Some terms

- Acquisition of Signal. The time at which a satellite rises above the local horizon. For a LEO satellite, it's passage across the sky will take around 15 minutes. The satellite's setting time is known as Loss of Signal, or LOS.

APT - The simple analog mode of NOAA image transmission is known as Automatic Picture Transmission, or APT.  APT images have a ground resolution of around 4km.  NOAA satellites also transmit a higher resolution digital mode known as High Resolution Picture Transmission (HRPT), where ground features as small as 1km may be observed.  By a slightly confusing coincidence, the building where our satellite receiver is housed is known as the Automated Patrol Telescope , more usually, "The APT".

Australian EST - or Eastern Standard Time, is used throughout most of eastern Australia and Tasmania. During Austral wintertime,  EST = UTC + 10 hours, and during summertime Eastern Daylight Time (EDT) = UTC + 11 hours. The date at which Australian daylight saving starts and stops can be found at this useful site.

Carrier - An unmodulated radio wave, what you hear if you tuned into an AM or FM radio station, and nobody was talking.

Footprint - How much of the Earth a satellite can see is dependent on the satellite's altitude.  NOAA polar orbiting satellites orbit at an altitude of ~800km, and from that height can view a circle of the Earth around 6000km wide.  The area of the Earth that can be seen by a particular satellite, is known as the satellite's footprint.  If one checks the current whereabouts of NOAA 12 and NOAA 15, the footprints are indicated by the circles drawn around the satellite.  If one checks the current whereabouts of NOAA 17 , the image presented shows only NOAA-17's footprint, and monitoring this particular image demonstrates just how much of the Earth is covered by ocean.

HRPT - See 'APT' above

LEO - Most Earth orbiting satellites actually fly fairly close to the Earth's surface, with altitudes typically between ~300 - 2000km.  Such orbits are known as Low Earth Orbit, or 'LEO'.  Placing satellites into higher orbits such as Geostationary and Molniya, involves vastly more rocket power and complication, and hence most satellites are placed low down, often skimming just above the Earth's atmosphere.

WXtoImg's Map Coloured IR enhancement (used for nighttime passes), with coloured highlighting of rain potential cloud.

MSA-precip - WXtoImg's Multi Spectral Analysis enhancement (used for daytime passes with solar elevation >15), with coloured highlighting of rain potential cloud.  For further technical details of MCIR and MSA image enhancements, see the WXtoImg User's Manual

Maximum Elevation
- The NOAA satellites are on near-polar orbits (orbital inclination ~98.6), meaning that they will normally be observed to track along a North-South line, southbound in the morning and northbound in the evening. An observer will normally notice that they reach the maximum angle above the horizon when passing the due-east or due-west direction.

Sucker Hole - Astronomer's slang for a hole in the cloud which closes up, just at the moment when a telescope has been laboriously repositioned to look through it.

UTC - or 'Universal Time' = Greenwich Mean Time (GMT) for all practical purposes. The Universal Time at which you loaded this page was: UTC

VHF - Very High Frequency.  Radio frequencies within the range 30 to 300 Megahertz.  For example, ordinary Broadcast-FM stations transmit somewhere between 88 to 108 Megahertz, and are therefore 'VHF'.