Ian – re. the charges, I was going from memory but apparently, since open-access became the norm for the MNRAS, I have been advised that page charges are usually thousands of pounds and these charges are usually paid by the organisation or funding body of one or more of the professional authors. But like you say, as an amateur one can plead poverty and have the charges waived, which rightly so were waived for you guys. Well done on avoiding the charges.
Your success in this instance is a good lesson for all amateur astronomers.
Clear skies,
Richard