1. Oct 26, 2007SALT Workshop UKZN1 Robert Stobie Prime Focus Imaging Spectrograph Science Rationale Modes –Fabry-Perot Spectral Imaging –Grating Spectroscopy; VPH Gratings, MOS –Spectropolarimetry –Mode table Status

2. Oct 26, 2007SALT Workshop UKZN2 What science should RSS do? SALT features –very large aperture –good field of view (8 arcmin) –excellent ultraviolet throughput –queue scheduling –modest imaging RSS: emphasize unique observing modes that do not require excellent imaging –UV spectroscopy down to 3200 Ǻ (rare on large telescopes) –higher resolution: high-throughput grating 3200 - 9000 Ǻ; Fabry- Perot 4300 - 9000 Ǻ (Visible Beam); later - 1.7 μm (NIR) –polarimetry (circular and linear) (very rare) –high-speed detector mode (very rare)

3. Oct 26, 2007SALT Workshop UKZN3 Optics All-refractive UV optics for high throughput At prime focus for UV and full-field access NIR upgrade path: simultaneous 3200 Ǻ – 1.7 μ

4. Oct 26, 2007SALT Workshop UKZN4 Mechanisms 2 Fabry-Perot Etalons (slides) Polarizing Beamsplitter (slide) 2 Polarimeter Waveplates (slides) 6-Grating Magazine 40-Slitmask Magazine Camera Articulation 0 - 100° Shutter 20-Filter Magazine 3 CCD Mosaic Detector

5. Oct 26, 2007SALT Workshop UKZN5 RSS on SALT Articulation Rail Camera Detector Etalons Collimator

6. Oct 26, 2007SALT Workshop UKZN6 Perseus Cluster of Galaxies Perseus A in Hydrogen Light Imaging/ Fabry- Perot Spectroscopy Filters Fabry-Perot etalons (scans wavelength) Many wavelengths

7. Oct 26, 2007SALT Workshop UKZN7 Hubble Deep Field (South) Up to 40 Spectra Slitmasks selects objects Filters "VPH" Grating disperses wavelengths Multi-Object Grating Spectroscopy

8. Oct 26, 2007SALT Workshop UKZN8 Hubble Deep Field (South) Waveplate rotates polarization Beamsplitter splits 2 polarizations Polarization of 20 Spectra Spectropolarimetry Submode Also works in Imaging/ Fabry-Perot Modes

9. Oct 26, 2007SALT Workshop UKZN9 High Efficiency with Volume Phase Holographic Gratings = λ/Δλ Resolution vs wavelength for 1.2 arcsec slit Constant Efficiency Contours

10. Oct 26, 2007SALT Workshop UKZN10 How VPH Gratings Work Created by exposing holograph material (“DiChromated Gelatin") to interference pattern from laser Index of refraction of DCG is modulated in space Large; inexpensive; custom design; efficient at high groove density

11. Oct 26, 2007SALT Workshop UKZN11 One RSS VPH 1300 gr/ mm VPH

12. Oct 26, 2007SALT Workshop UKZN12 Multi-Object Spectroscopy with custom masks Laser-cut slit masks Standard set of longslits Unique mask cut for each individual MOS observation Slit mask magazine will hold 10 longslits, 30 MOS masks Reload once/ week Giant Elliptical Galaxy NGC1399 at focus of telescope: Mask with slits cut in it to let through selected nebulae in galaxy "Longslit" mask to get spectrum along one position angle

13. Oct 26, 2007SALT Workshop UKZN13 MOS Test Field Courtesy: Petri Vaisanen

14. Oct 26, 2007SALT Workshop UKZN14 NGC6822 – Oct 20 4080 A 7180 A MOS Test Run Spectra Position Reference Stars HII and PNe

15. Oct 26, 2007SALT Workshop UKZN15 17 PFIS Modes Optics configurationDetector Configuration ConfigPolSlitNormalHi SpdShuffleDrift ImagingNo X xx L,C,SNox Multislit X x VPH Spectro- scopy No xx Longslit X Xx Multislit X X L,C,SLongslit X x MultislitX Fabry- Perot No X x L,C,SNo x Tried: 6 Team Commissioned: 9User Commissioned: 8

16. Oct 26, 2007SALT Workshop UKZN16 Status On telescope Nov 2005 - Oct 2006 –longslit mode, polarimetry commissioning –other mode tests –on-sky throughput tests Off telescope Nov 2006 - present –improving UV throughput, ghosts –Measured throughput to be 75 - 100% of design, sensitivity comparable or better than design throughput of other large telescope spectrographs Back on telescope for further commissioning April 2008