Last Sunday it was clear for some hours, but the next depression was on its way. In fact it was a race between the slowly darkening Summersky and the fast advancing cloud fields from the Southwest. An observing window of one hour.
One of the observers on
Finally I could see him and put him in the 100X field. Nothing whatso-ever. So I put in the normal max. I use on this telescope, 150X. Quite uncertain. In fact still a "NO". So I took out a 6 mm orthoscopic and put it in, 225X. Quite over the top. The seeing hindered, but most of the time I was able to see a slight bulge which apparently should be the B-component. Very soon after it was over again.
In the image below ( made in Aberrator) you can see how it looked like. The top image is like how a normal star looks like. The bottom one has a companion of the right size and on the right distance. Not really easy, but visible.
Thanks for reading!
Have you got a minute?
Furthermore the image shows a lot of aberrations which you can fill in yourself in the program.
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+Astigmatism- haven't seen it. Glad too.
+Lower Spherical aberration- somewhere around 0,3 Wave undercorrected, a bit too much as a matter of fact, since 0.25 is the limit for a "C". It causes a fatter first diffraction ring than it would be without this aberration.
+Higher Sperical aberration- in this case a zone in the mirror that causes a slender bright ring far outside the first thick diffraction ring. 0.4 Wave is too much. In or out focus a zone is visible as a well visible brighter or darker ring within the defocussed star.
+Pinch- a bit of pinching, not much. Hmmm, It would be better if it was not there.
+Tube currents. In our case I haven't seen them, since the telescope was out more than an hour and isolated as well.
In the graphics:
+ Modular Transfer Function. As a result of the central obstruction and the rather severe aberrations contrast in the telescope doesn't follow the ideal track. The straight line is the ideal one. The dotted line is my telescope. In the mid-zones there is a dip. You would hardly notice it, but very obvious if side by side compared with an ideal telescope. Which was not the case, lucky me.
+ Point Spread Function. A bit comparable with the famous Strehl-number.The extent to which the telescope is able to get the collected light in one point (the Airy disk). 0.8 is "C". 0.78 like mine is "D". Near perfection top telescopes come as far as 0.98- 0.99, but they tend to make a black hole in your wallet.
The rest speaks for itself.
Thanks for reading so far!