Jump to content

Narrowband

Rainbow Sirius!


BluPossum

Recommended Posts

I'm fairly new to stargazing and tonight is the first night I've thought to aim my small telescope at Sirius when it's low in the sky...boy am I glad I did! All the colors and blinking from going through so much atmosphere made me feel like I was witnessing my own personal light show!

I feel like there's a big difference between finding something cool because it was recommended is a magazine or website and finding it completely by accident. On New Year's Eve I stumbled across the Beehive Cluster and had to look up what it was on Sky Safari. It just delivers such a thrill!

Link to comment
Share on other sites

Hi and welcome to SGL.

You are right. Stumbling across things is a great thrill.

Not totally convinced I should tell you this at this stage, but Sirius should be white. The fact that you are seeing rainbow colours is actually due to the optics of your scope splitting the colours like a prism, added to the amount of atmosphere the light is having to travel through. Hopefully you did not spend vast amounts of money on the scope.

Enjoy the journey.

Link to comment
Share on other sites

Chromatic Aberration from an incorrect focusing of wavelengths and Atmospheric Dispersion are two quite different effects and together will provide a very colourful viewing experience. Dispersion Correctors can be used to compensate for Atmospheric Dispersion and Filters can be used to make the views through Achromatic Refractors with inherent Chromatic Aberration more appealing or more pleasant. The links below will give well detailed information on these two phenomena. Best of Luck...Freddie ? 

https://cseligman.com/text/sky/atmosphericdispersion.htm

https://www.astronomynotes.com/telescop/s2.htm

https://www.cloudynights.com/articles/cat/articles/tests-of-9-different-chromatic-aberration-filters-r2834

http://skyinspector.co.uk/atm-dispersion-corrector--adc

Link to comment
Share on other sites

9 hours ago, Demonperformer said:

Hi and welcome to SGL.

You are right. Stumbling across things is a great thrill.

Not totally convinced I should tell you this at this stage, but Sirius should be white. The fact that you are seeing rainbow colours is actually due to the optics of your scope splitting the colours like a prism, added to the amount of atmosphere the light is having to travel through. Hopefully you did not spend vast amounts of money on the scope.

Enjoy the journey.

That's interesting...Sirius is the only thing I've noticed it with and I even thought I saw some color variations when just looking at it with my eyes. I'm using a 20 year old Bushnell Voyager I got used for $30, so it's not a huge deal! I'm currently working on saving up for a better one.

On second thought, I have seen some prism like effects on larger objects such as planets, but it's different than what I observed on Sirius last night. It was more of a pulsing with color changing. I suppose it was a combination of both! Thank you for letting me know!

Link to comment
Share on other sites

Sirius is particularly bad for it. Partially this is because it is bright (Venus has a similar effect in getting color fringes) and because it is always so low down. The atmosphere moves, and as starlight passes through it the light "wobbles", but the wobbles are different for the different colours and so they get split. The lower down an object is the more atmosphere it passes through and so the more serious the effect. If you have a clear east view, you can take a look at Capella. It is a similar brightness, but is higher in the sky and so the colouring effect should be less. This will give you a better idea of how much is due to the scope's optics.

Link to comment
Share on other sites

10 hours ago, SIDO said:

Chromatic Aberration from an incorrect focusing of wavelengths and Atmospheric Dispersion are two quite different effects and together will provide a very colourful viewing experience. Dispersion Correctors can be used to compensate for Atmospheric Dispersion and Filters can be used to make the views through Achromatic Refractors with inherent Chromatic Aberration more appealing or more pleasant. The links below will give well detailed information on these two phenomena. Best of Luck...Freddie ? 

https://cseligman.com/text/sky/atmosphericdispersion.htm

https://www.astronomynotes.com/telescop/s2.htm

https://www.cloudynights.com/articles/cat/articles/tests-of-9-different-chromatic-aberration-filters-r2834

http://skyinspector.co.uk/atm-dispersion-corrector--adc

Thanks for the links!

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.