David Berry recently added a new feature to SMURF’s makemap. There is now a FITS header in the output maps which will let you know if makemap successfully converged.
The new header is NCONTNCV – the Number of CONTiguous chunks that did Not ConVerge. This should be zero if everything went well. If you are reducing data yourself, you can also check the makemap output or the ORAC-DR log for more information.
You will have access to this feature if you are using an rsynced Starlink build from after the 19th of June 2019. Observations in the archive reduced from 19th June 2019 onwards should also have this FITS header present.
You can check the fitsheaders in the output file with the KAPPA commands fitslist or fitsval, or if you are downloading a reduced file from the archive in .FITS format you can use any of your favourite FITS header viewers.