38 replies to this topic

[Polyphemos]

Or were my wife and I imagining things?  

 

We observed C/2022 E3 (ZTF) from a darkish site in Northern California around the 28th of December through a 102 mm SVX102D refractor, and both my wife and I believed we could detect a pale green cast to the comet.

 

Did anyone else make a similar observation, and if so through what type and size telescope?

[Kim2010]

Yup! Pale green. 8SE, urban city. 

[Rabbanah]

Swamp gas?

 

But seriously, I viewed it with my scopes from a Bortle 2 location and was not able to see any color. I also know of folks who looked at it through much larger instruments and had similar results.

 

Your description is the first that I have come across describing color for visual only. I wonder if there could be another possible explanation?

[Rabbanah]

Yup! Pale green. 8SE, urban city. 

That makes two. 
 

I would think my dark skies would help. Is it possible light pollution could add color?

[Kim2010]

That makes two. 
 

I would think my dark skies would help. Is it possible light pollution could add color?

Possibly? The green is super pale though. As in you question yourself, but then since my wife as well agreed with the pale green, that was that

[Kitfox]

I think there is an old theory that if you stare at something dim long enough, it turns green.  The author used the Orion Nebula as an example.  Something to do with the way rods are wired to the brain and the way the brain "fills in" info to as makes sense to itself.  I'm doubtful any amateur scopes brought the surface brightness up to a level to fire the color-sensing cones on the retina.

[John Miele]

14.5" dob, suburban bortle 6-7 sky - no color for me

[Chad7531]

Nope, not me.

[Polyphemos]

Possibly? The green is super pale though. As in you question yourself, but then since my wife as well agreed with the pale green, that was that

I disagree with my wife at great personal peril, and I’m not as quick as I used to be so I don’t do it often.

 

All kidding aside, I didn’t really doubt my own observation of the pale green cast other than the nagging thought in the back of my mind that I wasn’t supposed to see color in a small scope.

 

Neither of us looked at the comet for a particularly long stretch at a time, and neither of us could detect a tail, but the glowing center was relatively tight and bright.  Perhaps at that night, and at that time, the comet spiked up in brightness enough to reveal what it ordinarily did not? My wife’s vision is a bit better than mine and there was absolutely no doubt in her mind about seeing color.

[Polyphemos]

Possibly? The green is super pale though. As in you question yourself, but then since my wife as well agreed with the pale green, that was that

Kim, when and through what scope?  Conditions?

[Kim2010]

Kim, when and through what scope?  Conditions?

This was just this 2023 I think? January? Not so sure now. 8SE, city setting, seeing was average nothing special.

[Jethro7]

Hello Polyphemos,

I did not, in order to see the Comet, from my Bortle 7-8 backyard, I have to use a light intensifying device and the views are in shades of grey. However I will trade color for the beautiful views of the wispy tail. I am hoping next fall, we will have spectacular views of the Comet C/2023 A3 Tsuchinshan Atlas. No one can predict with any certainty how good a comet will be till it arrives. Something to look forward to.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

[Nucleophile]

Through an 8 inch reflector, I did not see any hint of green.   Can't recall exactly but likely this was through a Pentax 7XW or 10XW (def on the low end of magnification).  My backyard observing area is ~Bortle 4 at that time of night.  I observed the comet about 4 different times in January/February.

 

The last time I viewed the comet, it was directly overhead and just a bit after sundown, so I grabbed anyone else I could round up to come see "the comet".  "What comet," they said.  "You know, the one everyone is talking about."  They both shrugged.

 

Anyway, my son and my wife both did see a hint of green in the comet.  And this was an unprompted description on their part as well.  So, maybe my locations darker skies and their superior color vision had something to do with it.

 

Makes me wonder what else I am missing...

Edited by Nucleophile, 21 March 2023 - 06:32 PM.

[Kim2010]

Hmmm! What age are we? Not being an ageist, but

[Polyphemos]

Hello Polyphemos,

I did not, in order to see the Comet, from my Bortle 7-8 backyard, I have to use a light intensifying device and the views are in shades of grey. However I will trade color for the beautiful views of the wispy tail. I am hoping next fall, we will have spectacular views of the Comet C/2023 A3 Tsuchinshan Atlas. No one can predict with any certainty how good a comet will be till it arrives. Something to look forward to.

