Sh2-28 is a large but faint HII region next to the Trifid nebula.It is ionised by the O9Ib supergiant LS 4551 and the O-class LS 4538. It lies in the direction of the supernova remnant SNR G006.4-00.1 (W 28). Unfortunately SIMBAD (and therefore all plotting softwares) uses the incorrect original Sharpless coordinates for Sh 2-28 rather than the corrected BFS coordinates. This is a reason the nebula is off-centre on this image. Sh2-28 and RCW 145 are the same object. Perhaps because of the errors in the original Sharpless coordinates for Sh 2-28, the RCW catalog identifies RCW 145 as Sh 2-26. Sh 2-26 is a smaller even fainter nebula further from the galactic plane. The W 28 supernova remnant appears to be further away at a distance of 1800 to 3300 pc [Giuliani, A., Tavani, M., Bulgarelli, A., et al. (2010)] but, on the other hand, a 1978 paper by Crampton and Georgelin [Crampton, D., Georgelin, Y. M., & Georgelin, Y. P. (1978)] concludes that the nebula is the optical equivalent of W 28 and includes the supernova remnant. It appears to be associated with M 20, the Trifid nebula. Crampton and Georgelins conclude that Sh 2-28 is ionised by LSS 4551 and LSS 4538.