Object Of The Week September 25, 2022 - NGC 6744, a possible Milky Way clone

[wvreeven]

NGC 6744, Caldwell 101, ESO 104-42, PGC 62836

Spiral Galaxy

Pavo

RA: 19 09 44.3
DEC: -63 51 23.2

Mag: 8.27

Diam: 15.7' x 9.8'

At the moment of this writing, winter is over at the southern hemisphere and daily saving time has started in Chile. But this OOTW, NGC 6744, still is sufficiently high in the sky at the end of astronomical dusk, having just passed the meridian, to be well visible.

NGC 6744 was discovered by James Dunlop (see what I wrote about him earlier here) on June 30, 1826. It lies in the constellation Pavo at a declination so south that it can only be observed from sufficiently southern locations and it doesn't rise north of about 26º latitude north.

Wide_Field_Imager_view_of_a_Milky_Way_look-alike_NGC_6744.jpg
Image taken from Wikipedia

Of all nearby spiral galaxies, NGC 6744 is thought to be on of the most similar to our Milky Way in terms of appearance. It has flocculent spiral arms and a large, distinctly elliptical nucleus. One distorted companion galaxy, known as NGC 6744A (PGC 62815), resembling the Magellanic Clouds has been identified. The background galaxies IC 4820 and IC 4823 lie close by.

From my own experience, NGC 6744 is easy to see as a faint glow but the spiral arms are very hard to see due to their low surface brightness and low contrast with the rest of the galaxy and the sky background. Using a 12" dob in 2019 I noted

"At 160x a very large, oval glow with a bright central region and a stellar core. From the core a bar runs south-south-west and to the west runs a dark lane parallel to the bar. No further details visible."

Using my 20" dob at the end of August this year I noted:

"At 83x and 99x a large oval glow with a stellar core. Two dark patches (one larger than the other) are visible. Just outside a string of three stars an elongated glow is visible. At 151x and more at 256x the core becomes oval. Very subtle arcs become visible and are very hard to hold. The elongated glow next to the stars becomes clearer."

At the time of my observations I wasn't aware of NGC 6744A, nor of the two IC galaxies, so I certainly need to visit the area again. I am curious to know what any of you managed to make of this observing challenge.


As always,

"Give it a go and let us know!
Good luck and great viewing!"

[Steve Gottlieb]

Even in a very large scope, well defined spiral structure is elusive. My last observation was through a 30" near Coonabarabran, though I was really examining the galaxy for HII knots.

At 264x, I primarily scanned NGC 6744 looking for very small HII regions. The offsets stated here are relative to a very small bright nucleus, which was sharply concentrated within the core. A non-stellar knot was noted 2.5' NW of the nucleus. A second knot was seen 2.9' ESE of the nucleus and a third was just 1.6' NE of center. Roughly a dozen "stars" are superimposed on the galaxy and some of the fainter ones may be stellar HII knots. Spiral structure was too subtle to see any definite arms.

.

IC 4823, located 18' southeast of NGC 6744, is an interesting galaxy -- resolved as a double at 264x.

Fairly faint, moderately large,, elongated 3:2 SW-NE, 45"x30", relatively low even surface brightness. Forms a double with PGC 62891 barely off the southwest end [27" between centers]. The small companion is very faint, extremely small, round, 10" diameter. On first glance this double system could be mistaken for a single elongated oval as they seem to have a common envelope 1.1'x0.6'. Located 18' SE of NGC 6744 and 8.5' SW of mag 8.0 HD 178534.

.

IC 4823.jpg

[kisspeter]

I can contribute a 16" drawing from 2016, Hakos, Namibia (180-225x):
ngc6744_kisspeter.jpgngc6744_kisspeter_positive.jpg

The spiral structure was very difficult to see. Basically the whole galaxy is faint and low-contrast except for the tiny core. The spiral arms were much easier to see in a 24" (same location and time, no drawing).

[cloudbuster]

That's an impressive observation Peter, I did not even come close to that also with a 16" from Namibia. My notes:

The Pavo Galaxy proved to be a tough object, as is often the case with a face-on. It did not help seeing this object for the first time in my life and immediately having to draw it… This is a large galaxy and with a mottled appearance. The shape is slightly oval and the core is small, almond shaped and very bright. Five foreground stars could be seen on the face and two more near the edge. Spiral structure is seen, but it’s hard to see individual arms. I think I saw the N one (down in the sketch), but only because there is a dark zone between it and the core. On the S-side this is less clear. This galaxy screams for larger aperture. Sketched with a 16? Dieter Martini dobson @81x.

NGC-6744-uitsnede.jpg

[Uwe Glahn]

I found two (funny) entries in my logs.

12", 109x, NELM 7m5+ (Hakos/Namibia)
very bright and large but low surface brightness; 2:3 N-S elongated with large nucleus; faint, clockwise rotating spiral arms indicated through dark structures; NGC 6744A visible as a very faint but large structure 10' NW and looks like a part of one spiral arm

17", 182x, NELM 7m0+ (Hakos/Namibia)
very large; large N-S elongated bar-like nucleus; many stars and easy visible spiral structure; sketch cancelled because of to much details