M37 - 11/30/2007

Object: M37	Camera: Meade DSI-Pro II
Date: 11/30/2007	Telescope: Meade 80mm APO refractor w/6.3 reducer
Total Exposure: RGB - 30':40':40'	Subexposures: 2 minutes each
Location: West Boylston, MA

Processing:

Aligned/combined all files in AutostarSuite Image Processing software

Imported resulting files to Photoshop 7 via FITS liberator

Stretched each channel once via Curves

Reset the black point in each channel via Levels

RGB merged the three files

Stretched the RGB image via curves

Repaired stars vie clone and/or smudge tool

Removed slight gradient via Radial Gradient tool

Created a new layer

Set foreground color to color from edge of gradient

Set background color to color from center of gradient

Apply Radial Gradient(foreground to background) drawing from the edge to the center

Create a new layer between the gradient and background layers and fill it with the background color

Set the blend mode for both of these layers to "difference"

Merge the gradient layer down into the fill layer

Merge the fill layer down into the background layer

Gradient is gone

Selected brighter stars and adjusted the Hue/Saturation to taste

Duplicated the main layer (there was only one at this point)

Sharpened edges, set Opacity to 45% and merged down

Lowered the output level of the red channel to 226 to reduce the overall red cast

Description:
M37
Discovered by Giovanni Batista Hodierna before 1654.

Although Messier 37 (M37, NGC 2099) is the brightest of the 3 open clusters in southern Auriga, this cluster was missed by Le Gentil when he rediscovered M36 and M38 in 1749, so that it was to Charles Messier to find this one independently on September 2, 1764. Generally unknown until 1984, all three clusters had been previously recorded by Hodierna before 1654.

M37 is the also the richest of the 3, containing about 150 stars brighter than mag 12.5, and perhaps a total of over 500 stars. As indicated by the fact that it has a considerable number (at least a dozen) of red giants, and that the hottest main sequence star is of spectral type B9V, this cluster is a more evolved group with an estimated age of about 300 million years.