1. An Introduction to mini-SONG Project Xiaojun Jiang Natioanl Astronomical Observatories Chinese Academy of Sciences

2. Contents:  Overview of the mini-SONG project  mini-SONG telescopes  mini-SONG instruments  progress and project schedule

3. Overview of the mini-SONG project  Plan to setup on the 4 SONG sites in Northern Hemisphere  Consists of a 50-cm twin-telescope at each site  Scientific goals:  General multi-color survey of open clusters  Long term multi-color time-domain observations of selected cluster fields  Superiority:  Global network groups  Long time baseline  High resolutions in frequency space  Multi-color photometry

4. mini-SONG telescopes  Structure:twin telescope  Aperture:50cm  Mount: German EQ  Optical system:Ritchey-Chrétien  Focal ratio:F/3 primary; F/9.5 system  Focal length:4753mm ± 25mm  FOV:20' x 20'  Wavelength: B or V for one telescope and R for the other (covers Johnson, SDSS, Strömgren systems)  Mirror material:Astro Sitall  Coating:Al+SiO 2, Enhanced Aluminum (SiO2/TiO2) Overcoat  Wave front accuracy: ≤1/8 λ @633nm

5. mini-SONG telescopes cont.  RC Open Truss Carbon Tube  Precision Secondary Mirror Focuser  Conical Secondary Light Baffle  Lateral roller bearings support mirror cell  Active computer controlled cooling  “light weight” Dovetail Plates Dust Cover over primary mirror  Focuser capacity: 8Kg  RC Field Flattener/Corrector  Direct Drive Mount  8" RMS pointing accuracy(Zenith distance <70 degree)  Open-loop tracking: 0.1" over 10sec and 0.35" over 300sec RMS  Slew speed: 10deg/s for both axes

6. mini-SONG telescopes cont.  Dome Design  Diameter 4m  Total height 2.9m  Total height when parked 2.5m

7. mini-SONG instruments  CCD:  Andor, DZ-936  Pixel size: 13.5 μ m  Active pixels: 2048x2048 (20'x20')  Filters  Size: 50mmx50mm  Thickness: 5mm  Positions on each wheel: 4

8. Progress and project schedule  2011.6 – Completed project review and evaluation  2011.7 – Completed detailed design, review and evaluation  2011.8~2011.10 – Key components order  2011.11~2012.6 – Telescope structure machining  2011.11~2012.12 – Control sys. development and debugging 2011.11~2012.12 – Software development and debugging  2012.07~2012.09 – Telescope assembly  2012.12 – Complete whole structure assembly, development of control system/software/networking, etc.  2013.01 ～ 2013.04 – On-site installation and commissioning  2013.05 – Acceptance test

9. Problems  Sites: no confirmation/permission excepts Chinese site  Construction: finished preliminary design, need detailed site info to complete final construction design

10. Thanks!