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  1. SED Machine Bonding Woes

    As reported on 6 Dec the lens bond of camera 1/2 was a success. A little Sylgard-184 ended up on the lens girdle, but the lens is clear and beautiful. I stored the lens away in our humidity-controlled environment. I'm still trying to deal with the fact that some of my CaF2 elements are now coated on both sides (I wanted only a coating on one side).

    It turns out that an AR Coating tuned to operate on an air/glass interface performs about as well when going from a sylgard-184/glass interface over most of the wavelength range, but performs poorly at the red and blue ends. The realities of this project mean that we may just have to plow through and accept some throughput loss.

    I was also excited to see the work of Trinh et al. (2012) posted on the arxiv. Their work is exciting and has the potential to dramatically increase the signal-to-noise of background limited observations on large telescopes. It seems as if the technology is not quite there yet and their abstract is refreshingly honest:

    While these tests demonstrated high throughput and excellent suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS and IRIS2 is about the same as IRIS2.
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  2. Arrival of SED Machine (Painted) Barrels

    To reduce scattered light the SED Machine optical barrels are painted a dark flat black. We searched high and low for some good black paint, and though there are many good options, for our particular case we use Avian Black-S. Avian Black-S is water based and thus can be sprayed using the standard painting tools found at Caltech's paint shop.

    In addition to painting parts black, we designed a careful system of baffles to block stray light from hitting our detector.

    (Black) SED Machine Collimator and Camera Barrels
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  3. SED Machine Cam 3/4 & Gemini Observatory Future

    SED Machine Camera 3/4 Doublet

    Marin Anderson [CIT] and I bonded SED machine doublet camera elements 3/4 today. The camera is a 125-mm f/5 Petzval-style lens made of Ohara PBL26Y (n 1.57 and Abbe 42.8) and Heraeus fused silica (n 1.46 and Abbe 68). Lens centration is expected to be better than 30 micron or so.

    Camera 3/4

    Camera 3/4 doublet - a success. Cam 3/4 was bonded on 14-Dec 2012.

    Gemini Capabilities

    Talk by Gemini director at Caltech.

    The Partnership 2013-2015

    Annual budget 2013: ~ 27 M ops + 4 M instrumentation

    Country Share Cost
    US 65.50  
    CA 18.65  
    BR 6.53  
    AU 6.21 ~ 1.7 M / yr
    AR 3.11  

    Gemini 2016-2018

    Australia is not sure about plans post 2015. The board will work to find potential new parties.

    The Observatory

    About 180 employees distributed over two sites. Not staffed to build own instruments. [Note: Keck has ~115 at one site].

    Random note: no naysmith platforms for Gemini which makes Highres spec hard. Five casegrin ports but two are used for AO + Calibration. Any given time there are three instruments.

    New instruments: GRACES [March/April first test], GHOS, Flamingos-2, and GPI. Dying: Michelle, T-ReCS

    GPI commissioning July 2013.

    How to Remain Competitive in the Next Decade?

    Future is ALMA, JWST, and how to profit most with these synergies?

    New opportunites in instrumentation. The observatory will build a complement of facility class instruments to cover broad parameter space. New instrument every 2-3 years and thus cycle through all instruments takes about 20 years.

    R&D is $100 K / year Upgrades $500 K / year

    Next strategic instrument (GIROS; xshooter). Requirements:

    • Workhorse
    • Science driven and include science cases. Synergies with LSST, JWST, ALMA, etc..
    • Wide bandwidth moderate-resolution spectrograph is the current best leading instrument by the committee's opinion.

    [QUESTION: Who are the forerunners?]

    React to a science case and deploy on a short schedule provide visitor instruments by the community. Gemini now wants to encourage visitor instruments.

    • Instrument is certified
    • Apply for time via TAC
    • Install and observe
    • Typical visit is 2 weeks. Instrument can be offered to community during two weeks.
    • Large programs to request campaigns.

    Two examples of visitor instruments

    DSSI: Speckle imaging. Got 20 mas resolution at 700 nm, offering instrument to community. PI (Howell, NASA AMES).

    TEXES returns to gemini. On IRTF since 2000. Operates between 4.5 and 25 µ with 0.5% spectral coverage at high (R~80 K) resolution with a 2" - 5" long slit. Team helps with proposals and data reudciton.

    The team must support: John Lacy [PI], Richter (UCDavis), Greathouse (Solar System), Jaffe (UT A).

