SONG Telescope and Control System Dome Installation SONG. Telescope and Control System Dome Installation

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1 Page 1 of 11 SONG Statement of Work and Technical Specifications DocNo.: Date: May11, 2009 Prepared by: F. Grundahl, P. Kjærgaard Rasmussen, Anton Norup Sørensen Approved by: J. Christensen Dalsgaard, Hans Kjeldsen

2 Page 2 of 11 SCOPE OF DOCUMENT This document contains the statement of work and specifications for the SONG telescope, dome and control system. ABBREVIATIONS AND ACRONYMS ADC Atmospheric Dispersion Corrector AR Anti-Reflection BFL Back Focal Length CCD Charge Coupled Device FOV Field Of View P-V Peak-to-Valley SoW Statement of Work SONG Stellar Observations Network Group TBC To Be Confirmed TBD To Be Defined/Determined TCS Telescope Control System WFS Wave Front Sensor

3 Page 3 of 11 The SONG Project SONG is an acronym for Stellar Observations Network Group. The goal of SONG is to construct a global network of 8, identical, 1m telescopes with two instruments per telescope, a high-resolution spectrograph and an imaging station for high-resolution imaging via the use of LuckyImaging. The network is focused on attacking scientific problems which require long-term, near-continuous monitoring of few targets. This calls for stable instrumentation and reliable dome/telescope (in terms of uptime) with a minimum of maintenance as well as remote/robotic observations. SONG has obtained funding for the construction of a complete prototype network node, to be installed at the Observatorio del Teide on Tenerife ultimo The prototype network node will consist of a 1m telescope housed in a conventional dome with two imaging cameras placed at one of the Nasmyth focal stations and the spectrograph in a separate building (Coudé focus). The optical layout of the Nasmyth and Coudé Train, with focal stations is now fixed and the detailed design and ordering of components expected to progress at a rapid pace during the spring of The optical design for the spectrograph and the Nasmyth imaging station is completed and SONG will be in charge of the full construction of this. The scientific instrumentation, including an atmospheric dispersion corrector (ADC) and optical field de-rotator is to be built by SONG. Illustration 1: Basic layout of a SONG node. The telescope will be located on the concrete pier next to the container, and the dome on the round structure. The development of the SONG prototype is a collaborative effort between the Department of Physics and Astronomy (IFA), Aarhus University and the Niels Bohr Institute (NBI), University of Copenhagen in Denmark. The principal investigator is Jørgen Christensen-Dalsgaard (Aarhus), project manager is Per Kjærgaard Rasmussen (Copenhagen) and the project scientist is Frank Grundahl (Aarhus). It is the expectation that a large scientific consortium will ultimately take charge of the full network, including orders for subsequent, identical, network node telescopes.

4 Page 4 of 11 Statement of Work (SoW) General Description This call for bids cover the following main tasks: design and construction of the dome for SONG. design and construction of the telescope for SONG, with a complete control system. shipping to, and installation on Tenerife, training of SONG staff and acceptance tests documentation on TCS, manuals, and maintenance For the first 3 items we wish individual quotations but we expect bids for all three. The two last points are expected to be included where appropriate. Project planning Cash flow Penalties We expect the contractor to match the following schedule and milestones: Milestone Kick-off meeting Critical Design Review Factory acceptance on Tenerife Acceptance and Training, Tenerife Deadline T0 T0 + 4 months T months T months T months The contractor shall update this project planning as part of the tender at the kick-off meeting. The intermediate milestones are flexible. Changes in milestones must be approved by the SONG consortium (principal investigator and project manager). The payment schedule will follow the rules of Aarhus University. Reviews, Reports and Meetings Meetings will as a rule take place at the contractor's works. Kick-off meeting: Clarification of open points and interfaces. Agreement on project planning with milestones and action lists. Critical Design Review: Review of the optical design and the plans for acquiring the optics. review, TCS review and freezing of optical and mechanical interfaces. Alignment concept and plan. Final definitions of acceptance tests. Factory acceptance: Test protocols, verification of pointing/tracking/slewing of the telescope and initial alignment tests. If possible star tests would also be preferred. on Tenerife: Transport, erecting the telescope and installing the dome on site, training of SONG staff. Acceptance, Tenerife: Acceptance protocols will be defined later in this document. Reporting, problems: The contractor should provide bi-monthly updates on the project progress and status. In case of major problems which conflict with the punctual delivery or technical performance this must be reported within 5 working days to the SONG project manager and project scientist.

