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A Hunt for Spiral Arms and Bars

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#1 Araguaia

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Posted 10 August 2019 - 01:51 PM

Tomorrow is likely to be my last session for a while.  The Moon will set at 3:20 AM, and the sky is very clear.  After that the Moon will be out most of the night, and by the time it starts to set early enough for an evening session, the smoke is sure to be covering the sky.

 

I decided it will be a stroll through bright(ish) spiral galaxies I haven't seen yet this season.  Most of them are to the SE, and will be fairly high only just before first light.  It will be a bit of a race to get them all in between about 4:30, when they'll start to get high enough, and 5:15, when the Sun will be 18 degrees below the horizon - astronomical twilight, it is said, though the other night I thought the sky to the NE was already washed out by 5:00 AM, mostly due to the zodiacal light.

 

The plan is:

 

- NGC 1300 at 4:15 (60 degrees alt) - should see the bar, hope to see at least a hint of the arms.

 

- NGC 1433 at 4:30 (45 degrees), a new target for me - it is said to show arms to the patient.

 

- NGC 1566 at 4:45 (35 degrees) - usually shows a nice loose S shape.

 

- NGC 1672 at 5:00 (30 degrees) - logged last season as a TIE fighter shape, with much detail.  It was a bit higher, but the sky might be more transparent now...

 

I'll start with Uranus while sipping coffee and waiting for the last moon glow to fade. Between moonset and 4:30 I'll warm up for spiral arms with M33 and NGC 1365, which I have already observed the past few nights, stroll around the Fornax Cluster for a bit, and probably have a look at the eery Eye of Cleopatra.   I'll close with the rising Orion Nebula, of course, and enjoy the reds and greens just to spite the deniers... grin.gif


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#2 KidOrion

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Posted 10 August 2019 - 02:58 PM

NGC 7479 in Pegasus is a classic barred spiral. 

 

NGC 157 in Cetus will also show some spiral structure.


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#3 Araguaia

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Posted 11 August 2019 - 07:57 AM

A beautiful session!  12" Dob, 30mm, 14mm, 5.5mm, and 3.5mm EPs.

 

After Uranus, I started the hunt for spirals with NGC 157 - thanks for the tip, KidOrion.  It was right in Dobson's Hole.  At 51x I found a bright oval, slightly teardrop-shaped.  At 277x it would show a core with averted vision, and when the core appeared so did a swirl pattern in the halo, going clockwise.  I couldn't hold it in direct vision but it was quite clearly spiral.

 

NGC 1300 showed a bright bar right away, and soon showed the fainter stubs of its arms as well.  Not as easy to see them as with NGC 1365 - about as hard as the arms of M101.

 

NGC 1433 was an elongated patch, which only showed a hint of wisps around it after prolonged observing at 277x and 435x.  The toughest arms of the night.

 

NGC 1566 was spectacular, just as I remember.  A bright extended core with a superimposed S, trailing off a long way.  Almost as evident as the arms on M51.

 

NGC 1672 took a few minutes of observing to show the TIE fighter shape - it was rather low in the sky.  It must be very nice seen from further south.

 

I ended with a look at M42, the Double Cluster, and the Pleiades, awash in zodiacal light.

 

Five face-on spirals, besides M33.  A few years ago, I would have never imagined that I could see arms in so many galaxies if I gave it enough time...


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#4 Pcbessa

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Posted 26 August 2019 - 10:33 AM

Hello Araguia!

 

Long time, no see. Here in Scotland I have been away from observing due to the 3 month long bright nights, where the sky never gets dark.

 

And yesterday it was my first night with the scope, after this long pause. Whilst most of the night was focused in nebula hunting in Cygnus, I did noticed a mottled structure in NGC7338 in Pegasus, while I was searching for the Stephan's Quintext galaxies. The galaxy looked like a miniature of Andromeda galaxy with a prominent dark lane to one side. But I didn't pay much attention. I am sure it would reveal two faint arms in a very dark location.

