星網計劃 The NETS Project: The NEtwork of Transit Survey

1. 星網計劃The NETS Project: The NEtwork of Transit Survey 江瑛貴 Ing-Guey Jiang National Tsing-Hua Univ., Taiwan

2. Outline • Introduction • Why transit ? • Why another transit survey ? • Tsing-Hua Station • The Previous Progress • The Next Step

6. Why Transit ? • It is simple & fast • can scan more stars • It can determine the planetary orbital plane • And also size & mass of planets • It could be done by smaller telescopes • So, the cost is low • The timing of transit might be useful

8. TrES Network • The Trans-atlantic Exoplanet Survey (TrES) • Wide-field photometric surveys by small telescopes • Maximizing the monitered stars • Minimizing the time required of large telescopes • 3 small telescopes (10 cm) at (1) Tenerife, Spain; (2) Lowell Observatory, Arizona; (3) Mount Palomar, California • field of view: 6 degree • Spatial resolution: 11 arcsec/pixel

9. TrES-2

10. HAT-P-9b • HAT: Hungarian-made Automated Telescope • NATnet: 6 small (11 cm), wide field (8 by 8 deg) telescpes • Data was taken in 2004 and 2005 • Transit was found from data • Then, do following up

13. Why Another Transit Survey ? • The current on-going projects can only monitor up to a few tens thousand stars • To do a better job, we hope to monitor 10,000,000 (for 7 cm telescope) or 160,000,000 (for 12 cm telescope) stars • This will improve the statistics in the field of exoplanets • We hope to constrain long period exoplanets, too • We need a lot of time but small telescopes

14. Another Way of Sky Survey ? • Permanent non-tracking fixed telescopes • Drift Scan • Scan stars while the Earth Rotating • Can monitor much more stars automatically • Use an array of telescopes to continue the monitoring • It only suitable for certain events if the time scales are right • Data analysis is slightly more complicated

15. Would we miss any planets ? • Yes, but … (comparing with other projects) • For short period planets, the transit event would repeat. We will detect them finally. • For long period planets, the transit probability is much lower, so need to scan much more stars. • We get some constraints on the number of possible planets with longer periods

16. Tsing-Hua Station

21. Image Taken at Tsing-Hua

22. Preliminary Analysis • Sky Backgroud 3000 ADU • Many stars have 40000 to 50000 ADU • So, S/N is more than 10 • It is possible to do observations at Tsing-Hua Station • Flux variation is about several percent • The same order as O’Donovan et al. (2006)

23. a light curve

24. The Previous Progress • Oct. 2006: A prototype CCD-lens system is constructed • Jan. 2007: It took some testing data at Lulin • Feb. 2007: Starting the code development for data analysis (on going) • March 2007: Starting to plan the enclosure • April 2007: Observe with other telescopes • Oct. 2007: Theoretical Modeling of light curve

36. The More Previous Progress • July 2007: Weather Station arrived • Aug. 2007: WebCam (USB and PCI) • Nov. 2007: New Computer • Dec. 2007: Constructing the Enclosure • March 2008: Code for Enclosure Control • June 2008: CCD Install • Nov. 2008: Tsing-Hua Station Working

37. The Automatic Observation • Setting the time interval of observation • Open the enclosure on time • Only open when weather & UPS are o.k. • Start CCD whenever the enclosure is open • Stop CCD, stop taking images • Close due to weather condition, UPS • Close and stop observation when time is up

38. The Weather: Humidity

39. The Weather: Temperature

40. Enclosure Testing

41. The Next Step • Developing the data pipeline • Developing the codes • With the HAT results and our testing data, it is feasible. • We shall prepare to construct an oversea station, which will lead to scientific data • We shall think/talk about following up facilities