Sky and Telescope - September 2018 - 68

S&T Test Report by Rod Mollise

Backyard Spectroscopy with RSpec
Try your hand at real-time science with your telescope.

RSpec Real-Time
Spectroscopy
U.S. Price: $109
RSpec-astro.com

What We Like
Remarkably effective
for both capturing and
analyzing spectra
Works with inexpensive
diffraction grating
Intuitive

What We Don't Like
Lacks a printed manual
Sensitive to camera driver
problems

S E P TE M B E R 2 018 * SK Y & TELESCOPE

FOR ME, ASTRONOMY COMES IN
TWO PARTS. A portion of my time is

spent as an astronomy educator, teaching the science of the universe. But I'm
also an amateur astronomer, and in
that aspect I've mostly conﬁned myself
to observing pretty stuff. Occasionally,
however, I long to put a little more science into my amateur astronomy. I've
found just the thing for that, a clever
software program called "RSpec."
As you may have guessed from its
name, RSpec is concerned with spectroscopy. This software, combined with a
simple diffraction grating and a digital
camera, allows users to record and analyze the spectra of bright stars to reveal
which elements are present in these
distant suns.

It had been known for centuries
that shining a beam of light through
glass or crystal could produce a rainbow
(Isaac Newton coined the term color
spectrum for the rainbow produced by a
prism), but they were mostly considered
pretty curiosities until German physicist Gustav Kirchhoff came along in
the 19th century. Early researchers had
noted that some spectra showed curious vertical lines crossing the rainbow.
Kirchhoff realized these lines were the
ﬁngerprints of the elements. Each element has its own particular set of lines
at speciﬁc wavelengths.
Devices called spectroscopes were
developed that could tease more information out of starlight beyond the
elements that are present in the star's
atmosphere. For example, we can study
a star's spectrum to learn how massive
and hot it is. Is the star old or young?
How does it compare to other stars?
With a sensitive camera and enough
light-gathering aperture, you can even
move beyond stars, analyzing the light of
deep-sky objects including nebulae and
galaxies. Amateurs have become involved
in spectroscopy, but it typically required
substantial investment in equipment in
the form of a high-resolution spectroscope, a cooled CCD camera, and complex software. S&T Contributing Editor
Tom Field's RSpec changes all that, making spectroscopy affordable and easy.

Required Equipment
While RSpec works well analyzing spectra obtained with a spectroscope, the
program can analyze spectra recorded
through an inexpensive diffraction grating - a piece of glass ruled with thousands of lines that cause it to function
like a prism. And though diffraction
gratings are not as effective as a conventional spectroscope, they can still
produce remarkably detailed spectra.

A LL PHOTOS BY THE AU THOR

Backyard spectroscopy
used to be expensive
and difficult, but Tom
Field's affordable RSpec
software and grating lets
users identify elements
in the atmospheres of
stars and bright deepsky objects.

http://www.RSpec-astro.com

Sky and Telescope - September 2018

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