How much Andromeda Galaxy can you see?

[N3ptune]

I looked at the Great Andromeda galaxy last night and using averted vision and moving the instrument with the slow motion knobs to make it appear and disappear (not the core, the edges of it). The following image bellow is a log of what I saw, (It's written 0.5 secs, it's actually an error it should be degrees instead.)

And that's the point, with 203mm aperture I was able to see around 0.5 degrees of the galaxy, mostly the galactic core (which is not bad) The moon was there and the seeing was medium.

How much degrees can you see of it with your instrument? With a very dark sky and condition could it be possible for me to see it through my entire TFOV (2.24 d) the galaxy is wider. Or what size of instrument is required to see the edges of this large object? (in medium atmospheric condition and light pollution)

This thread is just a test , just to see since I am in no astronomy club and so, unable to compare instruments.

[ronin]

I can get it all in. Have a small ETX-70 goto and at about 350mm focal length and an 18mm BST that means 3 degrees so it sort of squeezes in, easier to drop the 25mm BST in for 4 degrees. Will say the ETX is more a finder with a goto glued to the base of it. But at a public night it is the one scope that gets it all in. And it tracks it. More or less.

[michael.h.f.wilkinson]

Everything depends on dark skies. I have seen at least 3 degrees under magnificent skies in southern France (near Olly's place) using my 80mm APM triplet and a 22T4 Nagler (3.76 deg true FOV). M31 filled a lot of the FOV. M33 was also HUGE with the same combination. Under moonlit conditions only the core is visible

[Linda]

I think a smaller instrument might be required to see the rest. In autumn when the sky at my home is darkest, I see M31 best in binoculars or my 50mm finder. In the Mak 127mm of de C8 I usually only see the nucleus.

[Peter Drew]

I had a look at M31 last night in a sky that was hardly dark even at 11.30pm with a 20". Not really the best instrument for this object, just the core showing and the two attendants being well ouside the FOV, the telescope had to be moved to see the dust lanes which lost the overall effect. The best view I've had this year was at Kelling with a 4" binoscope at 20x which took it all in at a glance.  

[N3ptune]

Ah thanks for your reply. @ronin @Linda @michael.h.f.wilkinson @Peter Drew

but... I am confused a little bit, Ronin your are using a 70mm instrument, Michael a 80mm, Linda binoculars or the 50mm finder and it seems like you all can see the entire object, ( >3 degrees.) On the image bellow, I can only see the red part and with extreme averted vision, some parts of the area between the red and blue boundary.

Peter you are saying a 20" is not the best instrument.. why?

? My current understanding is that a small instrument is required to see the area between the red and the blue. I feel there is something wrong.

 

 

 

[Peter Drew]

6 minutes ago, N3ptune said:

Ah thanks for your reply. @ronin @Linda @michael.h.f.wilkinson @Peter Drew

but... I am confused a little bit, Ronin your are using a 70mm instrument, Michael a 80mm, Linda binoculars or the 50mm finder and it seems like you all can see the entire object, ( >3 degrees.) On the image bellow, I can only see the red part and with extreme averted vision, some parts of the area between the red and blue boundary.

Peter you are saying a 20" is not the best instrument.. why?

? My current understanding is that a small instrument is required to see the area between the red and the blue. I feel there is something wrong.

A 2o" has such a small field of view so you barely see the area in the red outline, this loses the effect of seeing the whole object as you do with a small telescope. 

 

 

 

[N3ptune]

ohhhhhh

Ok I never though of that yet.. it would resume to this?:

TFOV = AFOV of eyepiece / magnification given by eyepiece:

My instrument is 203 x 1000 using my 32mm 70d EP for example.. 70°/(1000/32=31.25x) = TFOV = 2.24°

And let's say a 16" x 1800 mm with the same EP would be 70°/(1800/32=56.25) = TFOV = 1.24°

--> My instrument will show almost twice the TFOV then the 16 inches.. so a short focal length = a wide FOV instrument... ?

