Sky and Telescope - September 2018 - 69

Amateurs interested in dipping their
toes in the world of spectroscopy with
RSpec can get started with the addition
of a Star Analyser 100 Grating ($195,
available at https://is.gd/RSpec). This
diffraction grating is grooved with 100
lines per millimeter and mounted in a
1¼-inch filter cell that can be screwed
onto the threaded nosepieces included
with most astronomical cameras. There
are also adapters available that allow
the grating to be attached to the lens of
a DSLR camera.
Most popular picture formats,
including JPG, BMP, and FIT, are supported. The program is not demanding
in terms of computing horsepower and
worked fine with my seven-year-old
laptop running Windows.
The only requirement is that the
optical system has enough focal length
to provide good resolution of spectra. In
the interest of seeing how inexpensive I
could keep spectroscopy, I employed my
old ZWO ASI120MC, a color video-type
camera paired with an 8-inch SchmidtCassegrain telescope and an f/7 focal
reducer yielding an effective focal
length of 1,500 mm. This turned out to
be almost perfect for RSpec, providing
bright images with an image scale of

close to the recommended 10 angstroms
per pixel. Using the telescope at f/10 got
me even closer, but it became difficult
to fit the image of the star and its spectrum onto the small chip of my
camera. The 8-inch aperture
re
is more than enough to obtain
tain
the spectra of many stars and
deep-sky objects.
Lastly, there is the RSpecc
software. The program is available
vailable
for Windows (XP and newer)
er) as a
downloadable compressed ZIP file
from the RSpec website. Downloadownloading and installing RSpec was quick and
easy, and I was exploring its features
within minutes.
The program's user interface is clean
and relatively simple. The screen is
divided into two halves, an imaging half
that displays the camera's live feed or
still images, and a "Profile" half. The
Profile section in RSpec is the graph that
represents the spectrum. Many amateur astronomers think of spectra as
images of the spectral rainbow, but in
professional astronomy in the computer
age, spectra are almost always graphs
like RSpec's, plotting intensity on the
vertical scale versus wavelength on the
horizontal scale.

p Using the Star Analyzer 100 on the author's
8-inch Schmidt-Cassegrain with a ZWO
ASI120MC camera produces two spectra of
the target star (in this case, Vega) - one on
each side of the target. Only one spectrum is
required, so choose the brightest of the two.

u To begin analyzing a spectrum,
you first need to import your spectrum image or video and rotate the
image using the Rotate command
to place the target star on the left
and its spectrum on the right.

p RSpec accepts
a
two 1¼-inch cell-mounted
diffraction gratings required to spread your target's light into a spectrum that is then analyzed
by the software. The Star Analyzer 100 Grating
includes 100 lines per inch that mounts on the
nosepiece of your camera. The Star Analyzer
200 Grating provides 200 lines per inch, better
suited for use in filter wheels.

One issue I had involved my cameras.
After connecting the ZWO ASI120MC
camera to my laptop computer and
opening RSpec, I had trouble getting the
program to recognize the camera. An
email to the author brought the suggestion that I install the latest drivers
for my camera from ZWO's website.
After doing so, the program connected
to the camera immediately, and all was

