Alberto Micol

GaBoDS: The Garching-Bonn Deep Survey. I: Anatomy of galaxy clusters in the background of NGC 300

The Garching-Bonn Deep Survey (GaBoDS) is a virtual 12 square degree cosmic shear and cluster lensing survey, conducted with the WFI@2.2 m MPG/ESO telescope at La Silla. It consists of shallow, medium and deep random fields taken in R-band in subarcsecond seeing conditions at high galactic latitude. A substantial amount of the data was taken from the ESO archive, by means of a dedicated ASTROVIRTEL program. In the present work we describe the main characteristics and scientific goals of GaBoDS. Our strategy for mining the ESO data archive is introduced, and we comment on the Wide Field Imager data reduction as well. In the second half of the paper we report on clusters of galaxies found in the background of NGC 300, a random archival field. We use weak gravitational lensing and the red cluster sequence method for the selection of these objects. Two of the clusters found were previously known and already confirmed by spectroscopy. Based on the available data we show that there is significant evidence for substructure in one of the clusters, and an increasing fraction of blue galaxies towards larger cluster radii. Two other mass peaks detected by our weak lensing technique coincide with red clumps of galaxies. We estimate their redshifts and masses, and check for possible X-ray counterparts in deep XMM observations.

The STIS Parallel Survey: Introduction and First Results.

The installation of the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) allows for the first time two-dimensional optical and ultraviolet slitless spectroscopy of faint objects from space. The STIS Parallel Survey (SPS) routinely obtains broadband images and slitless spectra of random fields in parallel with HST observations using other instruments. The SPS is designed to study a wide variety of astrophysical phenomena, including the rate of star formation in galaxies at intermediate to high redshift through the detection of emission-line galaxies. We present the first results of the SPS, which demonstrate the capability of STIS slitless spectroscopy to detect and identify high-redshift galaxies.

Cosmic shear from STIS pure parallels I. Data

Following the second HST servicing mission in 1997 when the STIS instrument was installed and the capability for parallel observations was enhanced, a substantial archive of non-proprietary parallel data has been accumulating. In this paper, we discuss the use of unltered STIS imaging data for a project that requires deep observations along as many independent lines-of-sight as possible. We have developed a technique to determine which datasets in the archive can safely be co-added together and have developed an iterative co-addition technique which enabled us to produce 498 high-quality, deep images. The principal motivation for this work is to measure the Cosmic Shear on small angular scales and a value derived from these data will be presented in a subsequent paper. A valuable by-product of this work is a set of high quality combined elds which can be used for other projects. The data are publicly available at http://www.stecf.org/projects/shear/

The Hubble Legacy Archive NICMOS grism data

The Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescopexa0– European Coordinating Facility (ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with slitless spectroscopy modes are among the most difficult to extract and exploit. As part of the HLA project, the ST-ECF aims to provide calibrated spectra for objects observed with these HST slitless modes. In this paper, we present the HLA NICMOS G141xa0grism spectra. We describe in detail the calibration, data reduction and spectrum extraction methods used to produce the extracted spectra. The quality of the extracted spectra and associated direct images is demonstrated through comparison with near-IR imaging catalogues and existing near-IR spectroscopy. The output data products and their associated metadata are publicly available (http://hla.stecf.org/) through a web form, as well as a VO-compatible interface that enables flexible querying of the archive of the 2470u2000NICMOS G141xa0spectra. In total, spectra of 1923u2000 unique targets are included.

The Hubble Legacy Archive ACS grism data

A public release of slitless spectra, obtained with ACS/WFC and the G800L grism, is presented. Spectra were automatically extracted in a uniform way from 153 archival fields (or “associations”) distributed across the two Galactic caps, covering all observations to 2008. The ACS G800L grism provides a wavelength range of 0.55−1.00 μm, with a dispersion of 40 A/pixel and a resolution of ∼80 A for point-like sources. The ACS G800L images and matched direct images were reduced with an automatic pipeline that handles all steps from archive retrieval, alignment and astrometric calibration, direct image combination, catalogue generation, spectral extraction and collection of metadata. The large number of extracted spectra (73, 581) demanded automatic methods for quality control and an automated classification algorithm was trained on the visual inspection of several thousand spectra. The final sample of quality controlled spectra includes 47 919 datasets (65% of the total number of extracted spectra) for 32 149 unique objects, with a median iAB-band magnitude of 23.7, reaching 26.5 AB for the faintest objects. Each released dataset contains science-ready 1D and 2D spectra, as well as multi-band image cutouts of corresponding sources and a useful preview page summarising the direct and slitless data, astrometric and photometric parameters. This release is part of the continuing effort to enhance the content of the Hubble Legacy Archive (HLA) with highly processed data products which significantly facilitate the scientific exploitation of the Hubble data. In order to characterize the slitless spectra, emission-line flux and equivalent width sensitivity of the ACS data were compared with public ground-based spectra in the GOODS-South field. An example list of emission line galaxies with two or more identified lines is also included, covering the redshift range 0.2−4.6. Almost all redshift determinations outside of the GOODS fields are new. The scope of science projects possible with the ACS slitless release data is large, from studies of Galactic stars to searches for high redshift galaxies.

The ESO science archive: supporting and enhancing science from the La Silla Paranal Observatory

The archive of the La Silla Paranal Observatory is a powerful science resource for the ESO astronomical community. It stores both the raw data generated by all ESO instruments and selected processed (science-ready) data. We present the new capabilities and user services that have recently been developed in order to enhance data discovery and usage in the face of the increasing volume and complexity of the archive holdings. Future plans to extend the new services to processed data from the Atacama Large Millimeter/submillimeter Array (ALMA) are also discussed.

Enhanced Data Discovery Services for the ESO Science Archive

The Messenger 172 – June 2018 the characteristics and limitations of each collection of processed data. This is particularly important, as it enables users to decide whether the data are suitable for their specific science goals. The systematic archive publication of such processed data dates back to 25 July 2011, with the first products produced by the Public Surveys conducted with the Visible and Infrared Survey Telescope for Astronomy (VISTA) infrared camera VIRCAM (Arnaboldi & Retzlaff, 2011). Processed data that were generated at ESO have been available since September 2013. An up-to-date overview of the released data is available online for contributed and pipeline processed data 2, 3.

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 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.