NEBULAE
An Object Nobody Could Classify
— EGB 10 —
Processed by Nicolas Rolland, Paris, as part of the Astrofleet Team. 81.7 hours gathered at Saintes, France.
Nobody has been able to say what this is. It has been called three different things in forty years, and it has held none of them.
Forty years of reclassification
EGB 10 sits in Draco and is extremely faint. It was picked up in the 1980s as a possible planetary nebula, dismissed shortly after, and then filed at various times as a reflection nebula and as a distant galaxy. The designation comes from the EGB catalogue, compiled by Glen L. Ellis, Earl T. Grayson and Howard E. Bond at the Department of Astronomy of the University of Louisiana.
What the oxygen showed
Recent work by Xavier Strottner, Marcel Drechsler, Utkarsh Mishra and Sankalp Mohan changed the picture. Narrowband imaging in OIII revealed extended gaseous shells well beyond what had been catalogued — a structure both larger and more intricate than any of the earlier classifications allowed for. The object is not a small misidentified nebula; it is a large one that had only ever been seen in part.
Why it stayed unresolved for so long
The reason is straightforward: the emission is too weak to register on a survey plate or in a short exposure. An object that only shows its true extent after tens of hours of narrowband integration will look like whatever its brightest fragment resembles, and that fragment has resembled three different things to three different sets of eyes. The classification did not fail for lack of thought. It failed for lack of signal.
Eighty-one hours from Saintes
An ASKAR FRA400 at f/5.6 with a monochrome sensor, from Saintes in April 2025, over 664 frames. Nearly forty hours went to H-alpha and thirty to OIII, in ten-minute exposures, with twelve hours of colour in three-minute frames — eighty-one hours and forty minutes in total, the longest integration on this site. That is not a choice, it is the entry price: below a few tens of hours the shells simply are not there, which is the whole history of this object. Two things remain out of reach even so. The image samples at just under an arcsecond per pixel, which is coarse against structure this delicate, and the outer shells still sit at the edge of what the total will carry — eighty hours establishes that they exist rather than resolving what they are made of. Gathered at Saintes with the Astrofleet team.
