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South Africa plans to build an 8-m class telescope – the Southern African Large Telescope (SALT) – based on the novel design of the Hobby Eberly Telescope. These telescopes represent a different paradigm in design, at ∼20% of the cost of more conventional telescopes. Primarily designed for spectroscopic observations, the telescopes are restricted in what targets can be observed at any particular moment, necessitating a queue-scheduled observing mode. The telescope design concept is reviewed and the observing constraints discussed. The science goals for SALT are maximized when certain observational criteria apply.

Over the next five years, South Africa and its international partners will construct the Southern African Large Telescope (SALT), a 10-m optical/near-infrared spectroscopic survey telescope. This paper traces the arguments used to justify the construction of such a facility in Africa. The collateral benefits expected from this project are discussed, along with suggestions of how to realize these benefits. SALT has the potential to promote the development of astronomy on the continent. The creation of an African Network for Astronomy Education and Research is proposed as a way to stimulate such development.

The Southern African Large Telescope (SALT), to be built over the next five years, will be the largest optical telescope in the southern hemisphere. This large science and technology project will cost ~RIOOm and is jointly funded by the South African Government and an international consortium. This paper describes the telescope and the instrument used to position fibre optics at the focus. The latter is used as an example of the technologies required to accomplish this project and includes fibre optics, positioning and tilting mechanisms which involve precision motion to l0µm accuracy.

Recent history in South Africa has created unique problems in many areas. As a result of an unequal educational structure, particularly in science, there is a general lack of science literacy and awareness. Some years ago the South African Astronomical Observatory started a Science Education Initiative as a contribution to addressing this problem by using astronomy as a vehicle to stimulate an interest in science amongst teachers and students. This programme was given a boost by the South African government in 1998 and the construction of the Southern African Large Telescope will provide further stimulus to the Science Education Initiative.

Darragh O'Donoghue died on 25 June 2015 following a short illness. He worked in the Department of Astronomy at the University of Cape Town (UCT) for the South African Astronomical Observatory (SAAO) and, most recently, for the Southern African Large Telescope (SALT). He was elected to the Fellowship of the Royal Society of South Africa in 2005. He is survived by the family he adored - his wife, Liz, and daughters, Andrea and Alexandra. He left a hole in many of our lives and a chasm in the small community of South African astronomy.

We report our investigation of 1SWASP J234401.81-212229.1, a variable with a 18461.6 s period. After identification in a 2011 search of the SuperWASP archive for main-sequence eclipsing binary candidates near the distribution's short-period limit of approx. 0.20 d, it was measured to be undergoing rapid period decrease in our earlier work, though later observations supported a cyclic variation in period length. Spectroscopic data obtained in 2012 with the Southern African Large Telescope did not, however, support the interpretation of the object as a normal eclipsing binary. Here, we consider three possible explanations consistent with the data: a single-star oblique rotator model in which variability results from stable cool spots on opposite magnetic poles; a two-star model in which the secondary is a brown dwarf; and a three-star model involving a low-mass eclipsing binary in a hierarchical triple system. We conclude that the latter is the most likely model., 8 pages, 20 figures. Accepted for publication at Astronomy & Astrophysics. After publication, table 2 will appear at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/

We present spatially resolved long-slit spectroscopy from the Southern African Large Telescope (SALT) to examine the spatial extent of the narrow-line regions (NLRs) of a sample of 8 luminous obscured quasars at 0.10 < z < 0.43. Our results are consistent with an observed shallow slope in the relationship between NLR size and L_[OIII], which has been interpreted to indicate that NLR size is limited by the density and ionization state of the NLR gas rather than the availability of ionizing photons. We also explore how the NLR size scales with a more direct measure of instantaneous AGN power using mid-IR photometry from WISE, which probes warm to hot dust near the central black hole and so, unlike [OIII], does not depend on the properties of the NLR. Using our results as well as samples from the literature, we obtain a power-law relationship between NLR size and L_8micron that is significantly steeper than that observed for NLR size and L_[OIII]. We find that the size of the NLR goes approximately as L^(1/2)_8micron, as expected from the simple scenario of constant-density clouds illuminated by a central ionizing source. We further see tentative evidence for a flattening of the relationship between NLR size and L_8micron at the high luminosity end, and propose that we are seeing a limiting NLR size of 10 - 20 kpc, beyond which the availability of gas to ionize becomes too low. We find that L_[OIII] ~ L_8micron^(1.4), consistent with a picture in which the L_[OIII] is dependent on the volume of the NLR. These results indicate that high-luminosity quasars have a strong effect in ionizing the available gas in a galaxy., 9 Pages, 5 figures, accepted to ApJ

A visible astrocomb spanning 555-890 nm has been implemented on the 10-m Southern African Large Telescope, delivering complete calibration of one channel of its high-resolution spectrograph and an accurate determination of its resolving power. A novel co-coupling method allowed simultaneous observation of on-sky, Th-Ar lamp and astrocomb channels, reducing the wavelength calibration uncertainty by a factor of two compared to that obtained using only Th-Ar lines. The excellent passive stability of the master frequency comb laser enabled broadband astrocomb generation without the need for carrier-envelope offset frequency locking, and an atomically referenced narrow linewidth diode laser provided an absolute fiducial marker for wavelength calibration. The simple astrocomb architecture enabled routine operation by non-specialists in an actual telescope environment. On-sky spectroscopy results are presented with direct calibration achieved entirely using the astrocomb.

