astronomyrob I have been having difficulty in plate solving. Read lots of posts but today wondered if it is because my ipad is wifi only ?
iPads that do not have GPS will need WiFi to approximate your location.
However, GPS is not used for plate solving.
Plate Solving involves taking an image of the sky, and through pattern matching, find there the telescope is pointed to.
As usual, for everything with a telescope, make sure that you are perfecty focused -- use a Bahtinov mask. Large blobs of light will not be detected as stars.
Then you adjust the exposure so there are not too many overexposed stars (otherwise they will be rejected, and those are the stars that are in the database that ASIAIR is pattern matching). However, you do need at least about 25 to 50 non-over-exposed and sharp stars to be above the noise.
Start with a low exposure value. Try a plate solve. If it tells you there are not enough stars, double the exposure. Rinse and repeat until plate solving is reliable. It can change from which part of the sky you are pointed to. Near to the Milky Way, you will need lower exposure.
You also did not mention which version of ASIAIR hardware, and the plate scale (sensor pixel size and focal length) of your image. If you are close to the min or max (too short a focal length, or too long a focal length), plate solve will become marginal. Most people with a large SCT without a reducer and a with small camera sensor will have a problem with plate solving. Ditto anyone using very short camera lenses with a large full frame sensor. ASIAIR is much more limited than the web plate solver at astrometry.net.
Chen
