Visible compared to Hydrogen Alpha

Spiral Galaxy in Ursa Major

Uploaded 5/29/02



Left: Visible light image, Right: Ha image

This hydrogen rich face on spiral in Ursa Major is a large 30 arcmins across, and this image represents only the central core region. Rated at mag 8.3, this object however is spread out over such a large area of sky, it is of very low surface brightness. Classed as an Sc spiral, the core is surrounded by dark dust lanes and bluish spiral arms dotted with hydrogen clouds. Comparing the two images reveals the brightest objects in the Ha image are not stars, but are emission nebula.

Processing: Six images summed in Maxim, deconvolved in AIP, and gamma curve applied. LRGB combined in Photoshop. For the Ha image, five images were summed, and the Ha color palette in Maxim was applied.

Instrument:  12.5" f/5 Home made Newtonian
Platform:  Astrophysics 1200 QMD
CCD Camera:  SBIG ST7E w/Enhanced Cooling
Exposure:  LRGB = 60:20:20:20 (RGB Binned 2x2)
Exposure:  Ha = 50m 
RGB Combine Ratio:  1: .95: 1.8
Filters:  RGB Tricolor
Location:  Payson, Arizona
Elevation:  5150 ft.
Sky:  Seeing FMHW = 2.5 arcsec, Transparency 8/10
Outside Temperature:  10 C
CCD Temperature:  -25 C
Processing:  Maxim DL, Photoshop, AIP4WIN, PW Pro.




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