sk yandtelescope.com * S E P TE M B E R 2 018

69


https://www.is.gd/RSpec http://www.skyandtelescope.com

Table of Contents for the Digital Edition of Sky and Telescope - September 2018

Contents
Sky and Telescope - September 2018 - Cover1
Sky and Telescope - September 2018 - Cover2
Sky and Telescope - September 2018 - 1
Sky and Telescope - September 2018 - Contents
Sky and Telescope - September 2018 - 3
Sky and Telescope - September 2018 - 4
Sky and Telescope - September 2018 - 5
Sky and Telescope - September 2018 - 6
Sky and Telescope - September 2018 - 7
Sky and Telescope - September 2018 - 8
Sky and Telescope - September 2018 - 9
Sky and Telescope - September 2018 - 10
Sky and Telescope - September 2018 - 11
Sky and Telescope - September 2018 - 12
Sky and Telescope - September 2018 - 13
Sky and Telescope - September 2018 - 14
Sky and Telescope - September 2018 - 15
Sky and Telescope - September 2018 - 16
Sky and Telescope - September 2018 - 17
Sky and Telescope - September 2018 - 18
Sky and Telescope - September 2018 - 19
Sky and Telescope - September 2018 - 20
Sky and Telescope - September 2018 - 21
Sky and Telescope - September 2018 - 22
Sky and Telescope - September 2018 - 23
Sky and Telescope - September 2018 - 24
Sky and Telescope - September 2018 - 25
Sky and Telescope - September 2018 - 26
Sky and Telescope - September 2018 - 27
Sky and Telescope - September 2018 - 28
Sky and Telescope - September 2018 - 29
Sky and Telescope - September 2018 - 30
Sky and Telescope - September 2018 - 31
Sky and Telescope - September 2018 - 32
Sky and Telescope - September 2018 - 33
Sky and Telescope - September 2018 - 34
Sky and Telescope - September 2018 - 35
Sky and Telescope - September 2018 - 36
Sky and Telescope - September 2018 - 37
Sky and Telescope - September 2018 - 38
Sky and Telescope - September 2018 - 39
Sky and Telescope - September 2018 - 40
Sky and Telescope - September 2018 - 41
Sky and Telescope - September 2018 - 42
Sky and Telescope - September 2018 - 43
Sky and Telescope - September 2018 - 44
Sky and Telescope - September 2018 - 45
Sky and Telescope - September 2018 - 46
Sky and Telescope - September 2018 - 47
Sky and Telescope - September 2018 - 48
Sky and Telescope - September 2018 - 49
Sky and Telescope - September 2018 - 50
Sky and Telescope - September 2018 - 51
Sky and Telescope - September 2018 - 52
Sky and Telescope - September 2018 - 53
Sky and Telescope - September 2018 - 54
Sky and Telescope - September 2018 - 55
Sky and Telescope - September 2018 - 56
Sky and Telescope - September 2018 - 57
Sky and Telescope - September 2018 - 58
Sky and Telescope - September 2018 - 59
Sky and Telescope - September 2018 - 60
Sky and Telescope - September 2018 - 61
Sky and Telescope - September 2018 - 62
Sky and Telescope - September 2018 - 63
Sky and Telescope - September 2018 - 64
Sky and Telescope - September 2018 - 65
Sky and Telescope - September 2018 - 66
Sky and Telescope - September 2018 - 67
Sky and Telescope - September 2018 - 68
Sky and Telescope - September 2018 - 69
Sky and Telescope - September 2018 - 70
Sky and Telescope - September 2018 - 71
Sky and Telescope - September 2018 - 72
Sky and Telescope - September 2018 - 73