    New Ways of Operating

    Large/long programs at Gemini. The board has agreed to place 20% of the time in a pool for large/long programs. Implementation is being worked out but starts in 2014A.

    Want high-impact science.

    Also are considering putting some ten of percent of time in monthly proposal deadlines. Many possible issues and potential problems being considered and explored: partner percentage, rejected proposals, how long to remain in queue? The advantage is you can win 12 months over the competition.

    Summary

    • Some unique facility class instruments: GeMS, and GPI.
    • It's possible to bring your instrument to the telescope.
    • Chance to propose large, ground-breaking programs.
    • Unique flexibility in time domain for edge over competition.

    Questions

    • Some interest in continuing to use MICHELLE in visiting mode.
    • Fast track queue idea is intriguing. If review urgency is an important criteria, then you must observe it quickly.
    • Noticed nothing in far IR (+mm). Cannot look beyond 20 µ from ground.
    • Visitor instruments comment. Keck SSC considered visitor instruments as valuable about ten years ago. Complaint of visitor instruments is that they are too costly to commission. Gemini has had good experiences (compared to Keck) and believes visitor instruments are a good future step.
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  4. SED Machine Laser Alignment of Field Splitting Mirror

    The sed machine simultaneously images a large 12' field of view with the rainbow camera, as well as a small 30" field with an integral field spectrograph. The 60" telescope has an angular scale of 64 µ/arcsecond. This means that the focal surface that the spectrograph subtends is less than 2 millimeters on a side. It's hard to find such a tiny little mirror that also covers the broad wavelength range of SEDM (0.37 µ - 0.92 µ). Instead I've designed the field to be picked off with a prism that operates in total internal reflection.

    The prism has to be precisely aligned to be perpendicular to the optical axis of the telescope. Instead of relying on precision machining to align the prism (as I did for all other optics) the prism is aligned by hand. I use a UV-curing glass-to-metal epoxy which allows me to tweak the prism and then fix its position when I'm satisfied. I'm using a HeNe laser to align the prism as can be shown in the setup below.

    The final result is that the prism is aligned to better than 1 arcminute (or better than 1 µ from one end of the prism to the other). Great!

    SED machine field-splitting mirror laser alignment

    SED Machine field splitting mirror mount.

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  5. SED Machine on the Dome Floor

    Last night the SED Machine was delivered to the Palomar 60-inch telescope.

    SED Machine on the Palomar 60-inch telescope dome floor.

    The instrument arrived safely, and basic verification tests show in-focus spectra and images. In short, SED Machine is ready for observations.

    First light is in two nights.

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  6. SED Machine Laser Alignment of Field Splitting Mirror

    The sed machine simultaneously images a large 12' field of view with the rainbow camera, as well as a small 30" field with an integral field spectrograph. The 60" telescope has an angular scale of 64 µ/arcsecond. This means that the focal surface that the spectrograph subtends is less than 2 millimeters on a side. It's hard to find such a tiny little mirror that also covers the broad wavelength range of SEDM (0.37 µ - 0.92 µ). Instead I've designed the field to be picked off with a prism that operates in total internal reflection.

    The prism has to be precisely aligned to be perpendicular to the optical axis of the telescope. Instead of relying on precision machining to align the prism (as I did for all other optics) the prism is aligned by hand. I use a UV-curing glass-to-metal epoxy which allows me to tweak the prism and then fix its position when I'm satisfied. I'm using a HeNe laser to align the prism as can be shown in the setup below.

    The final result is that the prism is aligned to better than 1 arcminute (or better than 1 µ from one end of the prism to the other). Great!

    SED machine field-splitting mirror laser alignment

    SED Machine field splitting mirror mount.

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  7. SED Machine Rainbow Camera 5 Bonding

    A number of teams "pot" their lenses in cells with room-temperature vulcanizing (RTV) epoxy. We are using RTV60 to pot lenses into their aluminum cells. The method is to center the lenses in their aluminum cells using three precision pins as shown in the figure below.

    Rainbow camera 5 - potting

    The lens cell is made of 6061 Aluminum T6; which expands by about 1 micron every degree Centigrade. The glass in the cell is fused silica, which expands about 200x less. Thus the RTV which has a soft rubber-cement like consistency will absorb these differential stresses.

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  8. SED Machine Col 1/2

    SED Machine Collimator 1/2 Doublet

    I sound like a repeating record. Marin Anderson [CIT] and I bonded SED machine doublet camera elements 3/4 today. The collimator is a 95-mm f/4 lens with a telectrinc input.

