# Tag Info

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Optical observatories -- or commissions that allocate time on a national or international basis to one or more telescopes -- generally accept proposals twice a year, during a one-month period with a deadline in the middle or end of March or in the middle or end of August (in both cases, these are for observations that will take place starting about six ...

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As far as I have researched, there are really many countries that organize Messier Marathon, but also many astronomers organize it locally only for them and don't publish it on web, so I could write here nearly every country.

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I always believe that one picture can tell more than 1000 words. So, here you have it: The possibility of seeing the object is called declination $\delta$. It is the angular distance from the celestial equator. Thus, red star on the diagram has $\delta=75°$ while violet star has $\delta=-30°$. For the north pole: $\delta=90°$. For the celestial equator: \$\...

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Welcome to Astronomy SE! If the latitude φ of the observatory is equal to or less than (90° + δ), then the object is visible at least some of the time. For example, the Trifid Nebula (M 20) is at δ = −23° 02′, so any observatory at latitudes φ ≤ [90° + (−23° 02′)], viz. φ ≤ 66° 58′ (basically, any place below the Arctic Circle), will see it at least some1 of ...

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