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Calling All Comet NEOWISE Observers!

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#1 Carl H.

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Posted 07 July 2020 - 04:51 PM

Comet NEOWISE is looking like the best comet since C/2011 L4 (PANSTARRS) in 2013 resulting in CloudyNights being inundated with excellent observations. Please consider contributing your observations to one or more of the excellent organizations that archive, analyze, and publish comet observations and research. 

 

The Comet Section of the Association of Lunar and Planetary Observers (ALPO) is soliciting all types of Comet NEOWISE observations including, but not limited to, images, sketches, spectra, brightness estimates, and textual descriptions. One does not need to be a member of the ALPO to contribute, though joining the ALPO is greatly appreciated and includes a subscription to the Strolling Astronomer, the quarterly Journal of the ALPO.

 

Observations can be posted here (preferred so everyone can enjoy your observations) or sent directly to the ALPO at < comets@alpo-astronomy.org >. If there is an easier way for you to contribute, just let me know. There is no such thing as a bad observations, so please don't feel your observations are not "good enough". You can see what others have contributed at the ALPO Comet Section Image Gallery. A hearty thanks to everyone who is already contributing observations!

 

In addition to NEOWISE, there are a number of other reasonably bright comets visible. In the evening we have C/2019 U6 (Lemmon) at 6th-7th magnitude, C/2017 T2 (PANSTARRS) at 9th magnitude, and 88P/Howell at 10th magnitude. In the southern hemisphere, 2P/Encke is currently at 7th-8th magnitude. For more info on these and other comets, check out the ALPO Comet News for July 2020 forum.

 

The ALPO is only one of many organizations doing professional quality work in archiving, analyzing, and publishing comet observations. All of these fine organizations would also benefit from your observations.

 

Comet Observation Database (visual and CCD photometry) [ https://cobs.si/ ]

International Comet Quarterly (ICQ) (visual and CCD photometry) [ http://www.icq.eps.harvard.edu/

Cometbase (visual and CCD photometry) [ http://195.209.248.207/ ]

CARA Project (af(rho) CCD photometry) [ http://cara.uai.it/ ]

British Astronomical Society (all observations) [ https://britastro.org/section_front/10 ]

The German Comet Group (all observations) [ https://fg-kometen.v....de/fgk_hpe.htm ]

Observación de Cometas de la LIADA (all observations) [ https://rastreadores...-observaciones/ ]

Astronomical Ring for Access to Spectroscopy (ARAS) (spectroscopy) [ http://www.astrosurf.com/aras/ ]

 

This is not an exhaustive list and doesn't include numerous groups on Facebook and other social media sites that I should, be don't, frequent. If there are any organizations that I missed, just add them in the comments.


Edited by Carl H., 08 July 2020 - 01:24 PM.

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#2 Tyson M

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Posted 07 July 2020 - 04:59 PM

Great thread. I know myself (and likely many others) feel their observations, sketches or images might not be worthy.  

 

I will try to submit any observations I make through your channels.


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#3 cbellh47

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Posted 07 July 2020 - 06:09 PM

Hey Carl,

I noticed a new report "C/2020 F3 (NEOWISE) 2020-Jul-07 Chris Schur" that appeared in the ALPO comet gallery

reporting a possible sodium detection.

http://www.alpo-astr...-07-Chris-Schur



#4 Carl H.

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Posted 07 July 2020 - 06:23 PM

Yes, Chris reports a possible visual sodium detection through a Star Analyzer diffraction grating. I have one of those as well so I may take a look tomorrow morning.


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#5 Carl H.

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Posted 07 July 2020 - 10:15 PM

Great thread. I know myself (and likely many others) feel their observations, sketches or images might not be worthy.  

 

I will try to submit any observations I make through your channels.

Thanks, Tyson! Looking forward to your observations.


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#6 BrooksObs

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Posted 07 July 2020 - 10:46 PM

Yes, Chris reports a possible visual sodium detection through a Star Analyzer diffraction grating. I have one of those as well so I may take a look tomorrow morning.

 

Actually, it would not be at all surprising if NEOWISE is showing emissions of sodium. A heliocentric distance of about 0.3 a.u. is often the point at which typically more dust-dominated comets begin to exhibit the presence of that metal due to solar heating and giving rise to a yellowish hue to the comet's head and tail. NEOWISE passed within this limit only a few days ago This situation usually does not last any great length of time as the comet retreats from the Sun, so look closely for the yellowish tinge in the comet's head and tail in the coming days.

