defocused antares in scorpius has double diffraction rings

[chris shaw]

Dear all

I queried Meade on the double diffraction pattern I have been seeing with Antares and they wrote:

You are likely seeing a small dim secondary image of the star which is caused by a reflection off of one of the eyepiece elements. I have seen this before while testing eyepieces. The small amount of light in this image is spread out and not detectable when the system is focused on the primary image. No optical system is totally reflection free. If you look close enough through the out of focus range of the primary image, you will probably find this effect.

hope this is helpful.

Best regards,

Paul Hobbs
Director of International Sales & Procurement
Meade Instruments Corporation

What do you think of this explanation?

Cheers,
Chris

[weixing]

Hi,
This is the first time I heard about this type of reflection :?: and I had not seen this on my scope. Or may be my 6" scope is too small to cause this type of reflection :?:

Anyway, you can use the same setup and do the same star test on stars brighter than Antares, such as Vega, Altair and Arcturus. So if what he said is true, you should see the same image on the star test.

Have a nice day.

[MooEy]

ok, first step, test on all other stars and see if this double defraction rings is repeatable, if it is the same on all other bright stars, u may have a problem with the optics or possibly it's just the bad seeing. always rememeber to keep all other variable constant so as to get usable results.

i suspect that the double diffraction rings u are seeing is mostly due to the bad weather. lots of clouds in the atmosphere can cause all kind of wierd stuff in a scope.

if all other stars only show 1 set of rings and yet antares show 2, consider urself very lucky as u have split one of the harder double stars out there.

anyway, do not be too disturbed by the optics. most important is to spend more time enjoying seeing the gems in the sky.

~MooEy~

[chris shaw]

Dear MooEY

How does bad seeing produce this kind of resonant diffraction ring pattern?

Chris

[kayheem]

Dear all

Maybe you can help: Last night while viewing an out-of-focus Antares at about 300X, I noticed that embedded WITHIN Antare's diffraction rings is another dimmer, smaller airy disk with it's own diffraction rings. It was almost like having a smaller ripple within a larger ripple in a pond.


Hope this makes sense.

Chris

Hi,

I did notice the same effect a couple of nights ago when I was...collimating my scope using an artificial star...no kidding!

I realized later that it was due to a speck of dust or small drop of water on the eyepiece. The image rotated as I rotated the eyepiece and disappeared when I changed the eyepiece. While I am not saying that you had exactly the same problem, I am saying that there may be a myriad of causes that display a similar phenomenon.

Kay Heem

[[BPST]FerMIons&BOsOns]

Emm Antares has a companion?

[carlogambino]

Yes. Antares has a mag 5.4 blue companion that requires at least 75mm(more for our skes) aperture and the steadiest atmospheric conditions to be visible against the primary's glare. The orbital period of the companion around Antares is estimated to be nerly 900 years.