 

I have these on my records (I still haven't looked at many galaxies)

 

Spiral Arms or bar structure (11 seen)
M51, clear spiral pattern
M101, faint arm seen top rightwards with HII nebula, mottled structure
M33, two faint arms, faint arm seen going to HII nebula trail down rightwards and another right upwards
M31, dark lanes seen left and also right, and evidence of a curving arm top part
M81, good spiral structure seen faintly up rightwards and down leftwards quite away from core, upper arm seems to have HII regions
M99, Coma Pinwheel, a clear mottled and barred structure, SEE AGAIN
M100, galaxy with faint evidence of spiral arms, SEE AGAIN
M66 a beautiful bar structure
NGC2903, signs of arms extended outwards, also two bright arms, one up, one down, one of them is NGC2905

M64, what a galaxy, this one also revealed a dark lane and a very large galaxy, but dark lane not as evident. to be observed again

M94 signs of arms, like a ring around nucleus

 

Uncertain observations (4 suspected)

M109 some evidence of structure, to be observed again

Ngc3607, spiral-ish??, to be observed again

NGC7338 in Pegasus, dark lane, a miniature M31, elongated large halo, to be observed again

N2403, face on galaxy, but arms not seen yet

 

Good candidates/ Not seen yet: Fireworks galaxy, N7331, N7479, M77, M74, Ngc 936, IC342, NGC4236, NGC5033


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#5 Starman1

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Posted 26 August 2019 - 12:30 PM

Pcbessa,

A nice list--the others on you list may show considerable detail, too.

One irregular with odd details is IC10, and you will encounter others as you go.  Surprised you didn't mention NGC253

-25° shouldn't be too far south for you to see some details in it, though it will be low from Scotland.



#6 Asbytec

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Posted 27 August 2019 - 09:03 PM

 

NGC 1300 showed a bright bar right away, and soon showed the fainter stubs of its arms as well.  Not as easy to see them as with NGC 1365 - about as hard as the arms of M101.

 

I missed NGC 1365 last year, but I did manage NGC 1300. 

 

To me, it's kind of hard to talk about seeing spiral arms without talking about how to see them. I mean, once you're set up and observing, dark adapted, and under dark skies. All that is given. In my experience with NGC 1300, I did not so much see the spiral arms themselves, rather I could see where they were. The arms were not well exposed like an image, of course. So, forget seeing that. What I saw was a bar, as you did, an a faint halo. We know the arms are in the halo, so that's a start.

 

What I did manage to see, over time, was a very soft darkening in the halo on both sides of the bar. Not all at once, and not at all easy. But, those very faint and rarely perceived darker regions in the halo defined where the arms were barely seen in the outermost and admittedly very dim halo outside them. Those are the spiral arms causing that extended dim halo. Again, not actual arms like we see in an image, but a dim part of the outer halo that is barely visible beyond the core and beyond the very faint darker regions. 

 

That is how I know I've seen them, by the faint signature they create in the halo beyond the dark interspace. I even caught a brighter knot in the NW of the halo, probably a "root" of one of the arms. I could not make out where the arms ended, the halo was just to difficult to perceive that amount of detail. That's what they look like to me in my aperture, not like an image as clearly brighter arcs.

 

The sketch below makes it look easy, if it were realistic you'd be "observing" your monitor for an hour just to catch a glimpse or two. Not unlike the real thing. 

 

NGC 1300 Rev.png


Edited by Asbytec, 27 August 2019 - 09:06 PM.

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#7 jayrome

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Posted 27 August 2019 - 10:06 PM

 

NGC7338 in Pegasus, dark lane, a miniature M31, elongated large halo, to be observed again

 

Pcbessa,

 

Do you mean NGC 7331 the main Deer Lick Group galaxy? There is an NGC 7338 but its like magnitude 17, what kind of scope do you have that you are seeing a dark lane there? grin.gif

 

I do need to get back soon and try to spot Stephan's Quintet.  I've also been frustrated by this trio in Draco - I can only make out 2 of the 3. NGC 5981, 5982 and NGC 5985. For some reason I couldn't see 5981. I'll have to be more patient next time. 

 

But I digress, I'm not sure if OP can see these galaxies that far north from the deepest dark forests of Brazil.


Edited by jayrome, 27 August 2019 - 10:06 PM.


#8 Jeff Young

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Posted 30 August 2019 - 04:28 PM

Pcbessa,

A nice list--the others on you list may show considerable detail, too.

One irregular with odd details is IC10, and you will encounter others as you go.  Surprised you didn't mention NGC253

-25° shouldn't be too far south for you to see some details in it, though it will be low from Scotland.

I can't get NGC253 from 54ºN; it never gets above the trees on my horizon.

