Object name: M033

Designation(s): M033, NGC0588, NGC0592, NGC0595, NGC0604, IC0131, IC0135, IC0136, IC0137, IC0140, IC142, IC143,

M33, often called the Triangulum Galaxy since it is in that constellation, is the other rather large galaxy in our local group along with M31. Like M31 it is also approaching us but won't arrive here until well after we've merged with M31. Though eventually, all three will become one along with a lot of dwarf members of the local group that weren't ejected by these big boys gravity. Distance estimates range from 2.8 to 3 million light-years. Since it doesn't fit my field of view I have to use published size measurements of 70.8' at NED to estimate its size. That would make it about 58,000 to 62,000 light-years in size or about half that of M31. NED classifies it as SA(s)cd HII while Seligman adds a question mark SA(s)cd?. It contains one of the largest HII regions known. Originally it had enough mass to create a globular cluster though only created a rich open cluster. the detailed HST image is at:

Seen more face on than M31 its HII regions are much easier to see. Also, it seems to have far more big ones than M31. Many have IC and NGC numbers. I've included an annotated image showing all the IC and NGC nebulae and star clusters. Obviously, there are far more. They have names that only are positional which are long and would make a mess of the image so I didn't bother with them.

M33 was likely first recorded by Giovanni Hodierna before 1764. Though it is barely visible naked eye from a good site. I need averted vision to see it. Being visible naked eye I suppose someone saw it thousands of years ago and wondered what that fuzzy thing was but never recorded it. Even Hodierna's observation went unknown for 300 years. Thus it was Charlies Messier who brought it to the attention of astronomers when he added it to his list on August 18, 1775. William Herschel recorded it on September 11, 1784. Even though already in the M object observing program the AL put it in their original Herschel 400 program as well. My log from that on July 14-1985 with my 10" f/5 at 60x on a night with bright auroral activity visible from here in northern Minnesota reads: "Large, face on spiral. Two arms easily seen as is NGC 604. It is surprisingly good considering the auroral activity I'm having to observe through."

NGC 604 has been mistaken for a comet by more than one amateur on this list that shall remain nameless. It was discovered by William Herschel on September 11, 1784. It is in the second Herschel 400 program. Unfortunately, my notes from that didn't survive the move up here.

NGC 595 is another emission nebula. It was discovered on October 1, 1864 by Heinrich d'Arrest.

NGC 592 is a star cluster in an emission nebula. It was discovered by d'Arrest several 3 years before he saw NGC 595 on October 2, 1861.

NGC 588 is an emission nebula with a small star cluster in it. It was also found by d'Arrest on October 2, 1861.

IC 131 is often mistaken for the bright star with emission around it that is just west of the real IC 131 which is an emission nebula and star cloud per the IC description. Also the position better matches the object I've identified as IC 131. It was first seen by Guillaume Bigourdan on October 28, 1889.

IC 135 is on the eastern side of the galaxy showing many of the IC objects in this galaxy fail to follow RA order for some reason. It is an emission nebula and was discovered by Guillaume Bigourdan the same night as IC 131 and others. There's some uncertainty about the identification of this one. This is what most say is IC 135 but no one can fully make it work with Bigourdan's notes.

IC 136 is listed as an open cluster but it also is an emission nebula. At least the object I've identified as IC 136 is. It too is one Bigourdan found that fateful October night and it too doesn't quite fit his notes but again is the best anyone has come up with for this object.

IC 137 is an open cluster toward the south end of the galaxy. It too was found by Bigourdan that same night and it too has identification issues. Bigourdan's position is over a minute south of the object I've identified as IC 137 but it does match his description and there's nothing like it at his position so another somewhat questionable ID.

IC 139 is listed as an open cluster but I see emission nebula in it. Another Bigourdan discovery that October night. But this one has a rather certain identification for a change.

IC 140 northeast of IC 139 is an open cluster. Yep, another Bigourdan discovery that same night. Like 139 identification of this one seems certain.

IC 142 is listed as a star cluster though emission nebula surrounds it in my image. It is well north of the galaxy's core. Another Bigourdan discovery that October night. One that also has a rather certain identification

IC 143 lies northeast of IC 142 and is an emission nebula. Another Bigourdan find that October night. Its ID is pretty solid.

Many other nebulae, star clouds and star clusters can be seen in my image. I only identified those in the IC and NGC catalogs.

For a lot more on M33 see:

14" LX200R @ f/10, L=4x10'+3x30Ha, R=2x10'+80% HA, G=2x10' B=2x10+20%Ha, STL-11000XM, Paramount ME

Related Designation(s):

