Jump to the animations, or the Purvis et al. (1987) IPS survey at 81.5 MHz.
The Astronomy and Astrophysics group in the Physics and Astronomy Department of the University of Glasgow holds the primary data from the New Cambridge IPS Survey (1990 to 1994). This unique data set comprises daily measurements of the scintillation (or twinkling) of approximately 800 extragalagtic radio sources distributed over the sky as seen from the Mullard Radio Astronomy Observatory, Cambridge, UK. These scintillations reveal density fluctuations in the interplanetary medium and can be processed to produce daily maps of the sky, highlighting regions occupied by unusually low or high density solar wind.
The measurements were made continuously using fully automated equipment connected to the 3.6 hectare transit array at the Lords Bridge observatory site near Cambridge. Here is a picture of Graham Woan (left) and Fergus Gallagher (right) loitering around the IPS hut next to the array. An observing frequency of 81.5 MHz allowed us to detect both transient and co-rotating structures in the solar wind at all solar elongations greater than about 30° and declinations greater than -7°.
Picture: the 3.6 hectare array. (© Mullard Radio Astronomy Observatory, 1995.)
Some of the processed data have been distributed to research groups around the world, including The Space Environment Laboratory at Boulder, Colorado, the Rutherford Appleton Laboratory, Imperial College, The British Geological Survey and UCSD (California). Prospective users of the data should contact Dr Graham Woan in the first instance.
Picture: as an example, here is recent IPS image, which shows the whole sky, as seen from Cambridge, in a Hammer-Aitoff projection. The ecliptic is shown yellow with the Sun at the centre. Scintillation is expressed as the index g on a logarithmic scale. Blue (low g) corresponds to low solar wind density and red (high g) to high density. The graph in the lower portion of the picture displays the g values of individual radio sources as a function of solar elongation.
Animations (FLI) of the IPS images are available for the following months.
The source list from the Purvis et al. (1987, Mon.Not.R.astr.Soc., 229, 589) IPS survey at 81.5 MHz is available. Please refer to the published paper for details of the column entries.