Propeller in M13

[davo]

Very interesting reads and many responses. Didn't realise it had so much history to it (Rosse) or controversy? for that matter. As a purely visual observer i was interested to find out whether i could observe it through my 12" Dob? and where we needed to look for it. Thanks for all the info (far more than i expected) I cannot wait for my next clear evening to give it a go. I've look at this object before but now feel impelled (pun intended) to revisit it to see if i can glimpse this feature.

Clear and Happy Skies to you all!

Dave

[Talitha]

Got it at about 1:10 am on Monday, 18 May (7:10 UT) using Snoopy, my 8" SCT.

I tried using stupid power at first. At 622x there was some interesting internal mottling, but the image was extremely degraded. Those of you with larger apertures will be able to use the power and pull out more than i could.

The best view was at 222x with the 9mm University Optics ep. As expected, the best view was in my averted sweet spot which is in the 4:00 position of my left eye. What i do is place the target in the center of an imaginary clock, and then look up to the 10:00 position. It automatically moves the target down to the 4:00 position.

I made a quick outline sketch of M13 and added the tendrils cascading towards the SW and then added the propeller lines using the tendrils as landmarks.

After coming home at about 2:30 or so, i checked this thread to see if i was in the ballpark and it looks like i was spot on. The positon of the propellers matches some of the images linked to in this thread.

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Here are three pics..

The first one is the field sketch, North/up West/right.

Second one is last May's sketch with Monday's propeller shaded in.

Third one is the original of last May's sketch. It has a shadowy strip running towards the SW, right where the propeller is. Looks like i might have caught a hint of it last year without realizing it, which makes me a very happy camper.

[acey]

Well done! And I'm in awe of your magnificent sketch.

Still hoping to try for it, weather permitting, before the light nights put an end to the season, though I suspect I'm going to have to leave this one for autumn. Can't wait!

Andrew

[davo]

Weyhey! You got it! Very good observing indeed! I so need to have a go at this with me 12" Dob. A nice clear evening at about 11pm sould do it :-)

[Talitha]

Thanks, and best of luck to everyone. It'd be great if this thread keeps bobbing to the surface all summer with successful sightings.

(Forgot to mention, the transparency was average and M13 was about 76 degrees in altitude.)

[acey]

I've seen it!

Forecast said there might be clear spells so I took the 12" F5 dob to my dark site, still in twilight at midnight, with limiting magnitude only about 5, my eyes not dark-adapted.

M13 was easily visible in the finder, though, so it only took me a moment to get the scope aimed. And there was the Propeller, immediately obvious at x136 - just like all the pictures I've been looking at!

I've observed this cluster many times and never noticed it, but once you know what you're looking for it can be surprisingly easy. I could hold the centre of the Propeller with direct vision; to see it as a whole required slightly averted vision.

At x188 the lanes were wider but not as dark, possibly due to light scattering in the scope and consequent loss of contrast. The view was not as striking.

At x75 I could no longer see the propeller, except perhaps fleetingly. The lanes were now too narrow and didn't stand out enough against the brilliant stars of the core.

It would seem that aperture and sky darkness are not the main issues - it's more a case of knowing what you're looking for, then finding an eyepiece that gives the right balance of magnification and contrast.

I also looked for the "false propeller" I'd noticed in some images, couldn't see it, but did find all sorts of patterns popping out at me - short dark lanes or strings of brighter stars standing out against the core. Looking for the propeller was very instructive in this respect - it made me see M13 more in the way I'd look at an open cluster, rather than as a dizzying mass.

I also had a quick look at NGC6207, a very pretty sight, but couldn't see an IC galaxy marked as being closer to the cluster (maybe that will be my next M13 challenge). I decided to go for another nearby galaxy group - and the clouds rolled over. So it ended up being a short observing session - but a successful one!

Andrew

[themos]

Good stuff Andrew, I was out in the garden imaging M13 around midnight. I think I may have caught the propeller in just 135mm of focal length but we'll see what the processing brings.

[moondog]

Got it at about 1:10 am on Monday, 18 May (7:10 UT) using Snoopy, my 8" SCT.

Carol - Hadn't noticed this thread until now. I looked at M13 last night with my C8 @F10 with a 9mm EP giving 222x mag. and I clearly saw the propeller. It can be seen with an 8ins scope even in the UK. (I have a reasonably dark sky though).

MD

[Talitha]

That's great!! I'll give it a try with the 120 achro some night.. it'll be interesting to see how low in aperture we can go.

MD, i live out in the country and although the light pollution is minimal i can always see everything around me. It's not dark like those fantastic sites we hear of where Amateurs can't even see their own hand in front of their face.

[albedo0.39]

I was beginning to think that a few of you might be smoking a sustance not dissimilar to that which you might find in suspicious pockets...

However, one of the more recent images clinched it.

Great thread. A little bit like those 3D images from the 90's where you stare for 5 seconds then "ping" you can see it.

Thanks