Wednesday, October 05, 2016
Mars Amongst the Clusters of the Teapot
In early October Mars is in the “Teapot” of Sagittarius. Sagittarius lies across the heart of our galaxy, so as Mars moves through the “lid” of the teapot, it comes close to several bright stars and several bright globular clusters.
On the 5th and 6th Mars is close to the magnitude 6 globular cluster M28, on the 7th it is closest (at just half a lunar diameter) from Kaus Borealis, the star that forms the lid of the Celestial teapot. This is best seen in binoculars.
On the 8th it is closest (almost on top of) to the 9th magnitude globular cluster NGC 6638 (best in telescopes) and on the 9th and 10th it is closest to the iconic magnitude 5 globular cluster M22. Although this is potentially visible to the unaided eye in dark sky sites, with the waxing Moon, binoculars or telescopes are best to see the pairing.
The clusters and Mars are high enough from Astronomical twilight in the evening (roughly an hour and a half after sunset) until around 11 pm local time for viewing (and astroimaging) before they become too low.
There will be several challenges imaging these clusters and Mars. Mars's brightness will prevent long exposures, and the waxing Moon is close by, a mere 6 degrees on the 9th, making even narrow-band imaging a challenge.