The recurrent nova T Pyx was observed with the X-ray gratings of Chandra and XMM-Newton, 210 and 235 days, respectively, after the discovery of the 2011 April 14 outburst. The X-ray spectra show prominent emission lines of C, N, and O, with broadening corresponding to a full width at half maximum of ~2000-3000 km/s, and line ratios consistent with high-density plasma in collisional ionization equilibrium. On day 210 we also measured soft X-ray continuum emission that appears to be consistent with a white dwarf (WD) atmosphere at a temperature ~420,000 K, partially obscured by anisotropic, optically thick ejecta. The X-ray continuum emission is modulated with the photometric and spectroscopic period observed in quiescence. The continuum at day 235 indicated a WD atmosphere at a consistent effective temperature of 25 days earlier, but with a lower flux. The effective temperature indicates a mass of ~1 solar mass. The conclusion of partial WD obscuration is supported by the complex geometry of non-spherically-symmetric ejecta confirmed in recent optical spectra obtained with the Southern African Large Telescope (SALT) in November and December of 2012. These spectra exhibited prominent [O III] nebular lines with velocity structures typical of bipolar ejecta., Comment: Accepted to ApJ 2013 October 23, 14 pages, 9 figures, 3 tables

Most runaway OB stars, like the majority of massive stars residing in their parent clusters, go through the red supergiant (RSG) phase during their lifetimes. Nonetheless, although many dozens of massive runaways were found to be associated with bow shocks, only two RSG bow-shock-producing stars, Betelgeuse and \mu Cep, are known to date. In this paper, we report the discovery of an arc-like nebula around the late M-type star IRC-10414 using the SuperCOSMOS H-alpha Survey. Our spectroscopic follow-up of IRC-10414 with the Southern African Large Telescope (SALT) showed that it is a M7 supergiant, which supports previous claims on the RSG nature of this star based on observations of its maser emission. This was reinforced by our new radio- and (sub)millimeter-wavelength molecular line observations made with the Atacama Pathfinder Experiment (APEX) 12 meter telescope and the Effelsberg 100 m radio telescope, respectively. The SALT spectrum of the nebula indicates that its emission is the result of shock excitation. This finding along with the arc-like shape of the nebula and an estimate of the space velocity of IRC-10414 (\approx 70\pm20 km/s) imply the bow shock interpretation for the nebula. Thus, IRC-10414 represents the third case of a bow-shock-producing RSG and the first one with a bow shock visible at optical wavelengths. We discuss the smooth appearance of the bow shocks around IRC-10414 and Betelgeuse and propose that one of the necessary conditions for stability of bow shocks generated by RSGs is the ionization of the stellar wind. Possible ionisation sources of the wind of IRC-10414 are proposed and discussed., Comment: 15 pages, 8 figures, accepted for publication in MNRAS

We investigated the physical properties and dynamical evolution of Near Earth Asteroid (NEA) (190491) 2000 FJ10 in order to assess the suitability of this accessible NEA as a space mission target. Photometry and colour determination were carried out with the 1.54 m Kuiper Telescope and the 10 m Southern African Large Telescope during the object's recent favourable apparition in 2011-12. During the earlier 2008 apparition, a spectrum of the object in the 6000-9000 Angstrom region was obtained with the 4.2 m William Herschel Telescope. Interpretation of the observational results was aided by numerical simulations of 1000 dynamical clones of 2000 FJ10 up to 10^6 yr in the past and in the future. The asteroid's spectrum and colours determined by our observations suggest a taxonomic classification within the S-complex although other classifications (V, D, E, M, P) cannot be ruled out. On this evidence, it is unlikely to be a primitive, relatively unaltered remnant from the early history of the solar system and thus a low priority target for robotic sample return. Our photometry placed a lower bound of 2 hrs to the asteroid's rotation period. Its absolute magnitude was estimated to be 21.54+-0.1 which, for a typical S-complex albedo, translates into a diameter of 130+-20 m. Our dynamical simulations show that it has likely been an Amor for the past 10^5 yr. Although currently not Earth-crossing, it will likely become so during the period 50 - 100 kyr in the future. It may have arrived from the inner or central Main Belt > 1 Myr ago as a former member of a low-inclination S-class asteroid family. Its relatively slow rotation and large size make it a suitable destination for a human mission. We show that ballistic Earth-190491-Earth transfer trajectories with Delta-V < 2 km s^-1 at the asteroid exist between 2052 and 2061., 2 Tables, 11 Figures, accepted for publication in Astronomy & Astrophysics

We present a comprehensive review of the first two years of a site monitoring campaign at the South African Astronomical Observatory (SAAO) located outside Sutherland, South Africa. This campaign is in support of the Southern African Large Telescope (SALT), a 11-metre, fixed-elevation, optical telescope located at SAAO . The heart of this observing campaign involves continuous monitoring of the site by a MASS-DIMM instrument. The MASS-DIMM has been in routine use since March 2010 and its operation is now fully automated. At the beginning of this campaign, simultaneous observations were also made by a SLODAR instrument, which allows high resolution observations of the lower atmosphere. In August 2011 a two week campaign was carried out with a two-channel Generalized Seeing Monitor (GSM) telescope along with a lunar limb profiler (Profileur Bord Lunaire; PBL). Combined with the MASS-DIMM data these observations provide multiple independent measurements of atmospheric turbulence as a function of height. They also help improve the calibration of our site for more direct comparison to other major astronomical observatories. Our results so far indicate that the atmospheric conditions at the SAAO Sutherland site have deteriorated compared to past measurements. The ground layer accounts for the majority of the integrated seeing, while the free atmosphere seeing is comparable with other major sites.