 

M106 is another good one:

 

M106.2009.05.26.jpg

 

 

M33 can take a lot of work, but it's definitely one of my favourites:

 

M33.2008.11.30.jpg


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#9 Jeff Young

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Posted 30 August 2019 - 04:37 PM

Oh, and NGC2950:

 

NGC2950.2008.03.08.jpg

 


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#10 Starman1

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Posted 30 August 2019 - 04:46 PM

My site has tall trees, too.

My southern horizon is -55°, but the farthest south I can see at the site is about -40°.



#11 Asbytec

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Posted 30 August 2019 - 08:48 PM

Here's a tough one. NGC 1073. Below is the best digital image I found that closely resembles the visual appearance. 

https://www.cloudyni...0171022-231657/

 

This was a challenging observation. The core actually had a brighter knot to one (southwest) side. I recall not seeing the spiral arms, but only hints of indeterminate varying brightness in the halo, including a possible field star embedded in it to the north. It's amazing we can make out some detail in images we can sometimes not see at all. 

 

Trying to sketch it so others can see it, finding that balance between a realistic view and the realism that our monitors differ. It's amazing the tiny bar was actually visible. And by visible, I mean almost impossible. Almost. smile.gif

 

Below is my report of observation.

https://www.cloudyni...1073/?p=9064482

 

NGC 1073 rev.png


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#12 Pcbessa

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Posted 09 February 2020 - 03:38 PM

I am revisiting and reopening this thread as I suspect that in soon it will become active again, as galaxy season starts.

We still have a few days to wait until the moon is out of sight.

 

I did see IC10 a few weeks ago, the irregular in Cass. It is considerably faint, not obvious at first, but once seen, it is seen as an irregular very faint patch, with one side being brighter (where the HII region is).

 

IC342 is another very faint galaxy. This one is a spiral, but I was only able to faintly see an haze around the nucleus, and faint and wide. Some IC galaxies really make for considerably challenges for a 10" Dob. Much fainter than M101 or M33. But I heard reports of spiral arms seen in a 12". I guess I need a trip to a Bortle1/2 spot, to observe these two faint IC galaxies.

 

NGC253 is almost out of question. I could theoretically observe it if I drive to a Bortle 1/2 location and I am lucky with the transparency and with the timing as galaxy culminates at 5 degrees above horizon. I tried it several times in my Bortle 4 place, without being able to see anything. I think NGC1300 in Eridanus was the most southern galaxy I have seen, and it was easy as it is a bright one.

 

 

Pcbessa,

A nice list--the others on you list may show considerable detail, too.

One irregular with odd details is IC10, and you will encounter others as you go.  Surprised you didn't mention NGC253

-25° shouldn't be too far south for you to see some details in it, though it will be low from Scotland.


Edited by Pcbessa, 09 February 2020 - 03:41 PM.

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#13 tchandler

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Posted 10 February 2020 - 08:16 AM

Thank you for sharing your delightful impressions. 
 

The rich and varied morphology of galaxies is what drew me to astronomy. 
 

The astounding morphology of NGC 1300 is what sealed the deal for my fascination with galaxies. 



#14 Araguaia

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Posted 10 February 2020 - 10:27 AM

I am planning to try to observe spiral structure in NGC 1808 in Columba.  Unfortunately, it has been raining for over a month... no chance of that or of pre-dawn observations of Lynx, Leo, and Hydra.



#15 Philler

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Posted 11 February 2020 - 06:43 PM

I missed NGC 1365 last year, but I did manage NGC 1300. 

 

To me, it's kind of hard to talk about seeing spiral arms without talking about how to see them. I mean, once you're set up and observing, dark adapted, and under dark skies. All that is given. In my experience with NGC 1300, I did not so much see the spiral arms themselves, rather I could see where they were. The arms were not well exposed like an image, of course. So, forget seeing that. What I saw was a bar, as you did, an a faint halo. We know the arms are in the halo, so that's a start.

 

What I did manage to see, over time, was a very soft darkening in the halo on both sides of the bar. Not all at once, and not at all easy. But, those very faint and rarely perceived darker regions in the halo defined where the arms were barely seen in the outermost and admittedly very dim halo outside them. Those are the spiral arms causing that extended dim halo. Again, not actual arms like we see in an image, but a dim part of the outer halo that is barely visible beyond the core and beyond the very faint darker regions. 

 

That is how I know I've seen them, by the faint signature they create in the halo beyond the dark interspace. I even caught a brighter knot in the NW of the halo, probably a "root" of one of the arms. I could not make out where the arms ended, the halo was just to difficult to perceive that amount of detail. That's what they look like to me in my aperture, not like an image as clearly brighter arcs.

