I use a handful of websites to aid in my astronomy planning. To me the most useful one is any weather app that shows past, current and future cloud cover. I want to see for myself where the clouds are and what they are up to. Astropheric is good, and their app is pretty decent, too. Next in importance for me is Telescopius. I use this to prepare myself for faint galaxy searches, drawing by hand the area around a faint object in the hopes of getting there easier with the scope. My push-to computer gets me in the vicinity, but to pinpoint the exact location of a 14th mag. galaxy requires a lot more than being in the vicinity. The site is also useful for providing info on the degree above the horizon an object is at any given time. Those are my top two websites. However, when I am preparing a new constellation to observe I use Stelle Doppie to prepare my double star list. Users can customize which stars to try splitting (my way) or use their own prepared lists. My 12" list of double stars often numbers in the hundreds for a given constellation (say Cassiopeia, for example). Next I find Cseligman very helpful, especially when confusion arises regarding errors in the NGC or IC. I also like to use TimeandDate to get my accurate moonrise and moonset times. I use a host of other sites, but not as often as the ones above, which I find indispensable.
Moving on towards Messier 3 in this ongoing series, I should say here that I like to observe the area around bright deep sky objects to see if any other worthy sights are just a short hop away. In the case of M 3, there is. 24' following M 3 sits faint gc 5466. First seen in late July 1992, I was unable to see it earlier from suburban skies with my 8" Edmund reflector. But from Lake Penage west of Sudbury in northern Ontario it was easily swept up at 36x. It appeared as a large and faint round haze, with no resolution. However, 59x and 72x showed some resolution with averted vision. No bright center was seen; just a uniform dim haze. At 112x the cluster was dimming and fading, with higher magnifications being useless. Jump to early June 2013. Looking at the specs this sounds like a showpiece (Mag. 9.2, 9'). It isn't, even in a 12" scope. It is very faint, but very large. The bigger scope resolves the cluster fairly well, and it was observed at 60x, 100x and 120x. Stars were resolving well beyond the hazy ball itself, especially south.
Turning now to Messier 3 it was in late May of 1998 I viewed the globular cluster with the 8". This is a real treasure of the sky! Especially if one tackles the much fainter gc 5466 first. M 3 is an amazing and brilliant object. At 36x outliers were resolving. At 59x dozens of stars, mostly outside the ball of bright haze, resolve. At 112x stars were resolving to the core. 169x and 200x show countless stars, and a tantalizing sphere of unresolvable haze in behind. This is a showpiece for 4" and higher!
M3 (NGC 5272) is one of the finest globulars in the sky, and makes a very refreshing sight after viewing so many galaxies, my most frequent visual targets. Finding M3 is easy. Locate Arcturus, and then nearby Eta (just south preceding it, mag. 2.5). Make Arcturus and Eta the east-west baseline for a right-angle triangle, shooting north twice the distance of that baseline (see map: note M53 and M 64 are also shown, but are not part of this discussion). At a visual mag. of 6.3, even in binoculars M3 is impressive. It resolves nicely in a 6” mirror, and in my 12” at 170x I’m beginning to get that Hubble feeling. The main body spreads out over 18’, though outliers go well beyond. The brightest star is mag. 12.7, so in a really dark sky smaller scopes will partially resolve this cluster nicely. This is a cluster not to be missed, enhanced greatly by its high declination.
There is also a small 13 mag. galaxy just preceding M3 (not on map) which I have not observed. It will be added here in the future.
Mapman Mike
