ESO operates since April 2015 the new planet finder instrument SPHERE1 with three arms supported by a common path coronograph with extreme AO. Observing modes include dual band imaging, long slit spectroscopy, IFS and high contrast polarimetry. We report on the implementation of the SPHERE data flow and quality control system and on operational highlights in the first year of operations: This includes some unconventional parts of the SPHERE calibration plan like special rules for the selection of filters and the measures for an optimized calibration of the two polarimetric channels of the ZIMPOL arm. Finally we report on the significance of the SPHERE quality control system, its relation to the data reduction pipeline and which previously undocumented instrumental features have been revealed so far.
The European Southern Observatory Science Archive Facility is evolving from an archive containing predominantly raw data into a resource also offering science-grade data products for immediate analysis and prompt interpretation. New products originate from two different sources. On the one hand Principal Investigators of Public Surveys and other programmes reduce the raw observational data and return their products using the so-called Phase 3 - a process that extends the Data Flow System after proposal submission (Phase 1) and detailed specification of the observations (Phase 2). On the other hand raw data of selected instruments and modes are uniformly processed in-house, independently of the original science goal. Current data products assets in the ESO science archive facility include calibrated images and spectra, as well as catalogues, for a total volume in excess of 16 TB and increasing. Images alone cover more than 4500 square degrees in the NIR bands and 2400 square degrees in the optical bands; over 85000 individually searchable spectra are already available in the spectroscopic data collection. In this paper we review the evolution of the ESO science archive facility content, illustrate the data access by the community, give an overview of the implemented processes and the role of the associated data standard.
VIRCAM is the wide field infrared camera of the VISTA survey telescope on Paranal. VIRCAM, operated by
ESO since Oct. 2009, is equipped with 16 detectors and produces on average 150 Gigabytes of data per night.
In the following article we describe the back-end data flow operations and in particular the quality control
procedures which are applied to ESO VIRCAM data.
By 2010, the Paranal Observatory will host at least 15 instruments. The continuous increase in both the complexity and
quantity of detectors has required the implementation of novel methods for the quality control of the resulting stream of
data. We present the new and powerful concept of scoring which is used both for the certification process and the Health
Check monitor. Scoring can reliably and automatically measure and assess the quality of arbitrarily amounts of data.
Quality Control (QC) of calibration and science data is an integral part of the data flow process for the ESO
Very Large Telescope (VLT) and has guaranteed continuous data quality since start of operations. For each
VLT instrument, dedicated checks of pipeline products have been developed and numerical QC parameters to
monitor instrumental behavior have been defined. The advent of the survey telescopes VISTA and VST with
multi-detector instruments imposes the challenge to transform the established QC process from a detector-by-detector
approach to operations that are able to handle high data rates and guarantee consistent data quality.
In this paper, we present solutions for QC of multi-detector instruments and report on experience with these
concepts for the operational instruments CRIRES and VIMOS. Since QC parameters scale with the number of
detectors, we have introduced the concept of calculating averages (and standard deviations) of parameters across
detectors. This approach is a powerful tool to evaluate trends that involve all detectors but is also able to detect
outliers on single detectors. Furthermore, a scoring system has been developed which compares QC parameters
for new products to those from already existing ones and gives an automated judgment about data quality. This
is part of the general concept of information on demand: detailed investigations are only triggered on a selected
number of products.
The ESO Paranal observatory is operating a heterogeneous set of science detectors. The maintenance and
quality control of science detectors is an important routine task to retain the technical and science performance
of the instrumentation. In 2006 a detector monitoring working group was built devoted with the following tasks:
inventory of the currently existing detector calibration plans and monitored quality characteristics, completion
and homogenization of the detector calibrations plans, design and implementation of cross-instrument applicable
templates and data reduction pipeline recipes and monitoring tools.
The instrument calibration plans include monthly and daily scheduled detector calibrations. The monthly
calibrations are to measure linearity, contamination and gain including the inter-pixel capacitance correction
factor. A reference recipe has been defined to be applicable to all operational VLT instruments and has been
tested on archive calibration frames for optical, near- and mid-infrared science detectors. The daily calibrations
measure BIAS or DARK level and read-out noise in different ways. This has until now prevented cross
detector comparison of performance values. The upgrade of the daily detector calibration plan consists of the
homogenization of the measurement method in the existing pipeline recipes.
The Nasmyth Adaptive Optics System (NAOS) and the High-Resolution Near
IR Camera (CONICA) are mounted at the Nasmyth B focus of Yepun (UT4)
telescope of the ESO VLT. NACO (NAOS+CONICA) is an IR (1-5 micron)
imager, spectrograph, coronograph and polarimeter which is fed by the
NAOS - the first adaptive optics system installed on Paranal. NACO
data products are pipeline-processed, and quality checked, by the Data
Flow Operations Group in Garching. The calibration data are processed
to create calibration products and to extract Quality Control (QC)
parameters. These parameters provide health checks and monitor
instrument's performance. They are stored in a database, compared to
earlier data, trended over time and made available on the NACO QC web
page that is updated daily.
