This conspicuous spiral is a prototype of a grand-design Sc galaxy. Its distance may be about 30 to 40 million light years as it recedes with 793 km/sec. Then its spiral arms are about 1000 light years broad. They are traced with clusters of blue young stars and pinkish colored diffuse gaseous nebulae (H II regions), and reach out to cover a region of more than 10 minutes of arc in diameter, corresponding to roughly 95,000 light years, or about the same size as our Milky Way galaxy.
Credit: Simon Dye (Cardiff University).
Date: August 2004.
Standard data reduction was carried out in each filter using IRAF: bias subtraction, flatfielding, bad pixel/column removal, sub-exposure alignment then coaddition. To reduce photon noise (since the exposures are only short), the image was rebinned to half its original resolution. With seeing of 0.9" and a rebinned pixel size of 0.6", this only slightly reduces image sharpness. The colour composite was built using Adobe Photoshop with the help of the ESA/ESO/NASA Photoshop FITS Liberator plugin.
Telescope: 2.5-m Isaac Newton Telescope.
Instrument: Wide Field Camera (WFC).
Filters and exposure times: 2 × 100s exposures in B, 2 × 80s exposures in V and 2 × 60s exposures in R.
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