5 Page 5 of 11 Description and Specifications for the The dome for SONG is expected to have an inner diameter of ~4m (TBD), and at most 5m, outer diameter. We wish to have a conventional dome. Roll on/off roofs, or clamshell type enclosures are not desirable for this project. At all sites it can be expected that snow, rain, hail, frost and high temperatures can be encountered. In addition high winds >65m/s can be expected. The dome should have the following specifications/capabilities: 1. When closed, the dome must be weather-proof - ie. closed to rain and snow. 2. Ability to close in all expected wind/humidity/frosty conditions. 3. The dome must be insulated in order to limit heating of the telescope during daytime (insulation better than 0.67W/m 2 K) 4. It should be sufficiently large that no collision is possible with the telescope and Nasmyth platform. 5. Should be under control by the TCS. 6. Must have manual control (keypad in dome) for local work. 7. Must have the possibility for full manual close in case of total power failures. 8. Possibility for upgrade with Air Conditioning systems during daytime to keep the temperature near the expected nighttime value. Indications of pricing and power consumption are invited. 9. The dome should have a normal outer shutter that can fully close it during daytime and in bad weather. In addition to this an internal aperture screen should be available which can limit the effective opening during observations to a size corresponding to the telescope aperture and thus act as an extra screen to protect the telescope from high wind and allow operations under higher-than-normal winds. Several professional telescopes have such a screen, eg. the William Herschel Telescope on La Palma. 10. During daytime SONG will point the telescope to the blue sky (completely away from the direction to the sun) in order to do spectroscopy of the blue skylight. We therefore need a way to feed sky-light through the telescope to the spectrograph. To be able to do this, we imagine a fixed window at a suitable position in the dome. This window does not need to be of imaging quality and could be made from plexiglass the only requirement is that it is transparent to light in the nm wavelength range, and conform to all the weather constraints above. For points 9 and 10 we leave it to the bidder to suggest possible avenues that would fulfill these requirements, while keeping in mind the other constraints on the system described in this material. Interfaces SONG will build the dome-support system and a well defined interface for the support of the dome must be available from the telescope provider at CDR. Figure 1 illustrates the basic layout of a node: a container is used for housing of instrument control computers and for a Coudé-room. The shown support for the dome will likely be slightly (~1m) higher to allow installation of side ports that can be opened during night time in order to ensure proper ventilation (avoid dome seeing). These details will be finalized with the successful dome provider. The telescope for SONG

6 Page 6 of 11 The telescope for SONG shall consist of a 1m, alt-az mounted Cassegrain-Coudé telescope. This document elaborates on the detailed specifications. Overall optical layout SONG will have two focal stations: a Nasmyth (for imaging) and a Coudé focus (spectroscopy). The general layout of the container, telescope and dome support is shown in Fig. 1 and the optical layout in Fig. 2. At the Nasmyth platform a mirror can be inserted to allow imaging with two cameras located on the Nasmyth platform by removing this mirror light passes on to a M4 which directs the light into the Coudé train where a field lens and a collimator is placed (between M4 and M6, see Fig. 2). This allows a collimated beam to be transported via M5, M6, M7 and M8 to a Coudé focus. Note that at the Nasmyth focus the allowed wavelength interval should be from 400nm to 1000nm with no requirements to access shorter or longer wavelengths. The successful telescope provider shall be responsible for the optical beam until (and including) M6 which will be located near the telescope base. SONG is however responsible for the Nasmyth instrumentation (ADC, optical field derotator, cameras, mirror-slides). Optics The optical system shall be of a Cassegrain-Coudé type with a total of six mirrors. The main characteristics are listed below. Primary mirror M1, free aperture 1.0m Field of view at Nasmyth focus ø =15 (this defines the diameter of M2) Size of M2 baffle No direct skylight for ø5' FOV. 1 M2 focus resolution and travel System focal nasmyth focus 0.6µm or better and ±3mm. F/36.7±0.2 System accuracy (after M3) λ/6 632nm within ø90 and ZD < 45º System accuracy (after M6) Mirror Material M1-M3 roughness, scattered light Wavelength-range (M1,M2,M3) Coating, M1-M3 λ/5 632nm, in an ø16 field. Low expansion Scratch and dig 40-20, Rq < 5nm microroughness nm ( nm most important). Al, protected. M4-M6 (480nm - 680nm) R>99%, λ/20 (all-dielectric coatings, off-the shelf components do exist) Back-focal-distance from Nasmyth flange 634 ± 150mm. In addition to the properties described in the table we mention that a thin primary mirror will be preferred over a standard thickness mirror, in order to provide a rapid cool down time. This probably requires the possibility to actively control M1 if such a strategy is proposed, a wavefront sensing apparatus must be provided as an integral part of the telescope. 1 At a later stage a rotating M3 may be installed to allow an ø15' FOV at the second Nasmyth port. This will demand a new M2 baffle.

