Introduction to Star Analysers
The Star Analyser 100 grating screws onto
your camera nose or filter wheel
The Star Analyser 100 ($195) is a diffraction grating with grooves that are spaced at 100 lines/mm. The grating is durably mounted in a standard 1.25″ filter cell and is protected on both sides with anti-reflection coated glass.
The grating is designed specifically for amateur astronomical spectroscopy. It can be mounted on your telescope just like any other 1.25″ filter and works with most cameras. Capturing the spectrum of a star is easy. Use our grating, a DSLR or small telescope, and our award-winning RSpec software.
In this video, Tom describes how he got started in the field and how you can too
How to use a Star Analyser grating
You don’t have to have a Ph.D. to capture and understand the spectra of stars. With our gratings and software, it’s easy.
Our customers use these gratings on FITS, DSLR, and video astronomy cameras. We have gratings in stock and we can ship you one today — see our online store: link.
Note: To use a Star Analyser grating, you need to be able to capture images of deep-space objects. This means you should be able to locate specific stars in the sky and point your telescope at those stars. And, you will need to be able to capture images that are properly exposed, focused, and not smeared by star movement through the sky. If you don’t have those skills, you will need to acquire them before successfully using a Star Analyser. We’re happy to advise you on how to acquire these skills: contact form: link.
Are you a teacher? Check out our sister site for a great gas tube spectrometer for your classroom: https://fieldtestedsystems.com.
A typical star spectrum
When you put a Star Analyser on your camera, you capture images like the one below. The star is on the left; its colorful spectrum is on the right.
Above: this spectrum of a star was captured in a light-polluted urban location with a Star Analyser, an 8″ SCT, and an inexpensive camera.
When our RSpec software reads the image above, it displays an intensity graph like the one below. The narrow peak on the left is the star. And the broad peak on the right is the spectrum.
In the image above, the deep dips marked by the yellow lines are absorption lines caused by the star’s hydrogen. By studying these spectra, we can learn a lot about the star.
What can you do with a Star Analyser
Here are the kinds of projects you could do with a Star Analyser:
- detect Neptune’s methane atmosphere.
- determine any star’s OBAFGKM star type and temperature from its spectra curve.
- identify the composition of a star or nebula from its emission and absorption lines
- detect the red-shift of a distant quasar!
- measure the blue shift of a supernova’s expanding shell as it races towards us at millions of miles/hour.
- watch the spectral evolution of a nova as it goes through its different phases.
Click here to see some additional examples of Star Analyser spectra.
Use a Star Analyser like any 1.25″ filter cell on your astronomical CCD camera
You can get amazing results by mounting your grating on the nosepiece or filter wheel of your current FITS CCD or astronomical video camera. You can also use our grating on a DSLR – scroll down for more info on that.
With almost all telescopes and cameras, the Star Analyser works right out of the box to produce great spectra.
The Star Analyser grating mounts on FITS CCD cameras and astronomical video cameras.
How to use a 1.25″ Star Analyser on a system that uses 2″ filters
Use your Star Analyser grating with a standalone DSLR
Don’t have a telescope? No problem!
You can capture wonderful spectra by putting a Star Analyser on just a DSLR.
Here’s more information on how to do that: link.
How to get started with your telescope
Have questions? Get immediate answers! Use the green chat window in the bottom corner of your screen or send us a message using our contact form: link.
What’s the difference between a Star Analyser 100 and a Star Analyser 200?
Our SA-100 grating has grooves that are spaced at 100 lines/mm. This is the best grating for most systems.
In some situations, though, the SA-100 may just not physically fit in your equipment. For example, space may be restricted inside a filter wheel. Or, your filter wheel may position the SA-100 so that it’s too close to the CCD sensor for it to create a sufficiently long spectrum.
For those scenarios, we offer the Star Analyser 200 (link). Because the SA-200 is low profile, it more often fits inside the confined space of a filter wheel. And, because the SA-200 spreads out the spectrum twice as much as the SA-100, it can be mounted more closely to the CCD sensor.
As suggested above, use our calculator page to determine whether the SA-100 or SA-200 is right for you: Calculator link.
Spacers
In some cases, adding one or two of our 10 mm spacers ($13 link) may produce spectra with a bit more resolution. If you mount a grating too close to your camera, you lose resolution. If you mount the grating too far away, the whole spectrum will not fit in the camera frame, and dim object sensitivity is reduced as well.
Use our calculator to determine the best mounting distance of your Star Analyser grating: link. Questions? Contact our Help Desk for instant answers from experts: link.
If a 100 line/mm grating is good, is a 200 line/mm grating better?
That’s a great question! The short answer is ‘sometimes.’ Here’s why: Imagine observing the Moon through a telescope. You can increase magnification to see more details. But at a certain point, adding more magnification deteriorates the view. Similar optical limitations occur when moving from a 100 to 200 line/mm grating.
Our SA-200 grating, when mounted like the SA-100, spreads the spectrum twice as much, potentially offering higher resolution. However, a 100 line/mm grating performs better with faint objects, and longer spectrum from a 200 line/mm grating often doesn’t improve spectra due to optical constraints, as detailed in Doug West’s technical paper: link. But don’t worry about the details in his paper — our calculator handles them for you.
So, why do we offer the SA-200? In some setups, a 200 line/mm grating is more effective. For instance, certain telescopes don’t have enough space to mount a 100 line/mm grating far enough from the camera. Filter wheels with limited clearance may also require the thinner SA-200. Additionally, large aperture and long focal length telescopes often yield better results with a 200 line/mm grating. Our calculator helps you choose the best grating for your setup.
For more information on the SA-200, see this link.
See our great Periodic Table of Spectra poster!
As our Periodic Table of Spectra below shows, each element emits its own unique color spectrum. By splitting starlight and examining the spectrum, we can identify the composition of a star, its temperature, and other physical properties. A beautiful 36 x 24″ laminated version of this poster is available for $29.95. Great for classrooms or your man cave or woman cave!
Want to learn more about the poster? See this link.
