The Elusive Dust Torus of NGC 1068 Unveiled by Adaptive Optics Observations from 2.2 µm TO 4.8 µm

Near-infrared, adaptive optics observations of AGN achieve a spatial resolution comparable to that of the Hubble Space Telescope at visible and ultraviolet wavelengths. Using the ESO adaptive optics system, we have mapped the nuclear region of NGC 1068 in the near-infrared at 2.2, 3.5 and 4.8 μm. These data show the presence of strong near-infrared emission within the central 100 pc around the nucleus. At the K, L and M bands, the dominant emission peak is unresolved at resolutions of 35 pc (K), 15 pc (L) and 23 pc (M). We find that the emission peaks at 2.2, 3.5 and 4.8 μm are offset by 0.3±0.1" south of the HST optical continuum peak. The infrared peaks are coincident with the HST imaging polarimetry center thought to mark the hidden nucleus. We conclude that the infrared emission peaks are also directly related with the hidden nucleus and that they outline the dusty torus around the central engine, as expected from current AGN models. From our first estimate of the fluxes in L and M, we derive a dust temperature of 750 K for the unresolved component. This revised version was published online in July 2006 with corrections to the Cover Date.     

Far-infrared brightness temperature of Saturn's disk and rings

We present far-infrared observations of Saturn in the wavelength band 76–116 μm, using a balloon-borne 75-cm telescope launched on 10 December 1980 from Hyderabad, India, when B′, the Saturnicentric latitude of the Sun, was 4°.3. Normalizing with respect to Jupiter, we find the average brightness temperature of the disk-ring system to be 90 ± 3° K. Correcting for the contribution from rings using experimental information on the brightness temperature of rings at 20 μm, we find T_D, the brightness temperature of the disk, to be 96.9 ± 3.5° K. The systematic errors and the correction for the ring contribution are small for our observations. We, therefore, make use of our estimate of T_D and earlier observations of Saturn when contribution from the rings was large and find that for wavelengths greater than 50 μm, there is a small reduction in the ring brightness temperature as compared to that at 20 μm.     

The GraF instrument for Imaging Spectroscopy with the Adaptive Optics

The GraF instrument using a Fabry-Perot interferometer cross-dispersed with a grating was one of the first integral-field and long-slit spectrographs built for and used with an adaptive optics system. We describe its concept, design, optimal observational procedures and the measured performances. The instrument was used in 1997–2001 at the ESO3.6 m telescope equipped with ADONIS adaptive optics and SHARPII+camera. The operating spectral range was 1.2–2.5 μm. We used the spectral resolution from 500 to 10 000 combined with the angular resolution of 0.1″–0.2″. The quality of GraF data is illustrated by the integral field spectroscopy of the complex0.9″ × 0.9″ central region of η Car in the1.7 μm spectral range at the limit of spectral and angular resolutions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Past and future of ESO

In 1964, the European Southern Observatory (ESO) came into being as a response to the need of European astronomers for access to large telescopes in good observing conditions. The original plan called for a 3.6 m telescope in addition to a number of smaller instruments. The 3.6 m telescope took some 12 years to build, while ESO headquarters moved from Hamburg to CERN to Garching near Munich, and during the times of office of three Directors General, and it was built on La Silla in Chile, where superior sites had been found. After 1982, when Italy and Switzerland joined the original six member countries, ESO was able to expand by building the 3.5 m New Technology Telescope, and ultimately planning and constructing the VLT on Paranal. At present ESO is a stable organization that has been successful in its original aims, and in view of new plans can look forward in confidence.     

BeppoSAX observations of the Seyfert 2 galaxies NGC 7172 and ESO 103-G35

We investigate the X-ray spectra of the type 2 Seyfert galaxies NGC 7172 and ESO 103-G35, using BeppoSAX observations, separated by approximately one year. We find that the X-ray spectra of both NGC 7172 and ESO 103-G35 can be well fitted using a power-law model with an Fe K α emission line at 6.4 keV. We did not find any statistically significant evidence for the existence of a reflection component in the X-ray spectra of these two galaxies. The continuum flux has decreased by a factor of approximately 2 during this period, in both objects. However, the spectral index as well as the absorption column have remained constant. We find weak evidence for the decrease of the normalization of the Fe K α emission line in a similar manner to the continuum in NGC 7172. We also report tentative evidence for a broad Fe K α line in agreement with previous ASCA observations. In contrast, in the case of ESO 103-G35 the line flux does not change while its width remains unresolved.     

