M11 - Wild Duck Cluster

M11, the "Wild Duck Cluster", is one of the richest galactic star clusters, as it includes about 2.900 stars, about 500 of which are brighter than magnitude 14. It is located at the edge of the dense Scutum Star Cloud in the Summer Milkyway. Its diameter measures about 14 arcminutes. The age of M11 has been estimated to about 250 million years, as its brightest and hottest main sequence stars are of spectral type B8. The cluster is receding at 22 km/sec.

M11 was discovered visually by the German astronomer Gottfried Kirch at the Berlin observatory in 1681.

M11 - Wild Duck Cluster, Wright-Newtonian photograph.

Exposure Data

Instrument: 9.5" f/4.9 Newtonian
F/stop: 5.6
Exposure: 3 x 5 min + 2 x 2 min + 2 x 30 sec
Camera: Nikon D70 with Baader UV-IR-Cut-Filter
Sensitivity: ISO 1600
Date: June 24, 2006 / July 20, 2006
Exposure start: 3:03 MESZ / 1:14 MESZ
Location: Ebenwaldhöhe, Lower Austria
Conditions: Visual limiting magnitude 4.0 mag (decreasing), Seeing 6-7/10, Temperature 14°C, no wind, moderate humidity / Visual limiting magnitude 6.0 mag, Seeing 7-8/10, Temperature 17.5°C, no wind, low humidity
Autoguider: Meade Pictor 216 XT, max. error: 1" (RA), 1" (Dec)
Enhancement: Basic data reduction, combine, logarithmic curves, color enhancement, star size reduction, dynamic range extension, noise filtering, crop
Notes: Exposures taken in morning twilight (June 24) or with the moon up in the sky (July 20).