The Dumbbell Nebula is a planetary nebula in the constellation Vulpecula. M27 lies about 1200 light-years away, and is notable for being the first planetary nebula discovered. This occurred on 12 July, 1764, when Charles Messier first recorded his observation of this object.
It is estimated that the star which formed this nebula died sometime between 4 and 15 thousand years ago. The expansion rate of the nebula's gas is key to understanding the time elapsed since the death of its origin star, but thus far different measurements have not always been in agreement.
The Dumbbell Nebula is quite bright for deep sky standards; through smaller telescopes it still makes quite an appearance to the eye, and like many planetary nebulae, appears green. This is because the human eye peaks in sensitivity in the green part of the spectrum; the green light from the nebula is just bright enough to stimulate the eyes in this region.
This image was my first using filters, and a test to see how it compared to previous shots of this nebula. It was taken at Starfest 2016.
- Canon T3i (modified: missing IR cutoff)
- Skywatcher NEQ6 Pro (Guided: Orion StarShoot, PHD2)
- Vixen VMC200L (1950mm f/9.75)
- H-alpha (R): 16x 5min exposures @ ISO-1600 (1h 20min)
- O III (G): 25x 5min exposures @ ISO-1600 (2h 5min)
- H-beta (B): 10x 5min exposures @ ISO-1600 (50 mins)
- Average sensor temperature: ~27.0 °C
- 21x Darks
- 200x Biases
Processing was done in PixInsight v1.8. The images were calibrated using ImageCalibration and ImageIntegration. The R, G, and B image data was used to create a synthetic L image, which was processed separately. The R, G, and B images were combined into a single RGB image.
On the RGB image, ColorCalibration was used to fix the colour of the image, and the image was stretched. The saturation was set using CurvesTransformation, and SCNR was used to remove a green overcast, with masking to protect the nebula. The black point was reset, and Convolution was used to blur the edges between colours.
On the L image, deconvolution was performed, and MultiscaleLinearTransform was used for noise reduction with a linear mask applied. The image was then stretched and combined with the RGB data.
TGVDenoise was used on the image to make slight corrections for colour noise, and LocalHistogramEqualization was used to recover some structure inside the nebula. MorphologicalTransformation was used to slightly reduce star sizes, and MultiscaleLinearTransform was used for overall sharpening. HistogramTransformation was used to reset the black point, and CurvesTransformation was used for final adjustments of saturation and contrast.
Data was collected on the night of August 6, 2016, at River Place Park in Ontario, Canada. This is a Bortle 4 site.