Cornillac, autumn 2021

8 October - blog 4 of 4

A day of clear blue skies, filled with anticipation for the night ahead.

It had been more than a week since I arrived on site and not a minute had passed that I had not felt consumed by astronomy: my observing plan to tweak, observing guides to update, images to review and timelapses to set up.

I spent part of the afternoon taking images of my setup to add to this website, especially for the CSOG Image Orientations page.

Two cameras set up close to the scope, to capture an astronomer at the eyepiece with the Milky Way passing overhead. A bit tricky to avoid accidentally knocking into one of the setups at night, but worth trying.

As nightfall approached it was clear (...) that this night was to be as good as the previous one.

Kicking of this observing run, I observed the galaxies in CSOG's 12-14" edition in the constellation of Cygnus. There were only two in this guide I had yet to bag an observation for, but I decided to just (re)observe them all.

The first of these was NGC6764. Quite faint but revealing a core and a nucleus. Averted vision teased out a bit more of the outer regions. Flanking this galaxy, to the west, is the mag. 10 star that is component A of the double star Espin 979.

An irregular glow, elongated NE-SW and quite suddenly brighter in a core that is slightly elongated in the same direction in which the nucleus is just visible without AV. With AV the galaxy is clearly more elongated and more of the outer regions of the galaxies are visible. Not very bright but a nice galaxy.
To the south is a small, right angled triangle of stars with the right angle on the NW side.
1/4 FoV to the west is a mag. 10 star with a mag. 11.5 star to its NE, ±040°/15" (components A and C of the double star Espin 979).

PGC63573 is little more than a slightly elongated glow, for which I wanted to log an observation as I previously missed it when observing its neighbour to the east: NGC6826, the "Blinking Planetary".

A small, faint, slightly north-south elongated glow, gradually brighter in the middle, no nucleus visible.
Directly SSE is a mag. 11 star. 1/3 FoV to the east is the planetary nebula NGC6826 (the "Blinking Planetary").

As expected, NGC6949 (Arp 29), the "Fireworks Galaxy" was the prettiest galaxy in Cygnus. With the conditions as favourable as they were this night, it gave up plenty of detail and, unmistakably, two of its arms.

A large, quite faint, irregular glow, slightly elongated NE-SW, centrally brighter in a relatively large, round part, no distinct core. Many stars are superimposed but the nucleus is discernible. The galaxy is slightly flattened on the eastern side on a line from north to south. An open part is visible on the NW side of the galaxy. With AV an arm is discernible on the WSW side of the galaxy, subtly and very faint, a bend, through the west, curves towards the north. On the NE side the start of an arm is faintly visible, with AV that arm is visible curving through the east towards the SE. The NE arm is slightly brighter and longer than the western arm is.

A non-NGC galaxy worth a visit in Cygnus is MCG+08-36-000 (PGC63552). I observed this little glow twice before, in 2011 and 2014. The first time under light polluted skies in the Netherlands, the second under Alpine skies but with less than optimal transparency, both with my 12" SCT. Those two observations revealed no more than an evenly bright glow. This time around, under much better skies and with 2 more inches of aperture, I could make out its peculiar shape.

An oval, NNE-SSW elongated glow, gradually brighter in the middle and clearly slightly brighter SW of the middle, which is notable. With AV the brighter SW part is clearly flattened on the NE side on a line from NW to SE. No nucleus visible.
To the NNW is a mag. 11 star with a mag. 13 star to its SSW, ±200°/10". Four times that distance towards the ESE is a mag. 10 star with a mag. 12.5 star to its NE, ±040°/8". Neither of these are double stars in WDS.

The second of the two galaxies in my guide I had yet to add to my observing log, was MCG+06-47-004 (PGC67025). It also goes by KTG 73B. The one galaxy in this group I had yet to observe, was the only one to lack a visible nucleus.

IC1392 (KTG 73A) is a clearly NE-SW elongated, oval glow, quite suddenly brighter in a core that is very elongated in the same direction. With AV the nucleus and slightly more of the outer halo of the galaxy is visible. To the SSW is a group of 5 mag. 12 and fainter stars. To the SE is MCG+06-47-004 (KTG 73B).
MCG+06-47-004 (KTG 73B) is a faint, round glow, gradually brighter in the middle, no nucleus visible, no difference with AV. On the SE edge is a mag. 13 star. To the NW is IC1392 (KTG 73A).
MCG+06-47-005 (PGC67049, KTG 73C) is a slightly east-west elongated glow, gradually brighter in the middle with quite a bright nucleus that is visible without AV. With AV the central part is slightly larger.

Galaxy observations in Cygnus

Just as I was taking a short break from observing, the owners of the gîte stopped by for a peek at the heavens. I had prepared a tour of the brighter objects in the traditional summer constellations, along with a few showpieces in Pegasus and Andromeda.

