M46 - two for one (Tom Gray)

M46 - two for one

Revision title: Reprocessed less aggressively

M46 or NGC 2437 is a fine open cluster in the constellation Puppis, containing around 500 stars, with median age ~0.25 billion years old. Superimposed is a relatively bright Planetary Nebula NGC 2438, ~1370 LY away, made up of bright core (this image) and two much fainter shells, and is thought to be expanding ~37 km/s [Wikipedia].

This image is the result of a short integration to test my optical train at f10, after tweaking collimation, and is inspired by @Simon's recent much nicer image of the same. I collected the data 1x1 using 60s exposures, and had hoped to maintain better star colour, but the camera gain was set too high resulting in the stars saturating and losing the lovely blues and reds apparent in other images.

The original image comprises 25m calibrated in Nebulosity and processed using Startools. I had to bin the data 4x4 to reduce noise and excessive over-sampling, I then layered a less stretched version, revision B (mouseover) to try and rescue some star colour, but without much success. Revision C show the optical tilt using Han Klein's excellent CCD inspector.

Revision D is my final version with less aggressive processing, and better star colour.

Original
B
C
Final
D

B

Title: Layered image to reduce saturation in stars

Description: In this version I used a less stretched layer to try to avoid over-saturating the stars. Binning during processing, rather than on image capture helped. Startools 'layers' module has a number of presets - 'hardlight' tends just to darken (clip) the image, and reduce star glow. I'm not convinced.

Uploaded: ...

C

Title: Optical tilt

Description: Using Han Klein's CCD inspector

Uploaded: ...

D

Title: Reprocessed less aggressively

Description: Reprocessed less aggressively, no sharpening, minimum deconvolution and less colour saturation. I have largely managed to reduce the colour split in some of the stars, using the lens module. Shorter exposures will avoid saturating the brighter stars.

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	5573817
PixInsight job	K14FASFKL0T8B1HW78LTACSL4Q5YK9F5
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	07h41m45s.34
RA (top/left)	07h42m33s.97
RA (top/right)	07h40m56s.89
RA (bottom/right)	07h40m56s.74
RA (bottom/left)	07h42m34s.70

Dec (center)	-14°48′05″.3
Dec (top/left)	-14°40′23″.3
Dec (top/right)	-14°40′22″.3
Dec (bottom/right)	-14°55′47″.10
Dec (bottom/left)	-14°55′47″.8

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M46 - two for one

Revision title: Reprocessed less aggressively

M46 - two for one

Revision title: Reprocessed less aggressively

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M46 - two for one

Revision title: Reprocessed less aggressively

M46 - two for one

Revision title: Reprocessed less aggressively

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D

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