7 Page 7 of 11 Illustration 1: Schematic layout of the optical system for SONG, with telescope, pier and Nasmyth and Coudé foci. A collimator placed between M4 and M6 must create a beam with a diameter of no more than 30mm for a 20 FOV and project a pupil image of 18mm diameter approximately (TBD) behind the F/37 focal plane. The pupil image must remain stable within 10% of its diameter for all telescope orientations and operational temperature range. The optics (M1,M2,M3) must have interferograms to testify their surface accuracy at factory acceptance. Final acceptance will take place via on-sky WFS tests. Note that the detailed specifications on back-focal distance, M2 diameter, M1-M2 separation and M1 focal ratio are still TBD as they depend on other parameters the final values will be determined in collaboration with SONG. Mechanics

8 Page 8 of 11 Telescope dimensions These should be compatible with the dome, and allow for the telescope to rotate 360 degrees with respect to the dome, without collision. Telescope structure We anticipate the use of a Serrurier truss design with a very high stiffness. The Coudé beam going from M4 to M6 will be located in vacuum tubes on the side of and below the telescope. Telescope mount The telescope must be on an alt-az mount with two fork arms. SONG will provide the concrete pier on which the telescope will be located. The detailed specifications for this will be discussed in collaboration with the successful bidder. The telescope provider shall also deliver mounting- and anchoring-bolts and additional special tools that may be required. The interface to the concrete telescope pier shall also be defined by the contractor. Bearings We will not accept bearings for the telescope that use oil pumps/pressure. Slewing, pointing and tracking The system must be capable of tracking at non-sideral rates for all solar-system objects where an appropriate set of orbital elements are available. A keypad must be available for manual control locally (dome). The telescope must be capable of reaching a horizontal position for easy access to the main optics (maintenance/cleaning). Slewing speed > 20º s -1 should be possible Acceleration and deceleration > 2º s -2 should be possible Pointing accuracy (all sky, ZD<70degrees) Differential pointing (over 1.5 degrees) Better than 0.5" Encoder step-size < 0.01" Tracking accuracy (no auto-guide) Tracking accuracy (no auto-guide) Zenith (tracking) blind spot Better than 5" (with pointing model) < 1" per 30min. < ±0.3" per 90 sec. Not larger than 1º in diameter. Instrument, observing flanges (Nasmyth platforms), and instrument volume The Nasmyth flanges must be capable of carrying a load of up to 250kg (non-rotating, stationary). At a later stage in the project it may be desirable to put instrumentation at the second Nasmyth platform, which requires that M3 can rotate 180 degrees. Therefore we require that this is possible without any effect on M1 and M2 and also we require that a price estimate of this upgrade should be included in the offer. Note the added restrictions mentioned under Item 4 in the dome specifications. The volume for instruments should allow for a 1m square x 400mm (high) box to be mounted on the nasmyth flange. See illustration 3. The Coudè M4 will be located outside this box, it is the responsibility of the telescope provider to ensure that the dome is sufficiently large that they cannot collide.

9 Page 9 of 11 In addition, space must be available inside the hollow part of the altitude bearing this should have a diameter of at least 190mm and be (at least) 500mm long. This volume will be used for an ADC and field de-rotator. Coudé train In the Coudé train the expected beam diameter is ~18mm (up to 30mm between M4 and M6), allowing the use of circular mirrors of 50.8mm diameter as M4, M5 and M6. The path from M4 to M6 should be in vacuum tubes (made from stainless-steel, unless otherwise agreed) with a pressure amounting to less than 1% of atmospheric pressure. The ends of the tubes should be closed with AR coated windows of 50.8mm diameter and approximately 10mm thickness. Focusing M2 will be used to control the telescope focus. The required resolution of M2 movement is 0.6µm in order to be sufficiently in focus. The telescope control system (TCS) must be capable of including a model for focus change with temperature and altitude. After setting at a focus value there should not be any power dissipated from the motor controlling the M2 movement. Protection covers When not observing, protective covers for M1 and M3 must be available. These must be motorized and controllable from the telescope control system. Manual covers for M2 will be sufficient. Safety Illustration 2: Available space at the Nasmyth station. The yellow volume defines the minimal space which must be available. The M4 for the Coudè train will likely be located just outside this box. All relevant and needed safety equipment for the telescope must be supplied (limit switches, hard stops, hardware

