First Light on a 16” Dob

[glenc]

Between moonset (2:50 DST) and astronomical twilight this morning I had an hour and a half to try out my new black GSO 16”.
I put some wheels on it last night so it is easy to roll it out of the garage and use it.
The collimation was slightly out but it was still very impressive with a 21mm EP at 86 times (with no filters) on the following 90+ objects.

13 Open Cl. M35, M37, M44, M45, M46, NGCs 2477, 2516, 3293, 3532, 3766, ICs 2581, 2602, 2714
8 Globular Cl. NGCs 104, 121, 288, 362, 1261, 1851, 2808, 3201

27 Nebula. M1, M42, M43, M78, NGCs 346, 1435, 1499, 1931, 1973-5-7, 1999, 2023, 2024, 2070, 2071, 2175, 2261, 2237, 2359, 2467, 3199, 3247, 3324, 3372, 3581-2, 3603, ICs 434, 2944
14 PN. NGCs 246, 1360, 1514, 1535, 2371, 2392, 2438, 2440, 2818, 2867, 3132, 3242, 3699, 3918

28 Galaxies. Swept the SMC and the LMC, M77, NGCs 55, 134, 253, 1055, 1269, 1316-17, 1326, 1365, 1374, 1379, 1380, 1387, 1399, 1404, 1531-32, 1533, 1546, 1549, 1553, 1566, 1617, 1792, 1808
2 Planets. Jupiter, Mars

It was well worth the $1800 the 16” scope cost me.

[Paddy]

Congratulations Glen. Certainly sounds like your new kit got quite a work out!

[acropolite]

That explains the sale of your 10 inch. Congratulations on the new purchase Glen.

[astroron]

Congratulations onthe 16" Glen, that observing session we did at Tenterfield Airfield with my 16" a little while ago must have stuck in your mind ;)
Great set of objects to wet the whistle of the new scope :D
Great price too:thumbsup:

Cheers :thumbsup:

[glenc]

Thanks Patrick, Phil and Ron. It is cloudy now so I am glad I got to try it out before full moon. It fits in my hatchback so I hope to take it to Tenterfield airport next new moon. I have had some good nights up there, a bit cold when Ron was there but. :) The attached image shows the new and old scopes.

[erick]

Congratulations Glen, on the bigger aperture!

[mental4astro]

Glen, DON'T get rid of your old dob, you've got yourself there on heck of a big finder :rolleyes:!!! I'm sure it wouldn't be too difficult to make an attachment to fix it onto your new 16". :lol:

Top stuff, Glen. Happy viewing.

[barx1963]

Nice one Glen!
I have this little voice in my head at the moment saying "16 inch dob only $1800!" bit of a worry.

Anyway will be looking forward to hearing come reports.

Malcolm

[Groboz]

Welcome to the GSO 16 club Glen.:thumbsup: I've had mine for 6 months now and I love it. I'm always interested in other owners opinions on the strength and weaknesses of this scope so keep us all informed on your new journey of discovery.:)

[jjjnettie]

Wowee, you are incredible Glen. All those objects in one session!
Congratulations on the purchase. It's going to take your observing up quite a few levels now.

[glenc]

Thanks Eric, Alexander, Malcolm Gino, and jjjnettie.
The Herschel's 20 ft, 20 inch was roughly equivalent to a 16" so I should be able to see most of their objects.

If you want to buy a GSO 16" the base is 68cm high and 81 cm diameter. The EP is 183 cm above the ground when pointing to the zenith.
The two tubes are 49cm diameter, the lower one is 61 cm long and the upper one is 29cm long.
I am thinking I might replace the two base circles with MonoPan to make the base lighter.

[Lismore Bloke]

Hi Glen,

Congrats on the new scope - wow what a great first light session.

You must be close to exhausting the list of DSO's visible in a 12" from your location. Great value that 16 from Andrews. Can't wait to have a look one day. Cheers, Paul.

[glenc]

The 16" now has wheels and a shroud which is supported by 3 lengths of dowel. I keep it in my garage and roll it out.
The image shows the scope and my northern horizon.

[Kevnool]

Very nice Glen.
Welcome to the 16" club its a great choice youve made.
The lists you post will be looking alot better.

Cheers Kev.

[Gem]

Glen - was that 90+ objects in a night without goto or setting circles???
If so, that is a feat!
Hmmm... now you're making me covet a 14" or 16" dob for my hatchback! :)
Camera for the CGEM or a big dob... tough choice for the next tax return!

[glenc]

Yes Grant, I found them just by memory. It is faster than using goto.
The disadvantage of a 16" is you need a step to see objects high in the sky and two people to put it in the car.

[glenc]

NGC 2261 was the best I have seen it last night at 225 times with an 18' field. (Hyperion 8mm)
https://picasaweb.google.com/110048826379679252146/NGCNebulae#5281634790664524514

[Gem]

Did it need any mods? Or are you using it "as it comes"?
Definitely thinking of a 14 or 16 now!! :)

[glenc]

So far I have put wheels on it, a shroud and caps on both ends.
I used 3 lenghts of dowel to support the shroud.
I probably need to change the springs supporting the primary.
It moves nicely in all directions.

[glenc]

It is interesting to compare my 16" GSO scope with William Herschel's 18.5" aperture 20' focal length speculum mirror telescope.
Prior to 22 Sep 1786 Herschel used a secondary mirror and his 18.5" was equivalent to a 13.3" Newtonian.
After that date he observed with no secondary and his 18.5" was equivalent to a 16.3" Newtonian.
I am assuming the reflectivity of speculum is 67% and the reflectivity of aluminium is 93%.

Herschel's 39mm eyepiece magnified 157 times and had a field of 15' 4".
My 13mm EP has a magnification of 138 times and a field of 30'.
So my 16" with a 13mm EP has a similar magnitude limit but twice the field of Herschel's scope.
I am glad my scope is not 20' long, it is much easier to observe with just a small step.

Calculation
(18.5x18.5) x 0.67 = (16.3x16.3) x (0.93x0.93)
single mirror 67% compared with two mirrors 93%

William and John Herschel discovered 3931 DSO with their 18.5" telescope. Most of them (3259) were galaxies.
The rest were 492 open clusters, 48 globular clusters, 82 nebulae and 50 planetary nebulae.

[glenc]

On Tuesday night I had my first good look at IC 443.
Here is an image from Paramount in the UK http://www.imagingtheheavens.co.uk/USERIMAGES/IC443%281%29.jpg
The star is eta Gem.

[glenc]

This morning I observed from 1:30 am (Moonset) to 3:30 am DST.
I looked at nebula and PN first with a 21mm EP and UHC filter.
Then I looked at some of the nebula and PN again with a 13mm EP (no filter) as well as galaxies and globulars.
When it started getting hazy I finished off with Mars, Saturn and a few OC.
NGC 2261 was my favourite today https://picasaweb.google.com/110048826379679252146/NGCNebulae#5281634790664524514

[Gem]

Glen,

I'd tip that Herschell had darker skies... ;)

[astroron]

Glen what is your impression of IC433,is it as clear as say NGC6888 :question:
I have not looked at IC433,so that is something to observe in the next session,Whenever that is :rolleyes:
Cheers :thumbsup:

[glenc]

Ron, IC 433 in a 16" is like NGC 6888 in a 12".

[astroron]

Thanks Glen :thanx:
Cheers :thumbsup: