Keep those pictures coming...

[Fir Chlis]

A bit of a naff title for the thread but, being in my very early days of EAA, I'm finding it really useful to browse through the postings in this sub-forum to get ideas of what to look at. My scope goes onto the lee side of the house, depending on the wind strength and direction, so I generally just look at Stellarium and pick out randomly whatever Messier or Caldwell objects are in view from there, so the pictures on here are helpful in picking future targets. 

I'm still in the honeymoon period of looking at as much as I can each session, but I think I need to set aside some time each session for testing. I'd like to see what is the longest exposure I can get before starts begin to trail and still need to experiment with exposure /gain combinations. Although with the very dark skies here (I admit it - I'm very fortunate to live under Bortle 1 skies), long exposures matched with the lowest read noise gain settings on my camera do seem to over expose.

Cloudy last night, so I went through my pictures and had another look at these two images - Horsehead Nebula - something I used to try and pick out visually. So the first time I saw it on camera I was really quite moved, seeing this icon in real time from my own home.

Gear is Skywatcher 200PDS on HEQ5 Pro, ASI585MC, Sharpcap live stacking, Bortle 1.

First image is 5 March, 152 x 4s (~10min), gain 300, flat and dark applied, with Sharpcap histogram stretch. Second is 6 March, 25 x 8s (~3min), flat and dark, stretched. Despite the diffraction spike from Alnitak and the satellite trail, I find it to be a very dramatic image. The differences between the two images do appear to show the benefit of a longer total exposure time. I think you do need a darkened room to see the images at their best - I've just had to shut the blinds.

Geoff

 

 

 

Edited March 8 by Fir Chlis

[PeterC65]

The first image does look better, but that is probably down to the longer total exposure, the background sky tends to darken the more frames you collect. Emission nebulae do really benefit from longer sub frame exposure times and the Horsehead is one of these. It's also one of my favourite targets as it's one of the few objects I knew about as a child. It does benefit from a little post processing. Here is my best image of it, taken with the Explorer 200 (no Barlow but with a UV / IR cut filter) and with a small amount of post processing ...

With the x1.7 Barlow fitted the horses head fills the whole field of view and that is probably my next best image (using the L-eNhance filter also with a small amount of post processing ...

I keep a list of targets to try, obtained from looking at what people post, from the Sky at Night magazine, and from checking Stellarium. I keep the list in a spreadsheet so that I can note what I've observed and when, but it's also in a Stellarium Observing List, actually several Observing Lists for different fields of view. On the night I load the most appropriate Observing List into Stellarium and get it to highlight all those objects so that I can see what's visible and be reminded of what's interesting. Stellarium also has some great tools for searching for objects (What's Up Tonight).

I agree that EAA benefits from being viewed in the dark. I still switch off all the lights as even a dim house light can get picked up by the scope, and in the dark (with the laptop applications set to night mode) I can see much more on the second monitor that I use to show the image.

 

 

[bosun21]

6 hours ago, PeterC65 said:

. Emission nebulae do really benefit from longer sub frame exposure times and the Horsehead is one of these

I always thought that the horsehead itself is a dark nebula and the surrounding part a reflection nebula. Maybe I'm wrong.

[PeterC65]

1 hour ago, bosun21 said:

I always thought that the horsehead itself is a dark nebula and the surrounding part a reflection nebula. Maybe I'm wrong.

Yes I think you're correct. I'm not sure whether the horses head shape is just missing nebula (hydrogen gas) or something in the way blocking out that part of the nebula. I really should find out more about these things that I observe!

 

[Zermelo]

"The darkness of the Horsehead is caused mostly by thick dust blocking the light of stars behind it.The lower part of the Horsehead's neck casts a shadow to the left. The visible dark nebula emerging from the gaseous complex is an active site of the formation of "low-mass" stars. Bright spots in the Horsehead Nebula's base are young stars just in the process of forming."

Wikipedia

[bosun21]

35 minutes ago, PeterC65 said:

Yes I think you're correct. I'm not sure whether the horses head shape is just missing nebula (hydrogen gas) or something in the way blocking out that part of the nebula. I really should find out more about these things that I observe!

 

The dark part which is the horshead itself is indeed a dark nebula which is a dark cloud of non reflective gas and dust.

Edited March 8 by bosun21
Typo

[John]

Visually, it's tough:

"....Really, it's like trying to see a little bit of nothing with a little bit of less than nothing resting over it....."

Jeremy Perez, 2006

Edit: Unless you are using EAA of course 🙂

Edited March 8 by John

[PeterC65]

13 hours ago, John said:

Visually, it's tough:

"....Really, it's like trying to see a little bit of nothing with a little bit of less than nothing resting over it....."

Jeremy Perez, 2006

Edit: Unless you are using EAA of course 🙂

I've tried to observe the Horsehead Nebula visually a few times and never seen it, nor the adjacent Flame Nebula. I think part of the problem may be the brightness of very nearby Alnitak which may be drowning out its much fainter neighbours. I must give it another go with my relatively new 8" Newtonian.

On the other hand, I've never failed to observe the Horsehead Nebula via EAA. Here is one of my favourite snapshots, showing all three of the Orion Belt stars as well as the Horsehead and Flame Nebulae, and even the Lump Star ...

This image has had a little post processing, but even on the night I could just make out the horses head. All taken in one frame with the tiny FMA135, 30mm aperture, really just a finderscope. I was very lucky to get the orientation just right. The following night I couldn't quite fit Mintaka into the field of view.

 

[Mike JW]

8 hours ago, PeterC65 said:

I've tried to observe the Horsehead Nebula visually a few times and never seen it, nor the adjacent Flame Nebula. I think part of the problem may be the brightness of very nearby Alnitak which may be drowning out its much fainter neighbours. I must give it another go with my relatively new 8" Newtonian.

Hi Peter,

With my 20" Dob I once caught a hint of the HorseHead visually and only in very good skies. Easier in a 24" Dob. GB skies are just not good enough.

Cheers

Mike

 

 

 

[John]

I have seen the Horsehead Nebula visually a couple of times when I had my 12 inch dobsonian. I made this report on SGL the first time I did it - I was rather chuffed 🙂

Barnard 33: The Horsehead Nebula - At last ! - Observing - Deep Sky - Stargazers Lounge

 

Edited March 9 by John

[PeterC65]

I'll keep my expectations low then, even with the 8".

It's interesting that the Horsehead Nebula needs 12" for visual, yet I can see it via EAA with my 1.2".

 

Edited March 10 by PeterC65

[Saganite]

On 08/03/2024 at 19:56, John said:

Visually, it's tough:

"....Really, it's like trying to see a little bit of nothing with a little bit of less than nothing resting over it....."

Jeremy Perez, 2006

Edit: Unless you are using EAA of course 🙂

Must try that, I'm good at seeing nothing just lately....