The current trend in astrophotography is "bigger, more spectacular and more exciting".
Perhaps we can inspire a few people with something small, but no less beautiful.
We are very happy to present the planetary nebula Strottner-Drechsler 166 discovered by our team in 2022.




In a peripheral region of the constellation Cygnus and hidden behind the label "Strottner-Drechsler 166" (PNG 088.6+07.2) there is one of the smallest true planetary nebulae (PN) in the StDr catalogue which appears to be more than just a dot.
The PN was discovered in 2022 by Marcel Drechsler and Xavier Strottner, whose abbreviations also give the catalogue its name.
On 2 November 2022, Pascal le Dû and his team from 2SPOT confirmed StDr 166 as a true planetary nebula based on a spectrum (image below).




After the discovery of the PN, Marcel Drechsler and Xavier Strottner still assumed that StDr 166 is a classical bubble-shaped PN whose surface shows little to no details. However, the photographic data taken by Rochus Hess at the VEGA observatory in Salzburg with a 1m mirror and a focal length of just under 7m show that StDr 166 has more structures than expected; the PN is very close to PN Jones-Emberson 1, which also has ear-like structures.​​​​​​​




As already mentioned, StDr 166 is one of the smallest PNs in the StDr catalogue and its photography therefore posed a major challenge.
With an apparent diameter of only 15.7 arc seconds, the PN appears to be just under half the size of the planet Mars at its closest point to Earth (perigee).
The image below shows Mars photographed by the Rosetta space probe and StDr 166 in direct size comparison.​​​​​​​




Picture below:
StDr 166 in the light of the brightest spectral line of excited hydrogen (H-alpha).
H-alpha forms a ring with the ear-shaped structures already described above along the imaginary equatorial line.​​​​​​​




Picture below:
StDr 166 in the light of double ionised oxygen (OIII).
OIII forms a diffuse bubble in the centre - a very typical distribution of gases within planetary nebulae.​​​​​​​




Picture below:
Although StDr 166 was not discovered until 2022, the PN has a relatively high surface brightness, so that StDr 166 is even visible in some surveys.
In the PanSTARRS survey, the PN appears as a faint blue sphere with a tiny blue dot in the centre, which is probably the central white dwarf.​​​​​​​




Our very special thanks go to our friend and colleague @Rochus Hess from the "Haus der Natur Salzburg" (picture below).
The "Haus der Natur" operates one of the most powerful public observatories in Europe on the Haunsberg, just outside the city of Salzburg.
Rochus has accompanied us in our research for many years and we have already been able to realise many joint projects.
We are all the more pleased that we were able to create this wonderful photo together with Rochus and the VEGA observatory "Haus der Natur Salzburg".​​​​​​​