Object Information

NGC 4565, or the Needle Galaxy, is an edge-on spiral galaxy in the constellation Coma Berenices. Discovered in 1785, this galaxy is one of the narrowest galaxies in the sky as seen from the Milky Way, and can be seen through modest telescopes under good observing conditions.

The galaxy's precise distance is not well known, but it lies at least 30 million light-years away (and likely no more than 60 million light-years). The galaxy itself is a giant spiral - at a distance 30 million light-years, its apparent size indicates that it must be at least 140,000 light-years in diameter, larger than our own Milky Way.

Edge-on spiral galaxies are difficult to study, due to the obscuration of most of their light along the disk axis. Nonetheless, astronomers have determined that NGC 4565 is more luminous than the Andromeda Galaxy, and possesses a central bar. Smaller companion galaxies can be seen in orbit around the Needle Galaxy in this image, notably NGC 4562 above.

Image Information

NOTES

All of the data was slightly fuzzy, and there were tracking errors that manifested themselves. For the most part, these errors were averaged out, but the overall sharpness of the image can be improved with subsequent data sets.

EQUIPMENT

  • Canon T3i (modified: missing IR cutoff)
  • Skywatcher NEQ6 Pro (Guided: Orion StarShoot, PHD2)
  • Vixen VMC200L, with focal reducer (1209mm f/5.95)

DATA

  • 50x 5min exposures @ ISO-1600 (4h 10min) ~2°C
  • 17x Darks
  • 27x Flats
  • 200x Biases

PROCESSING

Processing was done in PixInsight v1.8. The images were calibrated using ImageCalibration and ImageIntegration. The L was extracted from the integrated image, leaving an RGB and L image. On the RGB image, ColorCalibration was used to set the colour, and the image was stretched. CurvesTransformation set the saturation, and a green overcast was removed with SCNR. The image was stretched slightly once more, and a light convolution was applied to blur colour edges.

On the L image, Deconvolution was performed, and noise reduction was performed with MultiscaleLinearTransform (operating under Starlet Transform). The image was then stretched and combined with the RGB data.

LocalHistogramEqualization was then used to bring out some extra contrast detail in the galaxy, and the black point was reset. MorphologicalTransformation was used to reduce some star sizes by a small amount, and sharpening was performed with MultiscaleLinearTransform (operating as MultiscaleLinearTransform). The DarkStructureEnhance script was applied very mildly for small gains in the dust of the galaxy, and the black point was reset. CurvesTransformation was used for final adjustments of colour saturation and contrast.

LOCATION

Data was collected on the night of March 18, 2015, at the Torrance Barrens Dark Sky Preserve in Ontario, Canada. This is a Bortle 4 site.