HST Primer for Cycle 25
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Hubble Space Telescope Primer for Cycle 25 > Chapter 1: Introduction > 1.3 Resources, Documentation and Tools

1.3
1.3.1 Phase I “Roadmap”
The Phase I Proposal Roadmap is a high level step-by-step guide to writing a Phase I Proposal. At each step, links are provided to relevant information.
1.3.2 Cycle 25 Announcement Webpage
They Cycle 25 Announcement webpage contains links to information needed for preparing a HST proposal. It also contains late-breaking updates regarding the Phase I process and a FAQ (frequently asked questions).
1.3.3 Cycle 25 Call for Proposals
The Call for Proposals discusses policies and procedures for submitting a Phase I proposal for HST observing or Archival Research. It also provides a summary of the proposal process from proposal submission to the execution of observations. The Call for Proposals document is available at the Cycle 25 Announcement webpage.
1.3.4 Instrument Handbooks
Instrument handbooks, the primary source of information for HST instruments, provide additional information beyond what’s presented in this Primer. Please use current versions of the handbooks when preparing the Phase I proposal. The latest handbook versions for active and decommissioned instruments are available at the HST Documents webpage. Other potentially useful documents, such as instrument science reports, data handbooks, and calibration conference proceedings are also accessible from that website.
1.3.5 The Astronomer’s Proposal Tool (APT) and the Aladin Sky Atlas
The Astronomers Proposal Tool (APT) is the software interface for all Phase I and Phase II proposal submissions for HST. Please refer to the APT webpage for information regarding the installation and use of APT.
The Aladin Sky Atlas, available through APT, can be used to display HST apertures on images of the sky. This software interface provides access to a wide variety of images and catalogs; note that the GALEX catalog is available to assist in checking for potentially dangerous objects for the UV detectors. Training documentation and videos can be found on the APT Training Materials webpage.
1.3.6 Exposure Time Calculators (ETCs)
Information in this Primer, together with the instrument handbooks, provides the means for estimating acquisition times, exposure times, and other observational parameters. Values provided in document tables, or as illustrations, are only approximations; reliable calculations that take into account the complex telescope and instrument operation are best obtained using software tools provided by STScI, such as the Exposure Time Calculators (ETCs) and APT (Section 1.3.5). The ETCs, for example, provide warnings for target count rates that exceed saturation and safety limits. Note, however, that Signal-to-Noise (S/N) predictions from the ETCs do not include the effects of degrading CTE (Charge Transfer Efficiency) for CCD detectors.
Descriptions of the ETCs for active instruments, including determinations of exposure time as a function of instrument sensitivity and S/N ratio, are available in these documents: Chapter 9 of the ACS Instrument Handbook, Chapter 7 of the COS Instrument Handbook, Chapter 6 of the STIS Instrument Handbook, and Chapter 9 of the WFC3 Instrument Handbook.
1.3.7 HST Data Archive
The HST Data Archive is part of the Mikulski Archive for Space Telescopes (MAST). The HST Data Archive contains all the data taken by HST. Completed HST observations from both General Observer (GO) and Guaranteed Time Observer (GTO) programs are available to the community upon the expiration of their proprietary periods. Observations taken by Large, Calibration, Treasury (see Section 3.2.5 of the Call for Proposals and subsections therein), and Large GO Pure Parallel programs (see Section 4.2.2 of the Call for Proposals) generally carry no proprietary period.
The HST Archive webpage provides links to information about getting started, search and retrieval, documentation, etc. (see also the introductory description in Section 7.2). You can search for HST data using either of two main search pages: the dedicated HST search page or the Data Discovery Portal. The Canadian Astronomy Data Centre (CADC) and the European Space Agency Centre (ESAC) maintain copies of the HST science data, and are the preferred sources for Canadian and European astronomers.
The Hubble Legacy Archive (HLA) is a project designed to enhance science from HST data by augmenting the HST Data Archive and by providing advanced browsing capabilities. Features of the HLA include a preview viewer, an interactive image display, a footprint service, individual, combined and mosaicked images, improved astrometric positions, object catalogs, and selected grism extractions. The HLA is a joint project of the Space Telescope Science Institute, the Canadian Astronomy Data Centre (CADC), and the European Space Astronomy Centre (ESAC). Section 7.3 contains more detailed information about the HLA.
The HLA provides source lists for tens of thousands of HST images. The Hubble Source Catalog (HSC) combines these visit-based WFC3, ACS, and WFPC2 source lists from the HLA into a master catalog with roughly 300 million sources. Searches that would have required months or years to perform in the past can be completed in a matter of seconds using the HSC. Version 1 of the HSC was released in February 2015, and Version 2 was released in the Fall 2016. More information about the HSC can be found in Section 7.4 The HSC is an invaluable resource for exploring a wide range of new archival proposals, a few potential examples of which are included in Section 7.4.
Cycle 25 proposers will be able to mine the HST Spectroscopic Legacy Archive for high-level data products intended to accelerate the scientific use of existing spectroscopic data. This archive will contain “science grade” co-added spectra of all usable public data, combining exposures for each target from across visits, programs, and cycles. This data will be organized into “smart archives” by target type (such as “hot stars” and “white dwarfs”) and by scientific purpose (“IGM absorption sources”) so that samples can be readily constructed and downloaded without manual interaction with MAST. The first generation of these products for the FUV modes of COS is available online via MAST. We encourage the development and submission of Archival Programs based on these new products.
Questions about the Archive and archival data should be sent to the Archive Help Desk at archive@stsci.edu or 410-338-4547.
1.3.8 Duplication Checking
The HST Data Archive provides access to several tools that allow you to check whether planned observations duplicate any previously executed or accepted HST observations. For details see Section 5.2.2 of the Call for Proposals.
1.3.9 Data Reduction and Calibration
Introduction to the HST Data Handbooks is a general overview of HST data formats and software tools. It complements the instrument data handbooks that contain more details about calibration and data analysis. The latest versions of the instrument data handbooks are available at the Documents webpage.
The Space Telescope Science Data Analysis Software (STSDAS) webpage has links to the software used to calibrate and analyze HST data, along with documentation on its use. More details are available in Section 7.1. The DrizzlePac Handbook provides information about the DrizzlePac software package that has replaced MultiDrizzle in pipeline calibration and post-pipeline processing. Some information about dither patterns, drizzling, and various observing considerations are included in it, but for more detailed information, please refer to the Phase II Proposal Instructions and instrument handbooks.

Hubble Space Telescope Primer for Cycle 25 > Chapter 1: Introduction > 1.3 Resources, Documentation and Tools

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