The Herschel Space Observatory (aka Herschel) was successfully launched on 14 May 2009. It has been designed to provide the astronomical community with a facility to carry out routine astronomical observations for a period of at least three years. General information about the Herschel mission, the observatory, its instruments, and the ground segment is provided in the Herschel Observers' Manual, and more general additional information is provided on the HSC website .

The majority of Herschel's observing time is made available to the astronomical community by the traditional route of calls for observing proposals, followed by peer review, in response to Announcements of Opportunity (AO), issued by the Herschel Science Centre (HSC). The observing time consists of Guaranteed Time (GT) and Open Time (OT). The GT (32% of the available time) is owned by contributors to the Herschel mission, mainly the science payload consortia. The remainder time is OT, that is awarded in a standard competitive manner to investigators worldwide. All observing proposals are reviewed by the Herschel Observing Time Allocation Committee (HOTAC).

This is the second (and final) in-flight Herschel AO, and currently open time (OT2) observing proposals are solicited for. The guaranteed time part (GT2) has already been conducted. The allocation of OT2 observing time is the subject matter of the present 'Policies and Procedures' document.

There is only one 'size' of proposal (as opposed to in OT1 where there were two: 'large' proposals for programmes requiring observing time in excess of 100 hours, and 'normal' proposals, for observing programmes requiring up to 100 hours). All proposals will be subjected to scientific and technical evaluation of the proposed observations, and checking with respect to the 'Reserved Observations List' (ROL) which together with the duplications policy is considered part of the AO package.

There is the possibility - under certain conditions - to apply also for XMM-Newton observing time in the current OT2 AO process (as was the case in OT1).

Responding to the AO is a two-phase process. Responses to this call consist of so-called Phase 1 proposals including Astronomical Observation Requests (AORs). After peer review by the HOTAC, successful proposers will have the opportunity and/or obligation to update their AORs under the technical advise of the HSC according to the recommendations made by the HOTAC entering them into the Herschel database in their final version (Phase 2).

Information about data products and proprietary time is provided as well as special information for investigators based in the USA only.

For an overview of the contents of this document Chapter by Chapter see below in 'Scope'.