12.1	Introduction

In this chapter, we provide a brief overview of the calibration observations obtained during ground testing and on-orbit through Cycle 20. Potential Cycle 21 observers should assume that all of these calibrations will be completed by the time that Cycle 21 begins.

Observers wishing to use instrument configurations that are not addressed by these calibration plans should assess their specific calibration needs and include time in their Phase I proposal for any additional calibrations that are required. Proposers who believe that more extensive calibration observations or analysis may be of general benefit to the COS user community should consider submitting a Cycle 21 Calibration Outsourcing Proposal (see the Cycle 21 Call for Proposals for details).