 

I'd also like to make mention of an even rarer display currently taking place in NEOWISE. A number of observers have called attention to the apparent bifurcation, or seeming splitting of the dust tail. The visible dark  lane in the dust tail, especially noticeable in images and less so visually in telescopies, is a rare cometary phenomena often referred to by 19th astronomers as "the shadow of the nucleus". Of course, it is not really a shadow, but instead evidence of a vacancy of material along the central axis of the dust tail. Would-be observers are urged to try and detect this as it is something you are only likely to see a couple of times in your lifetime in the brightest comets! And, like the sodium emission, the shadow of the nucleus tends to be highly transient and could soon disappear.

 

BrooksObs 


Edited by BrooksObs, 07 July 2020 - 10:48 PM.

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#7 SpaceConqueror3

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Posted 07 July 2020 - 11:34 PM

I'm at 47 degrees plus some change in Latitude. Has anyone observed it this far or farther North yet?



#8 Aquarellia

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Posted 08 July 2020 - 01:37 AM

I'm at 47 degrees plus some change in Latitude. Has anyone observed it this far or farther North yet?

I'm sure yes

I'm 45°N and can observe this comet since July 3rd.  Friends of mine from Québec 47°N are able to follow the comet too.  Another contact in Loraine (49°N) made a good observation yesterday morning.

Of course for you, it will be closer to the horizon, but this is not negative, mainly because of nice views you can have, earth and comet...

Michel


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#9 Jure Atanackov

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Posted 08 July 2020 - 02:48 AM

 

I'd also like to make mention of an even rarer display currently taking place in NEOWISE. A number of observers have called attention to the apparent bifurcation, or seeming splitting of the dust tail. The visible dark  lane in the dust tail, especially noticeable in images and less so visually in telescopies, is a rare cometary phenomena often referred to by 19th astronomers as "the shadow of the nucleus". Of course, it is not really a shadow, but instead evidence of a vacancy of material along the central axis of the dust tail. Would-be observers are urged to try and detect this as it is something you are only likely to see a couple of times in your lifetime in the brightest comets! And, like the sodium emission, the shadow of the nucleus tends to be highly transient and could soon disappear.

 

BrooksObs 

I still remember (like it was yesterday) you pointing 'the shadow of the nucleus' out with C/2006 P1 (McNaught) about 7 days prior to perihelion. How rare is it? Of all the comets I've seen over the past 26 years, there have been at least three that I recall seeing this feature in: C/1995 O1 (Hale-Bopp), C/2006 P1 (McNaught) and C/2020 F3 (NEOWISE). I did not see it in C/2011 L4 (PanSTARRS) at T+5d, my first post-T view, either in 11x70B or 20x110B.. C/2002 V1 (NEAT) did not show it at T-6d as seen through 10x50B. I do not recall it being reported with C/2004 F4 (Bradfield) or with C/2011 W3 (Lovejoy)?


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#10 Jure Atanackov

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Posted 08 July 2020 - 02:49 AM

I'm sure yes

I'm 45°N and can observe this comet since July 3rd.  Friends of mine from Québec 47°N are able to follow the comet too.  Another contact in Loraine (49°N) made a good observation yesterday morning.

Of course for you, it will be closer to the horizon, but this is not negative, mainly because of nice views you can have, earth and comet...

Michel

Been following it since July 5th here at 46°N. It was not a difficult object on that date.

Jure


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#11 kfiscus

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Posted 08 July 2020 - 05:20 AM

Actually, it would not be at all surprising if NEOWISE is showing emissions of sodium. A heliocentric distance of about 0.3 a.u. is often the point at which typically more dust-dominated comets begin to exhibit the presence of that metal due to solar heating and giving rise to a yellowish hue to the comet's head and tail. NEOWISE passed within this limit only a few days ago This situation usually does not last any great length of time as the comet retreats from the Sun, so look closely for the yellowish tinge in the comet's head and tail in the coming days.