We report on the status of the detector system for the Robert Stobie Spectrograph Near Infrared Arm (RSS-NIR) for the Southern African Large Telescope (SALT). The detector is a HAWAII-2RG array with a 1.7 μm cutoff wavelength. The controller incorporates a Teledyne cryogenic SIDECAR ASIC board inside the dewar and an FPGA interface card, developed by the Inter-University Centre for Astronomy and Astrophysics (IUCAA), outside the dewar. Data acquisition software written by IUCAA runs under a Linux operating system and communicates to the detector system through USB to fiber optic converters for electrical isolation on the telescope. System characterization is performed at the University of Wisconsin RSS-NIR Lab in a liquid nitrogen cooled test dewar. The test dewar contains a thermal control system that emulates operation of the cryocooler used in the instrument dewar and maintains a stable detector operating temperature of 120 K. Light is provided to the detector with near infrared LEDs mounted inside the dewar. We present preliminary data on system noise and plans for further characterization tests.

SALT HRS is a fibre-fed, high dispersion echelle spectrograph currently being constructed for the Southern African Large Telescope (SALT). In this paper we highlight the performance of key optical components, describe the integration tasks that have taken place and present some first light results from the laboratory. The instrument construction is well advanced and we report on the attainment of the required mechanical and thermal stability and provide a measurement of the input optics performance (including the fibre feed). The initial optical alignment of both the fibre input optics, including image slicers, and the spectrograph optics has taken place and is described.

The Southern African Large Telescope (SALT) began its re-commissioning phase in April 2011 following the completion of remedial engineering work on the telescope and the major science instrument, the Robert Stobie Spectrograph (RSS). The engineering work required modifications to the spherical aberration corrector, in order to improve the telescope’s image quality, and RSS, to improve its throughput. Positive test results included delivery of sub-arcsecond images, essentially meeting the original telescope image quality specifications and exhibiting none of the previous field-dependent aberrations, while the RSS has shown greatly improved efficiency performance. SALT has since transitioned to science operations, as from 1 September 2011, following the first open call for charged science proposals from the SALT partners. This paper discusses the current performance of SALT and it First Generation instruments, some initial science results, the proposal process and the operational model for the telescope.

Images obtained with the Southern African Large Telescope (SALT) during its commissioning phase showed degradation due to a large focus gradient and a variety of other optical aberrations. An extensive forensic investigation eventually traced the problem to the mechanical interface between the telescope and the secondary optics that form the Spherical Aberration Corrector (SAC). The SAC was brought down from the telescope in 2009 April, the problematic interface was replaced and the four corrector mirrors were optically tested and re-aligned. The surface figures of the SAC mirrors were confirmed to be within specification and a full system test following the re-alignment process yielded a RMS wavefront error of just 0.15 waves. The SAC was re-installed on the tracker in 2010 August and aligned with respect to the payload and primary mirror. Subsequent on-sky tests produced alarming results which were due to spurious signals being sent to the tracker by the auto-collimator, the instrument responsible for controlling the attitude of the SAC with respect to the primary mirror. Once this minor issue was resolved, we obtained uniform 1.1 arcsecond star images over the full 10 arcminute field of view of the telescope.

The Southern African Large Telescope (SALT), located at the South African Astronomical Observatory (SAAO) site near Sutherland, South Africa, is an 11-metre fixed-elevation telescope currently operating at UV-visible wavelengths (320-950 nm) with a near-infrared extension (850-1700 nm) due in the near future. SALT does not currently have an adaptive optics (AO) system and a feasibility study for adding one is under way. Using results from an on-going site monitoring campaign at the SAAO we have begun carrying out simulations to investigate how different AO systems might perform and could be optimized for SALT. We will present the parameters of an optimization study and performance results for a single on-axis natural guide star (NGS) AO system on SALT for operation at both visible (R) and near-IR (J and H) wavelengths.

The Robert Stobie Spectrograph is currently the prime spectroscopic instrument on the 11m Southern African Large Telescope (SALT), which is now in commissioning. The current visible beam of RSS was designed with spectropolarimetric versions of all its modes, imaging, grating spectroscopy (with Multi Object Spectroscopy capability) from 3200 to 9000 A, and Fabry-Perot Spectroscopy from 4300 to 9000 A, with spectral resolution up to R = 10000. The polarimetric field of view is 4×8 arcmin. The instrument was designed with an upgrade path leading to a simultaneous Near InfraRed beam (out to 1.7µm), now in development, which will duplicate the spectropolarimetric modes in the NIR. We describe results from early polarimetric commissioning of the visible beam.

Africa has the potential to make major contributions to international astronomy. The South African government has identified astronomy as an area in which the country has a strategic advantage, by virtue of its geographical position, good climate and well established astronomical community. They have therefore invested heavily in projects such as the Southern African Large Telescope (the largest single optical telescope in the Southern Hemisphere) and the Karoo Array Telescope (MeerKAT, as a demonstrator for the Square Kilometre Array). The investment is intended not only to facilitate an African contribution to astronomy, but also to use astronomy as a tool for national development. It is vital that all involved appreciate that scientific success is a prerequisite for any meaningful contribution to the development agenda. The success or failure of these endeavours will have far reaching consequences for Astronomy and for Africa. Which way it goes will depend as much on the international astronomy community as it will on African politics. In this contribution I will discuss how we might address the challenges brought about by this situation.

