HST ARCHIVAL PURE PARALLELS
January 23, 2003
What are the HST Archival Pure Parallels? Following on the recommendations of the Cycle 7 HST Time Allocation Committee, an HST Archival Pure Parallel Program was begun at the start of the Cycle 7 GO Observing era (June 1997) and has continued ever since up to and including cycle 10.

This program seeks to maximize the scientific return from HST to the community by taking parallel data with STIS, NICMOS, WFPC2 and in the future ACS, whenever these instruments are not prime. Policies and restrictions are described in section 4.2 of the Cycle 12 Call for Proposals and in the Instrument Handbooks which are available in the Cycle 12 Proposing page.

The data becomes immediately non-proprietary and passes into the HST Archive.

The Archival Pure Parallel observing programs are designed with the intent of building large, consistent and coherent datasets for the HST Archive.

What is Coming Next? During the summer of 1997, a Parallels Working Group (their report) was convened by the Director of STScI and chaired by Jay Frogel (Ohio State). In early 2000 with anticipation of the new survey capabilities on HST with ACS, and building on the experience gained with archival parallels over the preceeding years, another PWG was convened (their report) . They recommended that STScI continue with an archival pure parallel strategy. The new program designs emphasize simplicity and uniformity, while preserving scientific power. Descriptions of the cycles 9, 10 and 11 pure parallels by instrument follow:

ACS - Cycle 11 single orbit opportunities will obtain cosmic ray split pairs of images in the Sloan i and z filters. For opportunities longer than one orbit the program will obtain cosmic ray split images with a filter change as successive orbits are added, using the Sloan survey filters in order i,z,g,r. Longer pointings will cycle this sequence repeatedly. In half orbit opportunities a cosmic ray split pair of images in the i band will be obtained.

NICMOS - Cycle 11 will consist of broad band direct imaging using Camera 3 (NIC3), For visits with duration less than or equal to 1 orbit, observations will be made through F160W filter only. For any visits longer than 2 orbits, the time will be split equally between F110W and F160W filters.

STIS - Cycle 9 was dominated by a GO program 8562, PI Schneider (abstract). Following the recomendations of the PWG, the archival pure parallel program for STIS continued with this imaging program into Cycle 10, whereupon STIS reverted to the Cycle 8 program involving grism spectroscopy, (abstract). The program ID for the Cycle 10 default parallel proposals is 9246. Cycle 10 also includes a large spectroscopic parallel program 9066, PI Windhorst (abstract).

WFPC2 - continues with UBVI imaging through both Cycles 9 and 10, with some changes compared to Cycle 8, following the discussion of the PWG.

What is Available Now? Pure parallel programs executed through previous cycles are described below for each instrument:
STIS, NICMOS, and WFPC2.

To get an idea of the exposure time distribution and number of pointings per field you can expect, click here.

Retrieving Pure Parallel Data

Technical background

This parallel primer describes how to optimize your phaseII program structure for the pure parallel scheduling process.


Copyright Notice