This faint diffuse nebula is close in direction to the suspected supernova remnant GAL 013.1-00.5
and appears to be located in an empty region bordered by the OB regions Sgr OB1, Sgr OB7 and Sct OB3.
Avedisova places Sh 2-43 / RCW 156 into star formation region SFR 13.62-0.76
along with two infrared sources and many molecular clouds.
No ionising star for Sh 2-43 has been identified in the scientific literature and no ionising star in this direction appears in the Reed catalog or SIMBAD either. The bright star in this image is the K2 III giant HD 167720
The RCW catalog not very helpfully comments "Possibly local concentration of general diffuse emission present" and identifies a slightly brighter core region, RCW 156a
There is a 0.3 degree difference between the positions of RCW 156
and Sh 2-43. Sharpless gives the diameter of Sh 2-43 as 15 minutes = 0.25 degrees. RCW gives the diameter of RCW 156 as 50x50 minutes. These objects may
not be part of the same nebula, but they are clearly very close in the sky. The RCW catalog does identify them however, stating RCW 156 = Sh 1-34 = Sh 2-43.
Avedisova includes both Sh 2-43 and RCW 156 in the star formation region SFR 13.62-0.76
along with numerous molecular clouds and the radio HII region [CH87] 013.839-0.763
This is in the same location as the suspected supernova remnant GAL 013.1-00.5.[1
1. ^ Gorham, Peter W. (1990). "A radio/infrared/optical study of candidate
supernova remnants from the Clark Lake 30.9 MHz Galactic plane survey", The
Astrophysical Journal, Vol. 364, 187-197. [1990ApJ...364..187G]