But how can you guys watch large nebulae with large instruments? (Or long instruments)

 

[alan potts]

As much as I can get this into the field of a couple of my scopes I much prefer the view with my 10.5x70 binos, smaller objectives but some how better.

Alan

[swamp thing]

13 hours ago, N3ptune said:

ohhhhhh

Ok I never though of that yet.. it would resume to this?:

TFOV = AFOV of eyepiece / magnification given by eyepiece:

My instrument is 203 x 1000 using my 32mm 70d EP for example.. 70°/(1000/32=31.25x) = TFOV = 2.24°

And let's say a 16" x 1800 mm with the same EP would be 70°/(1800/32=56.25) = TFOV = 1.24°

--> My instrument will show almost twice the TFOV then the 16 inches.. so a short focal length = a wide FOV instrument... ?

But how can you guys watch large nebulae with large instruments? (Or long instruments)

 

Most nebulae will fit in the FOV of a 20" scope. The ones that don't we use a smaller scope for.
One can also be content with seeing the much greater detail that the  larger scope allows Eg I cannot get either parts of the veil in one eyepiece FOV of my 20" yet I prefer the view it offers over any view that a smaller scope may provide as the detail in the 20" is just staggering. 

 

[mdstuart]

I have a sixteen inch dob and I would say I can see the galaxy about half way between your red and blue line on a good night with rural skies. About where the dust lane is.

The galaxies surface brightness drops away as you go out from the core and once you get to a surface brightness below about mag 14 then I cannot pick it out from my skies.

Mark

 

[N3ptune]

14 hours ago, mdstuart said:

I have a sixteen inch dob and I would say I can see the galaxy about half way between your red and blue line on a good night with rural skies. About where the dust lane is.

That's strong thanks for that feedback. (looks like twice of what I can see with 8 inches in term of low surface brightness.

@swamp thing

I believe you on the 20 inches (:

@alan potts

Why do you prefer the view using the binoculars?

[alan potts]

3 hours ago, N3ptune said:

That's strong thanks for that feedback. (looks like twice of what I can see with 8 inches in term of low surface brightness.

@swamp thing

I believe you on the 20 inches (:

@alan potts

Why do you prefer the view using the binoculars?

I just feel it shows it better, I imagine it is the lower power offered by them, about minimum on the 115mm and 190mm M/N is between x22-28

[Moonshane]

Broadly if you have dark skies then you can see more of the galaxy. To fit more of the galaxy in you need a wider field. Ideally you want dark skies and a scope matched to be able to view between 3-4 degrees of field.

With my 102mm f7 ED and 26mm Nagler I can get 3 degrees but with my 16" f4 dob with paracorr I can only get 1.1 degrees so although I can see it 'bigger' in the field, you lose background context. Personally, I prefer 1.25" eyepieces with fracs and therefore get 2.3 degrees with my 24mm Panoptic which seems a happy medium for most things. Next time you are at a dark site, look critically at M31 through your finder. I bet you see almost the whole thing even though it's 50mm of aperture.

[mog3768]

THIS IS MY VIEW THROUGH MY EQUINOX 120 JUST GETTING INTO PHOTOGRAPHY SO NOT VERY GOOD PICTURE.

[Stu]

Best views I've had have been with a 106mm f6.5 triplet and a 31mm Nagler, giving around 3.6 degrees.

At a dark site, with good dark adaptation you can really begin to see the full extent of the Galaxy although it is still very subtle in its outer regions.

[jetstream]

8 hours ago, mog3768 said:

THIS IS MY VIEW THROUGH MY EQUINOX 120 JUST GETTING INTO PHOTOGRAPHY SO NOT VERY GOOD PICTURE.

Nice image and it shows the 2 dust lanes that are seen visually. From dark skies the lanes are much more contrasted than the image shows but the look is similar. Thanks for posting this.

[John]

My best views of M31 come with a relatively small aperture scope as well. In my case it's a 102mm F/6.5 refractor. With the 31mm Nagler eyepiece I get a true field 3.83 degrees wide. On really dark nights with this combination I've seen the furthest parts of M31 extend beyond the edges of even this size field but the sky does need to be both dark and transparent for this.