Jump to content


S shape of M1

  • Please log in to reply
9 replies to this topic

#1 Madratter



  • *****
  • Posts: 7629
  • Joined: 14 Jan 2013

Posted 16 February 2013 - 10:36 PM

I was observing with my 20" the other night and noticed that it looks somewhat S or spiral shaped. I have never noticed that before. Here is part of my log for that night:

" Quite large. Very bright. Between two stars. There are filiments that kind of come off on both ends towards those stars but angled so it almost looks like a shallow spiral shape. Those filiments are very dim compared to the main body, which is oblong, and elongated in the direction as the angle between the stars."

I had grabbed a couple of frames of this with my camera on a different night. Here is a picture using those frames that is adjusted to represent a more visual view than how these pictures are normally processed. Sure enough, that S like shape shows up.

Attached Files

#2 drbyyz


    Ranger 4

  • **---
  • Posts: 395
  • Joined: 04 Nov 2012

Posted 16 February 2013 - 10:48 PM

Interesting observation...I've never noticed any spiral shape to it before, but then again, I'm not looking through a 20". I can definitely see what you are talking about in the picture though.

#3 GlennLeDrew


    Voyager 1

  • *****
  • Posts: 11114
  • Joined: 17 Jun 2008
  • Loc: Ottawa, Ontario, Canada

Posted 17 February 2013 - 01:21 AM

I really like that image! A very good way to represent its visual aspect, indeed.

#4 BillFerris



  • *****
  • Posts: 3687
  • Joined: 17 Jul 2004
  • Loc: Flagstaff, Arizona, USA

Posted 17 February 2013 - 10:23 AM

The Crab Nebula is a complex and interesting visual target. Messier described it as, "elongated in the shape of a flame of a candle." A challenging object for me in a 4.5 inch Newtonian under Midwest suburban skies, the Crab (M1) presented as an S-shaped nebula in my old 10 inch. Observing with the 18 inch under pristine Arizona skies, this object reveals a wealth of subtle detail. A sprawling tangled shell encases a brighter, comma-shaped nebula.

Here's a link to my observations with the 10 and 18 inch scopes: M1, the Crab Nebula.

Bill in Flag

#5 Special Ed

Special Ed

    Fly Me to the Moon

  • *****
  • Posts: 7135
  • Joined: 18 May 2003
  • Loc: Greenbrier County, WV 38N, 80W

Posted 17 February 2013 - 11:52 AM


Is this the S shape you're talking about?

Nice sketches, Bill. :)

Attached Files

#6 Feidb


    Surveyor 1

  • -----
  • Posts: 1833
  • Joined: 09 Oct 2009
  • Loc: Nevada

Posted 17 February 2013 - 12:51 PM

I always see a fat S shape. In fact, I have to look really close to see more than that. It's when I let my eye soak in the light that the surrounding area starts to fill in a bit more. In fact, last weekend at Furnace Creek in Death Valley, that's exactly what I saw, the fat S shape. I never really got to take a serious look because it was outreach and I had a line. Everyone that looked saw the fat S. I DO remember seeing a surrounding halo but at just a quick glance. In fact, I remember some mottling surrounding it also but it was light. If I'd taken the time and upped the magnification, I could have drawn out more detail, but I kept the magnificaiton at 102X so I wouldn't have to nudge the scope so much between observers, which usually meant two people before I had to nudge, depending on how long they gazed at it.

I've also found that for the most part, an O-III cuts it out or just leaves the brightest part of the core. My UHC helps on some parts of it and once in a while, actually brings out more details than the raw image. Going back through my notes, once in a while the O-III actually helped and I don't know if that was because of transparency or other factors.

However, before I get too sidetracked, I ALWAYS see the fat S shape. Maybe it's my 16-inch aperture?

#7 Dave Mitsky

Dave Mitsky


  • *****
  • Moderators
  • Posts: 37780
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 17 February 2013 - 04:27 PM

M1 usually appears to have an S-like shape to me too, especially when observed with larger apertures.

Dave Mitsky

#8 Madratter



  • *****
  • Posts: 7629
  • Joined: 14 Jan 2013

Posted 17 February 2013 - 06:30 PM


Is this the S shape you're talking about?

Nice sketches, Bill. :)

The S I see is roughly outlined as pictured here. It is nice, and not at all surprising others have noticed this too. There is certainly nothing special about my skies (which were about 5.7ish) and eyes (which aren't getting any younger).

Attached Files

#9 JakeSaloranta



  • -----
  • Posts: 1009
  • Joined: 18 Sep 2008
  • Loc: Finlandia

Posted 18 February 2013 - 04:27 AM

8" Orion DSE

Object: Messier 1 / NGC 1952
Obs. place: Porainen, Finland
Date: 5./6.3.2011
NE Lim.mag: ~6.7 (zenith)
SQM-L reading: 20.47 (zenith)
Background sky: 6 (good)
Seeing: 6 (good)
Transparency: 6 (good)
Weather: -2.3°C, humidity ~80%..., 1020HPa, gusts of wind, snow depth 74 cm

Description: Bright, NW-SE elongated diffuse little peanut (or a large S). Slightly brighter in the middle. Several 14th magnitude stars visible in the vicinity.
Posted Image

#10 Madratter



  • *****
  • Posts: 7629
  • Joined: 14 Jan 2013

Posted 18 February 2013 - 10:07 AM

Nice sketch that corresponds very closely to the photo.

Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics