In
October of 2014, when I moved to China, my hope was to catch more DSOs and
complete the Messier list. All that I had then was a little more than 30
Messiers that I have seen from Bogota and my 15x70 Celestron Skymaster
binoculars. Upon arriving, the list started to grow faster. During the first 7
months I added to the list my firsty galaxies (other than M31), some more
globular clusters and a few open clusters. Later, I had completed 75% of the
whole list, but truly with the binos the list contained only smudges, fuzzy cottonish
balls and blurry like stellar objects.
I
often like to compare binocular vs telescope views to show what magnification
can do for one and this entry is one of those. This time the turn is for M46, a
like nebular object in binoculars with a few stars inside it. In fact, Caroline Hershel decribed it in 1783 like
this: “1 deg
S following the nebula near the 2nd Navis [Puppis; M47], a Nebula the figure is done
by memory”. If I did not know it
was an open cluster I could think it was a nebula region like the type of
Lagoon or Orion Nebula.
In
middle of the very starry wide FOV, one can discern M47, a bright cluster at 2
o’ clock in the sketch. Right diagonal to it there is M46, a nebulous area with
few resolvable stars.
Last
december, I decided to apply more magnification to M46 and apart from resolving
plenty of the individual stars in the cluster, I found a treasure among the
stars: NGC 2438, a planetary nebula superimposed on the stellar cluster. With
only 37.5x, but with averted vision, it was possible to see a circular and
fuzzy smudge. With 100x it lost some of its surface brightness and looked like
a ghosty and almost shapeless patch. In the sketch, it can be seen to the right of the cluster and it looks like a circular and dim fuzz.
M46 has
a an estimated population of about 500 stars with 150 of the stars between
magnitude 10th-13th. With direct vision I could see about 30 of those stars and
much more with averted vision. Unfortunately, while using averted vision I got
lost inside the cluster and decided it was time to finish the sketch.
And finally, here
is the original sketch with some additional information about this observation.
Clear skies,
LG
Edited by: Jennifer Steinberg (editor
in chief)
SOURCES
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