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: http://www.adass.org/adass/proceedings/adass99/P2-64/
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CONICA's and NAOS control softwares have been designed in close relation with VLT's general software to provide astronomers with an efficient support from the preparation of the observation to the effective observing runs, while hiding the technical complexity of the adaptive optics system.
From the NAOS standpoint, the control software also takes care of the adaptive optics system itself, a more complex instrumentation (Real-Time Computers (Rabaud 2000), Wave-Front Sensors, ...) which requires a more complex optimization.
The main concepts and novelties of the software design, to cope with the complexity of the CONICA/NAOS, are explained in the following.
Concerning the NAOS control software, a hierarchical structure with three level layers has been adopted. On the top level, the SOS coordinates the NAOS and CONICA instruments, providing only one access to the scientific instrument attached on the telescope (CONICA) and the intervening adaptive optics system (NAOS). As a software interface between the softwares in charge of the instruments control, BOB, the Telescope Control System, and the Archive System, the SOS also displays for the observer a summary of the instruments and observing conditions status.
The middle layer consists in the OS which handles the overall observation control with the NAOS instrument. It manages the various sub-systems that are involved during the critical tasks of the adaptive optics system such as the acquisition of the reference source or the centering of the scientific object on the CONICA detector or the observation itself.
The low level consists in sub-system supervisors which are in charge of the control of all functions belonging to the sub-system. Each supervisor has to handle a limited number of dedicated tasks, making easier implementation and improving the maintainability. This architecture offers advantages in modularity and flexibility; each sub-system can be developed and tested in independent ways, and re-used for other instruments.
Moreover, all these software modules have to provide common features such as transferring control information (typically in the form of commands) to sub-systems, synchronizing replies, handling of states and sub-states, etc. All these features have been grouped in a library called Instrument Server Framework (ISF), providing a rich foundation with services for instrument server implementation.
The preparation of an observation with a VLT instrument consists in building Observation Block (OB) from a list a pre-defined sequences of exposure (so-called template). A template is used to specify setup and/or actions for detector, instrument or telescope. It has input parameters to configure these setup/actions, in accordance with the scientific program. The OB is a set of templates allowing to acquire the science object and to produce astronomical data.
In the case of NAOS, a limited number of templates (about 20) has been defined allowing to prepare observation programs such as imaging, slit spectroscopy or polarimetry with possibility of chopping, nodding or mosaicing.
To support astronomer during this phase, the control software includes the Preparation Software (PS) (Marteau 2000) which is a sophisticated tool providing the accurate and optimized configuration of the adaptive system, according to the scientific program and the observing conditions, on the basis of a permanently updated performance estimation. It can be used by the observer, through a WEB interface, while preparing the observations to assess their feasibility and build observing block. The PS is also available during observing run, giving the possibility of reacting quickly to the changes in the weather and in other conditions by providing the optimized configuration of the system for those conditions.
The Broker for Observation Blocks (BOB) is the common VLT tool used to control, in the same way, all the instruments installed on VLT. It allows to carry out observations automatically, in accordance with the observation program defined by the astronomer during the Phase II Proposal Preparation, and with the pre-defined sequences of exposures.
The Real-Time Display (RTD) is a common VLT tool used by all instruments to display astronomical images, but it is also used to assist the operator during the acquisition of the object to be observed, as well as during the acquisition of the reference source used by the Adaptive Optics System.
All maintenance operations that require interactions with the instrument (e.g set-up of instrument) are based on the NAOS Control Software (OS, ICS, etc.). Likewise, the tests and calibrations benefit from VLT concepts, namely the templates and the observation blocks, and therefore may be seen as very special observing runs and may be submitted to BOB tool in form of complete Observation blocks.
Marteau S. et al. 2000, this volume, 365
Rabaud D. et al. 2000, this volume, 373