What is it?
The IOTA-VTI is a video time inserter: it derives precision Coordinated Universal Time from the GPS system, and stamps that time on every frame (and field) of a video signal. It was developed specifically to fill the needs of IOTA members who wish to use video methods to obtain precision timing of astronomical phenomena, but it is suitable for any video timing application. The time of any event, or change, can be read directly, either by stepping through the record one frame at a time or by using video analysis software.
[Front View - Click here to see larger view]
[Back View - Click here to see larger view]
An example of IOTA-VTI use
The image above, left, is a single video frame from a recording of a grazing lunar occultation of ZC1582, magnitude 6.4. Several sunlit peaks at the southern cusp of the 15% sunlit moon are at lower left. The star was about to be occulted by three lunar peaks in the span of 40 seconds.
The plot above, right, (only a part of the complete graze record) is star brightness in successive video frames, obtained using Limovie, a free video analysis application. The star was in the first valley for 2.44 seconds and in the second valley for 0.24 seconds. While occulted by the second peak, a shallow depression allowed a part of the star to be revealed briefly.
Across the bottom of the video frame is the time stamp provided by an IOTA-VTI, which shows: the GPS receiver was using 9 satellites; Universal Time was 12 hours 48 minutes 15.7840 seconds at the mid-point of the video frame (and 15.8007 seconds at the end of the frame); the video frame consisted of video fields numbers 309,226 and 309,227, indicating that the IOTA-VTI had been running continuously for one hour 26 minutes.