Sky and Telescope - September 2018 - 74
Sky and Telescope - September 2018 - 75
Sky and Telescope - September 2018 - 76
Sky and Telescope - September 2018 - 77
Sky and Telescope - September 2018 - 78
Sky and Telescope - September 2018 - 79
Sky and Telescope - September 2018 - 80
Sky and Telescope - September 2018 - 81
Sky and Telescope - September 2018 - 82
Sky and Telescope - September 2018 - 83
Sky and Telescope - September 2018 - 84
Sky and Telescope - September 2018 - Cover3
Sky and Telescope - September 2018 - Cover4
http://www.nxtbook.com/nxtbooks/newtrack/st_201811
http://www.nxtbook.com/nxtbooks/newtrack/st_201810
http://www.nxtbook.com/nxtbooks/newtrack/st_201809
http://www.nxtbook.com/nxtbooks/newtrack/st_201808
http://www.nxtbook.com/nxtbooks/newtrack/st_201807
http://www.nxtbook.com/nxtbooks/newtrack/st_201806
http://www.nxtbook.com/nxtbooks/newtrack/st_201805
http://www.nxtbook.com/nxtbooks/newtrack/st_201804
http://www.nxtbook.com/nxtbooks/newtrack/st_201803
http://www.nxtbook.com/nxtbooks/newtrack/st_201802
http://www.nxtbook.com/nxtbooks/newtrack/st_201801
http://www.nxtbook.com/nxtbooks/newtrack/st_201712
http://www.nxtbook.com/nxtbooks/newtrack/st_201711
http://www.nxtbook.com/nxtbooks/newtrack/st_201710
http://www.nxtbook.com/nxtbooks/newtrack/st_201709
http://www.nxtbook.com/nxtbooks/newtrack/st_201708
http://www.nxtbook.com/nxtbooks/newtrack/st_201707
http://www.nxtbook.com/nxtbooks/newtrack/st_201706
http://www.nxtbook.com/nxtbooks/newtrack/st_201705
http://www.nxtbook.com/nxtbooks/newtrack/st_201704
http://www.nxtbook.com/nxtbooks/newtrack/st_201703
http://www.nxtbook.com/nxtbooks/newtrack/st_201702
http://www.nxtbook.com/nxtbooks/newtrack/st_201701
http://www.nxtbook.com/nxtbooks/newtrack/st_201612
http://www.nxtbook.com/nxtbooks/newtrack/st_201611
http://www.nxtbook.com/nxtbooks/newtrack/st_201610
http://www.nxtbook.com/nxtbooks/newtrack/st_201609
http://www.nxtbook.com/nxtbooks/newtrack/st_201608
http://www.nxtbook.com/nxtbooks/newtrack/st_201607
http://www.nxtbook.com/nxtbooks/newtrack/st_201606
http://www.nxtbook.com/nxtbooks/newtrack/st_201605
http://www.nxtbook.com/nxtbooks/newtrack/st_201604
http://www.nxtbook.com/nxtbooks/newtrack/st_201603
http://www.nxtbook.com/nxtbooks/newtrack/st_201602
http://www.nxtbook.com/nxtbooks/newtrack/st_201601
http://www.nxtbook.com/nxtbooks/newtrack/st_201512
http://www.nxtbook.com/nxtbooks/newtrack/st_201511
http://www.nxtbook.com/nxtbooks/newtrack/st_201510
http://www.nxtbook.com/nxtbooks/newtrack/st_201509
http://www.nxtbook.com/nxtbooks/newtrack/st_201508
http://www.nxtbook.com/nxtbooks/newtrack/st_201507
http://www.nxtbook.com/nxtbooks/newtrack/st_201506
http://www.nxtbook.com/nxtbooks/newtrack/st_201505
http://www.nxtbook.com/nxtbooks/newtrack/st_201504
http://www.nxtbook.com/nxtbooks/newtrack/st_201503
http://www.nxtbook.com/nxtbooks/newtrack/st_201502
http://www.nxtbook.com/nxtbooks/newtrack/st_201501
http://www.nxtbook.com/nxtbooks/newtrack/st_201412
http://www.nxtbook.com/nxtbooks/newtrack/st_201411
http://www.nxtbook.com/nxtbooks/newtrack/st_201410
http://www.nxtbook.com/nxtbooks/newtrack/st_201409
http://www.nxtbook.com/nxtbooks/newtrack/st_201408
