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For various reasons, I find a correctly orientated image, (vertically & horizontally) as given by an Amici prism in a diagonal, much easier for me to use with my observing.
I absolutely loved the Baader Amici prism with the ClickLock. The build quality is lovely and it gave really great views - except when you try and use it on an object brighter than about magnitude 1.5, whereupon you see the infamous diffraction spike ruining your view.
I know this is a fairly common issue with prisms and with Baader Amici prisms in particular but I have also heard of people trying several and then finding one without the diffraction spike issue. Mine was bought from a reputable online only astronomy supplier on the USA west coast who assured me they tested the prism prior to my purchase but they obvioulsy did not. They did give me a refund in the end. I would really love to try and obtain another Baader prism but without the diffraction problem.
My question is, have you done the process of trying several prisms before getting a good one? Who did you use? (please feel free to PM me) Did you end going directly to Baader? I would do that ordinarily but I now live in the USA, not Europe. Have you another non Baader correct orientation prism that you could recommend to me ? (Although I have to say once you use a Baader diagonal with a ClickLock there really is no going back to the fiddly adjustment screws!!!)
Thanks for any advice, sharing of experiences or recommendations.
Baader Hyperion Eyepieces
5mm - £70
10mm - £70
24mm - £70
Or all three for £190
I bought these over on ABS a while back, used them a couple of times, and have never touched them again, so selling for future upgrade points.
They seem like perfectly OK eyepieces, but the Baader and TV zooms are perfectly good for my portable viewing, and take up less space and weight.
Price includes UK postage. Payment by bank transfer (preferred) or PayPal (buyer pays fees).
as well today the sun is shining brightly here. I set up the Lunt to have a look at it, at first just for observing. However, somehow I cannot resist and have to do a sketch This time I've chosen reddish pastels on grey paper to better catch the color of the view in the eyepiece.
Telescope: Lunt LS50THaB600PT
Eyepiece: Celestron X-cel 10mm
Date & Time: May 15th, 2020 / 1400-1430 CEST
Location: home terrace, Dusseldorf region, Germany
Technique: red and orange Koh-i-Noor pastels and pastel pens on grey Canson Mi-Teintes pastel paper
Size: 24 x 32 cm
Clear (and sunny) skies!
I finished observations of the Mizar A spectroscopic binary.
Calibration for the Hα line made on water lines contained in the Earth's atmosphere.
I used LowSpec spectrograph with 1800 grooves/mm reflective holographic grating, APM APO 107/700, QHY163M camera and HEQ5 mount with guiding.
It turned out that the Earth's movement practically compensated for the radial velocity of the Mizar A system.
Based on the analysis, I received the result:
vr = -8.8 km/s
in fact the system is approaching at a radial velocity of -6.3 km/s.
I also determined the phase plot of radial velocities based on my measurements for the Na (together for both lines) and separately for Hα line:
Error is based on half my spectral resolution (0.2 Å/pix corresponds to rv = 10 km/s). Each measurement corresponds to the stack a few images.
The most important purpose of observing this binary system was to record the historical Ca II line (often called as CaK, 3933.66 Å).
The distances in the violet part of the spectrum are almost 2x smaller than the corresponding shifts for the Hα line. This line initiated the discovery of spectroscopically binary systems, and Mizar A was the first discovered system of this type.
These were the spectroscopic observations in the 19th century:
I've made several observations of this line in the last two weeks:
Animation showing the changes in the CaK line based on my observations:
Not only the Ca II is split, but the surrounding lines also, shown below in a wider environment:
Balmer hydrogen lines are becoming more dense as Balmer's gap approaches (3646 Å).
Observation result of the Hα line:
And animation showing the changes in this line:
The Na I doublet was much more difficult to observe, because stars with A spectral type contain very faint lines of this metal:
Animation showing the changes in the sodium doublet:
We received the sodium quartet