There are three formats of SN:
- early tricolours had a simple sequential serial number stamped on a plate attached to the mount base (some OTAs which were sold separately had their own separate SN sequence with the SN stamped on a plate attached to the OTA)
- some time around the 3rd quarter 1972 the SN changed to a QxxxxY format where Q gives the quarter in which the 'scope was produced, xxxx is the sequential number since (probably) start of C8 production and Y is the last digit of the year of production
- around the time of the change from Celestron Pacific to Celestron International (late 1977/early 1978) the SN changed to a new style which, for C8s was 8xxxxx, the 8 signifying a C8 and the rest a sequential number with no production date indication.
- The Stargazers Lounge list reported a SN of 4936 (sale date 1973) – this however seems too high to fit into the early SN sequence of just a sequential number and also doesn’t tie in with the first date type SN of 37842 which suggests that the 784th C8 was made in the 3rd qtr of 1972. It may be that the last digit (which gives the year and in some case was spaced apart from the rest of the number) was omitted and the full number should be 49362
- orion61’s sandcast C8 with a SN of 223139 – this doesn’t fit in at all with the SN formats but as that scope may have been built as a ‘special’ for the use of Leo Henzl (Celestron VP Marketing) it may have been given a different style of SN
- SN 1 2563 4 has a sequential number which is out of step with the general sequence – it is hard to be certain from the picture of the SN plate in the thread which gave this number but it is possible that the number is actually 4 2563 4 which may fit better although there is still a bit of a jump to the only reported SN for the following quarter: 1 29845 5?
With the later 8xxxxx style SNs it helps to have the date code stamped on the RA drive motor(s) – in the few cases where I have found a motor date as well it seems as if some ‘scopes might have sat in stock for a while before being sold – of course it could also be that the motors sat in stock, either at the manufacturer or at Celestron for some time before being used.
Any corrections, clarifications, additions gratefully received!
7 Jan 2013 Edited: revised table with additional information highlighted in blue and column to record corrector SNs where known