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M20 - Trifid Nebula
The Trifid Nebula M20 is a rare combination of an emission and
reflection nebula. Hot young stars in the southern part of the Trifid have
excited the hydrogen atoms in the surrounding gas, causing them to emit red
light. In the northern part of the Trifid, in contrast, the stars are not hot
enough to excite the gas; but the blue glow of the starlight being reflected by a
myriad of dust particles is dominant in this color exposure. Some
dust lanes which are not illuminated by starlight run in front of the emission nebula,
forming the famous Trifid lines.
M20 - Trifid Nebula, Wright-Newtonian photograph and CCD-image.
Exposure Data
- Instrument: 8" f/5 Newtonian
- F/stop: 4.75
- Exposure: 5 x 10 min
- Camera: ZWO ASI294MC Pro
- Offset/Gain/Temp: 30 / 0 / -24°C
- Date: September 10, 2018
- Exposure start: 21:31 MESZ
- Location: Wallackhaus, Carinthia
- Conditions: Visual limiting magnitude 5.9 mag, SQM-L sky brightness 20.9 mag/arcsec2, seeing 3.9" FWHM, temperature 8°C, moderate wind, no dew
- Autoguider: Lacerta MGEN
- Enhancement: Basic data reduction, registration and combination, background flattening, color calibration, noise reduction, deconvolution, non-linearization, local contract enhancement, star size reduction, atmospheric refraction correction
- Notes: Bad seeing, wind, and low altitude somewhat degarded this exposure series. I even had to correct for atmospheric refraction.