    Collimator 1/2

    Collimator 1/2

    Above is a stop motion video of the col 1/2 bonding performed by Marin Anderson and Nick Konidaris [Caltech]. The positive element is a CaF2 (ISP Optical), while the negative element is a fused silica (Heraeus suprasil). You'll note that there are several key elements in order of appearance: a checklist, blue tape, pink lens cleaner, kapton-tape shims applied with a tongue depressor, Sylgard-184 applied with pipettes, and q-tips for cleaning the lens.

    New Parts in Hand

    In addition to bonding, some parts have completed fabrication. So far we now have the lens barrels that hold the rainbow camera, collimator, and camera!

    The Rainbow Camera delrin barrel

    The rainbow camera barrel that contains a doublet, triplet, and singlet is shown. The barrel is made using delrin of a well-measured coefficient of thermal expansion, in order to control aberrations that appear at different temperatures.

    The collimator aluminum barrel

    The 95-mm f/4 collimator barrel is shown. The barrel sits in a V-block and is held down with springs (inspired by the OSMOS spectrograph). The barrel contains six elements, with most of the positive power produced by CaF2, and negative power and residual-aberration correction provided by Ohara Corporation i-line glasses. The mix of fragile materials and large expansion differences makes for some interesting mechanical engineering challenges.

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  9. SED Machine Camera 1/2 Bonding

    Today we potted the achromatic doublet of the SED Machine spectrograph camera 1/2 in its aluminum cell.

    We pot our lenses in cells with room-temperature vulcanizing (RTV) epoxy (as described in a previous post). We are using RTV60 to pot lenses into their aluminum cells. The method is to center the lenses in their aluminum cells using three precision pins as shown in the figure below.

    The UCLA IR Laboratory coordinate-measuring machine (CMM) is used to confirm the position of each optic pre and post bond. Camera 12 is shown below with the CMM's Renishaw tip for scale. The post-potted element is also shown.

    SED machine camera 12 - potting
    SED machine camera 12 - potting

    The camera is a Petzval-styled lens.

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  10. SED Machine Collimator Potted

    The SED Machine collimator is a f/4 125-mm focal length lens that accepts a telecentric beam and has a 13-degree corner-to-corner field of view. The exit pupil is a good 120 mm away from the exit of the collimator in order to minimize the size of the dispersing prism.

    The lens design took several months. Production took longer. Glass blanks were purchased, optics polished, and finally coated by a slew of vendors including Ohara Glass (Japan), Heraeus Quarzglass (Germany), ISP Optical (USA), Hal Johnson (USA), and Cascade Optical (USA). Managing all these different pieces gave me multiple headaches, but I'm please to say that all optics are mounted to within a few tens of microns. I spent the past week at UCLA (thanks Ian McLean and Ted Aliado) confirming the position of all the optics.

    Check out the images below. The images

    |filename|/images/sedm/paper.jpg

    Test paper target.

    |filename|/images/sedm/col_paper.jpg

    SED Machine collimator images with a Canon camera focused at infinity. The image seen in the collimator looks nice and sharp, as predicted. Seeing this image is exciting for me, and even more work is needed to finish.

    |filename|/images/sedm/complete_col_barrel.jpg

    SED Machine collimator in all its glory.

    |filename|/images/sedm/complete_cam.jpg

    SED Machine camera in its V-block mount.

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  11. Chimera 2 Optical Design #2

    This post is out of date!!!

    This post describes the Chimera II optical design. Because of space constraints, I have designed a reimager system that uses a standard collimator-camera configuration. In order to cover two bands simultaneously, a red and blue camera are used. The design goals were (in order) to achieve f/1.2 focal reduction, have seeing-limited image quality over the Andor SCMOS device, try to keep fabrication costs as low as is reasonable and ensure the design is straightforward to build. To that end I have designed three lenses. The collimator start a fraction of an inch past P200 prime focus (the Wynne corrector is not used).

    Collimator

    The collimator sits about 1.5 inches past the focus of P200, accepts a full field of view of 13.2 arcminute (diameter) and a wavelength range from 0.4 to 0.9 µm. The collimator accepts the full f/3.3 beam from the 200-inch Hale telescope and with a 8.5 inch focal length delivers a beam diameter of about 2.6 inch. When imaged by a perfect f/1.2 camera the collimated beam delivers 0.9 arcsecond images over most of the field and 0.5 arcsecond images over the central half of the field.

