Draft: Mosaic imaging

@g-jruestig I just created an MR.

demo/multi_resolve/small/casa_sim_small.py

+# https://casaguides.nrao.edu/index.php?title=Simalma_CASA_6.5.4
+
+# Set simobserve to default parameters
+default("simobserve")
+# Our project name will be m51c, and all simulation products will be placed in a subdirectory m51c/
+project = "m51c"
+
+# Model sky = Halpha image of M51
+# os.system(
+#     'curl https://casaguides.nrao.edu/images/3/3f/M51ha.fits.txt -f -o M51ha.fits')
+skymodel = "M51ha.fits"
+
+# Set model image parameters:
+indirection = "J2000 13h37m00.75s -29d51m58.6s"
+
+incell = "0.05arcsec"
+inbright = "0.004"
+incenter = "333.0GHz"
+inwidth = "50MHz"
+
+# have simobserve calculate mosaic pointing locations:
+setpointings = True
+integration = "10s"
+mapsize = "20arcsec"
+maptype = "hex"
+# this could also be specified in units of the primary beam e.g. "0.5PB"
+pointingspacing = "9arcsec"
+# pointingspacing = "0.5PB"
+
+obsmode = "int"
+antennalist = "ALMA;0.5arcsec"
+totaltime = "3600s"
+
+graphics = "both"
+simobserve()
+
+
+integration = "10s"
+mapsize = "50arcsec"
+maptype = "hex"
+
+obsmode = "sd"
+sdantlist = "aca.tp.cfg"
+sdant = 0
+refdate = "2012/12/01"
+totaltime = "2h"
+
+simobserve()
+
+integration = "10s"
+mapsize = "30arcsec"
+maptype = "hex"
+pointingspacing = "5arcsec"
+
+obsmode = "int"
+refdate = "2012/12/02"
+antennalist = "aca.i.cfg"
+totaltime = "3"
+
+simobserve()