VMpalvelin / Astronomy / M51
M51 - Whirlpool Galaxy in IR and UV

M51 - Whirlpool Galaxy in IR (up) and UV (middle)
IR and UV images combinated: IR = red, UV = green (down)

There are two galaxies in the field. M51 (NGC5194) and NGC5195 (left from M51). What does the images tell about the galaxies? Centers of the galaxies are reddish so they emit more in infrared than in ultraviolet. Spiral arms of the M51 are greenish so they emit more ultraviolet than infrared. If all parts of the galaxies emit as much IR and UV then all parts of the image would be same greenish red.

Exposure time of the UV image is longer because the earths atmosphere is more transparent in IR than in UV. Also the camera is more sensitive to IR than to UV.

ITelescopes Telescope-17
0,43m (17inch), f/4,5 with focal reducer
(Located to Spain)

FLI ProLine E2V CCD47-10-1-109 Deep Depletion - Fused Silica
1,41 Arc secs/pixels

I (photometry infrared)
U (photometry ultraviolet)

3 * 300s IR
3 * 600s UV

Date: IR
02 Feb 2012
02.30 Local time

Date: UV
11 Feb 2012
02.30 Local time