We describe the SCORPIO focal reducer that has been used since the fall of 2000 for observations on the 6-m Special Astrophysical Observatory telescope. We give parameters of the instrument in various observing modes (direct imaging, long-slit and multislit spectroscopy, spectropolarimetry, Fabry-Perot panoramic spectroscopy). Observations of various astronomical objects are used as examples to demonstrate the SCORPIO capabilities.

Bright gravitationally lensed galaxies provide our most detailed view of galaxies at high redshift. The very brightest (r < 21) systems enable high spatial and spectral resolution measurements, offering unique constraints on the outflow energetics, metallicity gradients and stellar populations in high-redshift galaxies. Yet as a result of the small number of ultrabright z ≃ 2 lensed systems with confirmed redshifts, most detailed spectroscopic studies have been limited in their scope. With the goal of increasing the number of bright lensed galaxies available for detailed follow-up, we have undertaken a spectroscopic campaign targeting wide separation (≳3 arcsec) galaxy–galaxy lens candidates within the Sloan Digital Sky Survey (SDSS). Building on the earlier efforts of our Cambridge and Sloan Survey Of Wide Arcs in Thesky survey, we target a large sample of candidate galaxy–galaxy lens systems in SDSS using a well-established search algorithm which identifies blue arc-like structures situated around luminous red galaxies. In this paper, we present a new redshift catalogue containing 29 lensed sources in SDSS confirmed through spectroscopic follow-up of candidate galaxy–galaxy lens systems. Included in this new sample are two of the brightest galaxies (r = 19.6 and 19.7) known at z ≃ 2, a low metallicity (12 + log (O/H) ≃ 8.0) extreme nebular line emitting galaxy at z = 1.43, and numerous systems for which detailed follow-up will be possible. The source redshifts span 0.9 < z < 2.5 (median redshift of 1.9), and their optical magnitudes are in the range 19.6 ≲ r ≲ 22.3. We present a brief source-by-source discussion of the spectroscopic properties extracted from our confirmatory spectra and discuss some initial science results. Preliminary lens modelling reveals average source magnifications of 5–10 times. With more than 50 gravitationally lensed z ≳ 1 galaxies now confirmed within SDSS, it will soon be possible for the first time to develop generalized conclusions from detailed spectroscopic studies of the brightest lensed systems at high redshift.

We report the discovery of an almost complete (~300°) Einstein ring of diameter 10'' in Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5). Spectroscopic data from the 6 m telescope of the Special Astrophysical Observatory reveal that the deflecting galaxy has a line-of-sight velocity dispersion in excess of 400 km s^-1 and a redshift of 0.444, while the source is a star-forming galaxy with a redshift of 2.379. From its color, luminosity, and velocity dispersion, we argue that this is the most massive galaxy lens hitherto discovered.

We consider the energy budgets and radiative history of eight fading active galactic nuclei (AGNs), identified from an energy shortfall between the requirements to ionize very extended (radius > 10 kpc) ionized clouds and the luminosity of the nucleus as we view it directly. All show evidence of significant fading on timescales of ≈50,000 yr. We explore the use of minimum ionizing luminosity Q _ion derived from photoionization balance in the brightest pixels in Hα at each projected radius. Tests using presumably constant Palomar–Green QSOs, and one of our targets with detailed photoionization modeling, suggest that we can derive useful histories of individual AGNs, with the caveat that the minimum ionizing luminosity is always an underestimate and subject to uncertainties about fine structure in the ionized material. These consistency tests suggest that the degree of underestimation from the upper envelope of reconstructed Q _ion values is roughly constant for a given object and therefore does not prevent such derivation. The AGNs in our sample show a range of behaviors, with rapid drops and standstills; the common feature is a rapid drop in the last ≈2 × 10⁴ yr before the direct view of the nucleus. The e-folding timescales for ionizing luminosity are mostly in the thousands of years, with a few episodes as short as 400 yr. In the limit of largely obscured AGNs, we find additional evidence for fading from the shortfall between even the lower limits from recombination balance and the maximum luminosities derived from far-infrared fluxes. We compare these long-term light curves, and the occurrence of these fading objects among all optically identified AGNs, to simulations of AGN accretion; the strongest variations over these timespans are seen in models with strong and local (parsec-scale) feedback. We present Gemini integral-field optical spectroscopy, which shows a very limited role for outflows in these ionized structures. While rings and loops of emission, morphologically suggestive of outflow, are common, their kinematic structure shows some to be in regular rotation. UGC 7342 exhibits local signatures of outflows <300 km s⁻¹, largely associated with very diffuse emission, and possibly entraining gas in one of the clouds seen in Hubble Space Telescope images. Only in the Teacup AGN do we see outflow signatures of the order of 1000 km s⁻¹. In contrast to the extended emission regions around many radio-loud AGNs, the clouds around these fading AGNs consist largely of tidal debris being externally illuminated but not displaced by AGN outflows.

Galaxies with polar rings (PRGs) are a unique class of extragalactic objects. Using these, we can investigate a wide range of problems, linked to the