Stargazing app query

[Francois1988]

I have a quick question about stargazing apps. I have used StarTracker since my BlackBerry Z10 days. It is a wonderful app that was always more or less completely accurate (though at times I must aim slightly lo to the left of any star or planet). It has gotten worse on my Sony Z2. I also then downloaded "Google Sky Map" and "Star Chart". Both wonderful in their own ways. But I noticed that I need to be more and more to the left of something to have it centred on the screen.

I am curious as I know nothing of these apps. Do they use the phone's internal GPS or something? Or do they link up to satellites in the sky?
Not sure whether this helps, but I live in Cape Town in South Africa.

Is there a way I can fix it to make it more accurate again?

 

[B. Diddy]

Those apps will use whatever your Location Service is set to. High Accuracy (which uses GPS along with mobile data/wi-fi signal) is most accurate, but if you have the phone set to Battery Saving (which only uses mobile data/wi-fi signal), you might be off by several hundred feet to even a mile or so, depending on where you are.

They also use the phone's compass and accelerometer to figure out which way the phone is facing. If you have a case on the phone, there might be a small magnet embedded in it (which might be used to keep a cover closed, or to trigger the smartcover feature). This magnet might interfere with the compass, so try using it without the case.