    To control cost, the collimator delivers a pupil on the camera's first element. As a result, the collimator is physically larger than the camera, but there are two cameras required for this system so that the total volume of glass in the collimator is equal to the volume of the glass in the two cameras (about 650 for the collimator; and the same amount for both lenses).

    Blue Camera

    The blue camera has a beam that is split by a dichroic and operates from 0.4 to 0.55 µm. The blue camera (like the red) operates at f/1.20 and thus yields a 30 µm/arcsecond scale. A rendering of the blue camera is shown below, as well as RMS image diameter for polychromatic light. Note that the format of the Andor SCMOS is rectangular, so the rectangular format is shown in the image below. The color-coded radius is in units of inches so the range of 0.00033 to 0.0008 corresponds to 0.6 (blue) to 1.3 (red) arcsecond. Note that at the very corner the color-code is orange meaning that for the blue channel image diameters are always less than 1.3 arcsecond.

    Run 76m

    The blue camera (76m) is shown above. The P200 delivers a focal plane on the right hand side. A doublet-singlet-doublet serves as the nearly 230-mm focal-length f/3.3 collimator. The collimator has almost 100-mm of relief to bring the pupil onto the mouth of the camera. As a result, the two cameras are smaller than the collimator.

    Run 76m

    The blue camera polychromatic (wavelength 0.4 µm to 0.55 µm) RMS image radius as a function of field position is shown in units of inches. The color scale shown includes images from 0.6 to 1.3 arcseconds in RMS diameter.

    Red Camera

    The red camera accepts a beam that passed through the dichroic and operates from 0.55 µm to 0.80 µm. The red camera (like the blue) operates at f/1.20. A rendering of the red camera is shown below, as well as RMS image diameters for polychromatic light. The same scale applies as described in the Blue Camera section above.

    Run 76m

    The red camera (76m) is shown above. Note that the red and blue lenses look similar (by intent). The first doublet is the same, while the remaining elements are slight tweaks of one and other.

    Run 76m

    The red camera polychromatic (wavelength 0.55 µm to 0.8 µm) RMS image radius as a function of field position is shown in units of inches. The scale here ranges from 0.6 to 1.3 arcseconds in RMS diameter.

    Ghost Analysis

    A preliminary ghost analysis indicates the following:

    1. A 20-mm-diameter ghost-pupil image will be formed in a bounce from the back side of camera 3 to camera 1. Because of the hole in the primary, the ghost pupil may be non-uniformly illuminated. Further examination of the effect of the ghost pupil is required.
    2. The strongest ghost image is about 8 arcsecond in diameter which is roughly 4.5 magnitudes attenuated (-2.5 log(64)) and displaced from the object. How will this impact our science program?

    Sensitivity analysis

    Not yet performed.

    Thermal analysis

    Not yet performed.

    read more
  12. Install IRAF For MOSFIRE DRP

    I am attempting to install iraf on Ubuntu 12.10 within a virtual environment. This is an attempt to simplify the installation requirements for the MOSFIRE data reduction pipeline.

    Steps:

    1. Downloaded ubuntu desktop file (ubuntu-12.10-desktop-i386.iso).

    2. Installed on a 6 GB virtualbox disk. Drive was partitioned with 5.5 GB to data and 0.5 GB to swap.

    3. Downloaded iraf.lnux.x86.tar.gz from iraf.noao.edu. This is v2.16 of iraf.

    4. Added user iraf

    5. Installed tcsh

    6. Changed iraf's shell to /bin/tcsh; added setenv iraf /iraf/iraf to .cshrc

    7. As user iraf:
      1. cd $iraf/unix/hlib
      2. source irafuser.csh
      3. sudo ./install
    8. Complete

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  13. Moving Forward

    SED Machine has had its second "first light" and this time with a lot more success. Image quality is as uniformly excellent, with pupil images formed that are clean and sharp! The images in general look as predicted by zemax, which is great news.

    First light is now three weeks away.

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  14. SED Machine, Finder Telescope, Sagi Ben-Ami

    I'm back from a long hiatus! Full-steam ahead on the SED Machine project.

    The SED Machine camera ensures that the spectrograph is properly focused. Based on the range of temperatures at Palomar, we expect to only use a range of about 300 micron to maintain focus.

    Instead of using a dovetail system pushed by a lead-screw we use a pair of flexures from Riverhawk systems. The flexures are preloaded by a pair spring plungers (basically screws with springs to apply a load) against Newport actuator. Today in the lab I measured the final spring constant of the assembled system. The photograph below shows the testing setup: a simple scale gauge pulling on the camera barrel holder.