Classical T Tauri stars (CTTS) are young, late-type objects, that still accrete matter from a circumstellar disk. Analytical treatments and numerical simulations predict instabilities of the accretion shock on the stellar surface. We search for variability on timescales below a few minutes in the CTTS TW Hya and AA Tau. TW Hya was observed with SALTICAM on the Southern African Large Telescope (SALT) in narrow-band filters around the Balmer jump. The observations were performed in slit mode, which provides a time resolution of about 0.1 s. For AA Tau we obtained observations with OPTIMA, a single photon-counting device with even better time resolution. Small-scale variability typically lasts a few seconds, however, no significant periodicity is detected. We place a 99 % confidence upper limit on the pulsed fraction of the lightcurves. The relative amplitude is below 0.001 for TW Hya in the frequency range 0.02-3 Hz in the 340 nm filter and 0.1-3 Hz in the 380 nm filter. The corresponding value for AA Tau is an amplitude of 0.005 for 0.02-50 Hz. The relevant timescales indicate that shock instabilites should not be seen directly in our optical and UV observations, but the predicted oscialltions would induce observable variations in the reddening. We discuss how the magnetic field could stabilise the accretion shock., 8 pages, 9 figures, accepted by A&A

The high-resolution echelle spectrograph, SALT HRS, is at an advanced stage of construction and will shortly become available to the user community of the Southern African Large Telescope (SALT). This paper presents a commentary on the construction progress to date and gives the instrument's final specification with refined estimates for its performance based on the initial testing of the optics and the science-grade detectors. It also contributes a discussion of how the fibre input optics have been tailored to specific scientific aspirations to give four distinct operational modes. Finally, the use of the instrument is discussed in the context of the most common science cases.

At the Southern African Large Telescope (SALT), in collaboration with FOGALE Nanotech, we have been testing the recently-developed new generation inductive edge sensors. The Fogale inductive sensor is one technology being evaluated as a possible replacement for the now defunct capacitance-based edge sensing system. We present the results of exhaustive environmental testing of two variants of the inductive sensor. In addition to the environmental testing including RH and temperature cycles, the sensor was tested for sensitivity to dust and metals. We also consider long-term sensor stability, as well as that of the electronics and of the glue used to bond the sensor to its supporting structure. A prototype design for an adjustable mount is presented which will allow for in-plane gap and shear variations present in the primary mirror configuration without adversely disturbing the figure of the individual mirror segments or the measurement accuracy.

The Wide Field Upgrade presents a five-fold increase in mass for the Hobby-Eberly Telescope's* tracker system. The design of the Hobby-Eberly Telescope places the Prime Focus Instrument Package (PFIP) at a thirty-five degree angle from horizontal. The PFIP and its associated hardware have historically been positioned along this uphill axis (referred to as the telescope's Y-axis) by a single screw-type actuator. Several factors, including increased payload mass and design for minimal light obscuration, have led to the design of a new and novel configuration for the Y-axis screw-drive as part of the tracker system upgrade. Typical screw-drive designs in this load and travel class (approximately 50 kilonewtons traveling a distance of 4 meters) utilize a stationary screw with the payload translating with the moving nut component. The new configuration employs a stationary nut and translating roller screw affixed to the moving payload, resulting in a unique drive system design. Additionally, a second cable-actuated servo drive (adapted from a system currently in use on the Southern African Large Telescope) will operate in tandem with the screw-drive in order to significantly improve telescope safety through the presence of redundant load-bearing systems. Details of the mechanical design, analysis, and topology of each servo drive system are presented in this paper, along with discussion of the issues such a configuration presents in the areas of controls, operational and failure modes, and positioning accuracy. Findings and results from investigations of alternative telescope safety systems, including deformable crash barriers, are also included.

The Southern African Large Telescope (SALT) recently (2008) abandoned attempts at using capacitive mirror edge sensors, mainly due to poor performance at a relative humidity above ~60%, a not infrequent occurrence. Different technologies are now being explored for alternative sensors on SALT. In this paper we describe the design and development of a novel prototype optical edge sensor, based on the application of the interferential scanning principle, as used in optical encoders. These prototype sensors were subsequently tested at SAAO and ESO, for potential application on SALT and E-ELT. Environmental tests, conducted in climatic control chambers, looked at temperature and relative humidity sensitivity, long term stability and sensor noise. The temperature sensitivity for height and gap were, respectively, 10nm/°C and 44nm/°C, while for relative humidity they were 4nm/10% and 50nm/10%, respectively. These either met, or were close to, the SALT specification. While there were significant lags in response, this was due to the sensor's relatively large mass (~200 gm per sensor half), which was not optimized. This is likely to improve, should a revised design be developed in future. Impressively the sensor noise was

The Robert Stobie Spectrograph near infrared arm will provide high throughput, low to medium resolution long slit and multi-object spectroscopy with broadband, spectropolarimetric, and Fabry-Perot imaging modes over a 8' diameter field of view. The wavelength range of the instrument is 0.9-1.7 microns, and can be operated simultaneously with the visible arm to extend the short wavelength limit to 0.32 microns. Once fielded, RSS-NIR will be the only facility instrument on an 8-10 meter class telescope with multi-object spectroscopy capability covering this spectral range simultaneously. RSS-NIR is scheduled to be commissioned on the 11-meter Southern African Large Telescope in late 2012. This is an upgrade to the existing visible instrument, with which it shares the slit plane and an ambient temperature collimator. Beyond the collimator, the NIR arm is cooled to -40 °C, with a cryogenic dewar containing the detector, long wavelength blocking filters, and final camera optics. This semi-warm configuration has required extensive upfront analysis of the instrumental thermal background levels, which have been incorporated into the instrument performance simulator. We present the performance predictions for spectroscopic modes of RSS-NIR and preliminary performance estimates and NIR issues still being addressed in the design for Fabry-Perot and polarimetric modes.

This paper describes the cleaning of M5, one of the four mirrors that make up the Southern African Large Telescope's Spherical Aberration Corrector. As the top upward-facing mirror in a relatively exposed environment, M5 had accumulated a considerable amount of dust and dirt during the six years it had been on the telescope. With the corrector on the ground for re-alignment and testing, we had the opportunity to remove, wash and replace the mirror. Various cleaning techniques were investigated, including an unsuccessful trial application of First Contact surface cleaning polymer film - fortunately only to a small region outside the mirror's clear aperture. Ultimately, "drag-wiping" with wads of cotton wool soaked in a 10g/l sodium lauryl sulphate solution proved highly effective in restoring the reflectivity of M5's optical surface. Following this success, we repeated the procedure for M3, the other upward-facing mirror in the corrector. The results for M3 were equally spectacular.