 

The sketch below makes it look easy, if it were realistic you'd be "observing" your monitor for an hour just to catch a glimpse or two. Not unlike the real thing. 

 

attachicon.gifNGC 1300 Rev.png

What you show in your very good sketch looks like what I have seen in NGC 1300, but only on a couple of very good nights.  The bar will be pretty easily seen, but I will also see faint whispy outer streak-like intensities above and below the bar suggesting arms.


Edited by Philler, 11 February 2020 - 06:57 PM.


#16 Asbytec

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Posted 12 February 2020 - 12:21 AM

What you show in your very good sketch looks like what I have seen in NGC 1300, but only on a couple of very good nights. The bar will be pretty easily seen, but I will also see faint whispy outer streak-like intensities above and below the bar suggesting arms.


Larger aperture, probably. Yes? I like to describe it not so much as seeing whisky (I meant whispy :) ) or streak like, rather the remaining faint glow outside the difficult to see dark interspace. I can tell where the arms are rather than actually seeing them.


Edited by Asbytec, 12 February 2020 - 06:23 AM.

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#17 Philler

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Posted 14 February 2020 - 04:53 PM

Hello Araguia!

 

Long time, no see. Here in Scotland I have been away from observing due to the 3 month long bright nights, where the sky never gets dark.

 

And yesterday it was my first night with the scope, after this long pause. Whilst most of the night was focused in nebula hunting in Cygnus, I did noticed a mottled structure in NGC7338 in Pegasus, while I was searching for the Stephan's Quintext galaxies. The galaxy looked like a miniature of Andromeda galaxy with a prominent dark lane to one side. But I didn't pay much attention. I am sure it would reveal two faint arms in a very dark location.

 

I have these on my records (I still haven't looked at many galaxies)

 

Spiral Arms or bar structure (11 seen)
M51, clear spiral pattern
M101, faint arm seen top rightwards with HII nebula, mottled structure
M33, two faint arms, faint arm seen going to HII nebula trail down rightwards and another right upwards
M31, dark lanes seen left and also right, and evidence of a curving arm top part
M81, good spiral structure seen faintly up rightwards and down leftwards quite away from core, upper arm seems to have HII regions
M99, Coma Pinwheel, a clear mottled and barred structure, SEE AGAIN
M100, galaxy with faint evidence of spiral arms, SEE AGAIN
M66 a beautiful bar structure
NGC2903, signs of arms extended outwards, also two bright arms, one up, one down, one of them is NGC2905

M64, what a galaxy, this one also revealed a dark lane and a very large galaxy, but dark lane not as evident. to be observed again

M94 signs of arms, like a ring around nucleus

 

Uncertain observations (4 suspected)

M109 some evidence of structure, to be observed again

Ngc3607, spiral-ish??, to be observed again

NGC7338 in Pegasus, dark lane, a miniature M31, elongated large halo, to be observed again

N2403, face on galaxy, but arms not seen yet

 

Good candidates/ Not seen yet: Fireworks galaxy, N7331, N7479, M77, M74, Ngc 936, IC342, NGC4236, NGC5033

 

You should be able to see bars or arms or both in all your good candidates.  You might also look for detail in NGC 4389 in CVn. which showed me a central bar and two broken faint streak like intensities, one above and below the central bar.  

Also, NGC 2903 spiral, which I consider the best galaxy in Leo. It will show a spiral pattern of multiple lanes.

 

NGC 2403 in Cam.  Higher magnification seems to work best revealing its arms with are tight on its central area.


Edited by Philler, 14 February 2020 - 08:53 PM.

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#18 Araguaia

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Posted 15 February 2020 - 07:07 AM

Last night was clear for the first time in 2020 - not perfectly, there were no stars below 10 degrees to the west, but good enough.  Columba was at the meridian, so I gave NGC 1808 a go.  It has been a long time since I looked at an image of it, so I could not remember where the arms are supposed to be, which was good.

 

After observing for a while at 277x I started to see the faint suggestion of two arms spiraling counterclockwise.  The nucleus was quite bright, and the galaxy was nearly edge-on, so the bright portions looked like a fat cigar, but in averted vision I could see some asymmetry in it.  There were some "dents" on the top left and bottom right, suggesting the stubs of spiral arms.  Looking hard in AV I seemed to also see two very faint lines to either side of the galaxy.  They also seemed to be extending counterclockwise.