 

I'd also like to make mention of an even rarer display currently taking place in NEOWISE. A number of observers have called attention to the apparent bifurcation, or seeming splitting of the dust tail. The visible dark  lane in the dust tail, especially noticeable in images and less so visually in telescopies, is a rare cometary phenomena often referred to by 19th astronomers as "the shadow of the nucleus". Of course, it is not really a shadow, but instead evidence of a vacancy of material along the central axis of the dust tail. Would-be observers are urged to try and detect this as it is something you are only likely to see a couple of times in your lifetime in the brightest comets! And, like the sodium emission, the shadow of the nucleus tends to be highly transient and could soon disappear.

 

BrooksObs 

The comet looked quite golden today (4:24 AM CDT, July 8, 2020).

43.6 degrees N

ST80 and 13 Ethos

Galaxy S10E (zoomed-in)

Attached Thumbnails

  • 20200708_042449 35%.jpg

Edited by kfiscus, 08 July 2020 - 05:29 AM.

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#12 BrooksObs

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Posted 08 July 2020 - 10:44 AM

I still remember (like it was yesterday) you pointing 'the shadow of the nucleus' out with C/2006 P1 (McNaught) about 7 days prior to perihelion. How rare is it? Of all the comets I've seen over the past 26 years, there have been at least three that I recall seeing this feature in: C/1995 O1 (Hale-Bopp), C/2006 P1 (McNaught) and C/2020 F3 (NEOWISE). I did not see it in C/2011 L4 (PanSTARRS) at T+5d, my first post-T view, either in 11x70B or 20x110B.. C/2002 V1 (NEAT) did not show it at T-6d as seen through 10x50B. I do not recall it being reported with C/2004 F4 (Bradfield) or with C/2011 W3 (Lovejoy)?

The so-called "shadow of the nucleus" is more often displayed as a feature associated with Great Comets. However, it wasn't present in either Arend-Roland or Mrkos in 1957, nor Wilson-Hubbard ('61), but a few folks saw it in Ikeya-Seki in '65, I recall both Bennett ('70) and West ('76) displaying such prominently, as well as Hale-Bopp and McNaught more recently. In general this phenomena is not seen in conjunction with bright sun-grazing comets, nor those visitors fainter that roughly +2.0 at peak brightness. Seeing it in conjunction with NEOWISE is therefore rather unexpected. So, observers should make the most of trying to spot this feature as it is quite rare and often short-lived.

 

BrooksObs


Edited by BrooksObs, 08 July 2020 - 03:35 PM.


#13 chrysalis

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Posted 08 July 2020 - 10:56 AM

If not cloudy tomorrow morning 7-9-20 from ~36.5N, 80W, 5AM EDT finder for Comet Neowise; about 7° elevation, just about exactly at NE point (45° Azimuth):

 

NEOWISE 5AM EDT 7-9-20.JPG


Edited by chrysalis, 08 July 2020 - 10:58 AM.

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#14 chrysalis

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Posted 08 July 2020 - 11:03 AM

It would appear that the comet will be a morning AND evening object on 7-11-20 (a few other days around that too) but within about 6° elevation of horizon!


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#15 Carl H.

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Posted 08 July 2020 - 11:43 AM

The so-called "shadow of the nucleus" is more often displayed as a feature associated with Great Comets. However, it wasn't present in either Arend-Roland or Mrokos in 1957, nor Wilson-Hubbard ('61), but a few folks saw it in Ikeya-Seki in '65, I recall both Bennett ('70) and West ('76) displaying such prominently, as well as Hale-Bopp and McNaught more recently. In general this phenomena is not seen in conjunction with bright sun-grazing comets, nor those visitors fainter that roughly +2.0 at peak brightness. Seeing it in conjunction with NEOWISE is therefore rather unexpected. So, observers should make the most of trying to spot this feature as it is quite rare and often short-lived.

 

BrooksObs

While I don't remember visually observing the "shadow of the nucleus" in C/2011 L4 (PANSTARRS), its weak signature was visible in images I took.

 

C2011L4_2013mar15_CarlHergenrother.jpg


Edited by Carl H., 08 July 2020 - 11:47 AM.

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#16 Tyson M

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Posted 08 July 2020 - 01:25 PM

Thanks, Tyson! Looking forward to your observations.

