900 Million stars!
Up to now the PRO version of Starmap offered 2.5 million stars. Now our popular app has an upgrade with access to MUCH more data!
Why so many ?
Well, in addition to the idea of «the more the better», Starmap's eyepiece view now offers a much more accurate depiction of what you'll see for real in your telescope. And, when it comes to locating faint objects or finding a guid star for long-exposure photography, this makes a big difference. Small star patterns, even very faint ones, will help you zero in on an exact location in the sky. Because that's what a star map is for: finding one's way in the sky.
How it works:
900 million stars is about 20 GB of stellar data up to magnitude 20. Such a large amount of data cannot be embedded in your iPhone or iPad. Starmap will get what you need from the network when you need it, keep it for a while and then discard it. To access the data, zoom in the map to a field of view smaller than 2°. Leave the map untouched for a second, and Starmap will get and display the faint stars in that field. Then, look in the top right part of the map and note the percentage of downloaded data. For fields of view below 2°, this represents in average 100 KB. So the process should be rather fast. Even faster, since our servers are now located all over the world for more rapid data delivery.
In beta-testing with selected users, the download time was not too problematic and remains under 3 to 5 seconds. The data remain on the device for a while, since Starmap keeps a cache of 300 KB. The app clears older data and makes room for additional information. It also frees the memory when you quit the application ñ quitting and not suspending, like when you swap to another app.
No Network in the Field?
Actually that's good news for you. This mean you live far away from civilization and that you must have dark skies :) However, you still have a formidable amount of data without the network! As before, Starmap 2 offers 2.5 million stars downloaded to your device. This is, by the way, what takes time when you download the PRO version. It represents about 50 MB of data. For reference, the standard version has 2MB. So that remains unchanged.
I made some tests with users, and the download time is not too problematic and remain unders 3 to 5 seconds. And the data remains on the device for a while. Starmap keeps a cache of 300 KBytes. It clears older data and make room for new one. Starmap also frees the memory when you quit the application – quitting and not suspending, like when you swap to another App.
Let Me Know
Feel free to send me some feedback about this new feature, particularly if I should increase the caching mechanism. I am also thinking of a downloadable version, without network, with compressed data. But, that is for the future. For now, enjoy the expanded data access as you explore the sky!
Which catalogue is used ?
The fourth U.S. Naval Observatory CCD Astrograph Catalog (UCAC4).
