I first made the acquaintance
of this wide open star cluster in late July of 1971. I was observing with my Tasco Lunagrosso 4.5” Reflector. It was also the summer of a very favourable
opposition of Mars. Life was good! I wrote at the time: “A very large open
cluster of stars, mostly white. The
object filled about half of my field of view at 22x, and all of my 45x
eyepiece. At the lower power I counted
about 25 stars, several of them 6th and 7th magnitude, although some were much
fainter. M 39 is a very pleasant
cluster to view, and easy to locate.”
Cut to late August, 1978. I am now using my Edmund 8” Reflector, the
big red beast! My notes from then: "M 39 is a cluster so bright and widely
scattered that it is seen very well in the 9 x 30 finderscope [virtually a 1”
scope]. This also makes it a very
worthwhile object for binoculars. 36x
and 56x suited this very loose group. I
stopped the scope down to 4”, and the group was splendid to view! Indeed, full aperture added nothing but more
brightness, and a few much fainter stars.
At full aperture, an interesting way to view this cluster is to put it
well out of focus. My favourite view
was at 56x and 4” of aperture, however.
A lovely wide pair of stars lies near the very center (ARN 78:
7.6-8.8/52”).” Two other doubles with
bright primary stars are just south.
In late September of 2013 I
observed it with my Orion 12” Dob. “The
cluster looks best at low power. It is
suitable for a 2” refractor and anything larger. I used 43x and 60x, where the cluster appears like a slightly
more condensed version of the Pleiades.
The stars are nearly blinding in a 12” mirror. Not a rich cluster, but very bright and well scattered.” And I did indeed view it in Space Eye more
recently, my wonderful 2” refractor, declaring it a minor showpiece for that
instrument.
https://skyview.gsfc.nasa.gov/current/cgi/runquery.pl?Interface=bform&VCOORD=ngc+7092&SURVEY=Digitized+Sky+Survey&SCOORD=Equatorial&EQUINX=2000&MAPROJ=Gnomonic&SFACTR=0.35&ISCALN=Linear&GRIDDD=No&COLTAB=B-W+Linear&PIXELX=600&PIXELY=600
I consider M 39 a great summer
object to show people who are new to telescopes. It makes an immediate impact, and rewards longer views with the
bright double stars, as well as the many fainter members. For experienced observers an interesting
side trip can be made to oc Platis 1, marked as Anon Platis on Unronometria
Chart 32. Lying ½ degree north and 2'
preceding (west) the Messier object, this tiny cluster will reward viewers with
scopes of 8" or higher. The region
around Messier 39 is littered with small clusters and interesting star fields,
and makes a good starting point for some low power meandering.
M 39 (oc 7092): Size 31’; Mag. 4.6; Br. star mag. 7.
Oc Platis 1: Size 10’; Br. star mag. 8.9.
Clear skies.
Mapman Mike
No comments:
Post a Comment