Hmm for me at 53 deg north this might not be possible.  Checking Stellarium I have to view it at like 5am and it is likely going to be too bright from the sun.  I can try though, it is at 6 degrees in altitude though :(



#17 Robin

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Posted 08 July 2020 - 02:27 PM

A number of observers have called attention to the apparent bifurcation, or seeming splitting of the dust tail. The visible dark  lane in the dust tail, especially noticeable in images and less so visually in telescopies, is a rare cometary phenomena often referred to by 19th astronomers as "the shadow of the nucleus". Of course, it is not really a shadow, but instead evidence of a vacancy of material along the central axis of the dust tail. Would-be observers are urged to try and detect this as it is something you are only likely to see a couple of times in your lifetime in the brightest comets!

 

BrooksObs 

Hi BrooksObs,

 

Thank you for pointing this out! I noticed this feature visually, as shown in my sketch in post #64 in this thread:

https://www.cloudyni...-neowise/page-3

 

What is the physical explanation for this bifurcation? Does material leave the nucleus at opposite directions? Or is there another mechanism that channels material into these two distinct tail parts? Or why is a vacancy of material generated in the middle of the tail?

 

Clear skies

Robin



#18 futuneral

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Posted 08 July 2020 - 02:42 PM

Tried to process it to bring close to what I was able to see in my binoculars. The faint part of the tail was apparent as well as its bending towards the East.

Shot at around 4:00AM, about 36N

 

IMG_6096-r.jpg

 


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#19 Dave Mitsky

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Posted 08 July 2020 - 02:54 PM

The comet looked quite golden today (4:24 AM CDT, July 8, 2020).

43.6 degrees N

ST80 and 13 Ethos

Galaxy S10E (zoomed-in)

I wonder how much of the color seen in images is contributable to the comet being so low in altitude and how much to the sodium emission that's been mentioned.


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#20 Don H

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Posted 08 July 2020 - 03:25 PM

I was a bit concerned that the moon would be wrecking the view the last few days. But recent posts from Tucson and all over the world motivated me to try my luck this morning from a bit north of the Old Pueblo. I got out of bed as the sky was just beginning to brighten and realized I would not see it from the backyard due to a closeby foothill and the neighbor's rooftop. So I took our 8x50 binos out front and the view was superb! It reminded me of many of the photos here, showing the extended, gold colored tail and bright core. I ran inside and got my 4.5" reflector and a few eyepieces. In less than 2 minutes I was back out and noticed I could see the comet naked eye, which made putting the red dot finder on it a breeze. I enjoyed views at 25, 41 and 64x, each image very pleasing for various reasons. I also looked over at Venus at 25x, and with a 2.6 fov, enjoyed it in the midst of the Hyades cluster.

 

So if you were like me, do not hesitate to get up early the next few days. Neowise is putting on a show. It should be a bit better for the next few mornings, rising 1 degree higher each day before dawn. Around the 11th or 12th, it will then will emerge in the evening sky, too.


Edited by Don H, 08 July 2020 - 03:27 PM.

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#21 chrysalis

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Posted 08 July 2020 - 03:27 PM

I wonder how much of the color seen in images is contributable to the comet being so low in altitude and how much to the sodium emission that's been mentioned.

Reminiscent of Comet Holmes back in October 2007; but it actually WAS yellow.


Edited by chrysalis, 08 July 2020 - 07:03 PM.


#22 Carl H.

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Posted 08 July 2020 - 04:12 PM

After two morning of clouds, it was clear in my part of Tucson this morning. I estimated NEOWISE at magnitude 1.8 with both the naked eye and in 10x50 binoculars. The tail appears to be growing as the comet moves into darker skies and the phase angle increases. To the eye, I measured the tail at ~1 deg and ~2 deg in 10x50s.

 

I was finally able to get in some imaging this morning. 

 

C2020F3 NEOWISE 2020-Jul-08 Carl Hergenrother.jpg

 


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#23 Carl H.

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Posted 08 July 2020 - 05:32 PM

Actually, it would not be at all surprising if NEOWISE is showing emissions of sodium. A heliocentric distance of about 0.3 a.u. is often the point at which typically more dust-dominated comets begin to exhibit the presence of that metal due to solar heating and giving rise to a yellowish hue to the comet's head and tail. NEOWISE passed within this limit only a few days ago This situation usually does not last any great length of time as the comet retreats from the Sun, so look closely for the yellowish tinge in the comet's head and tail in the coming days.