The GREGOR adaptive optics system

The new 1.5‐m German solar telescope GREGOR at the Observatorio del Teide, Tenerife, is equipped with an integrated adaptive optics system. Although partly still in the commissioning phase, the system is already being used used for most science observations. It is designed to provide diffraction‐limited observations in the visible‐light regime for seeing better than 1.2″. We describe the AO system including the optical design, software, wavefront reconstruction, and performance (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

IFU Unit in Scorpio-2 Focal Reducer for Integral-Field Spectroscopy on the 6-m Telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences

We describe the scheme and design features of the new IFU unit (Integral Field Unit) meant to perform integral-field spectroscopy as a part of SCORPIO-2 focal reducer, which is mounted in the prime focus of the 6-m telescope of the Special Astrophyscial Observatory of the Russian Academy of Sciences. The design of the unit is based on the principle of the formation of array spectra using a lens raster combined with optical fibers. The unit uses a rectangular raster consisting of 22×22 square 2-mm diameter lenses. The image of the object is transferred by an optical system with a 23^× magnification from the focal plane of the telescope to the plane of the lens raster. The image scale is —0.″75/lens and the field of view of the instrument has the size of 16.″5 × 16.—5². The raster also contains two extra 2 × 7 lens arrays to acquire the night-sky spectra whose images are offset by ±3′from the center. Optical fibers are used to transform micropupil images into two pseudoslits located at the IFU collimator entrance. When operating in the IFU mode a set of volume phase holographic gratings (VPHG) provides a spectral range of 4600–7300 Å and a resolution λ/δλ of 1040 to 2800. The quantum efficiency of SCORPIO-2 field spectroscopy is 6–13% depending on the grating employed.We describe the technique of data acquisition and reduction using IFU unit and report the results of test observations of the Seyfert galaxyMrk 78 performed on the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences.     

GREGOR solar telescope: Design and status

The integration and verification phase of the GREGOR telescope reached an important milestone with the installation of the interim 1 m SolarLite primary mirror. This was the first time that the entire light path had seen sunlight. Since then extensive testing of the telescope and its subsystems has been carried out. The integration and verification phase will culminate with the delivery and installation of the final 1.5 m Zerodur primary mirror in the summer of 2010. Observatory level tests and science verification will commence in the second half of 2010 and in 2011. This phase includes testing of the main optics, adaptive optics, cooling and pointing systems. In addition, assuming the viewpoint of a typical user, various observational modes of the GREGOR Fabry‐Pérot Interferometer (GFPI), the Grating Infrared Spectrograph (GRIS), and high‐speed camera systems will be tested to evaluate if they match the expectations and science requirements. This ensures that GREGOR will provide high‐quality observations with its combination of (multi‐conjugate) adaptive optics and advanced post‐focus instruments. Routine observations are expected for 2012 (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: X. Astrometric measurements of visual binaries in 2009

We present relative astrometric measurements of visual binaries, made in 2009 with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 345 new measurements of 259 objects, with angular separations in the range 0.″18–4.″6, and an average accuracy of 0.″011. The mean error on the position angles is 0.°6. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We have found a possible new close component for ADS 2377, which would be a new quadruple star system. We also present new revised orbits for ADS 8035, 9982, 11484, and MLR 198, partly derived from those observations, and infer estimated values for the masses of those systems that are compatible with the spectral types (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The Galileo project

The Galileo project comprises the design, building, and operation of a 3.5 m Italian telescope the main elements (diameter, mechanical structure, active optics, etc.) of which consist of a duplication of the ESO New Technology Telescope (NTT). Modifications have been introduced in order to allow, beyond thef/11 Nasmyth foci, a prime focusf/2.2 station, a trappedf/6 focus, and a small Cassegrainf/20 facility. Other changes with respect to the NTT have been made to the control and data acquisition system, and to the service building. The telescope could be operational at the end of 1992.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.     

