Hi all, Thanks to all who are trying to assist. I'm not sure if y'all don't quite understand what I'm trying to do or if I'm not understanding the replies. So here's an example using real numbers from a recent night's data runs. Early in the evening I had my software come up with a list of NGC objects to image based on the type, size, brightness and if they are above my local horizon. After taking data on those objects I waited a few hours and ran a second list of targets based on the same specifications. As always happens there are objects on the second run's list that were on the first run's list. When that happens I do not want to work the duplicates so I'm trying to come up with some way of deleting the duplicates so all I work are the new objects. What follows is a text version I assembled manually showing what I'm hoping a spreadsheet could do automatically. In the first column I'd enter the NGC numbers of the objects in the first run. In the second column I'd enter the NGC numbers of the objects in the second run. The spreadsheet would then examine both columns and list the duplicates in the third column and the new objects in the forth column. I'd then feed the numbers from the 4th column into the software that controls the telescope mount and camera and away it would go taking data only on the objects that only appeared in the second run's list. So, NGC 1560 only shows up in column 2 so it survives through to the 4th column for further study while NGC 1530 was in the first column so it is moved to column 3 indicating no further study is needed and it will not be imaged during the 2nd run. I hope this all makes sense... :) patrick Run1 . Run2 . Dup . New 1530 . 1560 . 147 . 1265 6503 . 1530 . 185 . 1272 6643 . 1573 . 205 . 1275 6340 . 2146 . 221 . 1560 6412 . 2258 . 278 . 1569 6654 . 2441 . 812 . 1573 6395 . 2314 . 846 . 1961 6689 . 2655 . 891 . 2146 6434 . 2715 . 910 . 2253 6411 . 2748 . 1003 . 2258 6521 . 2634 . 1123 . 2273 6946 . 2523 . 1129 . 2314 6952 . 2732 . 1161 . 2320 6869 . 2633 . 1169 . 2337 6701 . 2646 . 1174 . 2340 6764 . 2591 . 1530 . 2344 6824 . 2551 . 7640 . 2347 205 . 2629 . . 2366 221 . 1569 . . 2403 185 . 2403 . . 2441 147 . 2366 . . 2460 278 . 1961 . . 2500 891 . 2273 . . 2523 1003 . 2460 . . 2537 812 . 2347 . . 2541 1129 . 2253 . . 2549 1123 . 2340 . . 2551 910 . 2320 . . 2552 846 . 2549 . . 2591 1161 . 2500 . . 2629 1169 . 2552 . . 2633 1174 . 205 . . 2634 6703 . 221 . . 2646 6702 . 185 . . 2655 6997 . 147 . . 2715 7640 . 278 . . 2732 . 891 . . 2748 . 1003 . 812 . 1129 . 1123 . 910 . 846 . 1161 . 1169 . 1174 . 1275 . 1272 . 1265 . 2344 . 2337 . 2541 . 2537 . 7640