    SED Machine camera barrel mount.

    I love Hooke's law! The applied load as a function of displacement is shown below. The spring constant of the SED Machine camera is determined to be about 1.21 mil / pound force. Note that a mil is defined as inch/1000 or 25.4 microns. Recall that 4 mil is about the same distance as the diameter of a human hair!

    Load applied as a function of displacement.
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  15. SED Machine, Finder Telescope, Sagi Ben-Ami

    A few days ago an Orion ø80-mm telescope arrived. This telescope will possibly be used as a finder telescope for the SED Machine. One of Marin Anderson's projects is to make an automated sky-monitoring system with this little telescope. It can also be used to test some photometry experiments.

    The ED80 telescope was tested on the roof of Cahill. We could not find focus, however, we did see a large out of focus star move across the field.

    Load applied as a function of displacement.

    During the rest of the day Sagi Ben-Ami [who is visiting from Weizmann institute] continued work on an SED Machine optical test setup. Sagi is going to test his optical system in the lab by mimicing the P60. This requires some careful raytracing with zemax to figure out the position of the rays as they enter the system, which Sagi has done. Thus Sagi has designed a telescope simulator that represents the pupil position through the secondary and field lens on just a few feet of aluminum. He has also produced a number of nice shop drawings for the mechanical setup to hold all of these pieces together.

    IRMS

    Work continues on the IRMS design document. Today I adapted Harland Epps' work from the MOSFIRE pdr documentation. It goes without saying that Har's work is inspiring!

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  16. Chimera 2 Optical Design #3: 76q and 76s

    Chimera Mk.2 Optical design as described previously (76m) delivered poor-quality images. I made a mistake by not allowing the optimization to settle enough after adjusting lens edge thicknesses for manufacturability. While reoptimizing 76m (which is now called 76q) I reexamined the possibility of using the Wynne corrector. Thus I produced run 76s which uses the Wynne corrector. The advantage of the Wynne is that 76s requires fewer lenses while at the same time delivering better quality images. The disadvantage is that 76s has 8 more surfaces and will thus suffer 8 air-AR coating losses.

    This post describes the Chimera II optical design. Because of space constraints, I have designed a reimager system that uses a standard collimator-camera configuration. In order to cover two bands simultaneously, a red and blue camera are used. The design goals were (in order) to achieve f/1.2 focal reduction, have seeing-limited image quality over the Andor SCMOS device, try to keep fabrication costs as low as is reasonable and ensure the design is straightforward to build. To that end I have designed three lenses. The collimator start a fraction of an inch past P200 prime focus (the Wynne corrector is not used).

    The three lens prescriptions can be found in zemax archive format below:

    Run 76q

    Run 76q
    Run 76q Blue Spots
    Run 76q Red Spots

    Run 76s

    Run 76q
    Run 76q
    Run 76q

    Collimator

    The main difference between 76q and 76s is the collimator. The 76q design does not use the Wynne; while 76s does use the Wynne. Both lenses start within two inches of the P200 focal plane and accept a full field of view of 13.2 arcminute (diameter) and a wavelength range from 0.4 to 0.9 µm. The collimator accepts the full f/3.3 beam from the 200-inch Hale telescope and with a 8.5 inch focal length delivers a beam diameter of about 2.6 inch. When imaged by a perfect f/1.2 camera the collimated beam deliver seeing-limited images. Detailed description of the full performance is described in the camera sections below.

    To control cost, the collimator delivers a pupil on the camera's first element. As a result, the collimator is physically larger than the camera, but there are two cameras required for this system so that the total volume of glass in the collimator is about equal to the volume of the glass in the two cameras (about 650 for the collimator; and the same amount for both lenses).

    Blue Camera

    The blue camera has a beam that is split by a dichroic and operates from 0.4 to 0.55 µm. The blue camera (like the red) operates at f/1.20 and thus yields a 30 µm/arcsecond scale. A rendering of the blue camera is shown below, as well as RMS image diameter for polychromatic light. Note that the format of the Andor SCMOS is rectangular, and the spot diagrams show a variety of fields sprinkled across the format of the detector. The circle at 54 µ represents a 1.8" field of view; but note that RMS spot radii indicate sub-arcsecond native image quality. Zemax reports radii rather than diameters -- recall that one arcsecond is 15 µ radially. The worst images (RMS radius 24 µ) yield roughly 1.8 arcecond (aberration-limited) images while the best images are are 0.7 arcsecond (seeing-limited) images.