The Robert Stobie Spectrograph Near Infrared Arm (RSS-NIR) is a new instrument on the 11-meter Southern African Large Telescope (SALT), scheduled to begin commissioning in 2012. This versatile instrument will add capabilities that are unique to large telescopes. The main instrument modes include NIR imaging, medium resolution long slit spectroscopy over an 8 arcminute field of view (FOV), multi-object spectroscopy with custom slit masks over an 8x8 arcminute FOV, Fabry-Perot narrowband imaging over an 8 arcminute diameter FOV, and polarimetry and spectropolarimetry over a 4x8 arcminute FOV. Limiting magnitude predictions are 21.1 and 20.1 for J and H band for S/N = 10 per spectral resolution element in 1 hour for 1 arcsec 2 at an R=7000. All instrument modes can be operated simultaneously with the RSS visible arm, providing spectral coverage from 0.32-1.7 microns. We list the science drivers and describe the way in which they have guided the design for this instrument. We also present a more detailed description of some several planned science programs that will take advantage of the unique capabilities of RSS-VISNIR and the queue-scheduled SALT telescope. Lastly we give a brief description of predicted instrumental performance, along with a comparison to several other NIR instruments at other observatories.

The large (~10 m) aperture of the Southern African Large Telescope (SALT) coupled with the unique capabilities of the Robert Stobie Spectrograph (RSS), promises unparalleled prospects for polarimetric observations on an 8 - 10 m class telescope. RSS is a highly versatile first-generation instrument of the SALT. Results from some of the first commissioning observations with the RSS are presented. A method for reducing SALT RSS spectropolarimetry data is proposed and verified on observations of unpolarised and polarised standard stars. The results provide estimates of telescope and instrumental polarisation as well as a calibration of the instrument's polarimetric position angle offset.

We report on extensive laboratory testing of the optical compatibility of immersion fluids often used in astronomical instrumentation. A strong near-ultraviolet absorption feature is seen after incubating several fluids with polyurethane often used in expansion bladders, and a lesser absorption in the farther UV with Viton O-Ring material. Substitute materials were tested, many of which show no such absorption. This program was started in response to a strong UV feature which developed over time in the Robert Stobie Spectrograph of the Southern African Large Telescope. A repair strategy was successfully implemented.

The construction of the Southern African Large Telescope (SALT) was largely completed by the end of 2005. At the beginning of 2006, it was realized that the telescope's image quality suffered from optical aberrations, chiefly a focus gradient across the focal plane, but also accompanied by astigmatism and higher order aberrations. In the previous conference in this series, a paper was presented describing the optical system engineering investigation which had been conducted to diagnose the problem. This investigation exonerated the primary mirror as the cause, as well as the science instruments, and was isolated to the interface between the telescope and a major optical sub-system, the spherical aberration corrector (SAC). This is a complex sub-system of four aspheric mirrors which corrects the spherical aberration of the 11-m primary mirror. In the last two years, a solution to this problem was developed which involved removing the SAC from the telescope, installing a modification of the SAC/telescope interface, re-aligning and testing the four SAC mirrors and re-installation on the telescope. This paper describes the plan, discusses the details and shows progress to date and the current status.

The Robert Stobie Spectrograph Near Infrared (RSS/NIR) upgrade for the Southern African Large Telescope (SALT) extends the capabilities of the visible arm of RSS into the NIR. The RSS/NIR instrument is at the prime focus of SALT. It is a versatile spectrograph with broadband imaging, spectropolarimetric, and Fabry-Perot imaging capabilities. The multiple modes and prime focus location introduce interesting engineering considerations. The spectrograph has an ambient temperature collimator, cooled (-40oC) dispersers and camera and a cryogenic detector. Many of the mechanisms are required to operate within the cooled and cryogenic environments. The RSS/ NIR upgrade includes the following mechanisms; an active flexure compensating fold mirror, a filter exchange mechanism, a Volume Phase Holographic VPH grating exchange and rotation mechanism, an etalon inserter, a beam splitter inserter, an articulating camera, internal camera focus and a cutoff filter exchange wheel. This paper gives an overview of the mechanical design and focuses on some of the unique testing and prototyping tasks.

We discuss the use of a Faro Arm - a portable coordinate measuring machine - in the re-alignment and testing of the Southern African Large Telescope's Spherical Aberration Corrector. In pushing this versatile tool to its limits, we have arrived at a better understanding of its true capabilities and developed ways to compensate for some of its weaknesses. It is possible to achieve excellent results (~5 microns) when making relative measurements and keeping the Arm's orientation relatively constant. The Faro is also extremely useful in providing live feedback while making fine adjustments. However, single measurements of the same position are considerably less reliable (~50 microns) when the Arm is operated in widely different orientations. If the latter is unavoidable, one may largely counteract this by taking continuous streams of measurements (1000 readings) for a given point while exercising the Arm as much as possible in order to average the encoder errors. Various other techniques and accessories that we have found useful, as well as some painful lessons, are described here and a few examples are given to demonstrate how we have used a Faro Arm in our challenging optical alignment project.

Segmented primary mirrors dominate the current generation of 10m class telescopes as well as the designs for the next generation of Extremely Large Telescopes (ELT's). The complex nature of these telescopes is demonstrated by the long time periods associated with their commissioning and the difficulty of performing high precision optical alignments. However, additional tools to provide in situ measurements of their optical alignment can be provided by making use of the individual mirrors of a segmented primary; with the ability to move in six degrees of freedom, the individual mirrors can be deployed to trace multiple optical paths through the telescope. In this paper we describe how it is possible to use the segments themselves to create a number of Hartmann masks that allow focus and other aberrations to be measured using a standard imaging camera rather than a dedicated wavefront sensor. The Southern African Large Telescope (SALT), with a primary mirror composed of 91 1m segments, is used as an example. The segments were arranged to create eight Hartmann masks to measure the optical alignment. Through imaging data obtained at the telescope, the sensitivity of this method to changes in focus along with aberrations inherent in the system is demonstrated through Zernike polynomial fits to the observed patterns. Finally, we present simulations of possible patterns for use on future ELT's.