NACO is an evolving instrument where new observing modes are offered
with every observing period. Naturally, the list of QC parameters that
are monitored evolves as well. We present current QC parameters of
NACO and discuss the general process of controlling data
quality and monitoring instrument performance.
The Data Flow Operations Group of ESO in Garching, provides many aspects of data management and quality control of the VLT data flow. One of the main responsibilities is to monitor the performance of all operational instruments. We have investigated if the statistical methods of process control can be applied to the quality control of the VLT instruments and the data flow has been analyzed in this concern. The efficiency of these statistical methods is found to be related to the calibration plan, that determines the sampling size and frequency of calibrations. We apply these principles to ISAAC health check plots and give examples to demonstrate performance and limitations.
For 3 years the Infrared Spectrometer And Array Camera (ISAAC) has been operating at the 8m Antu (UT1) telescope of the European Southern Observatory Very Large Telescope (ESO VLT). As part of ESO data flow operations ISAAC data are processed and quality control checked by the Data Flow Operations group (often known as QC Garching). at ESO headquarters in Garching. The status of the instrument is checked in terms of QC parameters, which are derived from raw and processed data and compared against reference values. Low level parameters include detector temperature and zero level offset, other parameters include image quality and spectrum curvature. Complicated instrumental behaviors like the odd-even column effect and the appearance of pupil ghosts require more sophisticated QC tools. Instrumental interventions of cryogenic instruments like ISAAC include a defrost and re-freeze sequence which can be traced in trending plots of the QC1 parameters, which are published regularly (see http://www.eso.org/qc). We present recent highlights of the ISAAC QC process and their role as feedback to the observatory to retain the performance of the instrument.
Currently four instruments are operational at the four 8.2m telescopes of the European Southern Observatory Very Large Telescope: FORS1, FORS2, UVES, and ISAAC. Their data products are processed by the Data Flow Operations Group (also known as QC Garching) using dedicated pipelines. Calibration data are processed in order to provide instrument health checks, monitor instrument performance, and detect problems in time. The Quality Control (QC) system has been developed during the past three years. It has the following general components: procedures (pipeline and post-pipeline) to measure QC parameters; a database for storage; a calibration archive hosting master calibration data; web pages and interfaces. This system is part of a larger control system which also has a branch on Paranal where quick-look data are immediately checked for instrument health. The VLT QC system has a critical impact on instrument performance. Some examples are given where careful quality checks have discovered instrument failures or non-optimal performance. Results and documentation of the VLT QC system are accessible under http://www.eso.org/qc/.
The FORS instruments are focal reducers and spectrographs which are built in two copies for the unit telescopes UT1 and UT2 of the ESO/VLT by a consortium of University Observatories. An overview of the instrument capabilities is given in a separate paper at this conference.
FORS is an all dioptric focal reducer designed for direct imaging, low-dispersion multi-object spectroscopy, imaging polarimetry and spectropolarimetry of faint objects. Two almost identical copies of the instrument were built by a consortium of three astronomical institutes under contract and in cooperation with ESO. FORS1 was installed in September 1998 and FORS2 in October 1999 at the Cassegrain foci of the ESO VLT unit telescope nos. 1 and 2. FORS1 is in regular operation since April 1999. Regular observation with FORS2 are scheduled to begin in April 2000.
FIMS is a graphical user interface to prepare observations off-line for the two astronomical instruments FORS1 and FORS2 of the ESO VLT at Paranal. FIMS was originally designed to support the main mode of FORS only: multi object spectroscopy, but supports now all observing modes. FIMS shows the focal field of FORS upon a background sky image. A typical FIMS session consists of a few cursor clicks on the stars or galaxies of the sky image to set a slit. The saved configuration will be sent to Paranal observatory to execute the observations with FORS. The slit positions as specified by FIMS and performed by the alignment methods of the FORS observation software are accurate to (sigma) equals 0.075 CCD pixel (equals 0.015 arcsec, 8 micrometer).
We used FORS2 at UT2 of the VLT to obtain low resolution spectra of early type emission line stars in the field of the young open SMC cluster NGC 330. This cluster is known for its exceptional large number fraction of Be stars and could play a key role in constraining the Be phenomenon in general. 48 of the 59 program stars identified as H(alpha) excess sources by CCD imaging photometry can be confirmed to show H(alpha) line emission superimposed on a strong continuum. Comparison with VLT-FORS1 spectra collected a year earlier shows no or only a low significance of variability on the time scale of a year. To test the prediction of the hybrid model for global disk oscillations in Be star circumstellar disks we compared the number ratio of Be stars with asymmetric line profiles to the total number of Be stars with the known ratio of galactic field Be stars. About 10 of 47 emission line stars show asymmetric line profiles hence the theoretical prediction is not matched. We discuss several possibilities which might explain the discrepancy.