Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Seagull Nebula - in binoculars, to boot

  • Please log in to reply
11 replies to this topic

#1 C.Hay

C.Hay

    Vostok 1

  • -----
  • topic starter
  • Posts: 154
  • Joined: 07 Jan 2015
  • Loc: Germany

Posted 17 January 2020 - 10:15 AM

The time is ripe for a thread on the Seagull Nebula, aka IC 2177, aka Gum 1/2/3, aka Sh 292/296/297.

 

Out last night with my newest acquisition, a Docter 8x56B Porro fitted with two Astronomik H-Beta filters on the eyepieces (see the thread on this in the Binoculars board: https://www.cloudyni...noculars/page-2), and following a pleasing sight of the California Nebula, I thought I'd give the Seagull another try following numerous failed attempts with other instruments. At my location, in a semi-rural setting in central Germany at 50°N, 130m above sea level, with NELM around 5m5 and the nebula never very high in the sky, the Seagull is a challenge. Yet now, with the right instrument, it suddenly popped out.

 

It presented as highly amorphous with boundaries almost impossible to define precisely. No question of the fine soaring bird that photos and some maps suggest. The image that came to mind was rather of a mottled potato, a little over 2° in extent from North to South and perhaps 1.5° from East to West. I saw two condensations in the nebulosity, each about 1/4° large. One was 1/4° northwest of the brightest star in the field, FN CMa (5m4). The other was about 1/2° north of that star.

 

In order not to skew my perceptions, I hadn't looked at maps or photos before viewing. I only had an idea of where the nebula should be, from a number of failed attempts in previous years, and pointed the binoculars there. Looking at photos afterwards, I'd say that the two condensations in the nebulosity are roughly where the bird's shoulders are.

 

I find it interesting that the two parts of the Seagull reported in the literature to be the brightest - Gum 2, the bird's head, and Gum 3, dripping off the bird's southern wing - were not evident. I think this is because both have brightish stars at their centre, which, combined with the small image scale at 8x, make it harder to perceive nebulosity.

 

The Interstellarum Deep Sky Atlas gives the Seagull an 8-inch-aperture visibility rating. We've followed that up to now in our BAfK observer's guide (see my signature). I shan't deny that may be correct to see the seagull structure, but following my sighting of 2°-large nebulosity, with stable condensations therein, using handheld bins under a mediocre 50°N sky I think we'll have to correct it to a binocular visibility rating.

 

I would be delighted to learn about the sightings of the Seagull by others. Please do chime in. I'm not a great sketcher myself, hence the lack of an image. I would be all the more pleased if others could show their drawings here.

 

CS, Christopher


  • Dave Mitsky, Inkswitch and SabiaJD like this

#2 Mark Strollo

Mark Strollo

    Explorer 1

  • *****
  • Posts: 98
  • Joined: 20 Mar 2006
  • Loc: Waterford, CT

Posted 17 January 2020 - 12:11 PM

Nice catch.  I had not observed it visually with a 10 inch, but was amazed after running across it while scanning at 1X with Night Vision and H-Alpha filter.



#3 C.Hay

C.Hay

    Vostok 1

  • -----
  • topic starter
  • Posts: 154
  • Joined: 07 Jan 2015
  • Loc: Germany

Posted 17 January 2020 - 12:39 PM

Hi Mark, do you remember the shape? Any notion of wings, or more a potato?

CS, Christopher



#4 j.gardavsky

j.gardavsky

    Viking 1

  • *****
  • Posts: 674
  • Joined: 18 Sep 2019
  • Loc: Germany

Posted 17 January 2020 - 02:08 PM

Hello Christopher,

 

and congratulations on nailing down the Seagull through the 8x56 binoculars.

You will love these Docter binoculars, I tell you.

 

I have just 3 observings of the Seagull in my logbook:

two of them through the 6" F/5 achro with the OIII filter from my backyard,

and one through the 82mm Leica APO Televid without filter from Silvaplana in the Swiss Alps.

 

The 6" aperture has revealed 1 condensation in the "potato", he 82mm aperture has shown just the potato.

 

I have never tried it through the binoculars, certainly I should do it.

 

CS,

Jiri


  • C.Hay likes this

#5 Pcbessa

Pcbessa

    Ranger 4

  • -----
  • Posts: 355
  • Joined: 26 Jan 2019
  • Loc: Forres, NE Scotland, UK

Posted 18 January 2020 - 04:38 AM

I find the Seagull as bright as the Heart and Soul nebula in Cassiopaea, and almost as bright as Pelican in Cygnus. So relatively easy for me.