10 Page 10 of 11 emergency buttons etc). The limit and emergency switches should be controllable via the internet. Observing/operating conditions The telescope must be operational under the following conditions: Temperature between -20 C and +35 C Relative humidity between 5% and 95% (non-condensing) Wind loads up to 20m/s (12m/s for head-wind observations). Telescope Control System All operational functions of the telescope and dome must be under computer control, and the telescope control system (TCS) must provide the following functions: Control of the dome (open/close (partial and full), slave to telescope position). Must accept input from weather station and other environmental information that affect operations (including stop due to humidity, rain, snow, wind... ). Accurate time keeping (GPS). Power management systems for elegant exits (ie. enough power should be available to close mirror covers, park the telescope in a safe position and close the dome) in case of total power failures. Procedures for restarting the system (both local and remote) must also be available. Provide for complete remote control via the internet and allow for remote reboot of the TCS computer(s). Provide well defined, and documented, software interfaces for user applications to interact with the TCS (ie. query and provide information to TCS). SONG will provide autoguide signals to the TCS as part of its instrumentation package as well as an optical de-rotator and an atmospheric dispersion corrector. These need to be interfaced to the TCS. A graphical interface for manual observing. Capability for tracking at non-sideral rates and also solar-system objects (planets, moons, asteroids, comets). Optical Alignment Tools and procedures for aligning the telescope and Coudé train (until and including M6) must be provided. These tools must be part of the delivery such that they can be used by SONG at a later stage during maintenance (check and realigning, typically after M1 re-coating). These procedures shall be developed in collaboration with the successful telescope provider. Maintenance and spare parts Since the ultimate goal is to construct a network of telescopes with a long operational lifetime, maintenance issues are important. In the design of components extra emphasis on this must be kept in mind in particular necessary tools must either be provided or mentioned in the building offer as well as descriptions of the primary maintenance tasks and expected frequency of maintenance visits. Tools for mounting and dismounting M1, M2 and M3 (re-coating) must be provided, as well as suitable boxes for transportation. Mirror coatings

11 Page 11 of 11 The coatings for M1, M2 and M3 should be protected aluminium. For later re-coats the chosen coating solution should be so easy to remove that re-figuring of the mirrors is not necessary. Final decision on the coating choice will be made at CDR. and training The telescope and dome provider should also include the costs related to installation and training of SONG staff at the telescope site. The provider will be in charge of transport to site (with insurance) and installation on site. The telescope provider should also describe the content of the training needed and for which staff this training could be given. As part of the installation material, manuals and all relevant reference documentation must be provided. This includes (but is not limited to): Full TCS manual, Manual for optics removal and re-installation (for re-coating), alignment of the Nasmyth and Coudé system. User- and maintenance manual for the telescope and dome. Acceptance tests The following describes/list the requirements and specifications to be checked. Much of this should be done in collaboration with SONG- and contractor- staff, and the results will be recorded in a report and test protocol. The contractor may propose alternative test methods, but these must address all the items listed below. General items to be checked (F = at factory acceptance; T at Tenerife acceptance) are given in the table below. We have assumed that some on-sky testing is available at the factory. If this is not the case alternate testing schemes must be agreed on at CDR. Note: We can accept if the tests of the and Windscreen are not carried out at factory acceptance. Requirement Acceptance Check/Test method Pointing F, T On-sky test, build of pointing model. Tracking/slewing/offset F, T On-sky test, after build of pointing model. Image quality F, T On / off-axis WFS dedicated WFS, or Nasmyth camera analysis of defocused images. Image scale F, T On-sky test, astrometry of field with Nasmyth instrument. Alignment (Nasmyth + M4-6). F, T On / off-axis WFS, focal plane tilt measurement, Pupil motion. Focus movement/resolution F, T Through-focus exposures with Nasmyth camera. Pupil location/stability T Pupil viewer, part of Coudé instrument suite. Open/close of dome and wind-screen F, T 100 open/close/track tests can be done in daytime. Remote control F, T Via internet. The telescope shall come with a 2 year warranty including support to limit any downtime due to telescope technical problems. We invite a brief description of the envisaged 'service' level during the warranty period.