Periodic Error Correction. All telescope mount drive gears suffer from periodic error. No gear can be machined perfectly, although some are certainly built with more precision than others (which is why some mounts cost $300 and some cost $10,000). Since the drive gear repeats its inherent errors at a given interval (however long the gear takes to revolve once, usually 5-10 minutes), the errors are repeated and, in theory, removable. PEC is built into certain mount electronics to record drive errors and repeat corrections to those errors. PEC allows longer unguided exposures. With guiding, PEC is usually not necessary since corrections are being made almost constantly.
Process Equipment Cost. Almost any activity to be performed in the design and manufacturing of a product demands the use of some kind of equipment. Basically, a basic model for equipment cost estimation implies the allocation of the capital cost over the life of the equipment and the overhead directly applicable. The objective is to determine an equipment cost per hour. In general, it can be considered that the cost per hour of any equipment exists independently of its operation. In most cases, only consumables and power can be considered additional expenses to include when the equipment is used. Factors to be considered are: equipment capital investment, depreciation factor, equipment life time, equipment residual value, rate of return on investment, equipment occupancy factor, working hours per year, power consumption, power price, floor space occupied, floor space price, maintenance cost, etc. Some of these factors are considered in the overhead, but in general it depends on the practices of each company. V-CES Consortium, D1.5, Report on Functional and Technical Specifications of the Virtual Cost Engineering Studio Keyword(s): Process Equipment Cost (PEC)