Sep 2009

Version 1.2 Draft

A release candidate for Satellites Version 1.2 is available on the downloads page.

Work in Progress

I wanted to show some screenshots of the work in progress and summarize other changes coming in v1.2 of Satellites.

The first changes relate to what's displayed in the 'orbital' views such as these. The time display is at the bottom and by default shows real time. The time can be changed by touching the two icons to the right and left. The acceleration of time can be stopped by touching the time display itself. Time can be restored to the current time by double-tapping the globe.

The views to the left are "Center ISS views" and always display with the International Space Station placed at the center of the screen. You can zoom in and out, but you can't rotate the globe.

This contrasts with a new view, on the right, called "Center Observer" in which the observers location is maintained in the center of the screen. For these two "centered" views there is a display at the top of the screen which relates to the position of the satellites being tracked. In the "Center ISS" view, those data fields show the latitude, longitude and height of the objects -- in the "Center Observer" view, they display azimuth (measured in degrees around the horizon 'clockwise' from looking North -- North=0, East=90, South=180 and West=270), elevation (degrees up from the horizon) and range (the distance of the object in Kilometers) whenever any object is close to being visible to the observer. In the screenshot taken, there is nothing near the observer (in Ann Arbor), though the current orbit will take ISS close by in a while.

The other orbital view allows the globe to be rotated and zoomed, but doesn't display any object information -- flexible and clean!

An entirely new view, not an orbital view, will also make its debut in v1.2 of Satellites. This is a "Predictions" view, and is seen here in a form which is not final but gives an impression of my intent.

In this view, every pass of the ISS over the observers location is described. Some of these will be during daylight, when the ISS is invisible to the naked eye (radio amateurs who like to listen in to ISS communications will find this useful). Some passes will be at night, but far enough from dawn or dusk for the ISS to be in shadow through the entire pass, again rendering it invisible to the observer. The visible passes are where the sun has set for the observer but not for the ISS. The final version of this display will endeavor to illustrate these various configurations with colored backgrounds and colored text showing rise or shadow exit time, highest elevation time and set or eclipse entry time.

V1.2 will also fix two small computational bugs. One relates to the "Center ISS" view in which the central indicator of the ISS location vibrated around the zero point; the other was a less visible slight drift in siderial time towards the end of each day.