Technology is a wonderful thing! It has provided the means for an amateur astronomer to do high level scientific research. Enthusiasts can do imaging from their backyards with a small telescope that only professionals could do with a large telescope just a few years ago. One of these amazing areas of science opened up by technology is spectroscopy.
At a conference in 2009 in Big Bear California I met Oliver Thizy from France. He was there promoting spectroscopy for small telescopes for his company Shelyak. (https://www.shelyak.com/?lang=en) One of the products featured at that time was the “Star analyzer” a 100 line per mm blazed grating maximized for low resolution spectroscopy with amateur equipment. While there I bought the “introductory priced” Star Analyzer.
This opened a new world of observing and imaging. Though you can use the grating visually, it really works best when coupled with a camera. Though spectra are mostly portrayed in color, a mono camera is preferred for imaging, but not required. In fact you can use a web cam or video camera, color or mono, as well as more traditional types of astronomy cameras. The main difference is sensitivity, since mono cameras are approximately 3 times more sensitive than a color camera. Plus, when measuring the lines with software, color does not matter.
The above image and link shows the type of work that is possible using a simple grating, telescope and camera. The Three Hills Observatory site is filled with useful info and links. With a simple setup it is possible determine the spectral classification of a star as well as velocities and variability in many instances. The article linked below shows how the velocity of a quasar can be obtained using a small telescope with a grating! http://www.astrosurf.com/buil/us/quasar.htm
In recent months the American Association of Variable Star Observers has premiered a new spectroscopy data base. It is already features hundreds of spectra from a number of observers. This type of effort opens up new possibilities of research when combined with light curves from the same or similar type stars.
A “must have” program is Tom Fields, RSpec. The web link below is loaded with information about amateur spectroscopy as well as a download page where you can download RSpec and try it out for a month before you buy. RSpec is easy to use, low cost, has thorough documentation as well as tutorial videos, and is geared to the basic amateur astronomy user. In fact with a Star analyzer grating (which is available for purchase on the website) and a DSLR you can take useful images of star spectra. Tom Field, the developer, is very accessible and accommodating. Often he is available for a live chat when you are on his website. Here is the link.
Using an 8″ Schimdt-Cassegrain LX200 telescope and a Meade DSI Pro mono camera I obtained the spectra of 13th magnitude stars. Using the 8″ I reproduced the results of the article from Christian Buil’s website using 3C273 with a magnitude of 12.9. With this spectra and RSpec it was easy to measure the red shift and come up with a velocity very close to the professionally derived value. Unfortunately, that data (and much, much more) went bye-bye when a hard drive crashed or I would include it in this post. Still it goes to show the possibilities for the amateur astronomer.
Amateurs are just beginning to scratch the surface of this growing field of research. In the years to come as prices of components fall and usage begins to grow it will be interesting to see what kind of new ideas and discoveries will come to light.