NGC 4490 - Cocoon Galaxy
NGC 4490, also known as the Cocoon Galaxy, is a barred spiral
galaxy in the constellation of Canes Venatici. It is estimated to be 25 million
light years away from earth. Together with NGC 4485, it forms an interacting
pair of galaxies (Arp 269), which is still connected by a so-called tidal arm
that reaches into space by about 24,000 light-years. This pair of galaxies
belongs to the class of double galaxies with connected arms.
Two supernovae have been observed in NGC 4490: SN 1982F, and SN 2008ax, with peak magnitude of 16.1 mag.
The object was discovered by the British-German astronomer Wilhelm Herschel in 1788.
- Instrument: 9.5" f/4.9 Newtonian
- F/stop: 5.6
- Exposure: L: 18 x 10 min + 1 5 min, RGB: 10 x 10 min
- Camera: L: ATIK 383+, RGB: ALccd 6c Pro = QHY8pro
- Offset/Gain/Temp: L: -20°C, RGB: 117 / 51 / -20°C
- Date: April 18-21, 2018 (3 nights)
- Location: Floridsdorf, Vienna
- Conditions: Visual limiting magnitude 4 mag, sky background brightness 19.3 mag/arcsec2, seeing 2.2-2.8" FWHM, temperature 11-15°C, no wind, low humidity
- Autoguider: Lacerta MGEN
- Enhancement: Basic data reduction, combine, logarithmic curves, crop, background flattening, noise filtering, star size reduction, local contrast enhancement, LRGB composition, color correction
- Notes: A combination of luminance and single-shot-color images taken during three succeeding nights in my backyard.