Journal of Astronomical Telescopes, Instruments, and Systems
VOL. 5 · NO. 1 | January 2019
ISSUES IN PROGRESS
SPIE publishes accepted journal articles as soon as they are approved for publication Journal issues are considered In Progress until all articles for an issue have been published. Articles published ahead of the completed issue are fully citable.
Our contribution presents a high bandwidth platform that implements traffic aggregation and switching capabilities for the Cherenkov telescope array (CTA) cameras. Our proposed system integrates two different data flows: a unidirectional one from the cameras to an external server and a second one, fully configurable dedicated to configuration and control traffic for the camera management. The former requires high bandwidth mechanisms to be able to aggregate several 1 gigabit Ethernet links into one high speed 10 gigabit Ethernet port. The latter is responsible for providing routing components to allow a control and management path for all the elements of the cameras. Hence, a simple, efficient, and flexible routing mechanism has been implemented avoiding complex circuitry that impacts in the system performance. As a consequence, an asymmetric network topology allows high bandwidth communication and, at the same time, a flexible and cost-effective implementation. In our contribution, we analyze the camera requirements and present the proposed architecture. Moreover, we have designed several evaluation tests to demonstrate that our solution fulfills the CTA project needs. Finally, we illustrate the general possibilities of the proposed solution for other data acquisition applications and the most promising futures lines of research are discussed.
The reflectivity of a telescope primary mirror is one of the fundamental parameters that determines the telescope performance. Due to a lack of suitable instruments, however, measuring the absolute value of the reflectivity, in particular wide spectral measurements in-situ, has been almost impossible. To solve this problem, we developed a portable spectrophotometer called the Subaru Portable Spectrophotometer (SPS). SPS covers a spectral range between 380 and 1000 nm with a resolution of 2 nm. Its dimension and weight enable in-situ measurement on the primary mirror. A modified V-N method is applied to SPS for obtaining the absolute reflectivity. A sequential measurement makes SPS compensate the instrumental drift. The great advantage of SPS is its capability of getting absolute spectral reflectivity in-situ, even after the primary mirror is mounted on a telescope. In the case of Subaru Telescope, SPS clarified the reflectivity of the primary mirror coated with aluminum 4 years ago. Periodic measurements have been on-going since the primary mirror recoating in 2017. It is now possible to study the telescope reflectivity degradation with SPS.
FRIDA (inFRared Imager and Dissector for Adaptive optics) is a near-infrared integral-field spectrograph operating at the wavelength range of 0.9 to 2.5 μm for use at the Nasmyth B platform of the Gran Telescopio de Canarias (GTC). FRIDA is a collaborative project led by the Instituto de Astronomía Universidad Nacional Autónoma de México (IA-UNAM, México) with the collaboration of the Instituto de Astrofísica de Canarias (IAC, Spain), Centro de Ingeniería y Desarrollo Industrial (CIDESI, México), the University of Florida (UF, USA), and the Universidad Complutense de Madrid (UCM, Spain). In imaging mode, FRIDA will provide scales of 0.010, 0.020, and 0.040 arc sec / pixel and, in IFS mode, spectral resolutions of R ∼ 1000, 4500, and 30,000. FRIDA is the first GTC instrument to use the telescope’s adaptive optics (GTCAO) system and is rescheduled to be delivered to the GTC shortly in 2020. This paper not only provides a starting point for possible future developers of GTC instruments but also presents a generic solution that we adopted in FRIDA to manage the sequences of operations and science observations. Specifically, this paper gives an overview of the high-level control software components of FRIDA. The main components are the mechanisms control system, whose primary task is to control the mechanisms of FRIDA, the data acquisition system, which interacts with the detector to take images, the data factory system, whose main tasks are to perform the reduction, storage and also to provide quality control for both engineering and scientific data, the Instrument Library (IL) component responsible for operating the devices associated with FRIDA, and the sequencer manager component responsible for the execution of both the operational sequencing of the telescope’s instruments and the observing sequences of FRIDA in close co-ordination with the GTCAO system. In other GCS instruments, the responsibilities of the sequencer manager are inside the IL representing an overload on this component with the added problems of extensibility and reusability.