The I-GALFA survey observations were completed at Arecibo on September 12, 2009. The images at right show the cumulative sky coverage of all the survey observations over the past two years, as detailed in the observing schedule and nightly position plots.
The upper figure shows positions in equatorial coordinates: right ascension and declination, which are like extensions of the Earth's longitude and latitude coordinates on the sky. The lower figure shows positions in Galactic longitude and latitude, where Galactic latitude = 0 is the Galactic equator, or the plane of the Milky Way, and the center of the Galaxy lies in the Galactic plane in the direction where the Galactic longitude = 0.
In both figures, each night's observation is marked with a single track showing how the position of the center beam of the ALFA array receiver moved over the sky during the observing session. An intermediate example of how these tracks add up to form a map is given elsewhere. The blue lines here represent all the 2008 observations, and the red lines represent all the 2009 observations. The solid black boxes mark the I-GALFA minimal field boundaries. The dashed lines mark the target zone extending 10 degrees on either side of the plane of our Galaxy. Because I-GALFA was observed in equatorial coordinates (the natural system for a telescope like Arecibo), and some extra observations were needed to make sure the tracks were woven together properly, the I-GALFA observations extend somewhat beyond the minimal requirements, allowing additional and exciting science on clouds farther from the plane of the Galaxy.