ESA’s Gaia space astrometry mission is performing an all-sky survey of stellar objects. At the beginning of the nominal mission in July 2014, an operation scheme was adopted that enabled Gaia to routinely acquire observations of all stars brighter than the original limit of G∼6, i.e. the naked-eye stars. Here, we describe the current status and extent of those observations and their on-ground processing. We present an overview of the data products generated for G<6 stars and the potential scientific applications. Finally, we discuss how the Gaia survey could be enhanced by further exploiting the techniques we developed.
This document describes the uplink commanding system for the ESA Gaia mission. The need for commanding, the main actors, data flow and systems involved are described. The system architecture is explained in detail, including the different levels of configuration control, software systems and data models. A particular subsystem, the automatic interpreter of human-readable onboard activity templates, is also carefully described. Many lessons have been learned during the commissioning and are also reported, because they could be useful for future space survey missions.
The ESA Gaia space astrometry mission will perform an all-sky survey of stellar objects complete in the nominal magnitude range G = [6.0 - 20.0]. The stars with G < 6.0, i.e. those visible to the unaided human eye, would thus not be observed by Gaia. We present an algorithm configuration for the Gaia on-board autonomous object observation system that makes it possible to observe very bright stars with G = [2.0-6.0). Its performance has been tested during the in-orbit commissioning phase achieving an observation completeness of ~ 94% at G = 3 – 5.7 and ~ 75% at G = 2 – 3. Furthermore, two targeted observation techniques for data acquisition of stars brighter than G=2.0 were tested. The capabilities of these two techniques and the results of the in-flight tests are presented. Although the astrometric performance for stars with G < 6.0 has yet to be established, it is clear that several science cases will benefit from the results of the work presented here.
The radiation environment at L2 is of great importance to the science instruments of Gaia. Especially the non-ionising damage to the CCDs and the resulting increase in charge transfer inefficiency will ultimately limit the achievable science performance. With its launch in December 2013 for a nominal mission of 5 years Gaia is continuously collecting invaluable information of radiation effects on the 106 CCDs in the FPA from the analysis of the science data and dedicated calibration procedures. The paper shows first results and discusses the detected irradiation background with respect to predictions and reviews operational implications for the mission.
ESA's cornerstone mission Gaia is planning to map 1% of the stellar population of our galaxy, around one thousand
million objects, to micro-arcsecond accuracy. In addition to high precision astrometric information, prism dispersion
optics will be used to provide multi-band photometry and a spectroscopic instrument provides information for deriving
radial velocities. Gaia's focal plane will be the largest ever flown to space comprising an almost Giga-pixel mosaic of
106 specially designed CCDs, the e2v technologies CCD91-72, operated synchronously in TDI mode. This paper will
address some operational aspects of these detectors in the Gaia focal plane array and report on recent test results with
respect to calibration needs.
Elmer is an imager and spectrograph in the visible range that has been designed and managed within the GTC Project Office. Elmer will be installed at the telescope at the beginning of the commissioning phase. The observing modes of the instrument are: Imaging, Long Slit, Mask and Slit-less multi-object Spectroscopy, Fast Photometry and Fast short-slit Spectroscopy. The pupil elements are a set of conventional broad band and narrow band filters as well as a set of prisms, grisms and VPHs, that allow spectroscopy with resolving powers of 200, 1000 and 2500 between 365 and 1000nm. Elmer has been exhaustively tested and each of its observing modes has been fully characterized at the laboratory. This contribution summarizes the results of this Test Plan, showing the excellent performance of Elmer in both, Imaging and Spectroscopy modes that, together with the GTC, will lead to a powerful scientific return.
ELMER is a multi-purpose instrument for the GTC designed for both, Imaging and Spectrosopy in the visible range. The CCD camera employs a E2V Technologies CCD44-82 detector mounted in a high performance LN2 Bath Cryostat based on an ESO design and a SDSU-II CCD controller with parallel interface. The design including the low-noise fan-out electronics has been kept flexible to allow alternatively the use of MIT/LL CCID-20 detectors. We present the design of the CCD camera and data acquisition system and first performance test results.
ELMER is an optical instrument for the GTC designed to observe between 3650 and 10000 Armstrong. The observing modes for the instrument at Day One shall be: Imaging, Long Slit Spectroscopy, Mask-multi-object spectroscopy, Slit-less multi-object spectroscopy, Fast Photometry and Fast short-slit spectroscopy. It will be installed at the Nasmyth-B focal station at Day One, but it will also be designed to operate at the Folded Cassegrain focal station. The physical configuration of the instrument consists of a front section where the focal plane components are mounted (Slit Unit) and a rear section with the rest of the components (Field Lens, Prism/Grism/VPH Wheel, Filter Wheel, Collimator, Camera, Folder Mirrors, Shutter and Cryostat with the detector). Both sections are connected through a hexapod type structure. The optical path is bent twice with the two folder mirrors providing a compact system.
The design phase of the ELMER Structure and Mechanisms finished on November 2002. Procurement and manufacturing covered from December 2002 to June 2003. Mechanical and electrical integration was accomplished on September 2003. Test campaign at factory covered from the end of September to mid November. Critical performance of the mechanics has been carefully tested during this period: positional tolerances of optical interfaces, repeatability of the 5 mechanisms (4 rotating wheels and collimator linear stage) and deflections of the instrument due to gravity. Results from the tests are widely within the specified values, providing a top performance instrument.
ELMER is an instrument for the GTC designed to observe between 365 and 1000 nm. The observing modes for the instrument at Day One shall be: Imaging, Long Slit and Mask-Multi-object Spectroscopy, Slit-less multi-object spectroscopy, Fast Photometry and Fast short-slit spectroscopy, over a FOV of 4.2 arcmin diameter. Spectral resolutions of 250, 1000 and 2500, covering the whole spectral range, will be available. ELMER has been designed and managed within the GTC Project Office. ELMER is currently in the final stage of testing previous to be shipped to the Observatory. The general description of this instrument and its expected scientific performance are summarised.
Elmer is an imager and spectrograph in the visible wavelength range for the Gran Telescopio CANARIAS, GTC. Elmer is being managed directly by the GTC Project Office, who has done the whole Preliminary Design and large part of the Detailed Design. This instrument shall operate at the telescope on Day One, as a back up in case of delays of the major instruments, guaranteeing the scientific return of the GTC. A brief presentation of the instrument is here given. The expected scientific performance of the instrument is summarized. Finally, the general description of the management strategy and project parameters are described.