Herschel OT1 Announcement of Opportunity: This is the formal letter from the ESA Director of Science and Robotic Exploration inviting the scientific community to apply for the Herschel OT1 observing time.

Executive Summary: Summarises the document package, providing the reader with an overview and help on where to find the relevant information.

Policies and Procedures (this document): The 'administrative' part of the call documentation, providing all necessary information about the policies adopted and the procedures to be followed.

Herschel Observers' Manual: Describes Herschel as an observatory facility, providing the background information that every proposer needs.

HIFI Observers' Manual: Provides instrument specific information and describes how to use HIFI to perform observations.

PACS Observers' Manual: Provides instrument specific information and describes how to use PACS to perform observations.

SPIRE Observers' Manual: Provides instrument specific information and describes how to use SPIRE to perform observations.

SPIRE/PACS Parallel Mode Observers' Manual: Provides specific information and describes how to use SPIRE and PACS simultaneously to perform so-called 'parallel mode' observations.

HSpot Users' Guide: Provides information about the Herschel observation planning tool HSpot and how to use it for the preparation of observing proposals.

The Reserved Observations List which is searchable using the Herschel Reserved Observations Search Tool (HROST, see below). Information on the accepted observations contained in the GT and OT Key Programmes and GT1 proposals (proposal id, title, PI name and institution, and links to the abstracts) is provided in the AO web pages, together with instructions on how to access their associated AORs through HSpot as well as on how to search the database of Reserved Observations to avoid potential duplications.