Construction of the Southern African Large Telescope (SALT) was largely completed by the end of 2005 and since then it has been in intensive commissioning. This has now almost been completed except for the telescope's image quality which shows optical aberrations, chiefly a focus gradient across the focal plane, along with astigmatism and other less significant aberrations. This paper describes the optical systems engineering investigation that has been conducted since early 2006 to diagnose the problem. A rigorous approach has been followed which has entailed breaking down the system into the major sub-systems and subjecting them to testing on an individual basis. Significant progress has been achieved with many components of the optical system shown to be operating correctly. The fault has been isolated to a major optical sub-system. We present the results obtained so far, and discuss what remains to be done.

A differential method was used to investigate the focal ratio degradation (FRD) exhibited by, and throughput of, a selection of current-generation optical fibres. These fibres were tested to establish which would be best suited to feed the High Resolution Spectrograph being built for the Southern African Large Telescope (SALT), as well as for future instruments on WIYN and SALT. The double re-imaging system of Bershady et al. (2004) was substantially modified to improve image quality and measurement efficiency, and to permit a direct FRD-measurement in the far-field. The re-imaging method compares the beam profile produced by light which passes through a fibre to that which does not. Broad and intermediate band-pass filters were used between 400-800 nm to test for wavelength dependence in the observed FRD over a wide range in beam-speeds. Our results continue to be at odds with a mico-bend model for FRD. We conclude that the new Polymicro FBP fibre is the most suitable product for broadband applications.

SALT HRS is a fiber-fed cross-dispersed echelle spectrograph designed for high resolution and high efficiency seeing-limited spectroscopy on the Southern African Large Telescope. The spectrograph, which has a dual channel white pupil design, uses a single R4 echelle grating, a dichroic beam-splitter, and volume phase holographic gratings as cross-dispersers. The echelle grating has 41.6 grooves/mm and is illuminated with a 200mm diameter beam. This allows R = 16,000 with a 2.2" fiber and complete wavelength coverage from 370 nm to 890 nm. Resolving powers of R ≈ 37,000 and 67,000 are obtained using image slicers. The dichroic beam-splitter is used to split the wavelength coverage between two fully dioptric cameras. The white pupil transfer optics are used to demagnify the pupil to 111mm which ensures that the camera dimensions are kept reasonable whilst also allowing the efficient use of VPH gratings. The spectrograph optics are enclosed inside a vacuum tank to ensure immunity to atmospheric pressure and temperature changes. The entire spectrograph is mechanically and thermally insulated. Construction of SALT HRS began at Durham University's Centre for Advanced Instrumentation in August 2007 and is expected to be complete in 2009. The spectrograph optical design is largely based on work completed at the University of Canterbury's Department of Physics and Astronomy.

This paper presents details of the instrument calibration system employed on the SALT. It is designed to inject light into the Spherical Aberration Corrector at about the position of the primary mirror caustic, thereby simulating the same degree of vignetting as experienced by celestial objects. A light-shaping diffuser screen, coupled with Fresnel lenses, modifies the beam to increase efficiency and attempt to illuminate the detectors in the same manner as a uniform sky. Light is conveyed by means of liquid light guides from either QTH flat field lamps or a choice of hollow cathode (CuAr, ThAr) and penray (Ar, Hg, Xe, Ne) lamps, used for wavelength calibration. Changing entrance pupil effects are accounted for by employing a moving exit pupil baffle, which can simulate the pupil geometry of a specific track.

The Southern African Large Telescope is nearing the end of its commissioning phase and scientific performance verification programmes began in 2006 with two of its First Generation UV-visible instruments, the imaging camera, SALTICAM, and the multi-mode Robert Stobie Spectrograph (RSS). Both instruments are seeing limited and designed to operate in the UV-visible region (320 - 900 nm). This paper reviews the innovative aspects of the designs of these instruments and discusses the commissioning experience to date, illustrated by some initial scientific commissioning results. These include long-slit and multi-object spectroscopy, spectropolarimetry, Fabry-Perot imaging spectroscopy and high-speed photometry. Early spectroscopic commissioning results uncovered a serious underperformance in the throughput of RSS, particularly at wavelengths < 400nm. We discuss the lengthy diagnosis and eventual removal of this problem, which was traced to a material incompatibility issue involving index-matching optical coupling fluid. Finally, we briefly discuss the present status of the third and final First Generation instrument, a vacuum enclosed fibre-fed high resolution, dual beam, white pupil echelle spectrograph, SALT HRS, currently under construction.

Eleven giant branch stars in 47 Tucanae were observed using the Robert Stobie Spectro‐graph (RSS) on the Southern African Large Telescope during the performance verification phase of this instrument. These stars were analysed as part of a quest to investigate s‐process element abundances throughout the colour‐magnitude diagram of 47 Tucanae. No abundance variations of Zr, Ba, Nd and Eu were found in these eleven stars, such that [X/Fe] = 0.0±0.5 3dex. Further, theoretical analysis indicates that the maximum resolution on RSS and AAOmega on the Anglo‐Australian Telescope is sufficient to detect s‐process element abundance variations. More detailed discussion on the abundance analysis of these stars and the theoretical analysis of spectrograph resolution can be found in [l].