 

I'd also like to make mention of an even rarer display currently taking place in NEOWISE. A number of observers have called attention to the apparent bifurcation, or seeming splitting of the dust tail. The visible dark  lane in the dust tail, especially noticeable in images and less so visually in telescopies, is a rare cometary phenomena often referred to by 19th astronomers as "the shadow of the nucleus". Of course, it is not really a shadow, but instead evidence of a vacancy of material along the central axis of the dust tail. Would-be observers are urged to try and detect this as it is something you are only likely to see a couple of times in your lifetime in the brightest comets! And, like the sodium emission, the shadow of the nucleus tends to be highly transient and could soon disappear.

 

BrooksObs 

Robin Ledbetter has posted the detection of sodium emission with a Star Analyzer and 50mm lens at:

 

Comet NEOWISE with the Star Analyser

 

I have the same setup as Robin except for some reason my CCD camera goes all flaky when connected to the 50mm. Not sure why. This did persuade me to finally invest in a filter wheel so hopefully I can get my Star Analyzer on my AT72EDII in a few mornings.



#24 BrooksObs

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Posted 08 July 2020 - 08:10 PM

Hi BrooksObs,

 

Thank you for pointing this out! I noticed this feature visually, as shown in my sketch in post #64 in this thread:

https://www.cloudyni...-neowise/page-3

 

What is the physical explanation for this bifurcation? Does material leave the nucleus at opposite directions? Or is there another mechanism that channels material into these two distinct tail parts? Or why is a vacancy of material generated in the middle of the tail?

 

Clear skies

Robin

Robin, you pose a most difficult question to answer in brief and simple terms But let me attempt a quick approximation that might serve to convey the general idea of what is going on.

 

Our impression of a bright comet as seen from Earth is created by our limited simple two-dimensional view but, comets are really three dimensional objects. In spite of the appearance, the tail is in no way actually bifurcated, our view is simply a misinterpretation of what we are viewing. Cometary material vaporizing and lifting off the comet's nucleus is like water spouting upwards from a decorative water fountain. Imagine the  fountain's spout as the comet's nucleus, the water rising up from the spout (sunward) and then falling down into the pool (anti-solar) in a 360 degree circular cascade, Alternately it can also be likened to looking up at the inside of an open umbrella and seeing its multiple spokes descending around you. The dust tail is likewise a three-dimensional, tube-like structure. So try  imagining the tail as a huge, thick-walled, milk glass tube, strongly illuminated at one end (the Sun). Seen edgewise from a distance, projection effects would make the differing densities seem like two denser parallel outer bands, or streams, separated by a semi-dark central channel, just as the comet's dust tail appears to us. The causative agent actually involved is a bit too complicated to describe here in any detail without creating an entire page of explanatory text, I'm afraid.

 

BrooksObs


Edited by BrooksObs, 08 July 2020 - 08:21 PM.

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#25 musicengin

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Posted 08 July 2020 - 09:11 PM

Robin, you pose a most difficult question to answer in brief and simple terms But let me attempt a quick approximation that might serve to convey the general idea of what is going on.

 

Our impression of a bright comet as seen from Earth is created by our limited simple two-dimensional view but, comets are really three dimensional objects. In spite of the appearance, the tail is in no way actually bifurcated, our view is simply a misinterpretation of what we are viewing. Cometary material vaporizing and lifting off the comet's nucleus is like water spouting upwards from a decorative water fountain. Imagine the  fountain's spout as the comet's nucleus, the water rising up from the spout (sunward) and then falling down into the pool (anti-solar) in a 360 degree circular cascade, Alternately it can also be likened to looking up at the inside of an open umbrella and seeing its multiple spokes descending around you. The dust tail is likewise a three-dimensional, tube-like structure. So try  imagining the tail as a huge, thick-walled, milk glass tube, strongly illuminated at one end (the Sun). Seen edgewise from a distance, projection effects would make the differing densities seem like two denser parallel outer bands, or streams, separated by a semi-dark central channel, just as the comet's dust tail appears to us. The causative agent actually involved is a bit too complicated to describe here in any detail without creating an entire page of explanatory text, I'm afraid.

 

BrooksObs

 

"... imagining the tail as a huge, thick-walled milk glass tube, strongly illuminated at one end (the Sun).

 

"Seen edgewise from a distance, projection effects would make the differing densities seem like two denser paralllel outer bands, or streams, separated by a semi-dark central channel..."

 

 

That is very helpful!

 

How does the ion tail relate to this tube?
 




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