More Spectra Imaging; Lighting Hall of Shame Addition
Posted: 16 September 2012
The observatory was opened Saturday, 15 September 2012, at 1835 MST, 85°F. The sky was clear and the wind was calm. Plan for this night was to resume imaging stellar spectra using the Star Analyzer with the "drift method".
At 1854 MST, viewed Saturn, low in the west, 77X. No details other than the ring were visible. Then viewed Mars, low in the southwest, 77X. No details were visible.
I then slewed to the star Arcturus, which would be my first spectrum for the night. I mounted the D7000 DSLR at prime focus of the 8" LX200-ACF with the Star Analyzer. I then focused on the spectrum, not the star. This technique was mentioned by Ray Gilchrist. (Thanks Ray!) I was ready for imaging at 1906 MST, but waited until 1915 MST before starting imaging to allow the sky to get a little darker. I imaged several spectra until 1952 MST. Here are the spectra I obtained. The top image is the raw spectrum captured by allowing the telescope to drift (turning off the Right Ascension drive) during the 5 second, ISO 200, exposure, followed by the processed spectrum. Fraunhofer lines are more visible by using the drift method than they were using my previous high ISO exposure technique, which added digital noise.
Arcturus - Spectral Type K1
Antares - Spectral Type M1
Altair - Spectral Type A7
Shedir (Alpha Cass) - Spectral Type K0
Caph (Beta Cass) - Spectral Type F2
Gamma Cass - Spectral Type B0
Ruchbah (Delta Cass) - Spectral Type A5
Segin (Epsilon Cass) - Spectral Type B2
I tried using the drift method on Polaris, but of course that failed during the short 5 second exposure.
My next spectra targets would not rise for awhile so I removed the camera from the telescope. I decided I would photograph another entry for my "Lighting Hall of Shame". Almost every night when the weather is good, the local horse stable and riding area is illuminated. Obviously their lighting is for safety. However, the lighting would be more effective if the lights were aimed at the ground instead of being aimed horizontally. One of the lights is aimed directly at my location and illuminates the entire hillside from a mile away.
The light is so bright that it casts shadows. This 30 second exposure shows the shadow of my camera tripod (circled) on some plants along the pathway to the observatory.
Fortunately, the observatory is protected from this nuisance lighting by low trees.
At 2023 MST, I did some DSO observing at 77X. I viewed M16 (Eagle Nebula), M17 (Swan Nebula), M20 (Trifid Nebula), M22 (globular cluster), M13 (globular cluster), M92 (globular cluster), M57 (Ring Nebula), and M56 (globular cluster).
At 2056 MST, I resumed spectra imaging.
Vega - Spectral Type A0
Fomalhaut - Spectral Type A3
Algol - Spectral Type B8
Menkib - Spectral Type O7
Capella - Spectral Type G8
I completed spectra imaging for this night at 2322 MST. I then did some DSO tours in three constellations at 77X. Capriconus: M30 (globular cluster). Aquarius: M72 (globular cluster), M73 (open cluster), NGC7009 (Saturn Nebula; planetary nebula), M2 (globular cluster), and NGC7293 (Helix Nebula). Pisces: M74 (spiral galaxy).
Last, at 2353 MST, viewed Jupiter and 4 moons, 77X. Jupiter was too low in the east for good viewing.
The observatory was closed at 0009 MST, 68°F.
Check out Ray Gilchrist's Spectroscopy. He has written a good article on his efforts.
Comments are welcome; use the Comments section below, or you can Email Me. Thanks.
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