 

You need dark skies, and then if have these good conditions, you can see all of these in binoculars (or in my case, my 10" Dob finder, when I place a UHC filter in the finder). Its nice to see the nebula that way.

 

In my 10" Dob, the nebula is still faint but well visible and very large. As just like you, I find the large elongated part easy to see, but I havent recall seeing the head still. I need to spend a night observing its details.

 

Nearby Thors Helmet is very bright in my 10". With a UHC filter and a transparent sky (down to horizon), it is as bright as M76 or M1, with detail easy to see.

 

The problem is that they are seen only 20 degrees above my horizon, so good conditions, free from any haze, are critical.


  • C.Hay likes this

#6 chemisted

chemisted

    Ranger 4

  • -----
  • Posts: 342
  • Joined: 24 Feb 2012

Posted 19 January 2020 - 07:22 AM

Hi Mark, do you remember the shape? Any notion of wings, or more a potato?

CS, Christopher

Mark's FOV would have been 40 degrees.  Last March I used my NV device with a 12 nm H-alpha filter attached to my 105 mm f/1.8 Nikkor lens which gives a 10 degree FOV.  The Seagull lives up to its name with its entire body visible and nicely framed with this equipment.


  • C.Hay and j.gardavsky like this

#7 C.Hay

C.Hay

    Vostok 1

  • -----
  • topic starter
  • Posts: 154
  • Joined: 07 Jan 2015
  • Loc: Germany

Posted 01 February 2020 - 05:18 AM

Out last week again with the 8x56 binoculars. Observing site 50°N in central Germany. NELM was only about 4m5 in the target area of the sky. Undeterred, I turned the binoculars with Astronomik H-Beta on both eyepieces to the Seagull Nebula. It presented again as a 2° potato, but now without any distinct condensations. No surprise given the poor transparency of the sky.

 

What did surprise me was that, despite NELM 4m5 in that area of the sky, the nebula still extended well to the south of W CMa (that orange-red star is, by the way, a member of the CMa OB1 stellar association to which the Seagull belongs). So it must actually be quite a bright object that would surely be rather dramatic if placed higher in the sky.

 

With OIII on both eyepieces the nebula became reduced in size, especially to the south, but was set off from the surroundings much better, i.e. was much easier to detect than with H-Beta.

 

CS, Christopher


  • j.gardavsky likes this

#8 PEterW

PEterW

    Surveyor 1

  • *****
  • Posts: 1,915
  • Joined: 02 Jan 2006
  • Loc: SW London, UK

Posted 01 February 2020 - 05:30 AM

It would be interesting to point those bins at the other large hydrogen nebulae that are scattered around, plenty on up through Gemini, Auriga etc. Big aperture is not always needed.
Peter

#9 Pcbessa

Pcbessa

    Ranger 4

  • -----
  • Posts: 355
  • Joined: 26 Jan 2019
  • Loc: Forres, NE Scotland, UK

Posted 01 February 2020 - 02:33 PM

The seagull is a bright object but the nearby Thor's Helmet and the Skulls nebula, are brighter. I saw the Skull nebula as a beight object at only 5 degrees above the horizon. Can't imagine how it would be if it was higher up.

In my finder, if skies are dark, I can spot the Heart and Soul, as well Pacman, Monkeyhead, Wizard, California and even the IC1396 (where the Elephant Trunk is located), if I place a UHC filter on the 9x50 finder.

I think the Flame would show up under very dark skies, and with some effort possibly even IC434, where the Horsehead is. It's actually not a very faint nebula.

The Veil seems to be better in a telescope because of its fine texture. But the North America nebula shoes up well even at naked eye if skies are dark, and great on the finder.

I haven't tried to spot IC410 on Auriga but its probably another target for dark skies. But its better under a telescope as it is small.

The flaming star nebula, in Auriga, is very faint and probably requires a h beta filter, which I don't have. The Barnard loop also requires very dark skies. The lobster claw in Cepheus is faint, not sure if it would be seen on a finder, but it is large. Finally the Christmas tree nebula is another possible target, but te brighter part of the nebula is a bit faint and small.

Another great one is Rosette.

