NGC 6781 in Aquila

NGC 6781 is an almost a perfect bubble of gas cast off by a single star. The remnant of this star can be found at the nebula's center, it is the dim blue star (a white dwarf), which has an apparant magnitude of 16.8. The ring has a true diameter of about 2 light years. Compared to the Ring Nebula it is relatively large and faint, yet not so faint that it isn't visible in small telescopes. It appears as an oval with a slightly darker center.

Exposure Data

Instrument: 9.5" f/4.9 Newtonian
F/stop: 5.6
Exposure: 47 x 2 minutes
Camera: Canon 350D with Baader UV-IR-Cut-Filter
Sensitivity: ISO 800
Date: September 22, 2007
Exposure start: 22:46 MESZ
Location: Edelweißspitze, Salzburg
Conditions: Visual limiting magnitude approx. 4 mag, seeing 2.0" FWHM, temperature 5°C, no wind, low to moderate humidity, moon up in the sky
Autoguider: Meade Pictor 216 XT, max. error: 1" (RA), 1" (Dec)
Enhancement: Basic data reduction, resample, logarithmic curves, combine, guiding error correction, star size reduction, local contrast enhancement, noise filtering, color correction
Notes: Image taken during my stay at the Großglockner-Hochalpenstraße in September 2007. See an Observation Report of this event (in German).