Designation: Messier 33, NGC 598 Constellation: Triangulum
Visual magnitude: +5.8 Apparent size: 62′ x 36′
Diameter: 50,000 light years. Distance: 2,800,000 light years
The Triangulum Galaxy (M33) is an unbarred pinwheel type galaxy which sits about 15° from the Andromeda Galaxy (M31).
At magnitude 5.8, M33 is technically a naked eye object in a perfect dark sky – which is something I am never likely to experience. I certainly would not see it from here in SW Sydney, looking through the murk and light pollution of Greater Sydney to my north.
Here’s a daytime telephoto picture, looking towards Sydney from The Australian Botanic Garden, which is situated between my home and the observing site I use with Macarthur Astronomical Society. Sydney is about 40 km away and Sydney Harbour Bridge is the arch at far left:
Sydney glows a lot at night – but I digress.
M33 is the third largest galaxy in the Local Group, after M31 and the Milky Way. It is closer to M31 than it is to the Milky Way and I understand it to be interacting with M31. It is possibly even a satellite of it and the two may well eventually merge. Hard to tell, I would have thought, because everything in astronomy happens really slowly – but professional astronomers are so darned clever they seem to be able to figure hard stuff out.
The number of stars in the four largest galaxies of the Local Group are estimated as :
Andromeda Galaxy: 1 trillion.
Milky Way: up to 400 billion.
Triangulum: 40 billion.
Large Magellanic Cloud: 30 billion.
I didn’t know that.
An interesting list of all the known galactic bodies in the Local Group (not including globular clusters) can be found >here<, which is where I pinched this fascinating pictogram of the objects in the Local Group:
Also in the field of view according to this Astrometry.net annotated overlay:
NGC 588, NGC 592, NGC 595, NGC 603, NGC 604, IC 132, IC 133, IC 134, IC 135, IC 136, IC 137, IC 139, IC 140, IC 142, IC 143.
Image & Processing:
|Location: outer suburban
Conditions: clear sky, no Moon
Sky brightness: 0.24 e/pixel/sec .
Image acquisition: SharpCap.
Image post-processing: GIMP.
|Telescope:||SkyWatcher Esprit||Type:||120 triplet refractor|
|Focal:||840 mm F/7||Mount:||SkyWatcher EQ6-R Pro|
|Camera:||ZWO ASI 071 MC Pro
||Type:||CMOS 28.4mm 16 Mpx
|Optical aids:||Flattener: Y; filter: LP||Guiding:||Yes|
|Polar aligning:||QHYCCD PoleMaster||Polar Error:||3′ 45”|
Geek Log, for my records:
[ZWO ASI071MC Pro]
Auto Exp Target Brightness=100
Images © Roger Powell