http://www.nxtbook.com/nxtbooks/newtrack/st_mars
http://www.nxtbook.com/nxtbooks/newtrack/st_201407
http://www.nxtbook.com/nxtbooks/newtrack/st_201406
http://www.nxtbook.com/nxtbooks/newtrack/st_201405
http://www.nxtbook.com/nxtbooks/newtrack/st_201404
http://www.nxtbook.com/nxtbooks/newtrack/st_201403
http://www.nxtbook.com/nxtbooks/newtrack/st_201402
http://www.nxtbook.com/nxtbooks/newtrack/st_201401
http://www.nxtbook.com/nxtbooks/newtrack/st_201312
http://www.nxtbook.com/nxtbooks/newtrack/st_201311
http://www.nxtbook.com/nxtbooks/newtrack/st_201310
http://www.nxtbook.com/nxtbooks/newtrack/st_201309
http://www.nxtbook.com/nxtbooks/newtrack/st_201308
http://www.nxtbook.com/nxtbooks/newtrack/st_201307
http://www.nxtbook.com/nxtbooks/newtrack/st_201306
http://www.nxtbook.com/nxtbooks/newtrack/st_201305
http://www.nxtbook.com/nxtbooks/newtrack/st_201304
http://www.nxtbook.com/nxtbooks/newtrack/st_201303
http://www.nxtbook.com/nxtbooks/newtrack/st_201302
http://www.nxtbook.com/nxtbooks/newtrack/st_201301
http://www.nxtbook.com/nxtbooks/newtrack/st_201212
http://www.nxtbook.com/nxtbooks/newtrack/st_201211
http://www.nxtbook.com/nxtbooks/newtrack/st_201210
http://www.nxtbook.com/nxtbooks/newtrack/st_201209
http://www.nxtbook.com/nxtbooks/newtrack/st_201208
http://www.nxtbook.com/nxtbooks/newtrack/st_201207
http://www.nxtbook.com/nxtbooks/newtrack/st_201206
http://www.nxtbook.com/nxtbooks/newtrack/st_201205
http://www.nxtbook.com/nxtbooks/newtrack/st_201204
http://www.nxtbook.com/nxtbooks/newtrack/st_201203
http://www.nxtbook.com/nxtbooks/newtrack/st_201202
http://www.nxtbook.com/nxtbooks/newtrack/st_201201
http://www.nxtbook.com/nxtbooks/newtrack/st_201112
http://www.nxtbook.com/nxtbooks/newtrack/st_201111
http://www.nxtbook.com/nxtbooks/newtrack/st_201110
http://www.nxtbook.com/nxtbooks/newtrack/st_201109
http://www.nxtbook.com/nxtbooks/newtrack/st_201108
http://www.nxtbook.com/nxtbooks/newtrack/st_201107
http://www.nxtbook.com/nxtbooks/newtrack/st_201106
http://www.nxtbook.com/nxtbooks/newtrack/st_201105
http://www.nxtbook.com/nxtbooks/newtrack/st_201104
http://www.nxtbook.com/nxtbooks/newtrack/st_201103
http://www.nxtbook.com/nxtbooks/newtrack/st_201102
http://www.nxtbook.com/nxtbooks/newtrack/st_201101
http://www.nxtbook.com/nxtbooks/newtrack/st_201012
http://www.nxtbook.com/nxtbooks/newtrack/st_201011
http://www.nxtbook.com/nxtbooks/newtrack/st_201010
http://www.nxtbook.com/nxtbooks/newtrack/st_201009
http://www.nxtbook.com/nxtbooks/newtrack/newtrack_st_201009
http://www.nxtbook.com/nxtbooks/newtrack/st_201008_v2
http://www.nxtbook.com/nxtbooks/newtrack/st_201008
http://www.nxtbook.com/nxtbooks/newtrack/st_201007
http://www.nxtbook.com/nxtbooks/newtrack/st_201005_v2
http://www.nxtbook.com/nxtbooks/newtrack/st_201006
http://www.nxtbook.com/nxtbooks/newtrack/st_201005
http://www.nxtbook.com/nxtbooks/newtrack/st_201004
http://www.nxtbook.com/nxtbooks/newtrack/st_201003v4
http://www.nxtbook.com/nxtbooks/newtrack/st_201003v3
http://www.nxtbook.com/nxtbooks/newtrack/st_201003v2
http://www.nxtbook.com/nxtbooks/newtrack/st_201003
http://www.nxtbook.com/nxtbooks/newtrack/st_201002
http://www.nxtbook.com/nxtbooks/newtrack/st_201001
http://www.nxtbookMEDIA.com