 

HAPPY SKIES AND KEEP LOOKING UP Jethro

Hi Jethro, and thanks for your observation.  The comet C/2023 A3 Tsuchinshan Atlas is scheduled to arrive in our vicinity in the fall of 2024, I believe, so that gives us plenty of time to acquire new gear for the event.  

[Polyphemos]

Hmmm! What age are we? Not being an ageist, but

I’m 66, and I can’t tell you my wife’s age if I hope to reach 67, but she’s quite a bit younger than I.

 

I’m sure we observed it through several eyepieces but one of them was a 2” 32mm Masuyama, which when combined with my f/7 scope gives a 4.5mm exit pupil.  The sweet spot, perhaps?

Edited by Polyphemos, 21 March 2023 - 06:45 PM.

[Nucleophile]

While not color related, I would also like to add that I very much enjoyed viewing this comet this year.  In years past, it seems the comets that were bright enough to garner hype were really low in the West just after sunset, and while detectable, were not that spectacular visually.

 

C/2022 (E3) on the other hand exhibited a bright core that (to my eyes) was asymmetric and interesting to see.  However, try as I might I did not see any tail structure through my 8 inch reflector.  Also, the comet was super easy to find--basically point the red dot finder in the general vicinity and there it was in the FOV of the finder--I appreciated that!

Edited by Nucleophile, 21 March 2023 - 06:42 PM.

[alnitak22]

While not color related, I would also like to add that I very much enjoyed viewing this comet this year.  In years past, it seems the comets that were bright enough to garner hype were really low in the West just after sunset, and while detectable, were not that spectacular visually.

 

C/2022 (E3) on the other hand exhibited a bright core that (to my eyes) was asymmetric and interesting to see.  However, try as I might I did not see any tail structure through my 8 inch reflector.  Also, the comet was super easy to find--basically point the red dot finder in the general vicinity and there it was in the FOV of the finder--I appreciated that!

Agree with all your points. The comet was easy to find in my sky even though I’m just a mile north of Manhattan. No color or tail visible in either TV85 or 6” f/8 Newt.  The core looked slight asymmetrical to me as well. 

[maroubra_boy]

I’m 66, and I can’t tell you my wife’s age if I hope to reach 67, but she’s quite a bit younger than I.

 

I’m sure we observed it through several eyepieces but one of them was a 2” 32mm Masuyama, which when combined with my f/7 scope gives a 4.5mm exit pupil.  The sweet spot, perhaps?

YES!  Exactly the reason.  Along that your colour perception at low levels of illumination is also good.

 

The key to vision is there being enough energy to trigger a response from the relevant cells in the retina.  The cells with the lowest energy trigger response are the rods.  With the cones, green has the lowest, followed closely by blue, but red has a higher trigger response, greater than that between green and blue, which is why red is the rarest colour to get a response to through an eyepiece.

 

And this response, being energy density dependent relates exactly to exit pupil.  If the exit pupil is too small or too large, then the energy density hitting the retina is not there to trigger a colour response.

 

Now this is assuming that you night vision is not compromised by gender (colour blindness is common in males but rare in females), illness, drugs (medical or illicit), alcohol, age, genetics, and health (diabetes for instance has a big impact on eye health).

 

If you are using a 7mm or 10mm eyepiece, the exit pupil will be way too small to see any colour.  Unless you were using the most appropriate eyepiece focal length for the scope you were using, the exit pupil would not have been enough to see colour.  Simple as that.

 

I used an 8" scope from a dark site, but I was using eyepieces that were too short in order to see as much detail as I could from the comet.  I did not bother with longer eyepieces, and of course no colour was to be seen.  If you saw a green tinge to the comet you would have been using a larger exit pupil than I was.