A recent study by Wylie et al 2006 has revealed that s-process element abundances are enhanced relative to iron in both red giant branch and asymptotic giant branch stars of 47 Tucanae. A more detailed investigation into s-process element abundances throughout the colour-magnitude diagram of 47 Tucanae is vital in order to determine whether the observed enhancements are intrinsic to the cluster. This paper explores this possibility through observational and theoretical means. The visibility of s- and r-process element lines in synthetic spectra of giant and dwarf stars throughout the colour magnitude diagram of 47 Tucanae has been explored. It was determined that a resolving power of 10 000 was sufficient to observe s-process element abundance variations in globular cluster giant branch stars. These synthetic results were compared with the spectra of eleven 47 Tucanae giant branch stars observed during the performance verification of the Robert Stobie Spectrograph on the Southern African Large Telescope. Three s-process elements, Zr, Ba, Nd, and one r-process element, Eu, were investigated. No abundance variations were found such that [X/Fe] = 0.0 +/- 0.5 dex. It was concluded that this resolving power, R ~ 5000, was not sufficient to obtain exact abundances but upper limits on the s-process element abundances could be determined., Comment: 7 pages, 11 figures

We report long-slit spectroscopic observations of the dust-lane polar-ring galaxy AM1934-563 obtained with the Southern African Large Telescope (SALT) during its performance-verification phase. The observations target the spectral region of the Ha, [NII] and [SII] emission-lines, but show also deep NaI stellar absorption lines that we interpret as produced by stars in the galaxy. We derive rotation curves along the major axis of the galaxy that extend out to about 8 kpc from the center for both the gaseous and the stellar components, using the emission and absorption lines. We derive similar rotation curves along the major axis of the polar ring and point out differences between these and the ones of the main galaxy. We identify a small diffuse object visible only in Ha emission and with a low velocity dispersion as a dwarf HII galaxy and argue that it is probably metal-poor. Its velocity indicates that it is a fourth member of the galaxy group in which AM1934-563 belongs. We discuss the observations in the context of the proposal that the object is the result of a major merger and point out some observational discrepancies from this explanation. We argue that an alternative scenario that could better fit the observations may be the slow accretion of cold intergalactic gas, focused by a dense filament of galaxies in which this object is embedded (abridged)., Comment: 19 pages, 13 figures, submitted to MNRAS. Some figures were bitmapped to reduce the size. Full resolution version is available from http://www.saao.ac.za/~akniazev/pub/AM1934_563.pdf

We present the design of the Fabry-Perot system of the Robert Stobie Spectrograph on the 10-meter class Southern African Large Telescope and its characterization as measured in the laboratory. This system provides spectroscopic imaging at any desired wavelength spanning a bandpass 430 - 860 nm, at four different spectral resolving powers ranging from 300 to 9000. Our laboratory tests revealed a wavelength dependence of the etalon gap and parallelism with a maximum variation between 600 - 720 nm that arises because of the complex structure of the broadband multi-layer dielectric coatings. We also report an unanticipated optical effect of this multi-layer coating structure that produces a significant, and wavelength dependent, change in the apparent shape of the etalon plates. This change is caused by two effects: the physical non-uniformities or thickness variations in the coating layers, and the wavelength dependence of the phase change upon refection that can amplify these non-uniformities. We discuss the impact of these coating effects on the resolving power, finesse, and throughput of the system. This Fabry-Perot system will provide a powerful tool for imaging spectroscopy on one of the world's largest telescopes., Comment: 17 pages, 14 figures, accepted for publication in The Astronomical Journal

The government of South Africa has identified astronomy as a field in which their country has a strategic advantage and is consequently investing very significantly in astronomical infrastructure. South Africa now operates a 10-m class optical telescope, the Southern African Large Telescope (SALT), and is one of two countries short listed to host the Square Kilometre Array (SKA), an ambitious international project to construct a radio telescope with a sensitivity one hundred times that of any existing telescope. The challenge now is to produce an indigenous community of users for these facilities, particularly from among the black population which was severely disadvantaged under the apartheid regime. In this paper I briefly describe the observing facilities in Southern Africa before going on to discuss the various collaborations that are allowing us to use astronomy as a tool for development, and at the same time to train a new generation of astronomers who will be well grounded in the science and linked to their colleagues internationally., Comment: Paper given at the 2007 meeting of the National Society of Black Physicists; 10 pages, 2 photographs. To appear in American Institute of Physics Conference Proceedings

By combining new long-slit spectral data obtained with the Southern African Large Telescope for nine galaxies with our previously published observations for 12 additional galaxies, we study the stellar and gaseous kinematics as well as radially resolved stellar population properties and ionized-gas metallicity and excitation for a sample of isolated lenticular galaxies. We have found that there is no particular time frame of formation for the isolated lenticular galaxies: the mean stellar ages of the bulges and disks are distributed between 1 and Gyr, and the bulge and the disk in every galaxy formed synchronously demonstrate similar stellar ages and magnesium-to-iron ratios. Extended ionized-gas disks are found in the majority of the isolated lenticular galaxies, in 72% ±11%. Half of all extended gaseous disks demonstrate a visible counterrotation with respect to their stellar counterparts. We argue that just such a fraction of projected counterrotation is expected if all of the gas in isolated lenticular galaxies is accreted from outside, under the assumption of isotropically distributed external sources. The very narrow range of the gas oxygen abundances we found for the outer ionized-gas disks excited by young stars, [O/H] from 0.0 to +0.2 dex, gives evidence for satellite merging as the most probable source of this accretion. Last, we formulate a hypothesis that the morphological type of a field disk galaxy is completely determined by the outer cold-gas accretion regime.

