rosette nebula ngc 2237 caldwell 49

2237 250mm 383l astronomy atik caldwell camera cloud cluster color colour cosmos dust f24 forming halpha hubble hydrogen imaged lens molecular monocerous monochrome narrowband nebula nebulae ngc ngc2238 ngc2239 ngc2244 ngc2246 oiii optics palette redcat rosette scheme sii space stars telescope universe using widefield william