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Sunday, January 26, 2020

Deep in to my heart, IC 1805 in mapped colors

I have published this image in visual colors at January 14. Since then, I have shot the emission of sulfur, S-II, and now I'm able to publish a version in mapped colors.
HST-palette separates emission areas nicely and it's visually pleasing. In visual palette emission from sulfur and hydrogen are both at red part of the spectrum. Emission from oxygen is greenish blue.

I made some testing with my new imaging system based on Tokina AT-x 300mm f2.8 camera lens.
The CCD I'm using has kind of large pixels, 9 microns, so I'm undersampled, the image scale is just over 6 arcseconds / pixel. Undersampling is not a bad thing when my targets are large and dim nebula complexes. This system collects photons very fast!

I selected the Heart Nebula as a target since I have plenty of reference material for it. Another reason is interesting and rarely imaged area after the bright tip of the heart. There are some remnants of a supernova explosion. I was really thrilled, when I saw the final stack of 12 600s H-alpha light frames. (Equal to 2h of exposures) I never have seen so much background nebulae and details from this popular target.

The Heart Nebula, IC 1805
Please, click for a large image

C 1805 in mapped colors, from the emission of ionized elements,
R=Sulfur, G=Hydrogen and B=Oxygen. (Hubble Palette)

IC 1805 in visual palette
Please, click for a large image

Red emission of an ionized hydrogen (H-alpha) is dominating the scene. Image is in visual color palette from emission of an ionized hydrogen and oxygen. R=hydrogen, G=Oxygen and B=oxygen. 
In this photo there is a large supernova remnant, marked as a white circle. I haven't seen any photos of it before. I must take more O-III exposures to see, if I'm able to pick up any signal from this supernova remnant. 

Radio image of the area shows mostly signal from OB6

SNR 132.7+1.3 at upper right. Source and more information,

IC 1805 H-alpha emission alone
Please, click for a large image

H-alpha emission, only two hours of exposures is enough for a very deep image. The combination of 300mm f2.8 camera optics and large 9 micron pixels makes this imaging system extremely hungry for photons. Image scale is just over 6 arcseconds / pixel. By using the drizzle stacking method with well dithered subframes I can avoid any square stars. 

Technical details

Processing workflow
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
Tokina AT-x 300mm f2.8 camera lens

10-micron 1000

Cameras and filters
Imaging camera Apogee Alta U16 and Apogee seven slot filter wheel
Guider camera, Lodestar x 2 and an old spotting scope of Meade LX200

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

Total exposure time
H-alpha, 12 x 600 s, binned 1x1 = 2 h
O-III, 3x 600 s, binned 1x1 = 30 min..
S-II, 2x1200 s, binned 2x2 = 40 min.

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