After a long spell of clouds, snow and rain, clear skies have returned. Apart from the streak artefacts in the background I like this image a lot, this is my first properly focused image with the Baader h-alpha filter.
When my wife noticed the beautiful thin crescent moon in a gap in the clouds I rushed to the deck on our roof, to take a picture of the conjunction of the Moon and Jupiter. At first I went bare-footed, but after a few seconds I couldn’t stand the snow under my bare soles, and put on some slippers. But I was still only wearing my sleeping attire, boxer shorts and a worn-out T-shirt. Temperature was -5°C.Read More
On December 26th we were invited to christmas dinner at my sisters place. I brought the Vixen Polarie, the Takahashi FS-60CB and the Nikon D750 to do some astrophotgraphy during the evening.
The image above records some faint nebulosity across central Orion. From the horsehead nebula B33 silhouetted against IC434 to the flame nebula NGC 2024. In the upper left, the M78 nebula with its surrounding NGC objects is also visible. In the corner a hint of Barnards loops is discernibleRead More
Barnard 33 is the horse-head shaped dark cloud silhouetted agains the glow of excited hydrogen which goes by the name of IC434. To the left is the Flame Nebula NGC2024, which is an odd nebula, because it is orange, and apparently a mixture between reflection and emission nebula.Read More
On sundey 16th Decmber 2018 – the comet had its closest approach to Earth, it was only 11.7 million kilometers away, the 10th nearest comet in history. Nikon D750 with 70-200mm lens at 200mm f/4, 39x30s, Vixen Polarie.Read More
Today I used a break in the clouds to test how the astro-modified Nikon D7000 works with a h-alpha Filter. As the weather was very unstable, I didn’t set up the laptop for guiding, so some images were unusable due to trailing and passing clouds and full cloud cover at the end of the exposure resulted in oly 83x30s unguided exposures. Which way too short, but I am happy with the result under these circumstances.
In the first night I used my 80mm f/7 ED Apo for unguided 30s sub-exposures, in the second night, the 127mm f/8 Apo with 120s guided exposures…
I was actually heading to bed when I noticed, that the sky cleared up enough to try to photograph Comet 64P/Swift-Gehrels.
As I wanted to create an image that included the Andromeda Galaxy, I used the 70-200 zoom and set it at about 130mm.
On November 5th I had the opportunity to do another test, this time using the 300mm lens, I also used the California Nebula as the target.
The California nebula is hydrogen gas which is irradiated by the intense UV radiaton from Xi Persei, the bright star near the center of the image. It is about 1250 light years distant and is one of the intrinsically brightest and hottest stars visible to the unaided eye. It weighs in at about 40 solar masses. The surface temperature is a whopping 35000 Kelvin.
After I bought the D750 I rarely used the D7000 any more. As it has been heavily used it would probably not get a lot if I sold it, so It mostly stayed in the closet.
Then I learned that the Nikon D7000 sensor is still used in current astronomical CMOS cameras (e.g. ASI071MC Pro or QHY168C) apart from the cooled sensor the main advantage of the astronomical cameras is the better response to H-alpha emission because of different IR-cutoff wavelength.
H-alpha emission is the red light created when young, hot stars excite hydrogen gas in the interstellar medium. Regions of onging star birth are usually distinctly red. Sadly regular DSLR cameras pick up that red light only very faintly.
After a discussion with a colleague of the Vorarlberger Amateur Astronomen I plucked up the courage to take the camera apart and get rid of the IR blocking filter. Read More