GPS versus Google Earth co-ordinates

[Tadpole]

Hi from a newbie

I have just purchased a Celestron CPC800 and spent last night setting up outside and letting the scope find my GPS location. When it had finished the handset gave me the longitude/latitude coordinates which, when I put them in Google Earth, put the scope 2.5 miles due west of where Google Earth says my location is.

Should I believe the handset or Google Earth?

[madatter]

Thats why the yanks keep bombing the wrong location, your gps should get you to within 10 yards, google earth will use you ip address to locate you unless you tell it youve got a gps connected.

[mcrossley]

... google earth will use you ip address to locate you unless you tell it youve got a gps connected.

Well, not if you pinpoint your address manually.

[Tadpole]

Thanks guys

After Googling I found out that the Compass ap on my iphone gives you long/lat so I will key it in manually. Oh, and Google Earth was right.

[knobby]

Don't forget... Decimal!

[Tadpole]

Could you please explain knobby . . . I am a newbie!

Thanks

[knobby]

On some apps it reads something like 0.1356 E but you want to input the data in 0’ 16'.

not decimal! As I mistakenly said earlier.

Ie ; the bottom set of numbers on the picture attached

A picture paints a thousand words

[Tadpole]

Thank you!

[LukeSkywatcher]

Google Earth gets me within a couple of metres of where i setup in my back garden. The GPS on my smart phone gets me setting up in the middle of the road outside of my house. Not a safe place to setup.

[Tadpole]

When you think of the distances between scope and target, does an inaccurate GPS location make too much difference?

[JamesF]

I'd not be surprised if a mobile phone GPS turned out not to be that accurate, but I'd have expected a mount with a built-in GPS to be good. Unless perhaps they only worry about it down to the level of accuracy that's known to be useful. 2.5 miles error is what, about two minutes of arc? Accurate to four decimal places? Perhaps that's considered sufficient.

James

[P_Monty]

Also, don't forget that GPS requires a reference to get your position. If you're using OS style grid references it needs to be set to WGS84 as in knobby's screenshot. I've found in the past that can have my position out by a couple of hundred yards ...

[Tadpole]

A footnote to this post.

I emailed Celestron support and had a swift reply: "A 3 mile variance is not going to make a big difference on star gazing. As long you are within 20 miles of the location that you are compared to the GPS it will not affect the telescopes ability to find the stars and planets."