M46 & NGC2438

Open Cluster with Planetary Nebula in Puppis

Uploaded 12/3/02

Select an image size for a larger view: 800 x 600 1200 x 800

It was an exciting moment when the image of this object poured onto my laptop screen for the first time. My previous shot with the ST7E had only the field to record the planetary, and a few surrounding cluster stars. The 8i chip can now show the whole cluster, the planetary, and the surroundings. Photography of open clusters is now a reality. There are two deep sky objects in this image. M46 is the large rich open cluster dominating the field. Rated at 6.1 magnitude, it is a moon sized 27 arcminutes in size. A foreground object is NGC2438, a neat red planetary nebula off to the north, a bright 10.1 magnitude. The central star is very faint, only magnitude 18 and can just be seen in the larger image. The planetary is a large 1 arcminute in size.

Why are the stars pinpoints right to the corners with a fast f/5 Newtonian? I use a Lumicon Newtonian coma corrector.

Processing: A "synthetic luminance" was created by adding the RGB frames for a low noise L channel.

Instrument:  12.5" f/5 Home made Newtonian
Platform:  Astrophysics 1200 QMD
CCD Camera:  SBIG ST8i
Guider: SBIG ST4
Exposure:  LRGB = 40:10:10:20 (Synthetic Luminance)
RGB Combine Ratio:  1: .8: 1.2
Filters:  RGB Tricolor
Location:  Payson, Arizona
Elevation:  5150 ft.
Sky:  Seeing FWHM = 3.8 arcsec (Maxim DL - 10min subframe), Transparency 8/10
Outside Temperature:  5 C
CCD Temperature:  -20 C
Processing:  Maxim DL, Photoshop, AIP4WIN, PW Pro.


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