1. Tim Abbott 2006 07 27 1 DECam & CTIO

2. Tim Abbott 2006 07 27 2 DECam & CTIO: CTIO’s preparations Active Optics –33-pad system, LUT driven, updated every few months –DECam will provide in-line updates (via “donut”) possibly allowing us to close the loop during observations

3. Tim Abbott 2006 07 27 3 DECam & CTIO: CTIO’s preparations Environment –Dome ventilation doors at telescope level –Dome covered with thermally insulated aluminum panels –Air ventilation around primary mirror and telescope structure –Better thermal management throughout the building, servo-control optimized system.

4. Tim Abbott 2006 07 27 4 DECam & CTIO: CTIO’s preparations More recently: –Radial support mechanism understood Supports were detaching from the primary due to mechanical interference and accumulated misalignments resulting from inadequate repairs. 24 supports, 3 pivot points each, gravity-driven system. –Primary mirror movement identified and (partially) resolved Broken radial supports generated imbalances in the radial support system Primary mirror movement in cell involved hysteresis and was unpredictable

5. Tim Abbott 2006 07 27 5 DECam & CTIO: CTIO’s preparations More recently: –Primary mirror repositioned 2.3mm in z-direction –Primary mirror is now centered in cell Coma was dominant and variable, is now the third most significant aberration and stable. Image Quality obtained by the SuperMacho program, 2005B, airmass corrected, VR filter. Dates: 2005-09-05 to 2005-12- 31, Blue: pre-shutdown, red: post-shutdown, approx equal number (~580) exposures each.

6. Tim Abbott 2006 07 27 6 DECam & CTIO: CTIO’s preparations More recently: –Radial support counterweights augmented –Telescope flexure measured Movements of primary w.r.t. corrector no longer show hysteresis and are believed to be due to flexure. –Aluminization chamber upgrade underway –Two degree slew time reduction from 35s to 17s - feasibility established –Telescope FEA model built, drawings supplied, design limits explored

7. Tim Abbott 2006 07 27 7 DECam & CTIO: CTIO’s preparations, To Do Complete radial support repairs –Either: complete review of repaired supports & retune as necessary –Or: upgrade & re-site all radial supports to virgin glass TCS upgrade –Retire irreplaceable, obsolete components –Move to modern, integrated system (Linux, ethernet, current gen PMAC, tape encoders) –To incorporate & supply observation telemetry & metadata Environmental improvements –More doors? –Additional cooling? –Replacement for plenum? –Active cooling at the top end (comes with DECam)

8. Tim Abbott 2006 07 27 8 DECam & CTIO: CTIO’s preparations, To Do Cleanroom –Coude room, required for assembly, testing & future repairs Interfaces –Gases N 2, dry air for venting, driving filter/shutter cryogenic system supply LN 2 –Coolant (glycol, alcohol/water) Power dissipation goal of 100W requries active cooling –Mechanical, electrical, computing, etc

9. Tim Abbott 2006 07 27 9 DECam & CTIO Many improvements will come with the instrument itself –Alignment sensors and active alignment correction –Contemporaneous focusing –Active instrument cooling –New corrector (better design, not damaged!)

10. Tim Abbott 2006 07 27 10 DECam & CTIO: Integration & Community Use DECam is to be a facility instrument. DECam will replace Mosaic II and must offer the same functionality and similar flexibility –f/8 secondary –Observation modes currently available with Mosaic II must also be available with DECam. Many DES requirements fulfill this, but attention must be paid to some functions not obviously covered by DES –Classical observing modes (as opposed to queued or service) 1.Single object (pointed) 2.Dithered 3.Survey 4.Planetary (non-sidereal) DECam U band is limited by CCD response, Mosaic II by corrector transmission → ~same efficiency

11. Tim Abbott 2006 07 27 11 DECam & CTIO: Integration & Community Use Filters –Must be able to use non-DES filters on non-DES nights 6 filter positions minimum, 8 preferred –Non-DES filters: high price will limit options Review panel convened, recommendations made Shutter –Speed, accuracy, precision, durability Observing environment –Observer interface GUI Real Time Display Quick-look and on-the-fly data analysis –Integration into NOAO Science Archive Consistent data format Pipeline access NOAO will make a non-volatile copy of all DECam data

12. Tim Abbott 2006 07 27 12 DECam & CTIO: Integration & Community Use Installation & integration considerations –Mechanical limits Instrument max mass ~5 tons –Interfaces –Assembly Coude room –Mounting DECam replaces the entire top-end, excluding top-rings and spider –Alignment Hexapod –Commissioning Installation & shakedown –Environmental conditions Temperatures, humidity, orientation changes, earthquakes –Maintenance, spares, tooling, documentation –Operations

13. Tim Abbott 2006 07 27 13 DECam & CTIO END

14. Tim Abbott 2006 07 27 14

15. Tim Abbott 2006 07 27 15 Radial Support M C B D E P G H A F F One radial support, in below- mirror (compression) position. M: Primary mirror H: H-bar attachment to primary (old style) A: Lever arm C: Counterweight D: Cast bracket E: Plug, fits into socket (not shown) mounted on inside of telescope barrel B: Point of attachment to mirror cell F: Force vector radial support applies to primary mirror G: Gravity vector P: Pivot points.

16. Tim Abbott 2006 07 27 16

17. Tim Abbott 2006 07 27 17 Current H-bar design: Strains are not uniform in the pads

18. Tim Abbott 2006 07 27 18 New H-bar design

19. Tim Abbott 2006 07 27 19 2006 04 28 – another spin around the pole

20. Tim Abbott 2006 07 27 20 4m TCS Upgrade: Current TCS Rack VME Chassis (Obsolete comms board) VME Interface (Wire-wrap & breadboarded components) Drive Interface (Wire-wrap and breadboarded components) Power Supplies

21. Tim Abbott 2006 07 27 21 Existing Blanco TCS

22. Tim Abbott 2006 07 27 22 4m TCS Upgrade: Rack Evolution Proposed Rack TCS App + TCS Kernel (Industrial PC) Dome Control (Industrial PC) Dome Control Interface Utility PC Lamps and Guider Utility Interface Mount Control Mount Control Interface Power Supplies Current Rack

23. Tim Abbott 2006 07 27 23 Current TCS: telescope control PMAC TCS (algorithms) 10Hz VME GUI SunOS, ctiot2 Incremental encoders Absolute encoders Telemetry & Interlocks Motors

24. Tim Abbott 2006 07 27 24 SOAR control model IN → PID → OUT SetpointStatus Motor Controller TCS App Kernel Setpoint Position Status Telemetry Encoders Motors Interlocks GUI In SOAR this is proprietary

25. Tim Abbott 2006 07 27 25 Planned Blanco TCS TCS App (Linux PC) GUI (Linux PC) Instrument Motor control PMAC Utility (Linux PC) Active OpticsTemperature sensors Guider Comp. lamps PFADC Encoders Interlocks PXI Ethernet

26. Tim Abbott 2006 07 27 26

27. Tim Abbott 2006 07 27 27 DECam as community instrument DECam will replace Mosaic II in all respects therefore must be able to perform as Mosaic II f/8 function must be maintained DECam U band limited by CCD response, Mosaic II by glass → ~same efficiency Shutter performance – driven by standard star observations, minimum exposure time 1s Filters – current concept is for 6, possibly 8. 4 DES, remainder for community Community/NOAO will have to purchase own filters beyond DES 4.