Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Optical telescope wikipedia , lookup
Arecibo Observatory wikipedia , lookup
James Webb Space Telescope wikipedia , lookup
Lovell Telescope wikipedia , lookup
Allen Telescope Array wikipedia , lookup
Spitzer Space Telescope wikipedia , lookup
Reflecting telescope wikipedia , lookup
Very Large Telescope wikipedia , lookup
Array for Microwave Background Anisotropy AMiBA hexapod commissioning and pointing AMiBA team ASIAA NTU Physics On-site control room: Remote TCS 2005: on-site testing Antenna control computer Example: identification of oscillation problem and debugging (ACU) Mount assembly and intstallation of optical telescope (OT) from oscillations to smooth trajectories from hard limits to working safety checks Pointing control computer commanding possibilities: • preset az el pol (PTC) • startrack ra dec skypol (hexpol=const or skypol=const) • program track: ‘any trajectory’ from manual operation to automatic schedule from no star images to correct star positions ...to smooth operation Pointing error model: a 2-step approach 1st pointing run: all known pointing corrections activated (PTC) → ccd star position error as a function of mount position → separate average mount error from optical telescope (OT) error mount error = left-overs interpolation table Pointing error corrections define telescope pointing! jack corrections: jack pitch error compensation (“geometry”) temperature compensation 2nd pointing run: all known pointing corrections + interp. table jack rotation correction mode → check improvement •Expected ujoints locations and jack lengths support cone compensation mode pointing accuracy: ujoints jacks telescope corrections: RF/optical refraction mode without laser system: 12 arcsec OT correction → dominant correction with laser system: 6 arcsec error table interpolation → “left overs” 2006: Improvement in optical pointing performance with interpolation table azimuth signature perfect axes mount axes without interpolation table mount/cone tilt automatic pointing schedule: OT axes 1 hour ~ 100 star images (const. solid angle distribution over accessible sky) ccd image analysis: split error into azimuth and elevation error with interpolation table identify main OT signature (solid green line) and remaining pointing errors (red scatter) one iteration with interpolation table: pointing error in az, el reduced from 0.8 to 0.4 arcmin rms cone N misorientation N 2006: radio pointing: drift scan versus offset tracking A) drift scan B) offset tracking step patterns of 2 arcmin offset Ideally the centers of cut intersections should approach a specific line... compare maximum to find relative misalignment of different antennas Ant 1 Ant 7 elevation signature Ongoing efforts and next steps use each dish to measure total power of the Sun A) cut the saturated power curve horizontally to find the center, vs. B) scan around the Sun by offsets and compare their step-like patterns to find relative misalignment Polarization pointing 1-night-tracking Long-term stability and repeatabilty of pointing model 2nd,3rd iteration for interpolation table (goal: 10 arcsec pointing accuracy) radio alignment: goal : 2 arcmin relative alignment w.r.t central reference antenna integration of 2nd and 3rd OT