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Register a new userHectospec, the MMTs 300 Optical Fiber-Fed Spectrograph
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The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. A pair of high-speed six-axis robots move the 300 fiber buttons between observing configurations within ~300 s and to an accuracy ~25 microns. The optical fibers run for 26 m between the MMTs focal surface and the bench spectrograph operating at R~1000-2000. Another high dispersion bench spectrograph offering R~5,000, Hectochelle, is also available. The system throughput, including all losses in the telescope optics, fibers, and spectrograph peaks at ~10% at the grating blaze in 1 FWHM seeing. Correcting for aperture losses at the 1.5 diameter fiber entrance aperture, the system throughput peaks at $sim$17%. Hectospec has proven to be a workhorse instrument at the MMT. Hectospec and Hectochelle together were scheduled for 1/3 of the available nights since its commissioning. Hectospec has returned ~60,000 reduced spectra for 16 scientific programs during its first year of operation.
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We present here CAFE, the Calar Alto Fiber-fed Echelle spectrograph, a new instrument built at the Centro Astronomico Hispano Aleman (CAHA). CAFE is a single fiber, high-resolution ($Rsim$70000) spectrograph, covering the wavelength range between 3650-9800AA. It was built on the basis of the common design for Echelle spectrographs. Its main aim is to measure radial velocities of stellar objects up to $Vsim$13-14 mag with a precision as good as a few tens of $m s^{-1}$. To achieve this goal the design was simplified at maximum, removing all possible movable components, the central wavelength is fixed, so the wavelentgth coverage; no filter wheel, one slit and so on, with a particular care taken in the thermal and mechanical stability. The instrument is fully operational and publically accessible at the 2.2m telescope of the Calar Alto Observatory. In this article we describe (i) the design, summarizing its manufacturing phase; (ii) characterize the main properties of the instrument; (iii) describe the reduction pipeline; and (iv) show the results from the first light and commissioning runs. The preliminar results indicate that the instrument fulfill the specifications and it can achieve the foreseen goals. In particular, they show that the instrument is more efficient than anticipated, reaching a $S/Nsim$20 for a stellar object as faint as $Vsim$14.5 mag in $sim$2700s integration time. The instrument is a wonderful machine for exoplanetary research (by studying large samples of possible systems cotaining massive planets), galactic dynamics (high precise radial velocities in moving groups or stellar associations) or astrochemistry.
SIDE (Super Ifu Deployable Experiment) will be a second-generation, common-user instrument for the Grantecan (GTC) on La Palma (Canary Islands, Spain). It is being proposed as a spectrograph of low and intermediate resolution, highly efficient in multi-object spectroscopy and 3D spectroscopy. SIDE features the unique possibility of performing simultaneous visible and NIR observations for selected ranges. The SIDE project is leaded by the Instituto de Astrofisica de Andalucia (IAA-CSIC) in Granada (Spain) and the SIDE Consortium is formed by a total of 10 institutions from Spain, Mexico and USA. The SIDE Feasibility Study has been completed and currently the project is under revision by the GTC Project Office.
Understanding the atmospheres of exoplanets is a milestone to decipher their formation history and potential habitability. High-contrast imaging and spectroscopy of exoplanets is the major pathway towards the goal. Directly imaging of an exoplanet requires high spatial resolution. Interferometry has proven to be an effective way of improving spatial resolution. However, means of combining interferometry, high-contrast imaging, and high-resolution spectroscopy have been rarely explored. To fill in the gap, we present the dual-aperture fiber nuller (FN) for current-generation 8-10 meter telescopes, which provides the necessary spatial and spectral resolution to (1) conduct follow-up spectroscopy of known exoplanets; and (2) detect planets in debris-disk systems. The concept of feeding a FN to a high-resolution spectrograph can also be used for future space and ground-based missions. We present a case study of using the dual-aperture FN to search for biosignatures in rocky planets around M stars for a future space interferometry mission. Moreover, we discuss how a FN can be equipped on future extremely large telescopes by using the Giant Magellan Telescope (GMT) as an example.
SIDE (Super Ifu Deployable Experiment) is proposed as second-generation, common-user instrument for the GTC. It will be a low and intermediate resolution fiber fed spectrograph, highly efficient in multi-object and 3D spectroscopy. The low resolution part (R = 1500, 4000) is called Dual VIS-NIR because it will observe in the VIS and NIR bands (0.4 ~V 1.7 microns) simultaneously. Because of the large number of fibers, a set of ~10 identical spectrographs is needed, each with a mirror collimator, a dichroic and two refractive cameras. The cameras are optimized for 0.4 - 0.95 microns (VIS) and 0.95 - 1.7 microns (NIR) respectively.
We present spectrograph design details and initial radial velocity results from the PRL optical fiber-fed high-resolution cross-dispersed echelle spectrograph (PARAS), which has recently been commissioned at the Mt Abu 1.2 m telescope, in India. Data obtained as part of the post-commissioning tests with PARAS show velocity precision better than 2m/s over a period of several months on bright RV standard stars. For observations of sigma-Dra we report 1.7m/s precision for a period of seven months and 2.1m/s for HD 9407 over a period of 2 months. PARAS is capable of a single-shot spectral coverage of 3800A - 9500A at a resolution of about 67,000. The RV results were obtained between 3800A and 6900A using simultaneous wavelength calibration with a Thorium-Argon (ThAr) hollow cathode lamp. The spectrograph is maintained under stable conditions of temperature with a precision of 0.01 - 0.02C (rms) at 25.55C, and enclosed in a vacuum vessel at pressure of 0.1 +/-0.03 mbar. The blaze peak efficiency of the spectrograph between 5000A and 6500A, including the detector, is 30%; and about 25% with the fiber transmission. The total efficiency, including spectrograph, fiber transmission, focal ratio degradation (FRD), and telescope (with 81% reflectivity) is about 7% in the same wavelength region on a clear night with good seeing conditions.
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