AST3: Robotic Operating Software & Data in 2012 from Dome A

Presentation on theme: "AST3: Robotic Operating Software & Data in 2012 from Dome A"— Presentation transcript:

1 AST3: Robotic Operating Software & Data in 2012 from Dome A
Ma Bin (NAOC) Shang Zhaohui, Hu Yi, Wei Peng China-VO Xingchang, Zhejiang

2 Outline 1 Robotic Operating Software Suite 2 Overview of the data
3 Image Reduction 4 Aperture Photometry 5 Summary

3 1 Robotic Operating Software Suite
AST3要在南极高原冰穹A无人值守地进行自动巡天，由于昆 仑站电力、通讯的限制，我们开发了一套自动控制软件： 与望远镜控制程序和CCD控制程序通讯，控制望远镜和 CCD 采集CCD数据，生成标准FITS格式图像文件 图像分发与存储 管理AST3运控系统串口、硬盘阵列等设备 完整的运行日志记录 不间断自动运行

4 ast3suite的设计方案 采用C/S架构，客户端只发出硬件操作请求，由单一的服 务器端程序完成实际的读写操作。
服务器端采用多线程编程模式，支持多客户端并发访问。 服务器与客户端程序之间采用TCP/IP的方式进行通讯。 脚本胶水语言串联客户端程序完成自动观测。

5

6 漠河运行测试 ast3suite所有守护进程 能开机自行启动，并提 供各自的服务。

7 2 Overview of the data 10K * 10K STA CCD 1”/pix SDSS-i filter
Retrieving 1.6TB compressed data ~26,000 frames, including both test and scientific images

8 Obs. targets Num of fields Sky coverage (deg2) Num of frames
Total exptime (hr) LMC 50 ~200 664 10.60 SMC 12 ~50 55 0.90 SN Survey 496 ~2000 3334 55.55 Num of frames Total exptime (hr) LMC-center 4753 62.00 Transit 3398 36.43 WR stars (9 fields) 3454 23.70

9 Image quality Issues: high tCCD high FWHM elongated
FWHM: seeing, optical, tracking Dark: C

10 I(x,y) = bias(x,y) + dark(x,y)*t + F(x,y)*t*f(x,y)
3 Image Reduction I(x,y) = bias(x,y) + dark(x,y)*t + F(x,y)*t*f(x,y) Crosstalk Overscan (bias) Dark current Flat field (by Wei Peng) Engineering-grade CCD

11 Dark current correction
high tCCD Dark(x,y,t) = D(t) + Δd(x,y,t) Δd(x,y,t): non-uniformity -> noisy Dark frame not Dome A Dark current changed since lab test raw Corrected by lab dark

12 Deriving dark frame from obs.

13 Derived dark 230 pairs of images @ -41.8℃ Fainter image: 660ADU k ~ 4
Median combining -> master dark frame Lab dark Derived dark

14 Correction effect background ~ 620ADU, -41℃ Raw RMS ~ 56 ADU
Corrected by lab dark RMS ~ 45 ADU Corrected by derived dark RMS ~ 24 ADU

15 Photometric precision & depth improved
Images with background ~ 550 ADU: Correction results in similar background rms (photon noise)

16 4 Aperture Photometry Photometry: Sextractor Astrometry: Scamp
Catalogs crossmatched based on RA, DEC Relative calibrations between catalogs Absolute calibrations to other surveys APASS: SDSS-i (I < 16 mag) DENIS: Gunn-I

17 Astrometry precision SCAMP ref. cat: PPMX (~0.04”)
External RMS: 0.09”(RA), 0.13”(DEC) Internal RMS: 0.1”(all), 0.04”(bright)

18 Photometric precision
Δmag between a and a Scatter of Δmag as photometric error 5-σ: 19mag, bright end: ~ 2 mmag

19 Calibration between catalogs
Relative calibration for long monitored fields dependent on CCD position(X,Y) --detrending

20 RMS of LCs XY-detrending calibration Constant calibration

21 LCs of HD

22 Data release Catalogs -> database (Tianjin Univ.) -> crossmatch, light curves Time cost: 30k sources: 40 sec -> 2k catalogs/day Data volume in the future SNsurvey: ~50k catalogs/yr Transit: 100k-200k sources/cat, 200k catalogs/month Released via China-VO

23 数据保护期，暂时只对AST3合作单位开放

24 5 Summary A new method to derive dark frame from obs. images
Astrometry precision: ~0.1” Limiting mag: i ~ 19 60sec ->SNe (low tCCD, small FWHM) Photometric bright end: ~3 mmag (single frame) ->transit (stable tracking & pointing) The catalogs (images?) will be released via China-VO

25 Thanks!