I'd like to make a mosaic of the Rho Ophiuchi region. I've successfully combined red tiles from Rho Ophiuchi to Antares using register union separate and gradient merge mosaic, but when I try to run register union separate on green or blue I get an error message that not enough stars can be found to create the separate registered images. It seems that the Rho Ophiuchi nebula is just to cloudy to tile. Is this true, or is there a way to tile with few stars?
