Viewed my first Nebula last night!!!

[icytailmark]

well i finally viewd the Orion Nebula in my new telescope!!! It was pretty easy to find. I used a UHC filter that i bought from DGM. However i was a little disappointed because i could not see any colour in the nebula.

[dpastern]

Hi Mark,

Colour is one of those things that the human eye typically doesn't do very well with faint things. I could only notice a faint tint of Green in M42 in a friends 16" dob from dark skies (and with a UHC filter). Just remember that in most cases, what you see visually will never match what you see in images.

Dave

[mozzie]

hi mark and what a sight you've looked at one of the best neb for your first the eta carina is another fine neb early morning if your out tonight have a look around scorpio and sagitarrius to the west there is plenty to see there and as for color you can get a little blueish color in orion but unfortunately planets and stars realy have the onlt color everything else varies from white to grey and several colors of grey has to do with the retina and the cones in our eyes another member can give more detail on that while im in the eyepiece i like to imagine the colors and detail of whats happening on these distant objects its great to think and imagine
mozzie

[Paddy]

Hi Mark,

Glad to hear that you're on your way with deep sky observing. Alas the rod cell photoreceptors that we rely on for low light vision come in only one population. They are exquisitely sensitive and when fully dark adapted, can respond to a single photon. But you will only see shades of grey with them. The "daylight" cone cells are much less sensitive and come in three populations sensitive to three different wavelengths. The brain perceives colour by comparing the relative activity of the 3 populations. So when there's enough light, you'll see colour. Cameras can accumulate photons over hours, so can show great detail andc colour.

The rod cells don't exist where the centre of you vision is, so viewing dim objects is best when you look a little to one side of the object you're interested in.

[Rod66]

Could I suggest Tarantula nebula in the Large Magellanic Cloud as a spectacular nebula to view if you get the chance. It offers both a good view at 25mm with the surrounding tendrils and 10-13 mm at its core. I saw this last night for the first time through a telescope and I almost wet myself.

But with your first viewing out the way, there is so much more that awaits you now. The sky is full of them.

Rod

[glenc]

Mark here are images of all the NGC nebulae. http://picasaweb.google.com.au/dunlop1826/NGCNebulae#
Try the big bright ones like M8, M17 and NGC 3372.

[supernova1965]

While I understand that I wont see colour's but is it just because I haven't seen M45 from a dark site that I have only been able to see the stars and not the Nebulous material even in black and white

[glenc]

Warren you can see the nebula below the lower star (Merope) in this image from a dark site with your 10" scope.
http://picasaweb.google.com.au/dunlop1826/NGCNebulae#5281636784330926770

[Astro78]

What size scope are you using?

I can easily see green, vivid green in my 8" newt, from Sydney, under low power.

[erick]

Some people see colour in M42, others don't. I'm towards the don't end of the spectrum, unfortunately. :sadeyes:

[Blackant]

I know what you mean Rod, I looked at it last night through my 26mm and 15mm eyepiece for the first time, it was gob smacking :eyepop:

I've only previously looked at it with binoculars.

[dpastern]

I've noticed a faint tint of Green with M42. I've never noticed any nebulosity around M45 though.

Dave

[Octane]

As I've mentioned before, I've been lucky enough to see pink and faint blue in M42 through a 25" Dobsonian.

Whilst I'm not a visual observer (on the imaging side of the camp), it is a sight that has been impressed upon me, and, one that I will never forget.

I exclaimed "this is the most beautiful thing I've seen in my entire life" after having spent a few moments peering and gathering my thoughts.

I've not seen anything more beautiful, yet. Except, Milla Jovovich.

Regards,
Humayun

[ngcles]

Hi Mark,

Congratulations of seeing your first nebula. M42 is a stunning object -- certainly in the top three nebulae in the sky.



What size 'scope are you using Mark?

I can understand your disappointment Mark but you seem to be labouring under a very, very common misconception among newcomers to amateur astronomy. Probably a majority, if not a large majority of first time viewers expect to see an image like the ones in the books, on the P.C screen or on the box the telescope came in.

These images are made with cameras that are in some ways better than the human eye

1.they can have their shutter open for long periods and collect light making the final image brighter and

2. They have different sensitivities to other wavelengths the eye does poorly with.

3. The image can be processed to enhance contrast and detail that would otherwise be buried in the noise.

However, the human eye is still, at least on a moment-for-moment basis, more sensitive than a CCD but unfortunately it is stuck in "real-time" -- it can't integrate an image. And the brain can't do the "tricks" done in photoshop to extract data out of the noise.