With the southern wing of the celestial swan still high in the western sky, I set out to unveil the fainter filaments of its splendid supernova remnant. I was inspired to revisit the Veil Nebula by Howard Banich's Object of the Week entry on Deep Sky Forum, along with his article in Sky & Telescope and of course the YouTube interview. Highly recommended.

In comparison to the equipment Howard used to unravel the Veil, I am looking through a straw. Therefor, instead of taking in a wide field, I hopped from one filament to the next. CSOG was my guide. The designations used for these segments match those in Sky & Telescope articles in 2011 and 2018, with the addition of one segment that I labeled [O].

I skipped NGC6960, NGC6992 and NGC6995 and set out by observing IC1340. An OIII filter attached for all observations, unless noted otherwise. Images below are CSOG guides and DSS images.

IC1340 and segment N made for a nice comparison, with the latter only being marginally fainter than the IC is. The brighter knot on the southern edge of IC1340 was evident, as was the arced shape of segment N.

Further to the south is a notably bright segment that is know as the "Southeastern Knot", informally designated Veil Nebula [H].

Remarkably bright, a NNW-SSE elongated glow, brightest in the SSW part (that is clear without AV) and in that part gradually wider towards the SSW. With AV slightly more elongated and centrally slightly wider.

Heading northeast, segments L, G and M were next. These segments are considerably fainter than the preceding ones I observed (yes, they are indeed following in astro speak - that pun was intended). Segment G was the toughest of the three but appeared subtly irregular with averted vision.

Further north-northwest are two larger segments that carry NGC designations. Despite their designations, they are notably faint.

Two more faint segments, before hitting one that is truly a grandeur of the Veil. Segment F was a bit easier to grab than NGC6979 was, but O required averted vision in order to be seen.

Simeis 3-188 - "Pickering's Triangular Wisp Fleming's Triangle"

This is a showpiece. A showpiece that requires good skies to do it justice. This was such a night, and it showed. Incredible detail filled my 26mm Nagler.

One FoV in size, much detail is visible, much threaded structure. Wider on the NNE side, centrally many dark areas are visible, clearly tapering towards the SSE. On the east side of the dark section an arc of nebulosity is visible with the bulge towards the east, the SW part thereof is the brightest. On the NNE edge of the arc are two mag. 10 stars aligned NNE to SSW. To the WNW of the mag. 10 stars a ragged part is visible that stretches towards to the WNW. On the west side, where the triangular shape of this segment is "closed" fainter nebulosity is visible. Where the triangular shape, on the east side, points towards the SSW the nebulosity is clearly brightest and quickly tapering: on the east side the nebulosity runs towards the SSE, on the west side a kink towards the SW is clearly visible, a bulging part with the bulge towards the west. Following an interruption the nebula continues to taper towards the SSE: the bulging part on the SSW side curves back towards the SSE after which, after the interruption, the nebulosity joins again with the eastern part after which the nebulosity ends quite suddenly towards the SSE. To the south thereof, before the part that is "the Funnel" starts, a very faint glow is visible with AV. A thin, NNE-SSW elongated glow that brightens towards the SSW, that is to the SSW of a mag. 10 star.
Never before have I observed this segment as clearly and as beautiful as this.

A relatively large segment, designated E, is to the west of Fleming's Triangle. South of it is an faint segment with a formal designation: Gaze-Shajn 222. Extending southwards from the triangle is "The Funnel": an extension so faint that I failed to pick it up until I observed Gaze-Shajn 222. The even fainter extension that runs southwards, the "Thin Thread", remained out of sight no matter how hard I tried.

South of where the "Thin Thread" is and east of NGC6960, are the two small segments I and J. Segment I was very faint but a relatively easy observation, as it was back in 2013, too. Not so for segment J. While I had a positive observation before, using a 12" SCT, this time I just couldn't make it out. Filtered or unfiltered, OIII, UHC and even H-Beta, no luck this time around.

An irregular glow, very faint, slightly NNE-SSE elongated, difficult to observe without AV. Clear with AV and flattened on the east side on a line from NNW to SSE. Approximately equally faint to the segment Gaze-Shajn 222.
Veil Nebula [J] to the NW is not visible, neither with an OIII or a UHC filter, which is remarkable as I was able to observe it in 2013. That part is very faint on POSS2 Blue plates.

As the DSS images reveal, segment J is much fainter on the blue plate, to the right - which is a much closer approximation of what the human eye perceives - than it is on the red plate, to the left. The blue plate reveals how truly faint the segment is. That being said, my observation in 2013 was a positive one, when I (me, the observer that is) described segment J as a faint glow surrounding several mag. 10 and fainter stars, just visible without averted vision, sharing the FoV with I (the other segment), 1/4 field of view to the southeast. Better luck next time, definitely one to attempt once more.

