.


Binary star measurements with the 20-inch Alluna RC

Rainer Anton has already for several years created images of binary stars to measure position angles and distances. The images beneath were made with a "Chameleon" web cam from PointGrey with pixels of 3.75 µm. This results in a nominal resolution of about 0.095 "/ pixel. By 4-fold re-sampling an accuracy of up to 0.005” can be determined. For the images, the focal length of 20 inches Alluna RC was extended with a 2x Barlow lens to 8.2 meters.
To reduce Seeing effects a NIR or red filter was used. From a series of 1000 to 1500 images, the best 50 to 100 images can be selected and stacked. This process is called "lucky images".  



binary stars
 


Through the "lucky images" process images of binary stars can be created even under less than favourable conditions. The quality of the telescope optics plays a crucial role. Exposure times were mostly around 100 msec , some of the top images were overexposed to show faint companions.

binary star measurements

The two stars HDO296 in the Indus at the time of imaging had a distance of 0.22 arcseconds. With the 20-inch telescope both stars were clearly separated. The theoretical resolving power of a 500 mm telescope after the Dawes or Rayleigh criterion was thus fully achieved and even exceeded.  A good example of the high optical performance of Alluna telescopes.



.
.
©2017 Alluna Optics Germany      .
.