Andreas J. Wicenec

ESO imaging survey - Deep public survey: Multi-color optical data for the Chandra Deep Field South

This paper presents multi-passband optical data obtained from observations of the Chandra Deep Field South (CDF-S), located at 3 h 32 m , 2748 0 . The observations were conducted at the ESO/MPG 2.2 m telescope at La Silla using the 8k 8k Wide-Field Imager (WFI). This data set, taken over a period of one year, represents the rst eld to be completed by the ongoing Deep Public Survey (DPS) being carried out as a part of the ESO Imaging Survey (EIS) project. This paper describes the optical observations, the techniques employed for un-supervised pipeline processing and the general characteristics of the nal data set. Image processing has been performed using multi-resolution image decomposition techniques adapted to the EIS pipeline. The automatic processing steps include standard de-bias and flat-eld, automatic removal of satellite tracks, de-fringing/sky-subtraction, image stacking/mosaicking and astrometry. Stacking of dithered images is carried out using pixel-based astrometry which enables the ecient removal of cosmic rays and image defects, yielding remarkably clean nal images. The nal astrometric calibration is based on a pre-release of the GSC-II catalog and has an estimated intrinsic accuracy of <0.10 arcsec, with all passbands sharing the same solution. The paper includes data taken in six dierent lters (U 0 UBVRI). The data cover an area of about 0.25 square degrees reaching 5 limiting magnitudes of U 0 AB =2 6:0, UAB =2 5:7, BAB =2 6:4, VAB =2 5:4;RAB =2 5: 5a nd IAB = 24.7 mag, as measured within a 2FWHM aperture. The optical data covers an area of 0.1 square degrees for which moderately deep observations in two near-infrared bands are also available, reaching 5 limiting magnitudes of JAB 23: 4a ndKAB 22:6. The current optical/infrared data also fully encompass the region of the deep X-ray observations recently completed by the Chandra telescope. The optical data presented here, as well as the infrared data released earlier, are publicly available world-wide in the form of fully calibrated pixel and associated weight maps and source lists extracted in each passband. These data can be requested through the URL http://www.eso.org/eis.

Galactic Planetary Nebulae and their central stars - I. An accurate and homogeneous set of coordinates

We have used the 2nd generation of the Guide Star Catalogue (GSC-II) as a reference astrometric catalogue to compile the positions of 1086 Galactic Planetary Nebulae (PNe) listed in the Strasbourg ESO Catalogue (SEC), its supplement and the version 2000 of the Catalogue of Planetary Nebulae. This constitutes about 75% of all known PNe. For these PNe, the ones with a known central star (CS) or with a small diameter, we have derived coordinates with an absolute accuracy of0: 00 35 in each coordinate, which is the intrinsic astrometric precision of the GSC-II. For another 226, mostly extended, objects without a GSC-II counterpart we give coordinates based on the second epoch Digital Sky Survey (DSS-II). While these coordinates may have systematic osets relative to the GSC-II of up to 5 arcsecs, our new coordinates usually represent a significant improvement over the previous catalogue values for these large objects. This is the first truly homogeneous compilation of PNe positions over the whole sky and the most accurate one available so far.

ESO Imaging Survey. VII. Distant cluster candidates over 12 square degrees

In this paper the list of candidate clusters identified from the I -band images of the ESO Imaging Survey (EIS) is completed using the data obtained over a total area of about 12 square degrees (EIS Patchesxa0C and D). 248 new cluster candidates are presented. Together with the data reported earlier the total I -band coverage of EIS is 17 square degrees, which has yielded a sample of 302 cluster candidates with estimated redshift in the range and a median redshift of . This is the largest optically-selected sample currently available in the Southern Hemisphere. It is also well distributed in the sky thus providing targets for a variety of VLT programs nearly year round.

