PanSTARRS' method of observation is very simple. The telescopes point at a selected patch of sky for about 30 seconds, then download the images to a computer. Depending on the scientific requirements, it may then take another look at the same patch of sky using a different color filter, or, more likely, it will move on to the next patch of sky, all under pre-programmed computer control.
About three quarters of the total sky can be observed from Hawaii, or about 30,000 square degrees. PanStarrs looks at about 7 square degrees in each 30 seconds exposure, so in an eight-hour night it can map about 6,000 square degrees. Given that the weather is not always perfect, it will therefore take about a week to survey the whole sky once, using one filter.
In practice, however, some parts of the sky will be surveyed more often than weekly, and some less often. Particular attention will be paid to those areas of sky in which potentially hazardous asteroids are most often found, and areas of the galaxy and universe which have been chosen for particularly close study.
The typical exposure time for a Pan-STARRS image will be around 30 seconds, depending on the filter used and the particular type of survey being carried out.
Longer exposures can detect fainter images, but have the disadvantages that a) a full-sky survey would take longer than a week, and b) the images of moving objects, such as asteroids, will be smeared out and less reliably detectable.
Exposures that are too short have the disadvantages that c) the read noise from the CCDs may become comparable to the intrinsic noise from the sky, and d) more exposures require more data handling.
A single observation with the broad-band filter will reach a 5 σ depth of 24th magnitude. These are types of observation that will be used to search for solar system objects. By adding observations taken over several years Pan-STARRS should be able to reach a maximum depth of magnitude 29.4.
Yes, very good. We expect to be able to determine positions on an individual image to within 0.07 arcseconds, based on an image size of 0.6 arcseconds FWHM, and a signal-to-noise ratio of 5. Systematics errors should be less than 0.1 arcseconds over a 10 arcminute field. This high precision will make Pan-STARRS invaluable for proper motion and parallax observations of nearby stars, as well as of solar system objects.
Yes. Accurate photometry is crucial to the detection and measurement of variable sources and of star and galaxy colors. The goal for absolute photometric precision in stacked and difference images is 0.01 magnitudes. Higher precision should be attainable for relative photometery of brighter objects.
Normal procedure will be to make observations of the same piece of sky a few tens of minutes apart, so that main-belt asteroids can be easily identified by their proper motions. More distant objects such as KBOs are best detected on a timescale of a few days, while different kinds of variable stars show up better in observations separated by anything from minutes to weeks.