mm	100.0%	0.00 mag
8.00 mm	100.0%	0.00 mag
10.0 mm	100.0%	0.00 mag
12.0 mm	100.0%	0.00 mag
14.0 mm	100.0%	0.00 mag
16.0 mm	100.0%	0.00 mag
18.0 mm	99.88%	0.00 mag
20.0 mm	96.18%	0.04 mag
22.0 mm	90.50%	0.10 mag
24.0 mm	83.85%	0.19 mag
26.0 mm	76.64%	0.28 mag"

What a great set of numbers Piero!

Can I bore everyone with another report?

The sky was good with structure in the MW and with M8 etc easily naked eye down south. I wanted to pursue Draco after seeing a nice galaxy near the Catseye nebula.  This scope seems to do well so far on galaxies so I put a few into the Sky Commander to see what I could get.

First a triple set consisting of NGC 6419 @ 15.5 mag, .95 arcmin, NGC 6420 15.5 mag, .45 arcmin and NGC 6422 15.1 mag .56 arc min. All three were bagged with NGC 6420 flicking in and out of averted vision. I was using the Nikon HW 14mm, good for this but not that good. Next time an ortho comes out, these galaxies sit in a triangle of 3 mag 8 stars for reference.

I had a failure on the NGC 6456 group with it being 15.7 mag and .34 arc min. At least I'm defining the limits so to speak.

Over to a great planetary- the Magic Carpet nebula- NGC 7027- what color! a very bright green in the 14mm HW with a hint of asymmetry at this lowish mag- next time more power goes on it.Man is it bright,small but bright. After galaxy observing a bit more relaxed sky cruising is nice so over to M24, a special favorite and what do you know? B93 and B92, 2 beautiful dark nebs stood in stark contrast to all those stars.

One last view...I picked M101 to finish the night- hey- who put all those faint galaxies near it?! I must have chosen not to see them before lol! Seriously though NGC 5485 @ 12.2 mag 1.6 arc min very easy and the faint NGC 5484 15.6 mag .34 arc min bounced in and out of averted with NGC 5486 held in direct at 14 mag and ,49 arcmin. NGC 5473 and NGC 5477 were there too along with the always bright NGC 5474.

So anyway, that was my night, time for bed. The scope used was the 24" with 20mm lunt HDC and the Nikon 17/14mm HW. Filters were the Lumicon UHC and OIII.

2 hours ago, niallk said:

Ooooo!! That would be amazing. 

Beyond my 15", but I've heard of "Andromeda's Parachute" which I might just be able to detect - another potential target with your new big gun...?

 

Thanks Niall, I'll try it out- these objects and stars themselves I find difficult and the Sky Commander was bought in part to help me find them.

Great recommendation!

16 minutes ago, MSammon said:

Thanks, yes the moon is incredibly sharp with it even with my highest power eyepieces. I might try get to an astronomy club this weekend to look through others.

Its most likely just the position of the planet, and local thermals then...

9 minutes ago, alan potts said:

What will it see down to on a decent night Gerry about 17mag. The centre star of M57 is a good one to try I have done here on a good night twice, without having to go to high power, Thing I was using around x210.

Alan.

Thanks Alan, I'm going to give that a try soon and will try an ortho possibly. I have no idea how deep this scope will go- I really want to see parts of Einsteins Cross with it.

6 hours ago, MSammon said:

Is this from northern hemisphere and this time of the year? What magnification please?

I live in northern Ontario Canada with different seeing conditions possibly. I can get good views between 200x-250x when seeing is up there but the planet is so low its not really worth pursuing much (to me).  This is current, last night actually. The 10" dobs are typically great lunar/planetary scopes, as @dweller25 pointed out to me years ago.

Test yours on the moon, when at about 1/4 full- you should be getting very sharp, clean views..

I would hold off on any purchases with the thought of improving Jupiter views at this time...

1 hour ago, Nyctimene said:

Congrats, Gerry, to your marvellous new scope, the woodwork looks excellent, as well as the optical data.

Where do you store your scopes? fully assembled and at ambient temperature, I assume (so do I).

Beautiful location, btw. Wishing you many clear, moonless nights with this great performer!

Stephan

Thanks Stephan, the scope is in a carport currently and is stored in a garage. It is always near ambient and the open carport offers a nice cool shade area that keeps the scope safe but cool. I've been putting the sec cage on and taking it off checking collimation repeatability- it doesn't change much at all.

I can be set up and observing in under 10 minutes.

Just now, Stu said:

Nice one Gerry, just reached the same conclusion on 6552. Good catch!

Thanks Stu!

It has a bright core with an elongated glow- that Catseye neb is something else I'll say!

It turns out that showy little galaxy is NGC 6552, a Seyfert 2(?) galaxy at 14.6 mag- a nice inadvertent catch.

Just in from another great obs session, what a night. The observatory will be up on the ridge, I was removing some rock with the track loader here today- there is supposed to be grass right here lol! The Catseye neb was a brilliant green just now with a little galaxy off to the side, gonna look it up.

I wrap my arm through the wrung and it seems to work- definitely tests the balance!

My 10" f4.8 dob gives much much better views than those images...

Cooling, collimation and dealing with local thermals are where to concentrate efforts IMHO.