11HUGS 027, 1AXG J013351+3039, 1ES 0131+303, 1RXS J013350.9+303932, 1WGA J0133.2+3045, 1XMM J013311.7+303843, 1XMM J013350.9+303937, 1XMM J013355.5+304529, 2MASS J01335089+3039365, 2MASX J01335090+3039357, 2XMM J013311.6+303842, 2XMM J013350.8+303937, 2XMM J013355.5+304527, 2XMMp J013311.7+303842, 2XMMp J013350.8+303937, 87GB 013046.8+302617, 87GB 013142.8+303139, 87GB[BWE91] 0131+3031, AKARI J0133119+303850, AKARI J0133337+304125, AKARI J0134156+303718, AKARI J0134327+304659, CGCG 0131.0+3024, CGCG 502-110, ChASeM33 067, ChASeM33 200, ChASeM33F 102, ChASeM33F 318, ChASeM33F J013311.75+303841.5 , ChASeM33F J013350.89+303936.6 , CXO J013350.9+303936, CXO J013350.91+303936.7, CXO J013351.0+303937, CXO J013433.7+304701, CXOU J013433.7+304701, GALEX J013350.92+303936.9, GALEX J013355.51+304526.8, GALEX J013358.02+303258.7, GALEX J013415.56+303712.6, GALEX J013415.57+303712.8, GALEX J013416.05+303344.2, GB6 J0134+3047, GSC 2293 01433, HIJASS J0133+30, IC 0131, IC 0135, IC 0136, IC 0137, IC 0140, IC 0142, IC 0143, IC0131, IC0135, IC0136, IC0137, IC0140, IC142, IC143, IRAS 01299+3023, IRAS 01303+3029, IRAS 01310+3024, IRAS 01314+3018, IRAS 01317+3031, IRAS F01303+3030, IRAS F01307+3025, IRAS F01310+3024, IRAS F01314+3018, IRAS F01317+3031, LDCE 0160 NED001, LGG 011:[G93] 002, M033, MCG +05-04-069, MESSIER 033, MESSIER 033:BCLMP 0049, MESSIER 033:BCLMP 0088, MESSIER 033:BCLMP 0277, MESSIER 033:BCLMP 0280, MESSIER 033:BCLMP 0290A, MESSIER 033:BCLMP 0301, MESSIER 033:BCLMP 0680, MESSIER 033:BCLMP 0688, MESSIER 033:[BB87] 25, MESSIER 033:[BB87] 26, MESSIER 033:[BCM85] 08, MESSIER 033:[BCM85] 36, MESSIER 033:[BCM85] 53, MESSIER 033:[CC65] 049, MESSIER 033:[CC65] 088, MESSIER 033:[DDB80] 2.16, MESSIER 033:[GDK99] 006, MESSIER 033:[GDK99] 006 ID, MESSIER 033:[GDK99] 032, MESSIER 033:[GDK99] 060, MESSIER 033:[GDK99] 102, MESSIER 033:[GDK99] 155, MESSIER 033:[GDK99] 174, MESSIER 033:[GDK99] 174 ID, MESSIER 033:[GKL98] 21, MESSIER 033:[HP2001] 045, MESSIER 033:[HP2001] 048, MESSIER 033:[HP2001] 102, MESSIER 033:[HP2001] 152, MESSIER 033:[IV74] 01, MESSIER 033:[IV74] 08, MESSIER 033:[IV74] 09, MESSIER 033:[IV74] 22, MESSIER 033:[IV74] 45, MESSIER 033:[IV74] 58, MESSIER 033:[IV74] 64, MESSIER 033:[LBW2010] 025, MESSIER 033:[LCB96] 12, MESSIER 033:[LCB96] 14, MESSIER 033:[LCB96] 28, MESSIER 033:[LCB96] 40, MESSIER 033:[LDC81] 03, MESSIER 033:[LDC81] 08, MESSIER 033:[MA42] 02, MESSIER 033:[MBH96] 058, MESSIER 033:[MBH96] 218, MESSIER 033:[MBH96] 315, MESSIER 033:[MBH96] 334, MESSIER 033:[MPH2006] 108, MESSIER 033:[MPH2006] 182, MESSIER 033:[MPH2006] 254, MESSIER 033:[OKT2012] 13, MESSIER 033:[PMH2004] 121, MESSIER 033:[PMH2004] 211, MESSIER 033:[PMH2004] 299, MESSIER 033:[PMH2004] 299 ID , MESSIER 033:[S71a] 06, MESSIER 033:[S71a] 09, MESSIER 033:[S71a] 13, MESSIER 033:[S71a] 16, MESSIER 033:[S71a] 17, MESSIER 033:[S71a] 25, MESSIER 033:[SB95] 04, MESSIER 033:[SB95] 16, MESSIER 033:[SB95] 22, MESSIER 033:[TFP88] X-03, MESSIER 033:[TFP88] X-08, MESSIER 033:[VBW78] 08, MESSIER 033:[VBW78] 10, MESSIER 033:[VGV86] II-022, MESSIER 033:[VGV86] II-026, MESSIER 033:[VGV86] II-041, MESSIER 033:[VGV86] II-095, MESSIER 033:[VGV86] II-106, MESSIER 033:[VHC2007] 184, MESSIER 033:[VHC2007] 187, MESSIER 033:[VHC2007] 238, MESSIER 033:[VHC2007] 340, MESSIER 033:[VHC2007] 457, MESSIER 033:[WWH2015] 0654, MESSIER 033:[WWH2015] 0934, NGC 0588, NGC 0592, NGC 0595, NGC 0598, NGC 0598:[FK2005] 03, NGC 0598:[L2011a] X0001, NGC 0598:[LM2005] ULX01, NGC 0598:[RPS97] 07, NGC 0598:[RPS97] 21, NGC 0598:[RPS97] 30, NGC 0604, NGC0588, NGC0592, NGC0595, NGC0604, NSA 130004, NSA 154372, NVSS J013245+303859, NVSS J013312+303845, NVSS J013312+304512, NVSS J013334+304133, NVSS J013351+303933, NVSS J013354+304532, NVSS J013415+303707, NVSS J013432+304700, PGC 005818, RBS 0214, RX J0133.8+3039, RX J0133.8+3039:[BEV98] 004, RX J0133.8+3039:[ZEH2003] 01 , SSTSL2 J013350.85+303936.6, SSTSL2 J013410.98+304635.9, SSTSL2 J013416.04+303344.6, Triangulum Galaxy, UGC 01117, UZC J013351.1+303922, [BWC2008] U02, [M98j] 104 NED02, [MHH96] J013351+303959, [SPB93] 026, [SSA2010] 1903, [VHC2007] Hra 37, [VHC2007] ISO 08, [VHC2007] ISO 09, [VHC2007] ISO 24,