1. DEIMOS Presentation to the SSC January 25, 2001

2. 2 Outline Quick overview of Budget and Schedule (web version has no Budget figures) Progress Since Last Report Technical Concerns Optical Testing Flexure Grating System Red CCD Status Schedule Details Budget Details

3. 3 Summary Schedule Status Completion has slipped one month since our October report. Reasons for the delay: –Software slipped one month (due to sickness and Lick software emergencies) and is on the critical path. –We discovered flexure in the detector support train and must remove the dewar to fix it. –The grating transport/insertion mechanism is requiring substantial redesign. –CARA cannot accept DEIMOS until Oct. 1, 2001.

4. 4 Summary of Critical Path Software dominates until testing begins. Grating implementation and flexure repair have only about 2 weeks float.

5. 5 Summary of Critical Path

6. 6 Milestone Summary As of Current Oct 14, 2000 date First image of spectraOct 24 Done Meeting plans to fix flexureOct 26 Done Slit mask system released to SW for functional testsJan 19 Rotation drive re-installed & under SW controlJan 8 Jan 21 Grating system operationalFeb 5 Mar 8 Instrument ready for integrated systems testsApr 4 May 8 Preship reviewJune 7 July 7 Marine ShipmentAug 9 Sept 11 First air shipment and start of assemblyAug 21 Oct 1 Hoist instrument into domeAug 24 Oct 4 Dewar installedOct 3 Nov12 First star light Oct 30 Dec 7 (dark) or Dec 28 (full moon)

7. 7 Progress Since Last Report Dewar system installed in DEIMOS (October 16); works well. Direct images and spectra taken with blue science mosaic. Flexure investigations using full mosaic detector completed. Software developed to analyze flexure and optical quality. Plan to address major source(s) of flexure developed. Major progress on grating transport/insertion system. Slit mask system under computer control. Calibration lamp and flat field illumination systems installed and tested. Flexure control system installed and tested. Dewar focus, dewar X stage, science filter wheel, calibration lamps, and shutter operated under keyword control and tested using automated scripts; now are working systems.

8. 8 Dewar System in DEIMOS

9. 9 Slit mask system insertion scissor lift

10. 10 Calibration lamps with slit mask form at bottom of picture

11. 11 Picture of spectra from 900 line grating

12. 12 Other Progress Linux computer for rotation control purchased and outfitted with Galil motor control system. DEIMOS rotation under computer control by end of January. Engineering GUI in use. Leach II video boards for 16-amp operation received. Dewar ion pump power under software control. Hewlett-Packard temperature sensor data logged remotely over network; 24/27 sensors installed. Power PC board mounted in test CCD controller for 100 Mb ethernet video connection; being tested.

13. 13 Technical Concerns Fixing flexure in grating box and other sources Extensive redesign of grating sliders is required; integrating grating system with all sliders mounted will occur late. Possible redesign of retraction “hotdog” for slit mask system Availability of high-rho CCDs for red mosaic; testing red mosaic out of spectrograph after DEIMOS is shipped Implementing complex rotation control system Telescope baffling

14. 14 Image Quality Image quality tested by direct images and spectra through pinhole/slitlet-mask. Hole diameter = slitlet width = 0.5 arcsec = 4 pixels. All images show radial coma, with maximum length approximately 20 pixels at detector edges (see plot). In addition, a small amount of constant coma appears to be present. FWHM data on good images is about 4 pixels, as expected.

15. 15 Image Quality (cont’d) Possible sources of radial coma: symmetry says must come from camera. –Bad aspheric surfaces on Elements 7 and 8. But this was not seen in Optical Shop testing. –Improper spacing between Element 8 and Element 9 (field flattener). This is possible, as parts were substituted between tests. Easy to fix. Possible sources of constant coma: symmetry says must also come from camera. –Tilt or displacement of Multiplet 4. –Tilt or displacement of Element 9. –Either of these can be largely nullified by the decentering adjustment on Multiplet 4. Easy to fix. Conclusion: Greater care in installing Element 9 and dewar (and possibly decentering Multiplet 4) should cure problems.

16. 16 Picture of aberration

17. 17 Other Optical Results Fringing is less than 4% peak to peak; we had been planning on 20%. Flat-fielding will be easier than expected. CCDs 1 and 4 in the blue mosaic are high-rho engineering- grade devices from Lot 14. They are exactly like the science-grade high-rho devices from this lot except they have a poor anti-reflection coating and low QE. Their PSFs are good, showing that the red science devices will have acceptably sharp PSFs. CCD 7 is a high-rho red-sensitive prototype from Phase 1 that we had been counting on. Its images have “wings” and slightly high FWHM. We no longer consider this suitable for the red mosaic and have relegated it to a spare.

