This giant diffuse nebula is one of the largest H II regions (ionized hydrogen gas) in our galaxy.  Eta Carinae itself is a very peculiar star, having varied widely in brightness in the past.  At one time in 1843, it was the brightest star in the sky after Sirius.  It is thought to be among the most massive and luminous stars in our Milky Way, at more than 100 solar masses.

Image info

Telescope:  Celestron 9.25" Schmidt-Cassegrain at f/6.3

Focus:  Prime focus

Filter:  Astronomik Hydrogen Alpha 13nm FWHM

Mount:  Vixen GPD with Skysensor2000

Camera:  Modified Canon EOS 300D, at ISO800

Guiding:  700mm refractor guidescope, SAC7 camera, autoguided with Guidedog software

Exposure:  Total 75 mins (25 x 180s)

Date:  9th March 2005

Processing:  RAW file conversion, Offset and Dark subtraction, flat fielding, registering and stacking done in IRIS.  Only the Red channel was used.  Curve stretching and a little unsharp masking in Photoshop CS.

Comments

First light with the Hydrogen Alpha filter.  This nebula appears at no more than 30 deg above the horizon within the murky skyglow of Singapore city.  Even with the filter, as the nebula got lower through the night, skyglow started to drown out the signal.