RCW 145 is an emission nebula in the constellation Sagittarius. RCW 145 contains both Sh 2-26 and Sh 2-28.[5] It is ionized by the supergiant stars LS 4551 and LS 4538.[6] It is possible it is associated with the Trifid nebula.[7]
Visibility
RCW 145 is often imaged alongside nearby the nebulae of the Lagoon Nebula and Trifid Nebula. The nebula responds well to Hydrogen-alpha filters. It is also easily visible with a Sulfur II filter, however is not very visible in an Oxygen III filter. It is difficult to image with standard RGB.[8]
Westerhout 28
Chandra X-ray Observatory image of Westerhout 28
In the direction of RCW 145 is also the supernova remnant SNR G006.4-00.1 (W28). W28 lies at a further distance of 1800 to 3300 parsecs. It contains multiple pockets of Maser activity. These pockets are 50-100 milliarcseconds in apparent size.[9] W 28 is visible in most wavelengths, from radio waves to gamma rays. There is some ionization caused by W 28. It was initially thought to be cause by x-ray emissions, however it has since been determined to be cause by cosmic ray emissions.[10]
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