HFG-1 and Abell 6

HFG1 ( PK 136 + 05) and Abell 6 (PK 136 + 4.1) form a couple of unique planetary nebulas, very interesting to image in narrow band filters.
HFG1 takes its name from its three discoverers: Heckathorn, Fesen and Gull.
HFG1 leaves behind a tail of gas emitting in the Ha and NII wavelengths. This tail of at least 20 ‘would be about 10,000 years old.
HFG1 presents an interesting structure, with an arc of a circle opposite the tail, i.e. in the direction of travel of the nebula, which suggests that it is a wave front shock of matter interacting with the interstellar medium. There are also three brighter lobes in the OIII line and a weaker central zone where the Ha signal dominates.
Abell 6 is a classic example of a bubble in this catalog (type 2b), but also remains quite weak (mag = 15.0), with a stronger OIII emission than in Ha. However, its structure has irregularities with in particular two thin lobes at the edge.
Newton TS ONTC 8 “at F4.5 with Paracorr Televue Type2 corrector
ZWO ASI294MM Pro Camera
Antlia SHO 3.5nm and Astrodon RGB filters
Ioptron CEM70 mount
ZWO AsiairPRO
Unit images:
ANTLIA H-Alpha 3.5nm: 91×600 “(15h 10 ‘) (gain: 120.00) -10C bin 2×2
ANTLIA OIII 3.5nm: 105×600 “(17h 30 ‘) (gain: 120.00) -10C bin 2×2
Astrodon Tru-Balance E-Series Gen 2 LRGB: 90×180 “(4h 30 ‘) (gain: 120.00) -10C bin 2×2
Integration: 37h 10

Autore: Christophe Vergnes