AST3 Experience Zhaohui Shang NAOC/Tianjin Normal University Chinese Center for Antarctic Astronomy

OUTLINE AST3 Project ( ) AST3-1 Story AST3-2 Story Other talks Xiangyan Yuan on telescope and tests HU Yi on operating softwares WEI Peng on special flat field correction MA Bin on dark correction and photometry

Antactic Survey Telescope x 3 (AST3) Three 50/68cm modified Schmidt Telescopes (NIAOT); - spherical corrector - short tube (optical length 2.4m) - aberration correction - atmosphere dispersion corrector (ADC) Filters: g, r, i Schmidt plate Aspheric primary filter CCD Window

AST3 CCD Camera (10k x 10k, STA1600-FT) No shutter, to avoid mechanical failure Operated in Frame Transfer mode ， 10k x 5k FOV: ～ 4.3 sq. degree (1”/pixel) 16 readout channels for fast readout

AST3 Sciences--- Time domain astronomy Supernova - Very early discovery - Uniform, multi-color light-curve Exoplanets - Transients - Micro-lensing Variable stars Quasar, AGN Gamma-ray bursts LMC,SMC - Nova - Micro-lensing … SN light curves Exo-planet micro-lensing

AST3-1 AST3 Solar panels Installed the 1st telescope at Dome A in January 2012 Power and communication by PLATO-A (UNSW) Instrument module Engine module A

AST3-1

CCD Controller Telescope Control Computer Disk Array Computer (x2) Pipeline Computer (x2) NAOC, Beijing PLATO-A Instrument Module Remote Computer AST3 MAIN COMPUTER LAN CCD Acquisition Card PCIe Optical fibre AST3-1 Operation in 2012 Iridium satellites

AST3-1 Timeline : installed at Dome A : started operation, for about 2 months : stopped due to power problem from PLATO-A : PLATO-A power restored : CCD controller failed (power supply?) Cannot move telescope in DEC, then in RA Cannot power-cycle operating computers （ ） Cannot boot telescope control computer （ ） 2013/2014: No traverse to Dome A

AST3-1 Data Sky Coverage 3TB ~26000 frames

AST3-1 Data Special treatment in data reduction Crosstalk correction (multiple readout) Dark correction (derived dark frame) Flat field (gradient in illumination) Results (details in Bin MA’s talk) Astrometry: ~0.1” Photometry: 5-σ: 19mag 2mmag for bright sources Catalogs to be realeased

AST : AST3-2 tested at Xinglong for 1 month : AST3-2 tested at Mohe until

AST3-2 ( Station, NAOC ） AST3-1

To be tested in Mohe village, China over the winter Lattitude: 52°N T: -30°C~-40°C (in winter) Planned during Tengchong meeting (2013)

AST3-2 Mohe Test Thanks to: NIAOT Chao Chen, Fujia Du, Bozhong Gu, Xiaoyan Li, Zhengyang Li, Qinghong Ling, Cheng Liu ， Haiping Lu, Chong Pei, Jun Shao, Haikun Wen, Linzhe Xu ， Shihai Yang, Xiangyan Yuan, Honghua Zhang, Kaiyuan Zhang, Ru Zhang ， Yi Zhang ， Zonghe Zhang PMO Lei Liu, Kelai Meng, Xueguang Zhang NJU Ming Yang NAOC Yi Hu, Bin Ma, Peng Wei

AST3-2 （ ）

AST3-2 Mohe Test : Started installation : Left Mohe Collected >10TB data SN survey from to Exoplanet survey from to (repeatedly observing two fields) Lots of engineering tests TPOINT Tracking CCD cooling (heat dissipated from the dewar)

AST3-2 Mohe Test—Real-time Status Following Michael Ashley’s idea on PLATO

CCD controller Power B currents AST3-2 Mohe Test—Real-time Status

Tempratures inside the main control computer AST3-2 Mohe Test—Real-time Status

The telescope and CCD controller survived -45 C. AST3-2 Mohe Test—Real-time Status

AST3-2 Mohe Test—Real-time Status

Control Room All computers survived -15 C. No cold start on-site. AST3-2 Mohe Test—Real-time Status

