NGC2237 - Rosette Nebula

NGC2244 - open cluster

Date: 11/02/08    Time: 2330hrs   Location: Sunningwell   Temperature: 5.6ºC  Relative Humidity: 75%

Camera: Nikon D80    Scope: William Optics Z66 Apo Doublet at prime focus   Mount: piggy-backed on Meade LX90 in equatorial mode  Exposures: (8x240) + (2x180)  seconds  ISO: 1600   F ratio: 5.9   Guidance: Autoguided

This large HII region of nebulosity covers as much area in the sky as the full moon. Its low surface luminosity however, renders it largely invisible to the human eye even with clever high contrast, narrowband filters.  It is located just east of ε Monocerotis, which is the fourth faint star in a curve arcing southwest from the foot star of Pollux in Gemini.  NGC2244 is the bright young open star cluster formed from the gas in the nebulosity, the stellar winds of which have driven the gas cloud apart to create the clearing in the centre of the nebula.  Close inspection of the nebulosity reveals dark patches known as Bok globules where active star formation is still taking place.  The spectral class O and B stars in the cluster are only approximately 1 million years old and lie about 2600 light years away.

The best of 17 exposures were stacked in Maxim DL making a cumulative exposure time of 38 minutes.  The sky was heavily light-polluted with a first quarter crescent moon setting in the west, and bright white floodlights to the south.  The discoloured orange-brown sky background was subtracted in Photoshop followed by white and black point setting, and midtone enhancement.  One pass of Noise Ninja was made prior to cropping of the finished picture.  The field is not flat and there is elongation of the stars in the radial axis at the very edge of the picture.

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