1. DEM Performance of LiJET (LiJiang Extremely High Precision ExtraSolar Planet Tracker) Liang Chang Yunnan Observatory changliang@ynao.ac.cn Aug.7th 2014 2.4m Telescope Group Yunnan Observatory of CAS 严谨求实 勤奋自强

2. Outline ： 1.Introduction 2.Mechanical and Environment Design 3.Calibration method 4.Performance of DEM 2.4m Telescope Group Yunnan Observatory of CAS 严谨求实 勤奋自强

3. 1.Introduction 1)LIJET (Lijiang Exoplanet Tracker ) Project collaborators: China: USTC, YNAO, NJU USA: UFL Supported by Chinese Academy of Science and National Science Foundation of China, University of Florida, and National Science Foundation of USA and also participating institutions including YNAO, USTC, and NJU. 2)Our Design Goals: (RVM) * Use low-cost, compact, robust, low maintenance, but high precision and throughput Doppler instruments * Target bright F,G,K dwarfs (V<8) with slow rotation for detection of super Earth mass planets, including habitable ones * Integrate at least 15 min to minimize RV noises from stellar oscillations for low mass planet detection * A nearly perfect match of ~15 min exposure time requirements and photon noise limit offered by a 2 meter telescope for 0.5-1 m/s * For asteroseismology, only target V<5 stars and ~1 min exposures * Target faint solar type stars up to V~12 for moderate-high Doppler precision measurements 2.4m Telescope Group Yunnan Observatory of CAS 严谨求实 勤奋自强

4. 1) Summary of DEM optical characteristics TelescopeLijiang 2.4m, F/8 Fiber Input Focal RatioF/4 Fiber Output Focal RatioF/4 Slit Size72um Main disperserR2 Echelle, 63deg blaze, 87 l/mm Cross disperserPBM2Y prism, 45 deg apex angle Collimated beam size85mm Detector4096 x 4096 CCD, 15 micron pixels SpectraDEM: 390nm-1000nm Spectra ResolutionDEM: R=30000 Fiber core diameterDEM: 50um

5. 2) Collimator and Camera

6. 3) Pre-slit Optics of DEM RVM and DEM have different pre-slit optics, dispersed interferometric fringe for radial velocity measurement and direct echelle spectra for other sciences. DEM Configuration

7. 7 Order 20, 1.0  m Order 52, 0.39  m Cross-dispersed echelle spectra of NSV 860 (K2 EB, V=8.7) in Jan. 10, 2010 R=27,000

8. 监视 CCD 科学光纤 定标光纤 LIJET telescope interface including a fiber feeding system, a fiber tip guiding and a calibration fiber light source. The calibration light was fed from the calibration lamps on the calibration bench inside the instrument control chassis 4) Guiding system

9. a) DEM Sky b) DFDI c) DEM

10. 2. Mechanical and Environment Design Top view of LiJET inside. An airtight chamber covers the entire instrument. The dimension for airtight chamber is 30”X30”X65”. The dimension for the thermal enclosure is W50”XL75”XH40”

11. 11 LiJET inside LiJET setup

12. 12 Chamber Thermal enclosure Echelle Prism Collimator/Camera 4kx4k CCD Interferometer RV input fiber DEM input fiber Pressure sensor

13. Temp. Control

17. Pressure. Control

20. 3 Calibration method Given LIJET is thermally and mechanically very stable over a long period of time, we only use bracketing exposures before and after science images to track local common path changes over the time and subtracting the small drifts during the exposure. We choose the ThAr emission spectra as our primary calibration source and the iodine absorption line spectra as a backup source and also zero offset checking. The ThAr calibration method has proven its power for measuring sub m/s velocity drift in HARPS (Mayor et al. 2003; Mayor et al. 2008). Fiber scrambler technology EXPERT ThAr 灯标灯通过加装扰频装置光纤后，视向速度的漂移，达到了 0.67m/s 的定标精度

21. 4.Performance of EXPERT DEM **RV results from EXPERT DEM to illustrate that the DEM can do quite good RV measurements (~5 m/s with a reference star, 36 Uma). ** 在安装了新的定标系统和光学扰频装置后，利用 DEM 模式，目前已经认证了 3 颗 太阳系外行星和 9 颗褐矮星，淘汰了一批太阳系外行星和褐矮星后选体。 左上为 EXPERT DEM 模式观测到的一颗 hot Jupiter(M=1.48 木星质量 ， P= 2.7 天 ) ，主星为 V=9.8 的 F 型恒星, KELT-3b (Pepper et al. 2013, ApJ, 773, 64). 左下为相应的光度测定数据， 右图为 EXPERT DEM 模式观测到的一颗 hot Jupiter(M=1 个木星质量 ), KELT-4b (Pepper et al. 2013, in prep).

22. 4.Performance of DEM Last update:201403,Change science fiber, Optical scrambler **HD 89269, V=6.65,G5V, 5min, S/N~125/pix (summed flux at 0.55um) **55 CnC, V=5.95,G8V,10min, S/N~300/pix **Based on this performance, we can reach S/N~40/pix for a V=12 star in 1 hour and **S/N~150/pix for a V~9 star in 1 hour. **Therefore, the current observational limit is about V~14 for the DEM mode,(good seeing for guider)

23. Conclusion * 尽管目前 LiJET 没有科学产出，但是 LiJET 的仪器性能已经被 EXPERT 仪器 所证明。 * DEM will Open to Astronomer from fall in 2014 * 致谢 所有利用 LIJET 数据发表的文章必须包括以下致谢： “The construction of LiJET was support by Chinese NSF, NSF, and participating institutions. The participating institutions are University of Florida, University of Science and Technology of China, Yunnan Astronomical Observatory and Nanjing University. The LiJET instrument technology development was funded by NSF, W.M. Keck Foundation, NASA, UCF-UF SRI program and UF. The operation of LiJET was supported by Yunnan Observatory of Chinese Academy of Sciences.”

24. The End Thanks