I was unable to find another amateur image of DeHt4, a faint planetary nebula in the constellation Aquila. Its coordinates are RA 19:26:26, DEC 13:19:42. It was discovered by Dengl, Hartl and Weinberger by detailed examination of the red and blue POSS plates. They described it as an “oblate ellipsoidal shell” in their discovery article published in Astronomy and Astrophysics in 1980:
Its surface brightness is listed as 22.4(red) to 26.3(blue) mag/arc-sec2, with an integrated nebular magnitude of 16.2-19.4. Its distance is estimated at 4500 pc. Its dimensions are reported as 44 x 34(?)”. However, this long exposure image demonstrates much extended nebula beyond the central core and measures 66” x 104” in angular separation. It is seen primarily on Ha exposures (Eight hours of 60 minute binned subs). Only a hint of the brighter eastern core shell was seen on long OIII exposures.
A suggestion of the southern looping extension was seen in an image from the IAC Morphological Catalog of Northern Galactic Planetary Nebulae (Manchado et al, 1996) obtained with the 2.56-m Nordic Optical Telescope.
The northern outer structure around DeHt 4 was discovered in April 2015 by the Galactic Planetary Nebula Halo Survey. Thanks Sakib Rasool for researching and recommending this target, for the GPNHS group. This is the first image to my knowledge detailing these structures.
Also seen at southern edge of this field is a small HII(?) region seen only on stretched 60 minute Ha subs. I am unable to find this on any of the deep sky surveys, nor when searching its coordinates RA 19:26:25, DEC 13:9:27. I initially thought it might be a reflection from mag 5.7 star HIP 95572 not seen but just south of the field, or artifact, but it appeared on successive nights and shifts appropriately with the field on CCD rotation.
UPDATE: I spent more time on the phantom "HII" region at the edge of the field, centering it in the the FOV. It is no longer visible (despite again confirming the faint extended nebulosity in DeHt4), suggesting that it is reflection from a mag 5 star south of the field.
Imaging Camera: QSI540wsg
Imaging Scope: Celestron 9.25"Edge HD
Guide Camera: SX Lodestar
Mount: Avalon M-Uno Fast Reverse
Filters: Astrodon 5nm Ha,3nm OIII, Gen II RGB
Exposure: 8 hours Ha (60 minute subs binned x2), 5 hours OIII (30 min subs binned x2), 1.5 hours each RGB (3 minute subs binned x2)
Processing: CCD Stack and PS CS2
Date: June 18,24 and July 16 2015
Location: My front driveway. Morristown, NJ