Infrared Observations from the New Solar Telescope at Big Bear

The 1.6 m clear aperture solar telescope in Big Bear is operational and with its adaptive optics (AO) system it provides diffraction limited solar imaging and polarimetry in the near-infrared (NIR). While the AO system is being upgraded to provide diffraction limited imaging at bluer wavelengths, the instrumentation and observations are concentrated in the NIR. The New Solar Telescope (NST) operates in campaigns, making it the ideal ground-based telescope to provide complementary/supplementary data to SDO and Hinode. The NST makes photometric observations in Hα (656.3 nm) and TiO (705.6 nm) among other lines. As well, the NST collects vector magnetograms in the 1565 nm lines and is beginning such observations in 1083.0 nm. Here we discuss the relevant NST instruments, including AO, and present some results that are germane to NASA solar missions.     

A new spectroscopic facility at millimetre wavelengths

A new millimeter-wave facility is in operation at the Bordeaux Observatory for spectroscopic observations of interstellar and stratospheric molecules. A cooled receiver has been installed on a 2·5m radio telescope. The overall system temperature is in the range 400 to 600 K (single side band) in the operating frequency range 75 to 115 GHz. The relatively broad beam of the telescope (∼ 5 arcmin) combined with a sensitive receiver will permit studies of extended molecular cloud complexes.     

The search for extrasolar giant planets using integral field spectroscopy: Simulations

We present here simulations of extrasolar planets detections obtained using a combination of extreme adaptive optics and integral field spectroscopy. The simulation code, written for IDL, provides images and, in particular, spectra, taking into account realistic Speckle Noise, AO correction effects and specific instrumental features. A detailed study has been done for ESO VLT telescopes (8.2 m), within the Phase A of the CHEOPS project, but the code is particularly flexible and can be updated for larger telescope diameters (ELTs) in order to give a realistic estimate of the detection limits, for giant telescopes, in standard conditions of seeing.     

Observations of cosmic gamma-ray bursts with the main detector of the SIGMA telescope onboard the Granat Observatory

We present the observations of cosmic gamma-ray bursts (GRBs) with the main detector of the SIGMA telescope onboard the Granat Observatory from January 1990 through September 1994. The observations were carried out in the energy range 35–1300 keV. We detected 36 GRBs and 31 high-energy solar flares during this period. No GRB fell within the main field of view; they were all recorded by the “secondary optics” of the telescope. The SIGMA telescope recorded relatively bright bursts with peak fluxes of 10^?6–10^?4 erg s^?1 cm^?2 in the 100–500-keV energy band. Stable detector background allows the long-term variability of GRB sources on a time scale of ～1000 s to be studied. The results of our search for early afterglows of GRBs are presented. The flux averaged over all bursts in the interval 100–800 s after the main event is 0.36±0.14 counts s^?(35–300 keV), suggesting that there is soft gamma-ray emission on this time scale after a considerable number of GRBs.     

Extended (15 × 6 AU) Hα Emission Around T Tau N

We present an image of T Tauri N reconstructed from speckle interferometry observations made at the 3.6 m Canada-France-Hawaii telescope (CFHT). Two spectral windows, at Hα [6540-6580 Å] and red continuum [6580-6840 Å] were used. The star is unresolved in the continuum (θ ≤ 0″038), setting an upper limit for its size of ≤ 5.3 AU (assuming a 140 pc distance). At Hα (continuum subtracted) two components are observed, an unresolved one with 70% of the Hα flux and a resolved 0″106 × 0″043 (15 × 6 AU) with 30 %. The extended component is elongated in the North-South direction. The extended Hα component scale, it's non-detection in the continuum, and TTau Hα profile shape suggest that the extension is a disk corona.     

First Light of the Near-Infrared Narrow-Band Tunable Birefringent Filter at Big Bear Solar Observatory

We discuss a near-infrared (NIR) narrow-band tunable birefringent filter system newly developed by the Big Bear Solar Observatory (BBSO). This is one of the first narrow-bandpass NIR filter systems working at 1.56 μm which is used for the observation of the deepest solar photosphere. Four stages of calcite were used to obtain a bandpass of 2.5 Å along with a free spectral range (FSR) of 40 Å. Some unique techniques were implemented in the design, including liquid crystal variable retarders (LCVRs) to tune the bandpass in a range of ±100 Å, a wide field configuration to provide up to 2° incident angle, and oil-free structure to make it more compact and handy. After performing calibration and characteristic evaluation at the Evans Facility of the National Solar Observatory at Sacramento Peak (NSO/SP), a series of high-resolution filtergrams and imaging polarimetry observations were carried out with the Dunn Solar Telescope of NSO/SP and the 65-cm telescope of BBSO, in conjunction with the high-order adaptive optics system and the Fabry–Pérot Interferometer (FPI). In this paper, we describe the optical design and discuss the calibration method. Preliminary observations show that it is capable of serving as either a stand-alone narrow-band filter for NIR filtergram observations or an order-sorting filter of a FPI applied to NIR two-dimensional imaging spectro-polarimetry.     

