The End-to-End Pipeline for HST Slitless Spectra PHLAG
The Space Telescope-European Coordinating Facility (ST-ECF) is undertaking a joint project with the Canadian Astronomy Data Centre and the Space Telescope Science Institute to build a Hubble Legacy Archive (HLA) that contains science ready high level data
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ESO, Space Telescope European Coordinating Facility, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany; [email protected] European Space Astronomy Centre, P.O. Box - Apdo. de correos 50727, 28080 Madrid, Spain
Abstract. The Space Telescope-European Coordinating Facility (ST-ECF) is undertaking a joint project with the Canadian Astronomy Data Centre and the Space Telescope Science Institute to build a Hubble Legacy Archive (HLA) that contains science ready high level data products to be used in the Virtual Observatory (VO). The ST-ECF will provide extracted slitless spectra to the HLA, and for this purpose has developed the Pipeline for Hubble Legacy Archive Grism data (PHLAG). PHLAG is an end-to-end pipeline that performs an unsupervised reduction of slitless data taken with the Advanced Camera for Surveys (ACS) or the Near Infrared Camera and Multi Object Spectrometer (NICMOS) and ingests the VO compatible spectra into the HLA. PHLAG is a modular pipeline, and the various modules and their roles are discussed. In a pilot study, PHLAG is applied to NICMOS data taken with the G141 grism, and the first results of a run on all available data are shown.
1 The Hubble Legacy Archive After a proprietary period of usually one year, all science data from the Hubble Space Telescope (HST) are offered for retrieval at the archives hosted at the Space Telescope-European Coordinating Facility (ST-ECF), the Canadian Astronomy Data Centre (CADC) and the Space Telescope Science Institute (STScI). These archives offer the individual images with calibrated pixel values for download. Any further, time extensive processing such as the coadding of the single images must be done by every archive researcher individually. The technical expertise on how to generate calibrated images of a certain HST instrument peaks towards the end-of-life (or decommissioning) of the instrument and, as the instrument team personnel move to other projects, that knowledge quickly dissipates. After seventeen years in orbit, HST is approaching the last phase of its life, and now is the right time to build a Hubble Legacy Archive (HLA) that contains high level science data products which can be immediately be used for research [1] and be exploited by the VO tools currently being developed. In the static HLA the accumulated experience of HST instruments will be
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Table 1. Some HST slitless modes under consideration for the ST-ECF HLA activities Instrument
Disperser
NICMOS/NIC3 ACS/WFC ACS/HRC ACS/HRC ACS/SBC ACS/HRC
G141 G800L G800L PR200L PR130L PR110L
Wav. Range (˚ A) 1100 − 19000 5500 − 10500 5500 − 10500 1700 − 3900 1250 − 1800 1150 − 1800
Resolution (˚ A/pixel) 80.0 38.5 23.5 20(@2500˚ A) 7(@1500˚ A) 10(@1500˚ A)
FOV (arcsecond) 51 × 51 202 × 202 29 × 26 29 × 26 35 × 31 35 × 31
preserved, and providing science ready products reduces the time archive scientists have to spend on non-science matters. The ST-ECF has a long record of supporting various spectroscopic modes of HST instruments and therefore has selected slitless s
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