So plenty of nebula that can be seen under a dark sky at this time of the year.
But Monoceros is a great place to start exploring.
  • C.Hay and j.gardavsky like this

#10 j.gardavsky

j.gardavsky

    Viking 1

  • *****
  • Posts: 674
  • Joined: 18 Sep 2019
  • Loc: Germany

Posted 02 February 2020 - 11:36 AM

Out last week again with the 8x56 binoculars. Observing site 50°N in central Germany. NELM was only about 4m5 in the target area of the sky. Undeterred, I turned the binoculars with Astronomik H-Beta on both eyepieces to the Seagull Nebula. It presented again as a 2° potato, but now without any distinct condensations. No surprise given the poor transparency of the sky.

 

What did surprise me was that, despite NELM 4m5 in that area of the sky, the nebula still extended well to the south of W CMa (that orange-red star is, by the way, a member of the CMa OB1 stellar association to which the Seagull belongs). So it must actually be quite a bright object that would surely be rather dramatic if placed higher in the sky.

 

With OIII on both eyepieces the nebula became reduced in size, especially to the south, but was set off from the surroundings much better, i.e. was much easier to detect than with H-Beta.

 

CS, Christopher

Hello Christopher,

 

this is an excellent observing report of yours, The Seagull through the 8x56, in our German skies!

Congratulations,

Jiri


Edited by j.gardavsky, 02 February 2020 - 11:36 AM.


#11 Eddgie

Eddgie

    ISS

  • *****
  • Posts: 25,604
  • Joined: 01 Feb 2006

Posted 02 February 2020 - 11:48 AM

Nice catch.  I had not observed it visually with a 10 inch, but was amazed after running across it while scanning at 1X with Night Vision and H-Alpha filter.

I would think that a 10" would be far to large to see the Seagull nebula with. I mean you could be looking right at it, but because it would fill your field of view, there would be no dark sky around it to give contrast. Now it is possible that some bright knots were visable in the 10", but the full nebula I think would over-run the field of a 10".

 

As with California Nebula, which is considerably larger than the catalogs list it as being, the catalogs list this nebula as being 2 degrees long and 2/3rd of a degree wide, but I think this figure understates the size by a considerable amount.

 

RCW 2, which is what would be considered the head of the bird, is quite bright and this might be visible in a 10" scope because it would fit into the field with enough dark space around it to show up well.

 

To see the full nebula, as with California Nebula, I think the Binocular or a small scope that can give a 3 degree field, are both better choices.

 

So, I think the OP saw it because he used the right kind of instrument.

 

And this is why.. A binocular gives you "Binocular Summation". This makes objects appear brighter than the aperture of one of the lenses would suggest.   Studies suggest that an object will appear about 30% brighter if two eyes are used vs 1 eye (using a true binocular, and not a binoviewer because the binoviewer dims each eye by 50% so the binocular summation never brings you back to the same brightness that you get with one eye).

So, if you use a telescope with a 6mm exit pupil and someone else uses a binocular with a 6mm exit pupil, they will see anything in the field as being brighter than you will see it because of binocular summation.

 

So, with the same exit pupil, the binocular observer sees the image as being 1.3x to 1.4x brighter than you get with a single eye.  For diffuse nebula the aperture itself does not matter.  What matters is exit pupil and when you max the exit pupil in both, the added brightness provided by binocular summation gives the observer using two eyes a great advantage. 

 

Binocular summation also improves visual acuity and makes things look larger than they are, and under very dark conditions, it improves your eye's signal to visual noise ratio.

 

This makes binoculars absolutely the best choice for nebula hunting, and will usually give are superior resul than a single eyepiece telescope would.  Things are brighter when you use a binocular (for a given exit pupil).

 

If you want to see large, faint, diffuse nebula, a binocular is absolutely the best way to do that. I even use a binocular even though I can see these things easily without it.. Everything is just brighter in a binocular. 

 

Mod 3 3x.jpg

 

Binocular summation is powerful stuff. 


Edited by Eddgie, 02 February 2020 - 12:23 PM.

  • paulsky and j.gardavsky like this

#12 Eddgie

Eddgie

    ISS

  • *****
  • Posts: 25,604
  • Joined: 01 Feb 2006

Posted 02 February 2020 - 12:28 PM

Christopher, 

A very good report! I did not really want to post my own observation because there is some hostility on the this forum when it comes to image intensifiers, but I did read your observation and you have my applause. 

The primary reason I posted was to explain the role that binocular summation played here.   I think it was a great observation report and I enjoyed reading it!  Good for you.  These are things people can be seeing and I wanted to highlight the contribution that binocular summation made to your success.   Bravo.  The right tool for the job, and short of using an image intensifier, you probably got about the best un-enhanced view possible because of that.

It is a beautiful nebula. I am sure you feel great gratification for having seen it. 

 

Fun report.  




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics