Messier 92

Target details

Messier 92 is a globular cluster in Hercules, about 26,700 light-years away. It's one of the brighter and older globulars in the northern sky and in very good conditions can just be seen with the naked eye – yet amateurs often overlook it, because it sits close to the even more spectacular Messier 13. Half of its light comes from within 1.09 arcminutes of its centre.

This image also features NGC 4645, an elliptical galaxy located around 121 Mly from Earth. It has a magnitude of 11.68 & a surface brightness of 21.6. It is to the lower right of the image.

Capture details

Data captured 11 October, 2017.
34x 4 minute exposures at ISO400.

Equipment details

Skywatcher Quattro 200 CF
NEQ6 Pro
Canon 40d (IR Filter removed)
Skywatcher ST-80
QHY5L-II

Processing details

This image was processed in Pixinsight & Lightroom.
Calibration and Stacking in Pixinsight.
Dynamic Crop - To remove black edges & integration artifacts.
Automatic Background Extraction - To remove gradients.
Canon Banding Reduction script - To remove horizontal lines.
Photometric Colour Calibration - To colour calibrate the image.
SCNR - To neutralise green.
Multiscale Linear Transform - Noise reduction.
Histrogram Transformation - To stretch the image and bring out the data.
TVGDenoise - Noise reduction.
HDR Multiscale Transform - To recover additional data in core, with star mask applied.
Local Histogram Equialisation - To sharpen and increase detail, with star mask applied.
Multiscale Linear Transform - To sharpen and increase detail, with star mask applied.

Export as JPEG and import into Lightroom.
Clip Blacks (-25)
Increase Saturation (+50)
Graduated Filter to reduce gradient in lower right corner. Exposure (-0.5)

Export final JPEG for upload.