South of the center of the Veil complex is another faint segment dubbed Veil Nebula [B]. Using the OIII filter, it wasn't there. However, switching to UHC did the trick. A very faint glow southwest of a mag. 11 and a mag. 12 star.

This segment was not visible with use of the OIII filter, but with use of the UHC filter and AV a very faint, round glow is discernible SW of a mag. 11 (north) and a mag. 12 (south) aligned north to south.
Remarkable that this segment was not visible with use of the OIII filter.

Simeis 3-210, the "Eastern Arc" is to the southwest of segment B. It is most prominent surrounding the mag. 6 star SAO89241 and clearest to the south-southwest of that star.

17mm Nagler T4: A glow surrounding a mag. 6 star (SAO89241), slightly elongated north to south. The SSW of this segment is clearly brighter to the SSW of the mag. 6 star. No nebulosity is visible to the east of the star. The nebulosity is visible to the north of the star but is slightly clearer to the SSW.
1/4 FoV to the NE is a faint, north-south elongated arc of nebulosity, with AV it is clear that it bends slightly towards the NNE on the northern side. The southern part is the brightest, there a mag. 10 star star is on the western edge with a mag. 12 star to its north.

26mm Nagler T5: Using this magnification the glow is slightly clearer and slightly larger. The part to the NNE is slightly clearer, too.
To the SSW of the part surrounding the mag. 6 star is a trapezium of mag. 12 stars with the top towards the NNE. To the SW of the trapezium, with AV, a small, faint, NE-SW elongated glow is visible, only visible with AV. That segment is Veil Nebula [K].

South-southwest of the Simeis 3-210 is the fainter segment Veil Nebula K, farther to the east-northeast are C and D.

Veil Nebula [D]

This segment of the Veil made for an interesting observation. The part that stood out most, was that at the eastern end of a U-shape of mag. 11 and fainter stars. There, the nebulosity of this segment "closed" the U-shape, with a streak running roughly north to south.

The image of the left is a POSS2 Red image, the one on the right is Blue.

17mm Nagler T4: A NNW-SSE elongated glow in the western part of a U-shape of mag. 11 and fainter stars with the open side towards the west. A distinct streak. The nebulosity is in the top of U, a slightly curved shape with the bulge towards the east. Slightly wider towards the north (inside the U-shape). The nebulosity stretches slightly towards the SSW to the SSW of the SW-most star in the U shape, where it tapers. Much clearer with AV and slightly longer, more elongated to the SSW of the U-shape.
Two parts of nebulosity are visible to the NNW of this segment, an eastern and a western part. The western part is a NE-SW elongated streak, a clearly irregular glow, clearly flattened on the SE side and gradually fainter on the western side. The eastern part is an ENE-WSW elongated streak, fainter than the western part is but clearly more elongated. With AV this part is even more elongated.

26mm Nagler T5: Using this magnification, to the north of the U-shape (to the north of the central star in the northern part of the U-shape) an part of the nebulosity is visible that runs north to south, is slightly wider towards the north and that is irregular and patchy.
Also with use of this magnification the two northern parts are clearly visible. The eastern part is slightly brighter and is clearly very elongated, the western part is slightly irregular.

As described in the text of the logged observation above, there are two, visually detached segments to the north-northwest of Veil Nebula D. Neither carries a designation but both provided for nice bonus observations. Perhaps these two deserve designations of their own: Veil Nebula P & Q..?

After a half hour break I continued with observations of the galaxies in CSOG's 12-14" Gx-2 guide for the constellation of Cetus. The elevation of these galaxies at transit, at this observing site, is right around the 40° limit I abide to for almost all of my planned observations. Any lower and the atmosphere will just eat away too much detail. Fainter objects can and often will vanish completely, while much detail in the brighter ones will drown. Remember, at an elevation of 30°, the amount of atmosphere is doubled compared to objects that are in the zenith. With that extra atmosphere comes extra moisture, seeing and layers affecting the skies' transparency. Thankfully, plenty remains to observe at higher elevations.

The first galaxy in Cetus was MCG-01-02-015 (PGC1646). Although it's small and not too bright, its elongation and suddenly brighter core is notable. Averted vision revealed a nucleus.

A faint, ENE-WSE elongated little streak, with AV it is clear that the galaxy is very elongated with a suddenly brighter core, which is notable. With AV the nucleus is visible.

A bit of irregularity was visible in NGC173. This galaxy is one of William Herschel's discoveries. The screenshot below is from CSOG's Herschel edition, by object.

An oval, ENE-WSW elongated glow, subtly brighter WSW of the middle. With AV subtly irregular and flattened on the east side on a line from north to south. No nucleus visible. With AV, just detached from the galaxy, a mag. 15 star (4UCAC460-000827) is visible to the SSE.

