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Sunday, March 8, 2015

IC 417, the "Spider Nebula"

My latest photo from March 6, IC 417, an emission nebula in Auriga.

IC 417
Click for a large photo

Image is in mapped colors from an emission of  the ionized elements. Golden areas 
are from emission of sulfur and hydrogen, bluish hues are from ionized oxygen.

A closeup
Click for a large photo


The cosmic spyder, IC 417, locates in constellation Auriga at a distance of about 10 000 light years.
A cluster of young stars around IC 417 makes elements in the gas glow and the stellar wind shapes the gas in various forms. 

Image in visual spectrum

Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission. This composition is very close to a visual spectrum.

An experimental starless image

There is an interesting  looking round formation at one o'clock position upper right.
Looks like a crater in a gas. It doesn't seem to be a planetary nebula since there is no O-III emission visible.

Image in H-alpha light alone

Orientation in an older wide field photo

Technical details

Processing work flow

Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Deconvolution with a CCDStack2 Positive Constraint, 33 iterations, added at 50% weight
Color combine in PS CS3
Levels and curves in PS CS3.

Imaging optics
Celestron Edge HD 1100 @ f7 with 0,7 focal reducer for Edge HD 1100 telescope

Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x2

Astrodon filter, 5nm H-alpha
Astrodon filter, 3nm O-III
Astrodon filter, 3nm S-II

Exposure times
H-alpha, 12 x 1200s = 4h
O-III, 4 x 1200s = 1h 20 min.
S-II, 5x1200s = 1h 40 min.
Total 7h

A single un cropped, calibrated and stretched 20 min. H-alpha frame as it comes from the camera

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