ESO imaging survey: infrared observations of CDF-S and HDF-S

This paper presents infrared data obtained from observations carried out at the ESO 3.5 m New Technology Telescope (NTT) of the Hubble Deep Field South (HDF-S) and the Chandra Deep Field South (CDF-S). These data were taken as part of the ESO Imaging Survey (EIS) program, a public survey conducted by ESO to promote follow-up observations with the VLT. In the HDF-S field the infrared observations cover an area of ∼53 square arcmin, encompassing the HST WFPC2 and STIS fields, in the JHK s passbands. The seeing measured in the final stacked images ranges from 0.79 to 1.22 and the median limiting magnitudes (AB system, 2 aperture, 5σ detection limit) are J AB ∼ 23.0, H AB ∼ 22.8 and K AB ∼ 23.0 mag. Less complete data are also avai]able in JK s for the adjacent HST NICMOS field. For CDF-S, the infrared observations cover a total area of ∼100 square arcmin, reaching median limiting magnitudes (as defined above) of J AB ∼ 23.6 and K AB ∼ 22.7 mag. For one CDF-S field H band data are also available. This paper describes the observations and presents the results of new reductions carried out entirely through the un-supervised, high-throughput EIS Data Reduction System and its associated EIS/MVM C++-based image processing library developed, over the past 5 years, by the EIS project and now publicly available. The paper also presents source catalogs extracted from the final co-added images which are used to evaluate the scientific quality of the survey products, and hence the performance of the software. This is done comparing the results obtained in the present work with those obtained by other authors from independent data and/or reductions carried out with different software packages and techniques. The final science-grade catalogs together with the astrometrically and photometrically calibrated co-added images are available at CDS.

Galactic orbits of Planetary Nebulae unveil thin and thick disk populations and cast light on interaction with the interstellar medium

We report reliable proper motion values for the central stars of four Planetary Nebulae (PNe). The proper motions have been compiled from existing optical catalogues i.e. Tycho-2, UCAC2, USNO-B and GSC-II, which are the product of large scale surveys. Results from the different sources have been compared and excellent agreement has been found in all cases reported here. Using known PNe distances and radial velocities, we then computed their Galactic velocity components which, by using a simplified model of the Galactic gravitational field, have allowed us to derive, for the first time, their Galactic orbits. These have provided the first kinematic evidence of the existence of thin and thick Galactic disk PNe populations. This approach, extended to a larger sample of PNe, will result in a statistically more solid basis. For our four individual objects though, the determination of the spatial velocity vector has already provided useful insights into their interaction with the ambient interstellar medium (ISM), confirming that the motion of the central star and the nebular shell through the ISM is the root cause for the interaction process. Our results therefore show how a more quantitative understanding of the interaction process can be achieved in the future. This would provide new insight into the return of metal enriched matter to the ISM, which in turn is in no small part responsible for the chemical evolution of galaxies.

Variable stars in the Tycho photometric observations I. Detection

We present an original way to detect variable stars in the Tycho photometric observations. A modied Kolmogorov-Smirnov statistical test has been constructed, based on a model of most of the satellites parameters, leading to the dispersion in the measurements. This allows us to build a treatment taking into account truncated detections and censored measurements, and to search for variability in the faint part of the catalogue. The selection threshold of variable stars has been calibrated to minimize false alarm rate. Reliable results were thus obtained for stars as faint as 11 mag. One thousand and ninety-one suspected variable stars have been listed, 407 of which are already known in Hipparcos, GCVS or NSV, and 684 of which are suspected variable stars to be identied soon.

Galactic planetary nebulae and their central stars II. Proper motions

Context. More than 1500 Galactic planetary nebulae (PNe) are known but only a tiny fraction of them have measured proper motions. To date, the largest set of proper motion (PM) data for PNe is the one by Cudworth (1974), which includes 62 objects 25 of which have PM with significance better than 3σ in at least one component. Aims. With our new compilation of 234 PNe we enlarge – compared to Cudworth’s 25 – by almost an order of magnitude the number of PNe and central stars (CSs) with reliably measured proper motion (i.e. with significance better than 3σ in at least one component) and confirm some previous measurements. Methods. We have used all-sky astrometric catalogues available via the Vizier database to collect proper motion information for a sample of objects selected from the catalogue of PNe positions of Kerber et al. (2003a, A&A, 408, 1029). Results. We have derived proper motion information for a total of 234 PNe (274 when including 40 doubtful candidates). We include all PNe for which a confidence level of at least 3σ was achieved in at least one proper motion component. For many objects PM data are available from more than one catalogue and agreement between different catalogues is usually very reasonable providing independent confirmation of the results. For comparison with Cudworth’s results we use the proper motion modulus as a metric. We cross-correlated his 62 objects with our master catalogue and found 12 matching objects out of the 18 with >3σ in his list. For these we find good agreement for 10 out of the 12 objects, while we find significant PM for another five objects with PM σ ≤ 3 reported by Cudworth. The number of objects we have in common was limited by several factors discussed in the paper. Conclusions. With 234 (274 including doubtful candidates) entries our work is the largest available compilation of proper motion data for PNe and their CSs. This compilation opens new opportunities for studies of orbital kinematics of PNe in the Galaxy.

