App accuracy

[Warped Drive]

When I am using the azimuth circle and my iPhone inclinometer app to locate objects with my Heritage 130p, the app I use on my iPad to get the Alt/Az co-ordinates is call Star Chart, it's a free app but all the frills are only availabe as in app purchases. I have been using Vega as my reference to set the Azimuth and so far it's been pretty accurate at finding things inside a 60-70deg arc but once past Arcturus heading into Leo I can't find any thing but if I reset the azimuth it Arcturus or another star in that area it seems to be ok again for another 60-70 degs right of that so last night as there was no view of the heavens in my location I got to thinking are the co-ordinates correct so I checked the alt/az co-rods from Star Chat with the Co-odds in Stellarium and lo and behold the were different. The Alt was very close but the Azimuth was up to 3 - 3.5 degs out on some of the objects I checked. Has anyone else noticed this or checked if the app they are using tallies with Stellarium. Is Stellarium the definitive app for co-ordinates?

[Owmuchonomy]

I'm not familiar with using Apps but Alt Az coordinates are not fixed points in space. They depend upon where you are, what time it is and what 'type' of time you are using. Therefore, these two parameters also need to be the same in your apps to make a direct comparison.

[-Aldebaran-]

Oh I'm so glad I only need to worry about whether my finderscope is lined up correctly. Alt/azimuth coordinates, phone apps?! Maybe I'm behind on the times but that seems to take the fun out of sky searching, unless it's for imaging purposes sorry I butted in.

sorry I'm no help

[Warped Drive]

Good point Owmuchonomy I must check the Lat / Long for both Star Chart gets it from GPS on my iPad and Stellarium must use my broadband connection location as for the time I imagine they are both synchronised to the same online clock, but maybe not.

Unfortunately in my light polluted sky star hopping is not so easy as I can just about see some of the stars needed to locate certain object with the naked eye. I do agree it is more fun and you get a much greater sense of satisfaction when you do find an object by looking for it unaided, bar a chart, I found the Ring Nebula the first time that way and I was very pleased with myself as I could hardly make out the two stars it lies between.

[Alien 13]

I use apps and Stellarium for the position of polaris hour angle and even with all relevent data added they give very different answers my gut feeling is that Stellarium is way off but its probably just me.

Alan

[Warped Drive]

Ok I just checked, Star Chart gives my position as 53deg xxm 58s N lat, and 006deg xxm 00s W long. And Stellarium gives it as 53deg xxm 48.01s N lat and 006deg xxm 0.00s long. I would think that Star Chart using the GPS on my iPad should be the closer within a 20-30 meter circle as Stellarium is giving a general location for Dublin. Should it make that much of a difference?