[AZ-Observing] M33's HII Regions

Most nights I observe, the target list includes about a dozen discreet 
objects, sort of like a trip through the deep-sky buffet. But last night I 
decided 
on a classier meal, seven courses in the same fine dining establishment known 
as M33.
 
The nights are starting to get a little crisp in northern Arizona, so I and a 
couple of friends from the Coconino Astronomical Society made the 45-minute 
drive south to Beaver Creek where the temps are about 10-degrees warmer and the 
hills to the north would provide some shelter from a cutting north wind. I 
arrived about an hour after sunset and quickly setup my 10-inch, f/4.5 Meade 
Newtonian. While the Starfinder was cooling I hooked up with Brent Archinal and 
Padraig Houlahan, chatting and catching up on the week's events.
 
This ended up being a very casual observing session. I didn't even break out 
my sketch materials. We spent most of the time talking astronomy and enjoying 
a gorgeous naked eye view of the Milky Way, zodiacal light and, later, the 
gegenschein. But we did do some telescopic observing. My first stop with the 
10-inch Starfinder equatorial was M33 in Triangulum. This Sa-type spiral covers 
roughly a 55'x30' area at 36X (32-mm Tele Vue Plossl) in the Newtonian. It is 
elongated nearly north-south with three faint spiral arms--one to the north and 
two to the south--tracing lazy arcs away from the nuclear region.
 
I pulled my copy of Vickers' "Deep Space CCD Atlas: North" from the equipment 
case and looked up his image of the Pinwheel. We used this as a finder chart 
to locate three HII regions within M33. These were NGC 604, NGC 595 and NGC 
592. NGC 604 is the largest and brightest of these. We first located a pair of 
10th and 11th magnitude stars blazing 11.5 arcminutes north-northeast of M33's 
core region. They lie about 5' north of the stellar nursery, are separated by 
about an arcminute and point the way to 10.9 magnitude Tycho 2293:642:1. This 
star shines immediately to the east of NGC 604. The HII region was seen as a 
hazy patch approximately 1' in size. Putting in the 8.8-mm Meade UWA eyepiece 
(129X), the HII region really popped out and presented an irregular form.
 
Having finished the first two courses of this meal, we set our sights on NGC 
595. This HII region resides about 5' west-northwest of the galaxy's core. As 
a reference point, I used 11.3 magnitude Tycho 2293:637:1, 11' due west of NGC 
604. A 12th magnitude GSC star simmers 50" to the east and, 3' to the 
north-northeast, is another 12th magnitude GSC star. All three were seen in the 
10-inch and they point the way to NGC 595, 5' distant. A 13th magnitude star 
smolders about two-thirds the distance along that path. The HII region was 
picked up 
as a smallish fuzzy spot a couple arcminutes south-southwest of this faint 
ember.
 
While observing NGC 595, Brent noticed an HII region further to the west. 
This was NGC 592, 5'.4 west-southwest of NGC 595. There are several other 
nebulous regions and clusters which can be observed with moderate to large 
aperture 
in M33. We stopped our tour with NGC 592. The galaxy was sailing high in the 
sky where the seeing is typically best. So, I paired a Meade 13.8-mm SWA with 
Tele Vue's 3X Barlow for a 247X view of NGC 604. High magnification really 
helps 
these small, bright nebulous objects stand out and show their stuff. This was 
the best view of the night and a fine way to wrap our visit to the five-star 
deep-sky diner, M33.
 
Regards,
Bill Ferris
"Cosmic Voyage: The Online Resource for Amateur Astronomers"
URL: http://www.cosmic-voyage.net


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