1. Oct 24, 2006SSWG1 Robert Stobie Prime Focus Imaging Spectrograph Status On-telescope throughput analysis Ghost analysis Repair plan Status of other current control and mechanical issues Commissioning progress Budget

2. Oct 24, 2006SSWG2 RSS Optics Throughput Shortfall Telescope system testing found RSS optics throughput ~60% of expected in visible, < 25% below 375 nm Either blank absorption or coatings at fault

3. Oct 24, 2006SSWG3 Blank Absorption Investigation Polished and measured spare NaCl blank - good Remaining possibility of effect found for UVES: coating process causing development of "color centers" in CaF 2. Curable by UV Flooding

4. Oct 24, 2006SSWG4 Throughput Test Apparatus To isolate optical subsystems with problem and narrow range of causes, develop apparatus to measure throughput of integrated optics at 375 and 635 nm Tests performed 23 - 30 Sept, 2006

5. Oct 24, 2006SSWG5 Throughput Experiments

6. Oct 24, 2006SSWG6 Subsystem Throughput Throughput of 7 subsystems derived: MgF 2 coatings, LLNL fold flat exonerated Visible loss in collimator main group and camera UV loss also in collimator doublet Multiplying losses consistent with on- sky system results

7. Oct 24, 2006SSWG7 Conclusions no common coatings => at least 2 separate problems. doublet shows transmission CaF 2 color center possible. Definitely multilayer coating problem. problem in collimator main group means instrument must come off.

8. Oct 24, 2006SSWG8 Ghost Flatfield ghost with interference filter imaging and Fabry-Perot –in interference filter sky images and flat fields see ~ 10% “doughnut” which appears to be an image of the pupil –does not show up with clear or color filters => one ghost surface is the filter (reflection 10 – 100% depending on wavelength) –a severe problem for FP mode –determined to be internal to RSS Ghost investigation –take flats with various pupil masks inserted in grating holder, field mask at slit –raytrace analysis to find surface that forms pupil image –circular polaroid between ghost surfaces should eliminate it

9. Oct 24, 2006SSWG9 Ghost Geometry Mask experiments -> 2nd surface in camera Polaroid experiment -> after filter Raytrace -> dewar front surface

10. Oct 24, 2006SSWG10 The trouble with the dewar window Predict surface reflectivity from observed ghost intensity vs wavelength: up to 20% peaking at 540 nm remove detector, measure and inspect window: yellow-green Another (different) multilayer problem Fix during throughput repair

11. Oct 24, 2006SSWG11 Repair plan

12. Oct 24, 2006SSWG12 Control Issues Grating insertion interlock problem –not interlocked against inserting grating when etalon or articulation is in wrong status. –this works on built-up spare at UW. Suggests wiring or board problem in RSS electronics box. –Found error and fixed. Waveplate homing problem –found that we need to turn off the waveplate rotator encoder when not moving it (stray light). Rotator homing then does not work. –again, this works on built-up spare at UW. Suspect a software or firmware incompatibility. –hardware verified with encoder diagnostic software. –software not waiting long enough after turning encoder on. Software problem identified

13. Oct 24, 2006SSWG13 Mechanical Issues Slitmask mechanism –severe reliability problems due to difficulty of aligning magazine, carrier, and focal plane chute –temporarily removing magazine, using insertor to inset and remove a manually loaded slitmask –SAAO redesigning slitmask assembly to make it monolithic, aligned on bench –install during down time Articulation fall arrestor –safety restraint to prevent catastrophic damage in case articulation motor fails during articulation –installation and testing within a few days Polarizing Beamsplitter –SAAO task to redesign and manufacture beamsplitter insertor to allow for beamsplitter removal/ rotation/ insertion in situ –clearance issues resolved. Now installed

14. Oct 24, 2006SSWG14 Commissioning - Longslit Spectroscopy Mostly done. Many PV proposals used. Autoguide setup procedure mature Calibration procedures developed

15. Oct 24, 2006SSWG15 Commissioning - MOS Slitmask cutting process tested Manual acquisition with MOS painful (10 - 20 m), but surprisingly possible Orientation control issue identified with slitmask cutting/ TCS software Needs slitmask magazine, more automated acquisition procedure to be practical

16. Oct 24, 2006SSWG16 Commissioning - Fabry-Perot On 20060922, first light RSS on-sky Fabry Perot observations: two spiral galaxies, NGC 1535 and NGC 1365, at Hα through the LR etalon. roughly 20-step etalon scans through the line. An initial reduction of the data cubes shows a velocity map for NGC 1365 which compares well with data obtained on other telescopes throughput is within 2x of expected

17. Oct 24, 2006SSWG17 Commissioning - Continued Polarimetric. Next two weeks: –linear polarization lamp calibration –spectropolarimetry on-sky first light –linear: standards, high and low-res PV –circular: mCV High speed: awaiting detector software issue All UV commissioning: after repair (starting May?)

18. Oct 24, 2006SSWG18 Cost to Completion Does not include ~50 - 100 $K for optics repair costs (mostly optomechanical) Predicting CTC ~20% over CDR budget