Compiled by:
Glenn Chaple
Introduction
Autumn can be a wistful time of year for the globular cluster aficionado as the globular-rich constellations of summer, notably Ophiuchus, Scorpius and Sagittarius, are rapidly disappearing in the western sky. Fortunately, a few stragglers remain visible on October evenings, including the bright globular cluster Messier 2 (NGC 7089) in Aquarius.
Charles Messier found and cataloged it on the evening of September 11, 1760, 14 years to the day after it was stumbled upon by the Italian-born French astronomer Jean-Dominique Maraldi while observing de Chéseaux’s Comet. To both Maraldi and Messier, the object appeared nebulous. It was William Herschel who, in 1783, was able to resolve M2 into its individual stars.
M2 is located at the 2000.0 coordinates RA 21h33m27,0s and DEC -00o49’23.7”, some 5 degrees north of the 3rd magnitude star beta (β) Aquarii and roughly 10 degrees east and slightly north of 3rd magnitude alpha (α) Aquarii. To find it manually, aim your telescope towards this location (refer to the accompanying finder chart) and conduct a low-power sweep until a hazy circular patch of light enters the field of view. From there, switch to higher magnifications for that “up close and personal” view.
M2 offers several challenges for the visual observer. 1. Can you see it with the unaided eye? At magnitude 6.3, M2 should be barely visible from a dark-sky location on a clear, moonless night. 2. What’s the smallest aperture that will resolve M2 into its component stars? This would be an interesting activity for an astronomy club whose members would observe M2 with different-sized telescopes and compare notes. 3. Can you see a dark curving lane that crosses the northeast edge of M2? In The Messier Album, co-author John Mallas includes a sketch of M2 and the dark lane as they appeared in a 4-inch refractor.
Most resources cite a distance to M2 of 37,000 light-years. It has a calculated diameter of 150 to 175 light-years and contains an estimated 100,000 to 150,000 stars.
(NOTE: Messier 2 was previously featured as the August, 2009, Observer’s Challenge)
Reports
John Bishop
Here is a report of my observation of Messier 2. Short and sweet. I don't image, I can't draw, this is all I can do.
On November 1, 2024, I observed Messier 2, a globular cluster in the constellation Aquarius. Luginbuhl and Skiff assign M2 a visual magnitude of 6.4. I observed from the ATMoB Clubhouse in Westford, Massachusetts. I used my 8.25 inch f/11.5 Dall-Kirkham reflector, a portable setup on a motor driven equatorial mount, without go-to. The sky was clear, and transparency was good. At sunset, there was a brisk breeze at ground level, and seeing was unsteady, but both settled down as the night went on. Air temperature was mild, dropping to 46 degrees F. at 11:30 pm. Clear skies, no bugs, no dew, no frost - with the Moon at new phase, the assembled group enjoyed very good observing conditions.
Previously, on October 5, 2024, I observed M2 from the Clubhouse with 10x42 image stabilized binoculars. Conditions were not quite as favorable as on November 1. I was surprised how small and faint M2 looked - a hazy patch. I was motivated to see it through a telescope.
On November 1, M2 was easy to locate by starhopping. It lies about five degrees north of the star Beta Aquarii. Centering that star in my 7x50 finder, a small nudge of the OTA brought M2 into the finder FOV, where it showed as a small, round nebulous patch. In the main eyepiece, I observed at 48x (50mm eyepiece), 134x (18mm), and 268x (2x Barlow). At low power, M2 was a featureless sphere with a soft outer boundary or halo. High power gave a bright, dramatic view. At 266x, the bright, dense core was prominent, and stars were resolved in the outer regions, with lines of sparkling stars running out from the core (but this was not as pronounced as the pinwheel effect in M13). The dense core was not resolved, although individual stars could be seen in the foreground. If I saw the dark lane mentioned by Glenn Chaple, I didn't realize it. The bright core was not uniformly round, but showed what I referred to in my notes as "extensions" in one direction or another
Mario Motta
M2 is a globular cluster in Aquarius, and about 55,000 LY away, it is 175 LY in diameter, and thus one of our galaxy's largest clusters, and contains 150,000 stars. The brightest of these are now red giants, which is why the brightest stars in the field are reddish in color. The stars in this cluster are 12.5 Billion years old.
Taken with my 32 inch F6.5, camera was ZWO ASI6200, using RGB filters each 45 minutes, then processed in Pixinsight.
Doug Paul
Canon 80D, 1200mm FL f8 lens (150mm aperture), ISO800, 30x1m = 1/2hr, 1/2 scale, North up
Venu Venugopal
Here is my catch of the M2 with a C11 Edge HD, 15 minutes exposure, no guiding, 10 second sub exposures. Flats, Dark and Bias applied
Dave Wilbur
Attached is an image of M2 taken Oct 12 with my Seestar smart telescope (50mm, f5).two images really, the original full frame and cropped
Glenn Chaple
Drawn on 10/20/2024
Telescope and eyepiece used: 10-inch f/5 refractor with a 6mm Ortho
Magnification: 212x
Field of view: 0.2 degrees
