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New out today #astrobook "Observing and Measuring Visual Double Stars" http://t.co/giC09mG2 A beautifully revised... http://t.co/te8p0l60
New out today #astrobook "Observing and Measuring Visual Double Stars" http://t.co/giC09mG2 A beautifully revised... http://t.co/te8p0l60