 

To check myself, I nudged the scope over to nearby NGC 1792, an irregular galaxy of high surface brightness where I should see no hints of arms - and I didn't, no matter how hard I tried.  Back on NGC 1808, I could see the same features as before.  I mentally logged it as "hints of counterclockwise spiral arms".  Now, checking the image, I see that my observation made sense.

 

Has anyone else seen hints of arms in NGC 1808?


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#19 Pcbessa

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Posted 15 February 2020 - 04:24 PM

Not much observation lately due to poor weather.
I have seen some galaxy clusters in the past couple of weeks but no hunt fot new spiral arms.

Sadly, Eridanus galaxies are placed very low in the southern sky. If I get lucky I might find a night without moon and good transparency when I drive to Bortle2 skies.

M33 hasn't been looking that great and it's often a good.marker for good or bad transparency.

Yesterday it was the worst transparency I ever experience. Stars were visible but even M96 trio in Leo was barely detectable. I packed the telescope within 2mins!
Today looked similar when there was a gap in the clouds.
The strongest storm of the season is just arriving, so the atmosphere must be charged of water, which explains the terrible conditions.

Your galaxies in Fornax and Dorado make me dream of southern skies. Ngc157 is a good target for me, but Cetus is already out of visibility, so I must wait until next autumn. Surprisingly I didn't know about this galaxy.

#20 sgottlieb

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Posted 16 February 2020 - 09:16 PM

Here's what I recorded for NGC 1808 using a 13.1-inch from Costa Rica (latitude 10°).  Apparently I noted part of the arm attached to the northwest end, but didn't mention seeing anything at the southeast end.

 

At 105x this striking starburst galaxy appeared bright, large, very elongated 4:1 NW-SE, 5'x1.3'.  The glow is sharply concentrated with a well-defined 20" core that brightens to a stellar nucleus.  There appears to be an irregular extension at the northwest end that brightens and is offset to the major axis [on photos this corresponds with the start of a spiral arm that is attached at the north edge of the NW end of the galaxy].  At 166x, the halo is irregular and mottled.  Brightest in a group (LGG 127) along with NGC 1792 40' SW and the galaxies may have experienced a tidal interaction in the past.


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#21 Pcbessa

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Posted 18 February 2020 - 03:06 AM

Yesterday I did a small hunt for galaxy arms.

I started first with Ic342 and then moved to Leo. IC342 looked faint but very easy to see, wide and upon attention it revealed a twisted structure with one brighter side, where a prominent HII region is located. But I couldn't see any of the thin arms. The halo was faint.

In Leo, I started with the bright NGC2903. The S shape was prominent with two arms in either side. This must be one of the best spiral galaxies after M51.

M95 andM96 pair: One showed a bar and a round halo around. The other showed a mottled structured with one possible arm. Nearby, the fainter spiral companion from M105 showed also a twisted structure, and a clear sign of two main arms.

M65 and M66 pair: One showed a mottled structure with good hints of arms. The other is the edge one with a compact dust lane. The third companion showed also an easy dust lane.
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#22 j.gardavsky

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Posted 18 February 2020 - 06:28 AM

Yesterday I did a small hunt for galaxy arms.
...
In Leo, I started with the bright NGC2903. The S shape was prominent with two arms in either side. This must be one of the best spiral galaxies after M51.
...

Agreed

The "Leo's Head Galaxy"  NGC 2903 is the easiest galaxy to resolve the both spiral arms in its oval glow, even for the small apertures and medium magnifications (75x).

It is also a good object to compare different eyepieces on the contrast performance.

 

JG
 



#23 KidOrion

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Posted 18 February 2020 - 07:16 PM

I noted an E-W bar in the otherwise diffuse Pegasus galaxy NGC 7741 with a 12.5" scope.



#24 JimP

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Posted 20 February 2020 - 10:14 AM

When you are looking for spiral arms do you look “blind” or do you look at photos ahead of time so you know where to look and what to look for?

Jim

#25 havasman

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Posted 20 February 2020 - 03:05 PM

I plan 95% of my observations and will have seen at least a Wikisky.org image before I set up the scope. But that doesn't mean I have the image in mind when I observe a Gx. Sometimes what I see will remind me of what I looked up but usually not. Much more often I have to look up a difficult observation the next day to see if what I think I saw had basis in reality.


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