Last week we passed a significant milestone at the HET. We brought the tracker bridge out from Austin and lifted it into place. It went very smoothly and you can find a video of the lift at http://het.as.utexas.edu/wfu/.

This week we are cabling up the last of the X and Y cables. Then we will test the X motion of the tracker including the X-skew prevention under full closed loop control. Late in the week and extending into the next expect to start the installation of the Y drive system (including the so called anti-gravity drive). We hope to be able to gain back some of the two weeks of time we have slipped on the schedule by also putting the hex drive together at the same time.

Have a look at the link below for the promised video of the Last week’s work.

Cable Wrap Installation

Notice the use of hard hats in the dome (good safety practice) but it is harder to notice that everyone is freezing cold.

Last week we finished the cabling of the DAS box and populating most of the cables in the Azimuth wrap. We pulled in Resident Astronomer’s, Telescope Operators, the full day staff and even some people from McDonald Observing support. Thanks to everyone for the hours of hard work in the freezing temperatures. With so many people working so hard we neglected to take any photos of the work but I think we may try to put something together using the dome safety cameras.

This week we are getting ready for the new tracker arrival next week. This means we need to get the upper and lower X in full working order with limit switches in place, using the encoders for active feedback and have our emergency-stop system integrated into the new Tracker hardware. In addition to this work, we will be finishing decommissioning of the MRS enclosure to make room for the first group of VIRUS spectrographs to be shipped to West Texas sometime in the next month. We will have several different contractors on site this week. One connecting our large UPS system for the tracker, and another mounting the cryogenic lines from the site of the huge liquid nitrogen tank to the inner pier.

Last week we were successful in moving and aligning both the lower and upper X-slew axes. We also began the really massive task of cabling the tracker. Based on the rates of cabling we will likely be cabling until Thursday afternoon this week. This requires a team of ~10 people to connect the cable up at the DAS box and then down the cable trays, through the cable wrap, down to the spectrograph room and then through the spectrograph room cable trays into the lower electrical room.

Once the cabling is done we will start testing full motion of both X axes including limit switches and simultaneous moves of upper and lower x. All of this in preparation for the new tracker lift on the 18th (weather permitting).

Last week the team controlled the upper X screw for the first moves. The electrical team put the new Az wrap in place. Over the weekend we had a one-woman-team come in and paint the remaining weldments.

This week the mechanical team should finish getting the lower X components in place: encoder, lead screw, and energy chain. After those lifts occur the structure will be locked out and the temporary test cables will be removed and the final cables for the tracker will be installed. This is likely to take the rest of the week and perhaps the first few days of next week.

This will allow us a few days to test the upper and lower X motion both independently and working together in preparation for the New Tracker lift mid-Feb.

Last week we got the upper X rail ready for testing. This involved putting in the motor, encoder, rail and trolley. The test cables for the communication and control of upper X have been hung in place but not connected.

This week Ron Leck is on site to begin testing of the communications to the motors on upper X and if we can get all of the components in place to lower X as well. This will require us to connect the test cables (which do not go through the Az wrap) and thus will largely lock out any structure rotation of the duration of the test. The first motions of the slew motors will be open loop and will allow the mechanical team to see if the X-axis is well aligned. If all goes very smoothly near the end of the week we may get the laser tracker up and running to see the relative distances of the lower and upper trolleys over their range of motion.

While the structure motion is locked out, this will give the electrical team time to rearrange the Az cable wrap and once that is done to install the new cable wrap. This is likely to carry over into the next week as well.

Last week the team worked on getting the upper X rail ready for the lift of the encoder. We should be able to get the encoder in place and wired up by the end of the week. Over the last weekend we had Praxair truck on site to make sure that we can start our liquid nitrogen deliveries once the tank and VIRUS are in place. This went smoothly and TxDot was on site and will make a recommendation to widen a small portion of the Y at SPUR 77 and SPUR 78 to give the truck good purchase when making its wide turn.

Last week I also reported “The original scheduled date for the tracker to arrive was the week of Jan 27, as see in the gantt chart blogged on August 12, 2013. We should be able to make this milestone without any delays.” Given the high price of the crane services and the delicate nature of the operation we wanted to make sure we had everything in place and well tested before the tracker goes on. Thus, we have rescheduled the tracker lift for the week of February 17th.

Next week we will have Ron Leck out from Austin to test the upper X rail motion while the mechanical team assembles the lower X rail.

Despite the Holiday break we are having contractors work over the break both on the electrical power in the lower electrical room (for the new tracker) and in the dome working on the new in-floor trench for the liquid nitrogen, glycol and nitrogen gas.

In the past week we have finished the weldments on lower and upper X. This allowed us to lift the rail adaptors into place. We finished the touch-up painting of the lower and upper X beams to cover up the welding work.

The next update will be on the 2nd or 3rd of January.

Happy Holidays everyone.