Two Problems: 1.High CCD Temperature 2.Large FWHM Daily Report

Limiting magnitude: i < 16.5mag 60sec Sky = 13.5ADU/s Dark = 31.7ADU/s Two Problems: 1.High CCD Temperature (High dark current) 2.Large FWHM

Limiting magnitude: i < 16.5mag 60sec Sky = 13.5ADU/s Dark = 31.7ADU/s Two Problems: 1.High CCD Temperature (High dark current) 2.Large FWHM

1. High CCD temperature Because TEC is used to cool the CCD Heat inside the telescope tube

2. Large FWHM 10 ms exposures Also because: Heat inside the telescope tube Because local seeing tube seeing mirror seeing optics tracking icicles in the air

Solution: Dissipate heat out of the telescope tube Date from Jan 1 st, 2014

Improved FWHM over time

Improved Limiting Magnitude ( ) Lower CCD Temperature Smaller FWHM Limiting magitude: r < 18.5mag 3x20sec down from i<16.5mag

AST3-2 Mohe Test – SN Survey First-time test of Photometry Pipeline with real data: (both aperture photometry and image subtraction) Dec 27started pipeline Jan 3made templates Jan 8started subtraction Jan 15 setup variable candidates website SN2014J in M82 discovered on 2014/01/ by Steve J. Fossey

AST3-2 Mohe Test – SN Survey Test of Automatic Photometry Pipeline with real data: (both aperture photometry and image subtraction) Dec 27started pipeline Jan 3made templates Jan 8started subtraction Jan 15 setup varible candidates website AST3-2 images (SN2014J in M82)

AST3-2 Mohe Test – SN Survey Test of Automatic Photometry Pipeline with real data: (both aperture photometry and image subtraction) Dec 27started pipeline Jan 3made templates Jan 8started subtraction Jan 15 setup varible candidates website TemplateNew image Subtraction result AST3-2 images (SN2014J)

AST3-2 Mohe Test – SN Survey AST3-2 Discovered SN2014M Spectroscopically confirmed by TNT

AST3-2 Mohe Test—COD performance COD: Control, Operation and Data system (Designed for fully automatic survey at Dome A) 1.Main Control Computer x 2 Survey Scheduling Data Acquisition Database Control other systems 2.Disk Arrays x 2 3.Pipeline Computer x 2 Real-time Pipeline (bandwidth too low to transfer images) １ ２ ３

Improvements of COD for AST3-2 Hardware redundancy (operation system) Control Computers and Network Data Storage Power Supply CCD Fiber-optic Communication … Software (operation & pipeline) Adding daemon processes ast3suite (HU Yi’s talk) 1-to-2 fiber-optic

AST3-2 Mohe Test—COD performance COD: Control, Operation and Data system Survey strategy needs to be improved

AST3-2 Mohe Test—COD performance COD: Control, Operation and Data system Computers never failed for 5 months Log(# of images)

AST3-2 Mohe Test—COD performance COD: Control, Operation and Data system Computers never failed for 5 months Fully automatic operation (unattended) Log(# of images)

CCD Controller Telescope Control Computer Disk Array Computer (x2) Pipeline Computer (x2) NAOC, Beijing PLATO-A Instrument Module Remote Computer AST3 MAIN COMPUTER LAN CCD Acquisition Card PCIe Optical fibre Simulating the Operation at Dome A Iridium satellites

AST3-2 Mohe Test—COD performance COD: Control, Operation and Data system Computers never failed for 5 months Fully automatic operation Data storage succeeded Pipeline succeeded Log(# of images)

AST3-2 Mohe Test—COD performance COD: Control, Operation and Data system Computers never failed for 5 months Fully automatic operation Data storage succeeded Pipeline succeeded Log(# of images) More work on: survey strategy pipeline generate light curves auto-identify variables …

A few words on traverse to Dome A No traverse 2013/2014. It is out of our control. There will be a traverse to Dome A in 2014/2015. We are not sure about the resources and man power we can get for AST3 project, so we need plan A, B, C, D, …

AST3 Experience It is not an easy project. We learned lessons in a hard way. We have gained lots of experience which are valuable for new/future projects. The entire AST3 system is more reliable now, but we still need to minimize possible single-point failures. Together, we can succeed!