Following NGC173 was Paul Hickson's group nr. 7. All four galaxies played nice and all but D - NGC197 were easily observed.

All four galaxies are visible, a nice group.
A - NGC192 is the brightest galaxy, a clearly NNW-SSE elongated streak, quite suddenly brighter in a core that is slightly elongated in the same direction with a bright nucleus that is visible without AV. With AV the galaxy as a whole, along with the brighter core, is more elongated.
B - NGC196 is a north-south elongated glow, gradually brighter in the middle with a bright nucleus that is clearly visible without AV. The nucleus of B - NGC196 is brighter than the nucleus of A - NGC192 is.
To the SSE of B - NGC196 is D - NGC197: A small, faint, slightly north-south elongated glow, difficult to observe without AV, with AV gradually brighter in the middle, no nucleus visible.
C - NGC201 is a large, round patch, with AV ovally shapped and slightly NW-SE elongated, with AV subtly irregular. With AV the galaxy is NW-SE elongated centrally and with AV the faint nucleus sometimes jumps into view, but can not be held. The arms of the galaxy can not be discerned.

A single galaxy that I thought was equally rewarding as the Hickson group was, is NGC245. It too was discovered by William Herschel. Visually, it appears clearly irregular.

An irregularly round glow, without AV it is clear that the galaxy faints quite suddenly on the eastern side. With AV the eastern part of the galaxy is flattened on a line from north to south, the galaxy as a whole is slightly elongated NNW to SSE and the galaxy is clearly brighter in the southern and SW part. Thereby the notable shape of the galaxy is somewhat discernible. Without AV the nucleus is just visible and the galaxy is clearly irregular.

Another recommendation is NGC259. This galaxy is Holmberg 22A, but do not put any effort into finding a companion galaxy: Holmberg 22B is a star. Luckily, the galaxy more than makes up for that misidentification. As I did for Hickson 7 and NGC245, I rated this one a 6/10, too.

Quite a bright, NW-SE elongated streak, quite suddenly brighter in an oval core that is slightly elongated in the same direction. With AV the outer regions of the galaxy stretch out more and the galaxy, along with the brighter core, is more elongated. Without AV the nucleus is just visible. A nice galaxy.
To the SSW is a mag. 11 star, 1/4 FoV to the WSW is a mag. 11.5 star, in between these two stars is the base of a triangle of three mag. 13 and fainter stars pointing NNE. The star in the tip of the triangle is the star that forms Holmberg 22B, that star is only visible with AV.

Galaxy observations in Cetus

Having observed 33 galaxies and galaxy groups in Cetus, I took a longer break. After an hour, I focussed on the final objects of the night. Planetaries in Perseus. Of the seven I observed, two were first time observations.

Böhm-Vitense 5-3 (PK 131-05.1) is small and faint, but visible in my aperture and is definitely not stellar. Filters made a difference, but the little disk that is the nebula remained even in brightness.

17mm Nagler T4: Visible with AV, a round, faint glow, even in brightness, no detail visible.
Is in the SW tip of a triangle with a mag. 11 star to the ESE and a mag. 12 star to the NNO that form the base of the triangle.

17mm Nagler T4, Lumicon UHC: Using this filter the nebula is subtly brighter, a round glow, remains even in brightness.

17mm Nagler T4, Lumicon OIII: Using this filter the nebula remains a round glow of equal brightness but is visible without AV. The filter has a better effect than the UHC filter has.

The other first was Kohoutek 3-66 (PK 167-09.1). Contrary to my preceding planetary observations in Perseus in this session, this one is stellar, resembling a mag. 14 star. A mag. 14.5 star to the west-southwest made for a good comparison.

17mm Nagler T4: The nebula is visible without a filter, stellar, resembles a mag. 14 star.
To the WSW is a mag. 14.5 star.

17mm Nagler T4, Lumicon UHC: Using this filter the nebula remains clearly visible while the mag. 14.5 star to the WSW is no longer visible, the nebula remains stellar.

17mm Nagler T4, Lumicon OIII: Using this magnification the nebula remains clearly visible, the effect of the UHC filter is subtly better.

Planetary nebula observations in Perseus

Fatigued, yet satisfied I called it a night at ten to four in the morning.

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Observations

4 double stars
8 planetary nebulae
20 supernova remnant parts
57 galaxies and galaxy groups
Total: 89 observations
First time observations: 42 objects

Details of the objects observed in this session are in the table below.

click here for my observing log

to top of table

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Observations astrotrip Cornillac, autumn 2021

Four nights under the stars, including one all-nighter. 367 Observations logged, 215 of which for objects I had not observed before. A great visit to this new site. And definitely not my last.

16 double stars
2 open clusters
4 globular clusters
6 nebulae
19 planetary nebulae
21 supernova remnants
292 galaxies and galaxy groups
3 asterisms
4 other