Answer 1. We do not find the idea of outdoor pre-erection very appealing. It means that the entire telescope structure and drives must be protected against rain and dust. A more serious worry is the thermal distortion caused by direct sunlight on the structure. This will make the alignment process difficult or impossible. The C-Rings and the Azimuth Track have quite tight dimensional tolerances for steel structures which are 14 meters across.
However, I would say that we are open to creative thinking about other ways to "skin the cat". It could be that there is some kind of temporary structure that could protect against rain, dust and thermal distortions.
Answer 2. The correct list of spiders and dummies to be installed during telescope pre-erection is the paragraph 1.4.1.3 in Technical Specification 401e036e. Paragraph 3.8 of 401e028e states incorrectly that a dummy will be installed for the tertiary (M3) spiders.
Answer 3. There are several sequences of drawings showing the assembly sequence of the telescope on the mountain. Drawings 400e003 - 400e009 show the seven phases of mounting the Azimuth Frame structure. Drawings 500e014 - 500e056 show 43 phases of manipulation and erection of the telescope Elevation Structure. Only drawings 400e003, 500e020 and 500e056 were included in the original RFP package as examples, because these drawings mainly have to do with manipulation of the telescope pieces with the enclosure cranes to be certain that they fit through the floor hatch.
We have now added these to the RFP web site so that they are accessible.
Answer 4. The position loop of the Telescope will be closed around the Farrand tape encoders on the Azimuth and Elevation axes. The tape encoders will provide at resolution corresponding to at least 27 bits (depending on the interpolator electronics). We do not plan to install these tape encoders until the telescope is erected on the mountain. There are reference markers (probably Sony Magneswitches) every 22.5 degrees to provide a permanent position reference for the tape encoders. See drawing 410e022c for the location of these markers on the Azimuth Ring. Final absolute calibration of the tape encoders will be done while tracking stars on the sky. The velocity loop of the telescope will be closed around incremental rotary encoders on the individual motors and pinions. These are shown as Heidenhain RON 806 on drawing 520a010a. This motor/pinion encoders will be used to control the drives of the telescope during Factory Pre-Erection. We do not need sub-arcsecond pointing for the factory tests.
Answer 5. We apologize for omitting the drawing from your package. This missing drawing 674a005a.dwg is available on the web if others are also missing a copy.
The Technical Specification for the (Hydrostatic Bearing) Support System, 401a003i.doc, was not included with the present bidding packages as it was part of a previously released package. The document is available on the web under the RFP for the Hydrostatic Bearing System. Please contact the Project Office if you would like a fax copy.
Answer 6. Items supplied by LBT directly or through other RFPs will generally have their own internal fasteners, but they will not have the fasteners required to connect to the other parts of the telescope. For example, the Azimuth Frame will have its own internal bolts to hold the three sections together. But, the bolts which hold the motors to the Azimuth Frame should be provided by the supplier of Pre-Erection. This seems like an answer which is certain to have some exceptions to the rule.
Answer 7. During the pre-erection phase it will be necessary to supply shims (where necessary) to connect the structures. They will be manufactured in the same factory where the pre-erection will be done with the same material of the telescope structure (Fe 510 C) adjusting the thickness as requested. The fasteners will be the same indicated in the Technical Specification referred to the Metric bolts class 10.9, CNR-UNI 10011.
Answer 8. Yes, it is agreeable to us if you send the proposals by DHL on October 29 so that they arrive a few days later. Please send us by fax a copy of the proposal summary including the cost before the deadline of 5PM Tucson time.
Due to the upcoming deadline, these are the final answers to written questions regarding the proposals. We do not anticipate any extension to the proposal deadline beyond the "courier allowance" indicated above.