VLT Interferometer Data Flow System: from observation preparation to data processing

In this article we present the Data Flow System (DFS) for the Very Large Telescope Interferometer (VLTI). The Data Flow System is the VLT end-to-end software system for handling astronomical observations from the initial observation proposal phase through the acquisition, processing and control of the astronomical data. The Data Flow system is now in the process of installation and adaptation for the VLT Interferometer. The DFS was first installed for VLTI first fringes utilising the siderostats together with the VINCI instrument and is constantly being upgraded in phase with the VLTI commissioning. When completed the VLT Interferometer will make it possible to coherently combine up to three beams coming from the four VLT 8.2m telescopes as well as from a set of initially three 1.8m Auxiliary Telescopes, using a Delay Line tunnel and four interferometry instruments. Observations of objects with some scientific interest are already being carried out in the framework of the VLTI commissioning using siderostats and the VLT Unit Telescopes, making it possible to test tools under realistic conditions. These tools comprise observation preparation, pipeline processing and further analysis systems. Work is in progress for the commissioning of other VLTI science instruments such as MIDI and AMBER. These are planned for the second half of 2002 and first half of 2003 respectively. The DFS will be especially useful for service observing. This is expected to be an important mode of observation for the VLTI, which is required to cope with numerous observation constraints and the need for observations spread over extended periods of time.

Data flow system for the very large telescope interferometer

The Data Flow System is the VLT end-to-end system for handling astronomical observations from the initial observation proposal phase through the acquisition, processing and control of the astronomical data. The VLT Data Flow System has been in place since the opening of the first VLT Unit Telescope in 1998. When completed the VLT Interferometer will make it possible to coherently combine up to three beams coming from the four VLT 8.2m telescopes as well as from a set of initially three 1.8m Auxiliary Telescopes, using a Delay Line tunnel and four interferometry instruments. The Data Flow system is now in the process of installation and adaptation for the VLT Interferometer. Observation preparation for a multi-telescope system, handling large data volume of several tens of gigabytes per night are among the new challenges offered by this system. This introduction paper presents the VLTI Data Flow system installed during the initial phase of VLTI commissioning. Observation preparation, data archival, and data pipeline processing are addressed.

Evolution and adaptation of the VLT data flow system

The VLT Data Flow System (DFS) has been developed to maximize the scientific output from the operation of the ESO observatory facilities. From its original conception in the mid 90s till the system now in production at Paranal, at La Silla, at the ESO HQ and externally at home institutes of astronomers, extensive efforts, iteration and retrofitting have been invested in the DFS to maintain a good level of performance and to keep it up to date. In the end what has been obtained is a robust, efficient and reliable science support engine, without which it would be difficult, if not impossible, to operate the VLT in a manner as efficient and with such great success as is the case today. Of course, in the end the symbiosis between the VLT Control System (VCS) and the DFS plus the hard work of dedicated development and operational staff, is what made the success of the VLT possible. Although the basic framework of DFS can be considered as completed and that DFS has been in operation for approximately 3 years by now, the implementation of improvements and enhancements is an ongoing process mostly due to the appearance of new requirements. This article describes the origin of such new requirements towards DFS and discusses the challenges that have been faced adapting the DFS to an ever-changing operational environment. Examples of recent, new concepts designed and implemented to make the base part of DFS more generic and flexible are given. Also the general adaptation of the DFS at system level to reduce maintenance costs and increase robustness and reliability and to some extend to keep it conform with industry standards is mentioned. Finally the general infrastructure needed to cope with a changing system is discussed in depth.