The Prime Focus Imaging Spectrograph (PFIS) is a first light instrument for the Southern African Large Telescope (SALT). PFIS is a versatile instrument designed to operate in a number of scientific modes by utilizing volume phase holographic gratings, Fabry-Perot etalons, and polarimetric optics, which are manipulated in and out of the beam using various placement mechanisms. The instrument is mounted at the prime focus 15m above the primary mirror and tilted at 37°. This remote placement and the need for 240° of rotation about the optical axis raises important design issues with mass, flexure and access. The instrument structure provides the interface to the telescope Prime Focus Instrument Platform (PFIP) as well as support points for all the optics, mechanisms and electrical equipment. The structure is a welded open truss of hollow, square-section Invar beams. The open truss provides the highest stiffness to weight ratio and minimizes the effect of wind loading, while the use of Invar negates the effects of thermal expansion. It has been designed using finite element analysis in conjunction with an optical tolerance analysis of the optics nodes to minimize effective image motion under the varying gravity load. The fundamentals of the design of the structure to minimize the flexure and its effect on image motion, the motivation for using the open Invar truss structure, and the design of the remotely operated mechanisms are discussed. In 2005 PFIS was installed and commissioned on SALT in South Africa. Included in this text are some of the results and experiences of taking PFIS into operation.

"First light" of the Southern African Large Telescope was declared on 1 Sep 2005 and the first scientific programs have now begun. This paper discusses the completion and commissioning of the first-light instruments: the UV-visible imaging camera, SALTICAM, and the prime focus imaging spectrograph, the Robert Stobie Spectrograph (RSS). The innovative aspects and tight constraints on the design of these prime focus instruments are described, as well as the first scientific results. These instruments, which are all seeing limited, operate in the UV-visible region (320 - 900 nm), and will provide capabilities for broad and narrow band imaging, long-slit and multi-object spectroscopy (R ~ 6000 for seeing limit), spectropolarimetry and Fabry-Perot imaging spectroscopy (R ~ 320-9,000). Time resolved studies are an important aspect of the overall SALT science drivers and special efforts were made to ensure an ability to run at ~10 Hz, with minimal dead time, by employing frame transfer CCDs. Finally, we present the design and status of the fiber-fed high resolution echelle spectrograph, SALTHRS, the last of the "first generation" SALT instruments.

The 10-m class Southern African Large Telescope (SALT) at Sutherland, South Africa, was inaugurated in November 2005, following completion of all its major sub-systems. It is the largest single optical telescope in the southern hemisphere. The SAMS (Segment Alignment Measurement System) is a unique capacitive edge sensing solution for the active alignment of the SALT primary mirror. Twelve thin film edge sensors are bonded directly onto the edges of each of the 91 segments, with heat-generating control electronics housed remotely in temperature-controlled enclosures. The SAMS is capable of measuring the tip/tilt and piston of each segment, as well as the change in global radius of curvature, a mode normally undetected by such a system. The primary objective was to build a system that offered an excellent cost-to-performance ratio without sacrificing measurement accuracy, a very necessary requirement because of the scale and number of sensors required for large segmented mirrors. This paper describes the results obtained during the commissioning and calibration of the completed system.

The Southern African Large Telescope (SALT) was completed in 2005 and began initial scientific operations in August of that year. Built in just under 6 years and on budget, SALT has been a good example of a successfully managed telescope project where systems engineering disciplines have been applied to good effect. This paper discusses the experiences of completing and commissioning SALT and its first-light instruments and the early scientific operations. Lessons learned in integrating the various telescope subsystems and implementation of the telescope control system are presented. First Light was announced on 1 September 2005 following the installation of the last of the 91 mirror segments and the commissioning of the UV-visible imager, SALTICAM. This was soon followed by the first scientific observations and the beginning of the commissioning phase for the active optics system.

The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope (SALT), RSS/NIR, extends the spectral coverage of all modes of the visible arm. The RSS/NIR is a low to medium resolution spectrograph with broadband imaging, spectropolarimetric, and Fabry-Perot imaging capabilities. The visible and NIR arms can be used simultaneously to extend spectral coverage from approximately 3200 A to 1.6 um. Both arms utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera is designed around a 2048x2048 HAWAII-2RG detector housed in a cryogenic dewar. The Epps optical design of the camera consists of 6 spherical elements, providing sub-pixel rms image sizes of 7.5 +/- 1.0 um over all wavelengths and field angles. The exact long wavelength cutoff is yet to be determined in a detailed thermal analysis and will depend on the semi-warm instrument cooling scheme. Initial estimates place instrument limiting magnitudes at J = 23.4 and H(1.4-1.6 um) = 21.6 for S/N = 3 in a 1 hour exposure well below the sky noise., Comment: 12 pages, 10 figures, presented at SPIE, Astronomical Telescopes and Instrumentation, 24 - 31 May 2006, Orlando, Florida USA

Astronomy is important to developing African countries. In this paper, a brief review of the situation of astronomical research in Africa before 1991 is given. During that period only South Africa and Egypt were carrying out observational research in astronomy. In other African countries astronomy research was in its infancy, except the University of Nigeria Space Research Centre (UNNSRC) in theoretical areas. A summary of the important recommendations for Africa at the United Nations/European Space Agency (UN/ESA) series of workshops on basic space science were itemized to help identify those which have now been accomplished. Additionally, UNNSRC has now embarked on further observational programmes through the establishment of strong collaborative ventures with two observatories in South Africa, the Hartesbeesthoek Radio Astronomical Observatory (Hart RAO) and the South African Astronomical Observatory (SAAO). UNNSRC has also made permanent arrangements with HartRAO, SAAO, and the Jodrell Bank for collaborations in data analysis. A new interest in astronomy appears to have awakened in Nigeria with three more universities joining this area of basic space science. It is recommended that the time has come for all African countries to contribute towards a common facility such as the Southern African Large Telescope (SALT. The efforts of UN/ESA which resulted in tremendous achievements are commended.