 

For wider information, I can see M42 in full colour, greens, blues and pinks.  But the exit pupil needs to be the right size for me to see the pinks.  If I make the exit pupil a little smaller I lose the pinks and the greens and blues are paler too.  Make the exit pupil smaller again and there is no colour at all.  Aperture is important too - a scope collects light and light is energy.  The larger the aperture combined with the right exit pupil the energy density will be larger as well, so the colour response will be greater.  The colours in M42 are stronger in my 17.5" dob than my 8" dob.  There is a French amateur who uses a 40" dob to produce the most exquisite full colour sketches that I know of - entirely only possible with the tremendous size of the scope and that the energy this aperture collects allows for smaller exit pupils to be used with the planetary nebulae he sketches in such fine detail.  His low light colour vision is also good.  Lucky sod!

 

Alex.

[scottinash]

13.1" f4.5 reflector, bortle 5 to 6, no color here except some imaginary green because that's what I wanted to see.

[maroubra_boy]

You "wanted to see it"...  really.  Why didn't you actually see it?

[Nucleophile]

Interesting, maroubra.  Sounds like my 19 or 24 Panoptics may have been a better choice for catching some color...will keep that in mind.  I can do some experiments on the Orion nebula to verify this for myself.

 

I am sure age and gender had some influence as well on my inability to detect color considering others in the family detected some color despite the rather small exit pupils.

Edited by Nucleophile, 21 March 2023 - 09:33 PM.

[maroubra_boy]

Age sees the diameter of our pupils reduce, so our ability to see colours also reduces because the amount of light/energy getting into our eyes is also reducing.

 

The first time I saw M42 in full colour was around 16 years ago during my first light with my 17.5" dob.  I was using a 30mm eyepiece.  Fast forward around 8 years and I was no longer able to see M42's lovely pinks any more.  I thought my eyes had just somehow crapped out or that newer eyepieces were somehow killing off the red from our vision because of their coatings (I was speculating this)

 

Then two years ago, five of my observing buddies and I did a dark sky session just to explore the aspect of colour vision through a scope.  The target was M42.  We had three scopes, an 8" f/8 Newt, a 17.5 f/4.5 dob/Newt and a 10" f/12 Mak, along with a bucket load of eyepieces.  The idea was to try different eyepieces, new and old to see if it was something to do with the eyepieces that was interfering with our ability to see pinks in M42.

 

As it turns out, it was entirely the exit pupil that was key to seeing M42 in full colour!  In the 8" f/4 scope, the key focal length was 24mm.  In the 17.5" it was 26mm, and the 10" Mak, it was 50mm!  YES, full colour of M42 in a Mak!  And we did have a 50mm eyepiece in our collective lot.  And the intensity of the colour was aperture dependent.

 

Of my five observing buddies, four were able to see M42 in full colour along with me.  One of our friends failed to see any colour at all no matter what eyepiece he used.  While we felt disappointed for him, his experience was an important control to what we were seeing.  This friend of mine has significant health issues and is on a ridiculous number of medicines.

 

For me, I was overjoyed that I had not lost all those lovely subtle pinks in M42!  I came to understand the key to this being exit pupil, and that over the years my pupils had reduced in diameter and I had to go shorter in eyepiece focal length in order to get an exit pupil that did put enough light in through my pupil, and that a 30 mm eyepiece produced too large an exit pupil that meant not enough light was now getting into my eye to trigger the necessary response from all the cones in my eyes.  As the years go by it may be the case that my pupils will get smaller again, and then no matter what exit pupil I use there just won't be enough light entering my eyes to get to see those soft pinks any more

 

Alex.

Edited by maroubra_boy, 21 March 2023 - 10:08 PM.

[maroubra_boy]

It should also be noted that colour vision with the planets is nothing considered special.  The difference here being the planets are bright enough to trigger the necessary response from our eyes, even with ridiculously short focal length eyepieces and wee exit pupils.  The difficulty comes in viewing items of very low illumination, such as nebulae, and in this thread, comets.

 

Alex.

[Nucleophile]

It should also be noted that colour vision with the planets is nothing considered special.  The difference here being the planets are bright enough to trigger the necessary response from our eyes, even with ridiculously short focal length eyepieces and wee exit pupils.  The difficulty comes in viewing items of very low illumination, such as nebulae, and in this thread, comets.

 

Alex.

agreed, same with double stars--my main area of observing interest