Object of the Week July 29, 2012 - NGC 6745 Bird's Head Galaxy

[FaintFuzzies]

NGC 6745 “Bird’s Head Galaxy”

Triple Galaxy System

Lyra

RA 19 01 42 DEC +40 44 40

Megastar listed size and magnitude
Size: 1.4x0.6’ Mag: 13.3

NED listed size and magnitudes
Component A (Main body of the head) – Size: 0.9x0.6’ Mag: 13.5
Component B (Tip of the head)– Size: 0.2x0.2’ Mag: 16.2
Component C (Beak) – Size: 0.3x0.2’ Mag: 15.9

This is a very interesting galaxy system in Lyra. It truly looked like a bird’s Head through a large telescope.
I’ve observed it several times recently through my 22” and Jimi’s 48” scope. This object was one the targets during evaluation of differences between several 6mm eyepieces over several nights. One evening, at least five different observers with skill levels ranging from novice to very experienced saw the same differences and realize the advantage of low glass count eyepieces.
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Below is the comparison of the 6mm Ethos, 6mm BGO (UO HD) and 6mm Zeiss Abbe Ortho – Series II (Note: I’ve copied the text from my website)
NGC 6745 (triple galaxy system) in Lyra was nearly overhead under NELM 6.9 skies, average seeing and above average transparency. Telescope used - 22" f/4 reflector.

The first image is with the 6mm Ethos and the second image is with the 6mm Zeiss ZAO-II, both giving about 383x. The details seen in the triple galaxy system was evident as the three cores were a bit more distinct, especially in the Zeiss. The two cores in the body were lost in the Ethos. The upside down house asterism shows only six stars in the Ethos and NINE with the Zeiss. We had at least five other observers that confirmed this observation, including at least one beginner. If a beginner can see the difference, than anyone can.


265
6mm Ethos


268
6mm ZAO-II



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A recent observing note:
22” at 306 and 383x – Bright glow with a separated beak.
The head is a bright 5:2 irregular elongated glow with well-defined with some diffuse edges that truly looks like the head of a bird. There were two slightly brighter cores in the head, component A and B. The two cores are about 0.5’ apart, one at the center of the head and the other at the north tip. The north tip is very sharply defined compared the base of the head at the south and west with fairly diffuse edges. Otherwise the rest of the “head” is fairly even surface brightness. About 1.0’ long and PA = 20.
The separated galaxy, component C the “beak”, has a slightly brighter surface brightness than the head. The beak is about 0.2’ north of the tip of the head and about 0.2’x0.1’ with somewhat defined edges.

266

267
Hubble Space Telescope

This is one of my favorite objects after Jimi showed it to me in his 48” reflector. He called it the “Bird’s Head Galaxy”. It was amazing with his scope! Sorry I don’t have those notes handy as I’m traveling on business now.


What do you see?

"GIVE IT A GO AND LET US KNOW"

GOOD LUCK AND GREAT VIEWING!

[Uwe Glahn]

Great galaxy Alvin,

my observation and sketch with 27" and 586x under NELM 6.5 you can see at the end.

So I could see the bright N knot (B) and a knot in the brighter E edge. Also I could detect a brighter center in the middle and the fainter nebula in the S. What I could not see was the Break (C). LEDA cataloged it with 16.9bmag, NED with 15.9?mag. Under normal conditions both no problems with my 27", but I definitive missed the Break. ..don't ask my why.

270

[RolandosCY]

This is a very nice target, especially sincy Lyra is at the zenith during August evenings. Will have a look at it in about 10 days (when the moon gets out of the way)...

[RolandosCY]

While preparing finder charts for NGC 6745 I noticed a long string of at least six NGC galaxies centered about one degree north of Vega. The string includes 6695, 6686, 6685, 6675, 663, and 6646, along with some IC and UGC galaxies. This string has also become a target (or should I say series of targets!) for the coming new moon window. Has anyone observed this string? Any comments?

[RolandosCY]

Well, I finally got around to observe this great galaxy system! It was much brighter than I expected and was readily seen with direct vision even at 67X. My best view was at 294X, obtained with my 7mm Nagler. I have to admit that to me it did not look as much like a bird's head, rather it reminded me of a rocket with a slightly curved plume behind. I could detect all three components, though the "beak" was noticed only after I increased the magnification to 558X (with NicosCY' s Ethos 3.7mm). After noticing it though at the high magnification, I could hold it at 294X. It certainly helps to scrutinize such objects at various magnifications. Another thing I noticed is what appears to be a "dark lane" sparating components "A" and "B". I could see this dark lane both at 294X and 558X, but it was more distinct at 294X. I did not try to count the stars in the "upside-down" house asterism that Alvin mentions, during ths observing run I only concentrated on the galaxy system. I attach my sketch below, though during the resizing process the component "C" almost disappeared! It is faintly visible (as I observed it) in the full size jpg of the sketch, if someone wants to see it let me know.

This observation was made at a mountain site at 4,600ft, with a SQM-L reading averaging 21.3, on a night of decent transparency and medium seeing.

281

[reiner]

Thanks for the post on this group, Alvin! I observed this group twice during the last week. The main body is very interesting, with the sharply pointed end. Also for me, the offset faint galaxy was not visible.

[RolandosCY]

I re-observed this system last night with a friend's C9.25 from SQM 20.4 skies. It was barely visible (the main part), direct vision maybe 60-70% of the time. I could not detect the "dark lane" that separates components A & B, and of course I could not dtect at all component C. Surely a toughie for smaller apertures under less than perfect skies, but I was not surprised it was visible (judging from what I saw with my 18")...

[Marko]

Well it took me till this year but this is a very nice object Alvin and worth the wait. I was able in 18" last new moon to see even the faint extended region beyond the bright knot at the start of the 'beak'. Here is the observation

Scope: 18SmF3.7 cmt1: BirdsBeak:
NGC 6745 UGC 11391 CGCG 229-13 PGC 62691
MltG 13.3 1.4x 0.6' 33 Sm RC3 19 01 41.5 +40 44 40
11:00pm 4.5mmDe 376x 1/8fov [1.45'] 1.7el W is to 9:30 in this view. The main glow fans out slightly and gets gradually much fainter on the south end of the main body of the galaxy. Glow gets stronger as we head north. A stellar glow appears just as the object necks down to 1/3 width and this is towards 'the beak'. 6mm SMono offers fair view where we see the stellar point is just after the neck down of the body where the object gets very dim. Then it picks up for the stellar glow at the tip of the neck down on the far northern obvious part of the body. If we move north from the NS elongated very short stellar glow the glow all but disappears but in that direction about half way to the closest star that is towards 7:30 [due NNNW]. of an obvious EQ tri [GSC 3124:251] 1/8fov N we can detect an elongated very faint, averted only, elongated glow in the direction of NS like the stellar glow. This glow is beyond the wonderful Hubble shot of this object. Going back to 4.5mmDe we still have a great view of the stellar points on the north. We can see the faint extension also in the 4.5mm, 376x, but I had noticed it first in the 6mm super mono. [this would be 1/16 fov or about 0.75' from the stellar northern glow]