I’d been hearing lately about some astronomy software for the iPhone/iPad called SkySafari (made by Southern Stars), but not owning either one of those devices myself, I hadn’t really bothered to look into it at all. That all changed when I came across an ad for SkySafari in Sky and Telescope magazine that showed that an Android version was available. Now I became much more interested to see what the fuss was about, so I dropped $14.99 in the Google Play store for the Plus version so I could try it out on my HTC Incredible phone as well as my rooted Barnes and Noble Nook Color. Mostly, I wanted to see if SkySafari would connect to my digital setting circles box via bluetooth. Initial impressions are very good.

SkySafari comes in three different versions. The basic version is $2.99 and contains a catalog of 46,000 stars and does not include telescope control. The Plus version ($14.99) includes 2.5 million stars and thousands of deep-sky objects and adds telescope control. The Pro version ($59.99) includes many millions of objects in its catalog plus additional features. I chose the Plus version to get the telescope control functionality, figuring that its catalog would be sufficient for my needs.

My test setup was my Barnes and Noble Nook Color tablet that I’ve rooted and converted into an Android tablet running CyanogenMod 7.1.0. CyanogenMod thankfully includes support for the built-in bluetooth radio in the Nook Color. On the telescope side, I’m using a U.S. Converters serial-to-bluetooth converter plugged into my encoder box.

Someone recently told me that SkySafari doesn’t send the command to the encoder box to initialize the encoder resolutions, so before I began testing I connected my box to my PC and used my EkBoxTester software to make sure the encoders were initialized with the correct resolutions. The resolutions are saved in EEPROM, so they’ll be remembered even when the power’s off.

Once I was confident that the resolutions were set correctly, I fired up my Nook Color, turned on the bluetooth radio, and paired it with my serial-bluetooth adapter (Settings -> Wireless & Networks -> Bluetooth Settings). You need to do this step before running SkySafari and attempting to connect with the telescope. Once it paired, I fired up SkySafari.

SkySafari opening screen
Default sky view

I have to say that I was immediately impressed with the look of SkySafari–they sky display is very nicely done (there are plenty of screenshots on the Southern Stars website–go check them out for yourself). The first thing I did was to go to the Settings menu to set my location (SkySafari will use your GPS to do this if it can, but the Nook Color doesn’t have a GPS).

Specify Location

Next, I needed to specify the type of telescope I have. The Southern Stars website mentioned my encoder system specifically under supported telescope types, so I thought maybe I’d find it listed in the available scope types, but it wasn’t there. I chose “Basic Encoder System” as my telescope type. SkySafari also needed to know the type of mount I have as well as the encoder resolutions. My mount is a German Equatorial–that part was easy enough. It turns out that I had to experiment a bit with the encoder resolution entries before I found something that actually worked.

SkySafari Settings menu
SkySafari Scope Settings

SkySafari allows you to specify the resolution of an encoder as either a positive or negative number. The sign indicates the directionality of the encoder. Since there two encoders and two possible values for each encoder (positive and negative), there are four possible unique combinations to be tried in order to find the right one that results in good alignments. I had to play around a bit here in order to find the right combination. It took me several tries before I got an accurate alignment, but that could be partly due to the fact that I was doing this testing in the middle of the day using my mount’s regular setting circles to approximate accurate pointing at alignment objects.

Select Telescope Type
Select Mount Type

The alignment process is pretty straightforward. Tapping the Scope menu item will display the telescope controls. Hit the Connect button to connect with the telescope, tap on an object in the sky display to select it, point your telescope at the object, and hit the Align button. For a brand new alignment, that’ll be your first alignment star. Repeat the process with another star and tell SkySafari to use that as a second alignment star, and you’re in business. SkySafari will warn you if your alignment stars are too close together, or if it appears that your telescope isn’t really pointed at the second alignment star. Once complete, SkySafari will display a cross-hair of sorts to show where your telescope is pointed. There’s even a Lock button that will cause the sky display to follow your telescope as you move it about the sky. You can continue to update your alignment by repeating the process of choosing and aligning on a second alignment star if your original alignment isn’t so great in some parts of the sky.

Telescope Alignment
Telescope Alignment

Manipulating the sky display in SkySafari is simple: drag your finger across the screen to scroll the display, and pinch/unpinch to zoom in and out. Tap to select an object and then choose Info from the menu to learn more about the object. I haven’t even begun to explore all the features and functions that are available.

Zoomed in
Andromeda Galaxy

I’m hoping to get SkySafari and my telescope outside one evening soon to give it an actual run under the stars, but my initial impression is that this is quite the package for $14.99. If you have any experience with SkySafari, share it with me by leaving a comment below.

2 thoughts on “SkySafari for Android

  1. Hi David
    It’s several years since I built your encoder box into a Celestron C8.
    Not long ago I got an iPad mini then found out about sky safari. I was so impressed I bought the plus version and also the SkiFi box.
    This set up is awesome, my mount is semi permanent so it is accurately polar aligned. I can align SkiSafari on any one star then move all over the sky with amazing accuracy.

  2. I’ve been using Ski Safari on an iPad with SkyFi for a couple of years now, and it works great with your DSC hardware. I find that I can do a one-star alignment and if my scope is properly polar aligned, it’s pretty dead on, but if I don’t do a good polar alignment, then it’s not a big deal to do a 2nd one-star alignment near what I’m looking for. I’ve also used your DSC with Sky Safari and the cable version (costs about 1/2 as much, but it prevents you from charging your iPad when it’s hooked up, so that may limit you use of it during long observing sessions.

    I’m looking to upgrade my DSC box to the USB version since it it’s a much smaller circuit board and the latest Ski Fi has an USB interface in addition to an RS-232 interface.


Leave a reply

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>