Abell 31

Sh2-290 (also known as Abell 31, PK 219.1+31.2, A 31 or ARO 135) is a very old planetary nebula in the constellation Cancer.

Both its big size (one of the largest planetary nebulae of the sky) and its very low brightness are due to its age : indeed gases have expanded to such an extent that it begins to disperse in the surrounding interstellar medium (like all PN over time).

The southern part is surrounded by a bow shock effect, while the northern part has extremely faint and nuanced edges, a sign that dissolution is already advanced there.

 

I am happy that the very long exposure time in Halpha allowed to see the far and faint extensions and HII presence in the background which are not often visible.

 

I began this one in December and finished it in March as it was only accessible during less than 2h each night from my location, between 2 buildings!

It was definitely an hard target to shoot and process, on the 300s subs at f/4 almost nothing was visible on both HII and OIII filters.

I should have done many more exposures in order to bring more details, but the target began to be very low at my location so maybe next year i will ad more datas!

 

32h exposures (H : 266x300s / O : 94x300s / RGB : 20x120s chacun)

Newton 250mm f/3.8 on Ioptron CEM70

Camera ZWO ASI2600mm + Antlia filters HO 3.5nm & RGB

Acquisitions from 22 december to 26 march in Amiens (Bortle 7)

Processing HOO-RGB Pixinsight & Photoshop

Done