Figure 1 – Messier 7, Ptolemy Open Cluster, image take with iTelescope,net T72 in Chile. (c) DEWolf 2023
When you first get involved in amateur astronomy and start searching for Messier objects with a visual telescope, everything looks like a grey fuzzy and you think that there are four types of Messier objects: globular clusters, open clusters, nebulae, and galaxies. Never make a statement like that without checking the web first and needless-to- say there are formally six types: open clusters, globular clusters, diffuse nebulae, planetary nebulae, supernova remnants, and galaxies. So put a fine point on it!
Aesthetically, each form has its own appeal. And it’s like the old almond joy commercial: “Sometimes you feel like a nut. Sometimes you don’t.” Two years ago I encountered Messier 7 the Ptolemy (Open Cluster). Nestled in the deep Milky Way portion of Scorpius, we see it against an amazing array of stars!
Messier 7 is referred to as the Ptolemy Cluster in honor of the ancient Greek astronomer Claudius Ptolemy, who first recorded it in the 2nd century. Charles Messier cataloged it in 1764 as part of his famous Messier Catalog, a list of astronomical objects that helped astronomers distinguish between comets and fixed stars.
Messier 7 is an open star cluster situated approximately 980 light-years away from Earth. Open clusters, unlike globular clusters, consist of stars that are loosely bound together by gravity, and they are often found in the spiral arms of galaxies. M7 contains around 80 stars, and its most noticeable feature is its relatively young age, at only about 200 million years old a mere blink in the vast timeline of the cosmos.
I’ve imaged it with my Seestar 50s, not yet my Celestron Origin. This was a pretty pathetic image; so I am anxious to give it a try with the Origin this summer.
However, I did photograph it with the iTelescope T72 a fabulous 510 mm telescope (T72 3411 mm f/6.8 PlaneWave L-500 + FLI ML16200) in Deep Sky Chile at Rio Hurtado Valley, Chile. That is Figure 1 revealing Messier 7’s in all its celestial beauty. Now here is another important point. T72 is at 30°31’34.712″ South latitude and altitude 1710 m above sea level. M7 is the Messier object with the lowest declination, -34° 47′ 43″. It is always very low in New England skys. But it transits near the zenith in Chile. So clear skies high telescope altitude, and high celestial altitude. It’s a winning combination all around.