    Red Camera

    The red camera accepts a beam that passed through the dichroic and operates from 0.55 µm to 0.80 µm. The red camera (like the blue) operates at f/1.20. A rendering of the red camera is shown below, as well as RMS image diameters for polychromatic light. The same scale applies as described in the Blue Camera section above.

    Path to construction

    To take this design to a pre-construction state a ghost, sensitivity, and thermal analysis should be performed.

    Ghost Analysis

    Not yet performed.

    Sensitivity analysis

    Not yet performed.

    Thermal analysis

    Not yet performed.

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  17. Lots of software and software-engineering discussion in this blog today.

    MOSFIRE data reduction pipeline

    Worked with Andreas Faisst on a nasty mosfire data reduction bug. We engaged in some pair programming which turned out to be quite useful for me. I hope that in the future Andreas will be able to help me in the future!

    Reed Riddle's Talk

    Reed gave a nice talk about robotic astronomy. The key point is an essential one. It requires deep though to design something that is efficent, maintainable, and flexible. It is challenging to make a system behave well. Software often grows organically, sometimes organic growth works. Reed argues that best performance comes from good design -- though this is never demonstrated. The talk was architected to demonstrate both sides of the coin, first with TMT second with robo ao.

    TMT Site Testing

    Pre-selection of five candidate sites based on satellite studies of cloud cover and water vapor. Used identical equipment with emphasis on proper cross-calibration validity.

    TMT Candidate sites:
    Tolar, Armazones [VLT], Tolonchar, San Pedro, and Maunea Kea.

    Out of a suite of 12 instruments there was one seeing monitor and then some kind of turbulence or environmental monitor. The sites are environmentally tough so software has to be robust. The site-testing software was significant with 7 operating systems plus 12 scripting and programming languages. All of this grew organically.

    The organic growth meant that there was no way to design the system. As a result, the operations were sequential requiring blocked state. But as a result there was no coordination between the instruments and efficiency is low with something like 30% science time. It was also to difficult to maintain this system.

    Learned that there is no single right way to create a system. Early design decision affect the operational efficiency. No initial planning for software. It was hard to find time to make the system robust. Ultimate lesson: temporary fixes become permanent fixtures. Perfect is the enemy of good enough.

    Robo-AO

    Fully automatic adaptive-optics system. Lots of good details at the robo-ao website. End result is that seeing-limited images of 1" are converted into fraction-of-an-arcsecond images produced by Robo AO.

    'Half the resolving power of HST at less than a ten-thousandths of the cost'

    Robotic ao operations usually require a large staff. The vis AO at magellan has a team of engineers and staff monitoring the AO system.

    Robo-ao uses a modula control software syste. Robotic system, watchdog, system monitor, data system, and status system. Each subsystem is a demon and the demon has inherited a variety of code from one and other.

    Performance of robo-ao is impressive! Over half the observing time is science time.

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  18. Debonding Sylgard-184

    I accidentally bonded the achromatic camera 1/2 doublet in backwards. Camera 1 is a biconvex lens with a slightly different radius on side 1 than side 2. Yes, I _thought_ that I took all precautions: I compared the radius of surfaces by eye, and I also saw interference fringes from the matched ROCs of both elements. In retrospect, I should have marked both lenses so that during the application of the PDMS (aka Sylgard 184) I would not be able to make this mistake.

    Never-the-less both camera 1/2 were bonded incorrectly. The project cannot continue in a meaningful way until this problem is solved. I have now decided on taking two simultaneous forward paths and will use the path that will produce results faster. The most promising path, at this point, is to attempt to debond the doublet. Here I'll use toluene which turns out to stretch the sylgard-184 and cause it to delaminate.

    Thus, the next week and a half are now dedicated to fixing this problem. First light is six weeks away.

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  19. SED Machine Bonding Woes

    The bond of achromatic doublet cam1/cam2 went down without a hitch. Cam 1 is a CaF2 element and Cam2 is an i-line glass from Ohara. The bond with Sylgard-184 looks clean.

    Camera 1/2

    Camera 1/2 doublet - a success. Cam 1/2 was bonded three days ago, and it will cure for about three more days before it will be installed in the lens barrel.

    Today Marin Anderson and I planned to bond collimator 1 and 2. Unfortunately, collimator 1 is AR coated on both sides. I've put a call into the vendor and need more information to proceed.

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