NOTE: WFPC2 has been removed from HST, and is therefore not available for proposing new observations. Archival Research proposals using existing WFPC2 data are of course supported.
The HST General Observer proposal process is divided into two Phases. Phase I proposals contain a scientific justification and abbreviated technical specifications for review by the Telescope Allocation Committee in a particular Cycle. Phase II proposals provide many more technical details for programs recommended by the TAC and approved by the STScI Director for implementation. The information required by proposers for Phases I and II are provided in the links, below.
Cycle 19 Announcement
HST Proposing Overview
Phase II Instructions
WFPC2 Proposing FAQs
The Astronomers Proposal Tool (APT) will be of great utility for both Phases.
Proposing Resources:
Instrument Handbook
Phase I Updates for APT
Phase II Updates for APT
WFPC2 Exposure Time Calculator
Information about Existing HST Programs