Most if not all the images you see in books and on the P.C have been taken with expensive and sophisticated equipment and frequently amount to several minutes -- if not several hours of exposure time over multiple exposures that are stacked over each other. The CCD that takes the image is very sensitive to the pink and red colours that emission nebulae shine at so strongly (the H-Alpha emission line) and that is why the images are so strongly colour oriented that way. Our eyes are pretty lousy at those wavelengths in low light-levels.

The eye has two different cells that do the work to make an image -- the rods and the cones.

In basic terms, rods only see black and white but are much more sensitive than the cones that see colour. Hence a lot of what you see through a telescope aimed at the night sky seems black-and-white. A lot of light is needed to make those cone cells work which is a prime reason we do not see colour well in the dark -- there isn't enough light present to get those lazy cones up of their bums and doing what they do. The most easily seen colour in low light levels is a greenish/cyan.

Our cones are conspicuously poor at the red stuff in low-light levels and we perceive none of the red-light as red. When the light levels are just barely high enough to get the cones going we generally see a greenish tinge first and brightest. This colour also happens to be one of the other wavelengths that the emission nebulae shine most strongly at -- the OIII and Hydrogen-Beta lines are smack in the middle of that green/cyan zone. Your nebula filter is isolating those wavelengths for you and blocking out the others.

With the broadband, narrowband and line filters like a Deep Sky filter, UHC filter, OIII and H-Beta filter it is these wavelengths that are isolated and apparently enhanced because the other colours and light is blocked -- increasing contrast. You cannot see any other colour when using these filters -- for all intents and purposes relevant here, they only pass green/cyan.

Returning to the unfiltered view, obviously the larger the 'scope you use, the more light is available at the focal plane and the image is brighter. The brighter the image, the more likely it is that it will turn on some other colour receptors in your eye. But every human set of eyes is different -- either by genetics or environment we all seem to see colour a little (at least) differently.

I was lucky enough once to discuss this issue with David Malin when he did a talk at my club (SASI) and he claims (and has a very fixed view on it) that he could (and indeed we) see (should see) no colour at all looking at emission nebulae through the telescope -- no matter what size the telescope is. He claims there simply isn't enough light at the right wavelength to get the cones up off their bums and doing their thing. He has only ever seen M42 as shades of grey.

But some people (many people) plainly do see some colour (mostly greenish tinges) in emission nebulae.

For what it is worth, without filters, my old 8" showed a plain lime-green tint in most of M42 -- more weakly in M8 and M17.

The 10" showed it more strongly but no other colours. But, the 12" just started to show subtle hints of other colours in M42 -- in the "wings" under a truly dark sky I was beginning to see bluish overtones and occasional dirty pinks.

With the 18" many nebulae are greenish M42 is an intense emerald green overall but distinctly shows blues and a pinky russet in the wings under a dark sky. One thing I see (using my 18") often and pretty clearly in M43 (adjacent to M42) is a very deep, dark madder lake colour over fainter green.

I hope that helps to explain what you saw and perhaps lessens your disappointment -- we all have trouble seeing those spritzy colours in the astro-images. Even when the colour (other than green/cyan) is there it is always subtle and you have to be patient. Experience (longer the better) at the eyepiece also helps quite a lot to properly adjust the "expectations" ... If you have the right expectations you are more likely to see it that with under/over expectations.

As for the other comments -- The Merope nebula (NGC 1432, -35, IC349) is the brightest part of the nebulosity around the Pleiades. It is a reflection nebula (not an emission nebula) and therefore has a continuous spectrum -- like a star's light has a continuous spectrum. It isn't really hard to see but you need squeaky clean optics (to take out the scattered-light factor from bright Merope itself) and a really dark sky. I've seen it in big binos but very faintly. It shouldn't appear to have a any real colour -- (whitish/grey/ashy?)

The Tarantula nebula (NGC 2070) has always looked a more bluish shade of cyan to me (tending towards prussian blue or cobalt) than other nebulae. I almost wet myself regularly there too ...:D. In large 'scopes, this is the best emission nebula in the sky -- incredible detail.

Eta Carinae (NGC 3372) is a close runner up to the Tarantula in large apertures I think. M42 is third -- in large apertures. In 8" say, that order is probably reversed.


Best,

Les D

[jjjnettie]

If you're super keen to see colours in your nebulas may I suggest the purchase of the new Gstar CLR. It's a super sensitive video camera that allows you view in near real time via your computer or a colour tv.
You just slot the camera into the focuser, plug it into the telly, focus and observe. No need to squint through eyepieces.

[erick]

Yep I'm going to save my pennies towards a future GStar-ex colour camera.

[jjjnettie]

One moment I want one, the next undecided.
The reviews and initial images from the camera are starting to flow in on the Gstar Forum.
I want one for the TOT.