(click to enlarge, source: WikiMedia)
If you look carefully near the center, each of the pulsar line segments have a gap at a specific radius. I can't find any mention of the meaning of this. Any ideas?
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It is explained in the original paper from Sagan:
A Message from Earth Author(s): Carl Sagan, Linda Salzman Sagan and Frank Drake Source: Science, New Series, Vol. 175, No. 4024 (Feb. 25, 1972), pp. 881-884
I found a copy on the website of Swarthmore College: link to PDF
On page 2, it is explained:
Those radial lines for which the earth-pulsar distance is not accurately known are shown with breaks.
Partial answer, exploring some details
It's clearly not an artefact of the SVG vectorised file on Wikipedia. A photograph of the Voyager Golden record (which features the same map), shows the same gap.
Using this to decode the pulsar map, the distance of the most similar pulsar can be established (280 parsecs)
The gap is then around ~200 parsecs. I recognise nothing special about this distance.
It's too large to be some solar system distance, but too small to be a galactic distance.