John looked up on CADC information on MD fields observed in U Band.  Here it is:


||  TJD||  MD 01||  02||  03||  04 || 05||  06 || 07||  08 || 09 || 10 ||
|| ~4681 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 || 44 || 39 || 16  ||
|| ~4710 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  6   ||
|| ~4740 || 4 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  9 || 39 ||
|| ~4769 || 4 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~4799 || 26 || 26 || 47 || 44 || 27 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~4828 || 29 || 28 || 21 ||  3 || 28 || 40 ||  0 ||  0 ||  0 ||  0 ||
|| ~4858 || 0 ||  0 || 62 ||  6 ||  0 || 24 ||  0 ||  0 ||  0 ||  0 ||
|| ~4887 || 0 ||  0 || 60 || 34 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~4917 || 0 ||  0 || 13 || 44 || 14 || 50 ||  0 ||  0 ||  0 ||  0 ||
|| ~4946 || 0 ||  0 ||  0 ||  0 ||  0 || 42 || 14 || 36 ||  0 ||  0 ||
|| ~4976 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 || 12 || 16 || 48 ||  0 ||
|| ~5005 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 || 23 || 28 || 28 || 30 ||
|| ~5035 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  5 || 64 || 25 ||
|| ~5064 || 17 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 || 31 || 44 ||
|| ~5094 || 11 || 25 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 || 10 ||
|| ~5123 || 37 || 40 || 26 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~5153 || 0 ||  6 || 25 || 25 ||  7 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~5182 || 65 || 23 || 30 ||  0 || 20 || 27 ||  0 ||  0 ||  0 || 13 ||
|| ~5212 || 0 || 27 ||  0 ||  1 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~5241 || 27 || 25 ||  7 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~5271 || 0 ||  0 || 53 || 25 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~5300 || 0 ||  0 ||  0 || 22 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||
|| ~5359 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  5 ||  0 || 17 ||  0 ||
|| ~5389 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 || 25 ||  4 ||
|| ~5477 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 || 11 ||
|| ~5507 || 0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 ||  0 || 23 ||

This is the number of observations on the field, where there are 7
pointings per field and evidently many dithers.  Our job will be to
put together the dithers into a stack, probably for each lunation,
and then the JTMD stuff can assemble the full-up stacks.  But this
may turn out not to make sense if there are not all 7 pointings per
lunation, so it's all TBD.