Old love renewed

[Nyctimene]

My 13.1" f/4.5 Coulter Odyssey 1 Dobsonian, bought in 1987 directly from Coulter, USA (prepaid, never tried - all went well), sat almost unused in the shed after the arrival of the Obsession 18" in 1999. Last night, I hauled out it's 28 kg  red cardboard OTA and the 24kg particle board Dobsonian mount - both rugged and almost indestructible, and gave it a try (with the question in mind, whether to sell the old companion or put it again to good use). Average NELM of 5.6 mag (still 1h astronomical darkness  from 01.00 to 02.00 CEST here at 49.36° N, according to SkySafari), and very good seeing, allowing mags of 400+. I started with M 51 and it's companion and was surprised - the spiral structure was faint, but clearly visible! So over to the fainter M 101, which showed  initially just the core region; careful inspection revealed slowly several H II regions in the galaxy's outer area, with 5471 the most prominent. Two small accompanying galaxies, 5473 and 5485, were visible  in the same field of view directly with brighter core regions. I went to Izar as an intermezzo, and could split it easily with a clear, wide gap at 422x (Seben zoom 8mmf+ 2,25x Baader barlow). The star test at Polaris showed nice, round diffraction images in-and outside of focus - I had been lucky with a really good Pyrex mirror 32 years ago. M5 and M 13 with 6207 gave stunning and contrasty views. So the decision was easy - I'll keep the scope and intend to upgrade it with a Rigel and decent RACI finder, as well as wheelbarrow handles for easy transport. This old scope has deserved to stay here and to enjoy the rural skies together with it's owner! Again, pleased and so to bed.

Attached two pictures:

Thanks for reading

Stephan

 

Edited June 3, 2019 by Nyctimene
typos

[Trikeflyer]

Stephan, Nice report. Glad you enjoyed the scope after all this time.  I had a similar experience but with a smaller -  scope etx 125, my first scope. I fell out of love with it and only recently looked through it again at some double stars. I’m back in love with it now for specific targets.

sometimes a break from a scope can be a good thing.

steve 

[jetstream]

On 03/06/2019 at 06:09, Nyctimene said:

This old scope has deserved to stay here and to enjoy the rural skies together with it's owner! Again, pleased and so to bed.

Great report Stephan!

Yes this scope sound VG and a keeper and I personally use Rigels myself. Astrosystems installs a battery pack that takes AA batteries that last a long time even in the cold.

Eagerly waiting reports!

btw- nice location

Edited June 22, 2019 by jetstream

[Paul73]

Nice writeup Stephen. M101 seems to be much overlooked. I’ll have to give it another go next time we get clear & dark sky.

I still have my first scope. A 10” Skywatcher which hasn’t had a look in since the 16” OOUK arrived.

Paul

[Paz]

Great report and a good looking scope you have there.

I was wondering though, what is the function of the black box in between the focuser and the finder scope?

[Nyctimene]

On 23/06/2019 at 10:53, Paz said:

I was wondering though, what is the function of the black box in between the focuser and the finder scope?

Well spotted, Piero

It's an ancient DIY precursor of today's RDF's, that I built in 1987 (pre-Rigel times; and I didn't like the Telrad). Following a suggestion in the Sky&Telescope ATM section, I made this 90°-angled RACI zero magnification finder:

The following picture shows the interior: to the left, a 20 mm pentaprisma, (you look "vertically down" on it); in front of it a microscopy cover glass as a "combining glass". A surplus singlet lens microscopy eyepiece (chrome-plated cylinder) acts as a collimator, that brings the red LED-illuminated crosshairs (fixed at the plywood part to the right) into the view. Switch and dimming potentiometer at the right side. It's nice and relaxing, to point the scope roughly in the target's direction, and, without any neck contortions, to look "vertically" down and find the object in the finder's approximately 25° field of view; and then just to turn the head slightly to view it in the eyepiece.

Atm., it's been replaced by a Rigel. But I intend, to fix it's minor drawbacks (somewhat prone to dew; adjustment of the combining glass difficult; little brightness range of the LED), and to put it again to use. I've never found a 90° angled non-magnifying RACI for sale (but would like to).

Stephan

 

Edited June 24, 2019 by Nyctimene

[Paz]

Very nice, and with a wide field of view very practical. Maybe there's a business opportunity there!

I have a mirror I can flip up on my telrad to allow 90 degree viewing but the image is mirror flipped and only a small field of view is doable so its less practical than your set up.