Hexagonal Mask

Forums Deep Sky Sirius B Hexagonal Mask

David Basey


I had a dim memory in the dusty recesses of my mind that many years ago S&T ran an article on detecting Sirius B and the benefits of using a hexagonal mask.

I have now dug it out and it may be of some interest and indeed utility. The issue in question is June 1975 p407.

Basically Dennis di Cicco created a carboard mask that fitted over the aperture of a C14. Cut out from the cardboard was a hexagonal hole scribed on a 13.25 inch circle.

The idea is that this creates six strong diffraction spikes around the primary which suck a lot of the glare out of Sirius A. Rotate the mask so that the secondary is positioned between the spikes and Sirius B is more readily seen.

The reported results look good, it was indeed more easily detected with the mask. Also included in the article are photographs with and without the mask and the difference is clear.

While this approach is fine for refractors and SCTs, something like a Newtonian with a spider mounted secondary which already creates diffraction spikes might be more problematic.

Anyway, it could be worth a try.