The date of the latest farside image is at It consists of a single line containing the date.

Images are prepared in several formats, each with a type code.

The lastest image of each type is located in the directory as simple "gif" files.

These are:

Type Link Description Sample
  Latest_Image.html Date of most recent images 2011.01.11_00
syn lastest.syn.gif Synoptic chart with labels
N lastest.N.gif North pole view
S lastest.S.gif South pole view
syn_small lastest.syn_small.gif Synoptic chart with no labels, 2:1 ratio
syn_nolab lastest.syn_nolab.gif Synoptic chart with no labels, new 2.5:1 ratio
synanim lastest.synanim.gif Animated gif of syn_small, 2.0:1 ratio, 10 days
qual lastest.qual.gif

The quality index is computed from the number of images available for the analysis. The present analysis uses 2048 minutes of Dopplergrams centered on the specified time. This requires six of the MDI 6-hour datasets. The analysis requires some data from all six datasets. If any of the datasets is missing no farside image will be available for that time and the quality image will be white. The number of minutes of good data is counted and the fraction of the color bar colored green is (2048 - 3*(missing images))/2048. Where missing images is the count of minutes without good data. The factor of 3 is used since in the farside analysis each missing minute affects (roughly) the minute itself, and a minute 4 hours before and 4 hours after which will be less effective since they will not have a companion minute. The missing fraction is colored red. If any of the datasets uses quicklook data amber will be used instead of green. This should usually happen for the most recent data and should be recomputed after a few days with final data.

So, the message is, the best quality will be a solid green bar.

In the original farside analysis, synoptic chart images were prepared with a 2:1 ratio of width to height. Since these were sine-latitude vs longitude plots they were conformal at 37 degrees latitude. Several observatories prepare sine-lat/longitude charts with a ratio of pi which makes them conformal (equidistance on the image is equidistance on the Sun) at the equator. These are too wide for easy use on the web and emphasize latitudes where there is little farside signal. We have adopted a ratio of 2.5 to 1 which is conformal at about 27 degrees which is closer to the latitude of active regions. With this mapping active regions near the start of the cycle will appear undistorted. We maintain the 2:1 version for convenience of some users.

RAW DATA: The binary format data is also available. The data is in several forms.

These data are all stored in the "/synoptic/farside/" directory tree which may be reached via the web at:
The use of a tool such as wget is advised for access.

The source code is available at