18. 18 Other Optical Results (cont’d) The wavelength calibration system contains Hg, Ne, Ar, Xe, Kr, Cd, and Zn lamps. There are many dim but highly usable spectral lines in the blue. The internal quartz continuum lamp is dim in the blue an has broad spectral “features” impressed by the fiber feed system. However, it is usable now and can be improved later if time permits. The flexure compensation spectra look good. They land on the FC CCDs and have spots of good brightness and spectral density.

19. 19 Flexure Restatement of problem: peak to peak image motion of 40 pixels (600 microns) when DEIMOS is rotated. Roughly 26 pixels ascribed to grating box. Range of motion of FC system is only 20 pixels peak to peak. Progress since last report: –In-house review (Oct 26) recommended three strategies: 1)Brace existing grating box with elbow braces. Tried, gave little improvement. 2)Remove grating box, strengthen, weld, and replace. Due to be implemented Feb 1, results by Feb. 15. 3)Replace grating box with new system based on 4-5 tripods attached directly to drive disk. We are beginning to study this and will implement if necessary.

20. 20 Flexure (cont’d) –Direct images of detector inside dewar showed ~6 pixels flexure peak to peak. Dewar is being removed and disassembled to fix this. Replaced Mar. 15. –Analysis scheme was developed using ghost images and higher-order distortions to disentangle collimator, tent mirror, grating, and detector motions. Very promising. –Present image rotation is a little less than 2 pixels peak to peak at edge of detector. Error budget is 1 pixel peak to peak.

21. 21 Grating box with slider 2 at top

22. 22 Grating System All parts fabricated (original design). Grating tilt system is entering keyword control. Grating insertion system is being tested with slider 2 and imaging mirror. –Clamping mechanism passed initial tests. –Slider body flexes slightly under rotation. Needs reinforcing. –“Hand-off” mechanism needed rework; too floppy. New design seems to work well. –Capture range of homing pin seems comfortably longer than flexure of drive-screw system. –Final end-to-end tests of slider 2 expected next week.

23. 23 Grating System (cont’d) Grating sliders are heavier than slider 2. –Their hand-off mechanisms are harder, due to extra weight and grating tilt complexity. –Slider 1 is very heavy – carries 8 x 12 grating. Latest vignetting study indicates only 5% light gain. –WE PROPOSE TO REPLACE SLIDER 1 WITH A VERSION OF SLIDERS 3/4. Concerns: –Complex redesign of sliders 3 and 4. –Greater weight and flexure with all four sliders installed. –Final integration of grating system will come late, after reinstallation of grating box.

24. 24

25. 25 Red CCD Mosaic The second distribution of Lot 14 MIT/LL high-rho devices has occurred. Our allotment of high-rho devices is as follows: 6 excellent science-grade devices 1 very good spare, possibly science-grade if operated cold enough 1 acceptable spare (CCD 7 in blue mosaic) 1 B-grade device not suitable for science mosaic We need 1-2 more science-grade devices to fill out the red mosaic. Possibilities for getting these include: –Six more CCDs are due to be packaged from Lot 14, of which we would get 1. –Luppino may be able to trade us 1-2 devices, depending on availability. –We may be able to trade devices with ESO, who have a surplus.

26. 26 Red CCD Mosaic (cont’d) We should know about the Luppino trade by March 1. CARA have accepted our plan to assemble and lab-test the red mosaic AFTER the Pre-Ship Review, pending a review of our test plan.

27. 27 Major Schedule Concerns The grating insertion mechanism re-design needs to be successful; the full-up system with all sliders needs to work as well as slider 2 alone. Planned fixes of flexure need to work, and our diagnosis of the sources of flexure needs to be correct. Software continues on critical path. Delays will result if key software people are distracted or hit by illness. No surprises in switching to 16 amp read-out of the mosaic. We assume that we can integrate the “red” mosaic after the Pre-Ship Review. We have agreed with CARA to postpone mask fabrication at CARA until after DEIMOS commissioning. This eases the software schedule by about 3 man weeks.

28. 28 Thumbnail of DEIMOS Schedule

29. 29 Schedule, PS to Commissioning

30. 30 CARA Preparations Needed Extend the N platform. Deflection of N platform under DEIMOS load. Design, fabricate and install the cable boom. Install the N tracks on the DEIMOS side. Increase the elevation axis telescope cable wrap. Test carriage mover. Produce a drawing for the DEIMOS lift into the observatory. Run air, glycol, co-ax fiber and power lines to the cable boom. Mount and install DEIMOS computers and disk drives.

31. 31 CARA Preparations Needed (cont’d) Interface control document Guider work - software - Lick Configuring of accounts Data archive to tape Telescope interlocks Preparation for slit mask Cryogen Handling Documentation specification Commissioning and characterization, image reduction Documentation of instrument procedures SW for instrument control and initialization