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Technical card

Resolution: 3062x2269

Dates: Jan. 21, 2017

Frames:
Baader Planetarium Ha 7nm: 29x200" -30C bin 1x1
Baader Planetarium Hb 8.5 nm: 29x500" bin 1x1
Baader Planetarium IR pass >685nm: 26x200" bin 1x1

Integration: 7.1 hours

Avg. Moon age: 23.10 days

Avg. Moon phase: 39.97%

Bortle Dark-Sky Scale: 6.00

Astrometry.net job: 1428112

RA center: 83.739 degrees

DEC center: -5.503 degrees

Pixel scale: 1.202 arcsec/pixel

Orientation: -91.409 degrees

Field radius: 0.636 degrees

Locations: Castenedolo, Castenedolo, Italy

Description

Here my latest Job: an unconvenional test with an IR Pass Baader Filter

It is a false color rendition of the Great Orion Nebula, obtained with amateur level instruments from a suburban, light polluted, sky in northern Italy:
The telescope is a William Optics FLT 110 Triplet APO with a 0.8x focal reducer on a 10Micron GM1000 HPS Mount.
The camera is an old SBIG ST 2000 XV Camera.
All the exposures was unguided

The first image is a pseudo-Hubble Palette

Red channel is mapped to an IR image (Baader Planetarium IR-Pass filter >685 nm)
Green channel is mapped to an H alpha image (Baader Planetarium 7nm bandwidth)
Blue channel is mapped to an H beta image (Baader Planetarium 8.5 nm bandwidth)

In my opinion this image is very interesting because it shows this ultraphotographed object in a new way for an amateur.

The hues from yellow to reddish-brown show dusty zones, where IR emission dominates on narrow band emission from hydrogen.
The hues from teal green to blue, follow the variations in the Halpha - Hbeta ratio (Balmer decrement).

The second image (Marked as B) is a map of the Balmer decrement (uncorrected for interstellar reddening) obtained by the ratio between the two narrow band images.
It is only a rough estimate of the real ratio because the Ha filter has a quite broad passband, but it can be interesting anyway.
As you know, the Balmer decrement depends on many factors, between them the electron temperature inside the nebula and the interstellar reddening.

Comparing the two images (See image C) it is easy to see a correlation between the dusty areas and a higher Balmer ratio (reddening), but it is also evident that there are uncorrelated structures for which a different explanation is needed.
The white and black pixel are out of range values in areas of the image where poor S/N is present.

Comments

Author

Edoardo Luca Radi...
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An Inusual false color Orion Nebula, Edoardo Luca Radice (Astroedo)

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