First off, if I may, a quick comment on the process we use for these challenges. I would suggest that at a minimum, the two challenges at least be in their respective celestial hemispheres. While I have no issues with M74, I feel it should not be included in the southern hemisphere. While it is indeed visible to many in the southern half of the globe, technically it is a northern object. Given the vast number of objects that fall within the visibility parameters used for the monthly challenges in both celestial hemispheres, I don't see a need to pull both objects in the same month from only one of them. Okay, off my soapbox!
NGC 457 (Cassiopeia, open cluster, mag=6.4, size=13.0', class=I3r):
I have observed this autumn and winter staple countless times over the decades. Variously nicknames the owl cluster, E.T. cluster, kachina doll cluster and dragonfly cluster, it is well suited for small to large apertures. In 10x50 binoculars I find the owl's eyes stand out well, though the overall cluster is only partially resolved. I have observed it using apertures of up to 12 inches. Here are my notes from one such observation with the 12 inch:
"The owl’s eyes (Phi Cass and HD 7902) were easy to spot in the RACI. At 84x, the field exploded with little jewels comprising the owl’s body and outstretched wings. Its eyes were sizzling diamonds dominating the field. Rich and very detached from the surrounding field, this cluster is one of the prettiest ones in the sky in my opinion and one of my personal favorites."
NGC 628 / Messier 74 (Pisces, spiral galaxy, mag=9.4, size=10.5'x9.5', SBr=14.2):
This spiral galaxy is often cited as the most difficult target in Messier
's list of objects. Though it sports a reasonable visual magnitude, its face-on orientation and larger angular size reduces its average surface brightness noticeably. This creates problems for folks observing from areas of moderate to heavy light pollution, particularly with smaller apertures. As with all the Messier
objects, I have observed it numerous times over the years from various locations and with different apertures. From a semi-dark area I suspected it in 10x50 binoculars, while from my typical suburban backyard it has been observed in both 10 and 12 inch scopes with little difficulty - though it could hardly be described as a showpiece. I even observed a supernova within M74 (SN 2013ej) with the 10 inch from our backyard. My most recent observation of this elusive galaxy is at our dark site with the 17.5 inch just last month, where I recorded it thusly:
"M74 was easily swept up at 110x it presented a large and very obvious rounded disk that was quite diffuse in appearance. The core was a broadly brighter central brightness. Using 152x and 198x it was quite pretty and large in the FOV, with hints of subtle spiral structure within the diffuse glow."