Adaptive Optics on a 3.6-Meter Telescope. The ADONIS System.

ADONIS is an adaptive optics (AO) user friendly instrument offered to the European astronomical community on the ESO 3.6-m telescope at La Silla. It is an upgraded version of COME-ON-PLUS, the VLT AO prototype, which already produced significative astrophysical results in a wide range of fields, from planetology to extragalactic astrophysics. ADONIS is now allowing the astronomer to use adaptive optics as a common user instrument thanks to the implementation of an open artificial intelligence software that handles the large number of parameters needed to optimise the AO correction. We will describe the ADONIS system, including the two dedicated infrared cameras, summarize its performances and discuss the observing procedures.     

Polarimetric and Photometric Phase Effects Observed on Transneptunian Object (29981) 1999 TD10

The Kuiper-Belt Object (29981) 1999 TD₁₀, classified as a Scattered-Disk Object, has been observed at three different phase angles with the ESO 8.2-m VLT and FORS 1 instrument in polarimetric mode in November and December 2003. These observations have been used to compute the Stokes parameter q, which represents the linear polarization degree. We have also used the previously published photometric observations to improve the R-band phase function. The main conclusions are as follows: (i) a negative linear polarization degree decreasing with phase angle α up to, at least, α=3°, (ii) for α=3°, (iii) a possible color effect between the R and V band, the polarization degree being more negative in R. The R-band polarimetric observations can be explained by the coherent-backscattering mechanism and fitted by a two-component Rayleigh-scatterer model for a spherical small body. The rotation period of 15.382±0.001 h published by Mueller et al. (2004, Icarus 171, 506–515) and Choi et al. (2003, Icarus 165, 101–111) is confirmed. The R-band phase curve provides H=8.35±0.02 and G=−0.25±0.022 parameters with the IAU H–G formalism.Based on observations obtained at the Cerro Paranal observatory of the European Southern Observatory (ESO) in Chile.     

Astrometric and photometric studies of the asteroid 2008 TC3

Near real time astrometric and photometric observations of the asteroid 2008 TC3, discovered 19 hours before it fell to Earth in the area of northern Sudan, were conducted on the night of October 6–7, 2008, using an automated telescope ZA-320M of the Pulkovo Observatory. In the interval of 4 h, 270 observations in the integral band of the telescope were performed, which was about one-third of all global observations of the asteroid. Based on the analysis of all cases, physical parameters of the asteroid were assessed. The estimates of the absolute magnitude of the asteroid (M _V = 30.6 ± 0.4 μm), its size (4.8 ± 0.8 m), and weight (131 ± 5 t) were obtained. A frequency analysis of the observational series was conducted, which helped to detect the periodicity in the brightness variation of the asteroid. The elements of the heliocentric orbit of the asteroid were refined. The trajectory of the asteroid, taking into account the atmospheric drag and nonsphericity of the Earth, was simulated.     

Optical variability of NGC 7469 in 1967–1987

Within the framework of a five-year campaign of coordinated multifrequency observations of the 3 Tauri star RU Lupi, we present results obtained in X-ray, UV, optical, and IR spectral regions. In five cases, simultaneous data from UV to IR were collected. Data analysis shows a large variability at different wavelengths both in the continuum and lines, stronger in the UV and weaker in the IR. Correlations among variations in the UV and optical continua have been found. Moreover flare-like events (FLEs), probably due to strong activity in the surface layers of the star and burst phenomena on large scale, were detected. No forbidden coronal lines were detected in UV and optical regions with IUE and ESO 1.4m CAT telescope, respectively. This means either the used instruments have not enough sensitivity to detect the predicted forbidden lines, or the low X-ray detected intensity — with ASTRON satellite (2–25 keV) — is due to the absorption of the X-rays in the circumstellar envelope. In this paper we will discuss these results within the framework of the current models.Based on observations with IUE satellite (VILSPA) and ESO telescopes.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain