M107 is a loose globular cluster of eighth magnitude located in Ophiuchus. It's a difficult binocular object that's much easier to spot with small telescopes. This globular was discovered by Pierre Méchain in April, 1782 and independently re-discovered by William Herschel on May 12, 1793. Herschel was also the first person to resolve it into stars. The cluster is one of the additional items that were not included in Messier's final catalogue version, but added much later by Helen Sawyer Hogg in 1947. She also added M105 and M106.

M107 is located 20,900 light-years from Earth and spans 13 arc minutes of apparent sky, which corresponds to a spatial diameter of 80 light-years. It contains 100,000 stars and has an estimated age of 13.95 billion years, making it one of the oldest known globulars.

M107 globular cluster by the Hubble Space Telescope (credit:- NASA, The Hubble Heritage Team (AURA/STScI))

Finder Chart for M107 (credit:- freestarcharts)

Finder Chart for M107 - pdf format (credit:- freestarcharts)

Locating M107 is relatively easy as its positioned 2.75 degrees southwest of zeta Ophiuchi (ζ Oph - mag. +2.5). This star is located 16 degrees north of Antares (α Sco - mag. +1.0). M107 can be also found by imagining a line connecting Yed Prior (δ Oph - mag. +2.7) with Yed Posterior (ε Oph - mag. +3.2) and extending it in a southeasterly direction for 9 degrees.

At magnitude +8.0, M107 appears as a faint small diffuse object through small 80mm (3.1-inch) refractors. There is a subtle increase in brightness from the outer to the inner region but it doesn't have a particularly bright centre. A 150mm (6-inch) telescope will start to resolve members at the outer edges, but the view is much better with larger scopes. Instruments of 300mm (12-inch) aperture or greater reveal a superb object with many stars spread across the entire face of the cluster. What's also noticeable is the looseness of this globular.

At least 25 known variable stars have been identified in M107. It appears to contain regions obscured by darkness, which is unusual for such objects. M107 is best observed during the months of May, June and July.

M107 Data Table

Messier107
NGC6171
Object TypeGlobular cluster
ConstellationOphiuchus
Distance (light-years)20,900
Apparent Mag.+8.0
RA (J2000)16h 32m 32s
DEC (J2000)-13d 03m 10s
Apparent Size (arc mins)13 x 13
Radius (light-years)40
Age (years)13.95 Billion
Number of Stars100,000

Sky Highlights - July 2017

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for July

Meteor Shower
Southern Delta Aquariids (Aquarids) meteor shower peaks on July 29

Northern Hemisphere
Evening
West:- Mercury (mag. -0.5 to +0.3) (second half of month)
Southwest:- Jupiter (mag. -2.0)
South:- Saturn (mag. +0.2)
Midnight
West:- Jupiter
South:- Saturn
East:- Neptune (mag. +7.8)
Morning
Southwest:- Saturn
South:- Neptune
Southeast:- Uranus (mag. +5.8)
East:- Venus (mag. -4.1)

Southern Hemisphere
Evening
West:- Mercury (second half of month)
Northwest:- Jupiter
East:- Saturn
Midnight
West:- Jupiter
North:- Saturn
East:- Neptune
Morning
West:- Saturn
North:- Neptune
Northeast:- Venus, Uranus

Deep Sky

Small telescopes:-
Messier 13 - M13 - Great Hercules Globular Cluster
Messier 92 - M92 - Globular Cluster
Messier 11 - M11 - The Wild Duck Cluster (Open Cluster)
Messier 7 - M7 - The Ptolemy Cluster (Open Cluster)
Messier 6 - M6 - The Butterfly Cluster (Open Cluster)
Messier 4 - M4 - Globular Cluster
Messier 8 - M8 - Lagoon Nebula (Emission Nebula)
Messier 16 - M16 - Eagle Nebula (Emission Nebula with Open Cluster)
Messier 20 - M20 - Trifid Nebula (Emission and Reflection Nebula)

Shop at Amazon US

Contributions

If you like the website and want to contribute to the running costs then please do so below. All contributions are most welcome.

PayPal - The safer, easier way to pay online.