Sky and Telescope - August 2017 - 62

Quick Look by Sean Walker

Sky Guide
Here's a great app for casual and experienced stargazers alike.

Sky Guide
by Fifth Star Labs
U.S. Price: $1.99, and $9.99 per year for
SUPERMASSIVE in-app subscription
Available from the Apple App Store
64-bit device recommended.

What We Like
Excellent graphics
Ease of use

What We Don't Like
Only available for Apple devices
Doesn't permit free rotation

p The planetarium app Sky Guide for
iOS devices incorporates several all-sky
survey mosaics into the appearance,
including coauthor Nick Risinger's own
Photopic Sky Survey (left). Users can
switch between several wavelength
"skins," including infrared from the WISE
survey (right).

A U G U S T 2 0 1 7 * SK Y & TELESCOPE

THESE DAYS THE MARKET for
smartphone planetarium apps is pretty
crowded. Simply go on your Android
or Apple app store, search for "planetarium," and you'll be presented with
dozens of options, each with a dizzying array of looks and features. While
many have speciﬁc uses for observers or
imagers, it can be hard to ﬁnd one that
quickly shows you the sky without sorting through a lot of bells and whistles.
Sky Guide by Fifth Star Labs is a planetarium app for Apple devices (including an alert function for the Apple
Watch) that sets itself apart from the
crowd in a number of ways. Produced
by photographer Nick Risinger and
software developer Chris Laurel, the
app features Risinger's seminal all-sky
color Photopic Sky Survey (S&T: Feb.
2012, p. 70) as the base for the sky map.
Like many other planetarium apps, Sky
Guide will match the ﬁeld of view when
your device is held up to the sky, and it
includes the Sun, Moon, and planets as
well as the brighter moons of Jupiter,
Saturn, and Mars (though none around
Neptune and Uranus). But unlike other
planetarium apps I've used, objects are

represented by their appearance - or at
least as a camera would see them in a
moderately deep exposure - giving me
a better appreciation for where objects
really are in the sky in relation to other
targets. The brightness of the stars
and the background sky is adjustable
by sliding two ﬁngers up or down on
the screen, allowing you to match the
conditions at your location. This feature
is very realistic and even imparts the
familiar reddish-brown cast of urban
light pollution along the horizon.
The app is unencumbered by a
multitude of controls; there are only
three tiny icons at the top of the screen.
One brings you to a menu of options,
another turns on or off the accelerometer that matches the view to the sky. The
third at the top right is the search icon,
which allows you to quickly ﬁnd many
objects, including those in the Messier
and Caldwell catalogs, plus many other
bright targets arranged by type.
Sky Guide has a nifty option that lets
you change the appearance of the sky
to different wavelengths in the electromagnetic spectrum based on other
all-sky survey data. Holding your ﬁnger
in one place for two seconds opens the
ﬁlter window, which you use to reposition the pointer to select your desired
wavelength ﬁlter. These include gamma
ray, X-ray, ultraviolet, visible light (the
default), hydrogen-alpha, infrared,
microwave, and radio wavelengths. I
found this feature particularly useful
when hunting for astrophotography
targets, especially nebulae.
Another feature within the app is its
real-time tracking of 250 bright satellites. Sky Guide can send you a 5-minute advance alert when a particularly
bright event, such as the appearance of
the International Space Station or an
Iridium ﬂare, is about to occur. You can
disable this setting in the menu, or set
time periods when you'd prefer not to
receive notiﬁcations.
Comets are another neat feature of
Sky Guide. It looks like a lot of time went
into presenting their appearance, and it
was well worth the effort. Most bright
comets visible at the time are displayed
similar to their predicted photographic

Sky and Telescope - August 2017

Table of Contents for the Digital Edition of Sky and Telescope - August 2017