JCMT Pointing

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	General topics : current performance, problems, fact sheet
	Catalog : a caution re extended sources
	Pointing model : data acquisition and handling
	Inclinometry - measuring track irregularities
	Other things affecting pointing - e.g. : refraction, seeing
	Pointing Documents : including this year's occasional reports
	Pointing of other mm/sub-mm telescopes
	Time issues

General Topics

• General description of the pointing model of the JCMT
• Coordinate Concepts
• Techniques & tactics of pointing & focussing
• Latest Fact Sheet - the latest dedicated pointing run, and links to previous runs
• PROBLEMS - old and new
• History -
  • . . . of events affecting pointing
  • . . . of residuals with SCUBA and the heterodyne FEs
• Pointing catalog - blazars, UCHIIs, the Stephenson (2005) catalog of Carbon stars (of which our catalog contains a few).
  • Notes on Individual sources
  • Upgrade to J2000 - The case of the blazars
  • Distribution of blazars
  • (Optical) Finding charts for AGN
  • ICRS - the International Celestial Reference System; the foundation of all these positions.
  • SMA list - with 0.85mm, 1mm & 3mm flux updates

THE POINTING MODEL

• The 7 parameters of the basic model - their algorithmic forms and illustrations showing their effects on the pointing residuals.
  • Parameter Derivation : with TPOINT
  • Clock errors, and how to check the ASM clock.

• Data Acquisition
  • Pointing run tactics
  • The LOGGER task
  • TPOINT data format
  • Observational considerations
  • Discrete pointing observations
    • The heterodyne FIVEPOINT command
    • Heterodyne spectral line pointing
  • Continuous Tracking Experiments
    • Heterodyne tracking using fives

• How to Plot JCMT Pointing Data

• Data Processing
  • The analysis of JCMT pointing data is done with TPOINT
    (try here or here if the local .ps version doesn't work).
    The use of TPOINT is also described by Pat Wallace at his commercial website.
  • Single pointings may be used to update the collimations.
  • The case of multiple receptor options for pointing - as with HARP - requires knowledge of the receptor positions.
  • Full model determination and how to install the new model

• HARP K-mirror complications

Inclinometry - what it is, and where you do it. Example data, and the track model.

• Protocols
• Taking data
  • locally
  • remotely
• Trouble-shooting
• Levelling technique
• Format of inclinometry output
• How to reduce inclinometry data and install a new track model.
• Azimuths of wheel-joint interactions
• Prediction of pointing errors from track model parameters (F1,F2,F3)
• Roll
• Yaw
• Constructing a hybrid model
• analyzing inclinometry data for harmonic components
• transit-inclinometry -- see the transit step archive.
• Strain gauge data

Other quantities affecting pointing :

• Refraction
• thermal effects
• SMU & TMU alignment
• Water Vapour Meter archive (since ~ Feb 2004)
• Opacity archive and Opacity & Seeing GUI
• Seeing analysis by Jason Stevens (1995)

Documents

• Pointing Project Documents
• Search for documents on 'pointing' in JACdocs on 01 Nov 2000
• Reports to the JCMT Board
• Occasional Pointing Reports (by year)

• Pat Wallace's TPOINT program

• Related telescope documents
  • Telescope motion during slews/rasters - algorithms for accelerations & velocities

(Pointing of) Other (Submillimeter) Telescopes

Telescope
Pointing                         document	CSO	SEST	IRAM 30m in part. A.Greve et al, 1996. A&ASuppl. 115,3791	HHT
Telescope
Pointing                         document	OVRO Scott 1993	ASTRO Stark et al 2001 PASP 113, 567	KOSMA             (in German)	LMT
Telescope
Pointing                         document	ALMA J.G.Magnum et al 2006. PASP 118, 1257) Section 6	GBT Constantikes, 2006	CBI Cosmic Background Imager (26-36 GHz) useful trig formulae

Time

• 2005 IAU Resolutions on Astronomical Reference Systems, Time Scales, and Earth Rotation Models (G.Kaplan, USNO)
• IERS central Bureau
• Clock errors, and how to check the ASM clock.
• NIST page on time
• IRIG-B coding of time signal
• The U.S. Naval Observatory - keepers of the Master Clock.
• The IERS product Bulletin A provides UT1-UTC for updating the TCS pointing model. Predictions for the upcoming month or so have been used in the past with no noticeable loss of pointing accuracy. Updating THI.tide any more frequently would be tedious. I also receive this file by email once a week or so - see the main IERS page for their Request form. (See How to get UT1-UTC).
  
• For other Earth rotation parameters see the IERS Earth Orientation Parameters product centre. (eg Click on 'EOP combined series' then Series of the current year').
• Watch the USNO pages or IERS for announcements/status of Leap Seconds.
• AAS/DDA proposal to allow UT1-UTC to exceed 1^s, and to effectively eliminate the leap second.