School2009/Agenda

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DAY 0: Sunday 12 July 2009

  • Arrive at CARMA. Campers go to Nelson Campground 1 mile from CARMA site after checking in at the CARMA Control building; others to dorm/cottage at OVRO as assigned by Mary Daniel.
  • Dinner will be not be provided on Sunday, so eat before you arrive or go to a restaurant in Big Pine or Bishop.

DAY 1: Monday 13 July 2009

7am-8am Breakfast at CARMA Site or Owens Valley Kitchen

If you are staying in the valley, eat in the kitchen. If you are camping, eat in the CARMA control building.

9am Welcome (Douglas)

  • Go round the room and everyone introduce themselves.

9:15-10:15am Introduction (Melvyn)

  • Goals for the week
    • Get some data, reduce it, make maps
    • Student presentations on Friday
    • Write a CARMA memo
  • Astronomy from comets to cosmology
  • Emission mechanisms: thermal and non-thermal
    • source selection: astronomy, frequency, size, brightness sensitivity
  • Atmospheric windows at optical, IR, and radio frequencies
  • CARMA site characteristics

10:15-10:30 am Break

10:30-11:30 am Aperture Synthesis Basics (Melvyn)

  • Radio antennas: collecting area and resolution
  • Aperture arrays
  • Response of a 2-element interferometer to point source.
  • Coordinate systems: (u,v,w), u,v tracks for different arrays.
  • CARMA array characteristics. antennas, Rx bands, correlator.
  • Aperture Synthesis Imaging.

11:30-noon Intro to CARMA computers (Marc)

  • Wireless setup
  • School data reduction and analysis space, login, passwords.
  • Computers, data flow, archiving
  • Control computer: roadmap of machines, disks, directories and subdirectories
  • basic observing procedures, on-line monitors and data inspection
  • key programs: sac, checksource, checkcat, checksafe (E array)

12pm - 1pm Lunch at CARMA Site

1:00-2:00 pm Basic demos (students guided by Nikolaus)

  • observe a point source (maser or quasar) and a planet.
  • plot amplitude and phase vs. uvdistance
  • constant amplitude for point source, Bessel function (with phase flips) for planet
  • set up correlator in various modes, take spectra of Orion

2:00-3:00 pm Observing Procedures (Melvyn)

  • Calibrations:
    • gain(t,f,p) - gain, bandpass, polarization, pointing.
  • Calibration intervals. V' = gain(t,f,p) x V + noise
  • Observing scripts
  • Selecting suitable observations for the target sources.
    • sensitivity
    • source size; mosaicing.
  • DEMO: CARMA sensitivity calculator
  • CARMA correlator capabilities; selecting a correlator setup (DEMO: Correlator Graphical Setup)
  • Choosing calibrators for gain, bandpass, flux and pointing. (DEMO: xplore)

3:00-3:15 Break

3:15-4:00 pm Group discussion selecting student projects. (Marc)

  • Students pair off on projects.
  • After discussion period, each group should
    • email one paragraph about project to memo organizer Marc
    • insert project via the proposal web page

4-6 pm Intro to preparing CARMA observing scripts (John)

Tutorial: generate the script for the first observing project. Afterwards student work on their individual scripts guided by staff.

6 pm Dinner at the CARMA site

Student projects observed on CARMA array overnight.

DAY 2: Tuesday 14 July 20

7am-8am Breakfast at CARMA Site or OVRO Kitchen

9:00-9:45 am Data Inspection and Analysis (Melvyn)

  • Overview of data reduction procedure
  • Introduction to MIRIAD data reduction package.
  • Basic Miriad data format: header, history, uvdata, gains, bandpass
  • Inspecting uvdata: uvindex, uvlist, uvplt, uvspec
  • Selecting uvdata: keywords select= and line=
  • Flagging bad data with uvflag
  • Antenna based calibration; selfcal and mfcal. gpplt. gains bandpass polcal
  • Rewriting edited data sets with uvaver, uvcat, uvcal

9:45-10:30 Observer's Everyday Responsibilities (Nikolaus)

  • creating master schedule and running observing scripts
  • deciding whether to do 1mm or 3mm
  • data quality reports
  • data archiving and disk management
  • flux calibration
  • etc

10:30-10:45 Break

10:45-11:15 Create draft observing schedule for the week (Marc with students)

  • compare with schedule() command.
  • DEMO: PDBI

11:15-noon Imaging (Melvyn)

  • Review of basic math: brightness distribution is FT of visibility data.
  • FFT requires convolving onto a grid; choosing the pixel and image size.
    • mosaicing
  • invert; choice of natural, uniform, robust weighting, effect on the synthesized beam
  • deconvolution algorithms: clean, maxen, mossdi, mosmem, restor

12 - 1 pm Lunch at the CARMA site

1-2 pm. Antenna tour (James Lamb; Dick; Erik Leitch)

  • Visit to telescopes. Intro to antenna hardware
    • antenna structure
    • drive system
    • manual, computer control
    • limits and switches
    • cable wraps

2-3 pm. CARMA Hardware I. Receivers and Calibration (Dick)

  • Introduce system block diagram;
    • receiver, cal load, local osc, phaselocks, fiber, downconverter, correlator
  • compute energy collected if observing 20 Jy source for 1 yr; would need to observe for 10^5 yrs to heat 1 drop of water by 1 C
  • receiver types:
    • bolometers: not suitable for interferometry because they don't preserve phase
    • HEMT amplifiers: not yet competitive at 1mm
    • heterodyne rcvr: downconvert to lower freq in a nonlinear device
    • SIS mixers: photon-assisted tunneling; not a Josephson effect
  • cryogenics; closed-cycle refrigerators, compressors
  • local oscillator: Gunn oscillator
    • must be synchronized between all antennas; discuss in lecture 2
    • both USB and LSB are downconverted to IF; can be separated with 90 degree phase switch; also defer to lecture 2
  • combining LO and signal: mylar beamsplitter
  • receiver and system temperature
  • calibration:
    • ideally, calibrate on loads outside the earth's atmosphere
    • the chopper wheel method

3:00-3:45 pm Troubleshooting on a real observing script (Students, John, Marc)

3:45-4:00 pm Break

4-5 pm Example data reduction using student data.

5-6 pm students prepare observing scripts, analyze data.

6pm Dinner at the CARMA site.

Student projects observed on CARMA array overnight.

DAY 3: Wednesday 15 July 2009

7am-8am Breakfast at CARMA Site or OVRO Kitchen


9:30-10:30 am Calibration (Melvyn)

  • Calibrations - gain, bandpass, polarization, pointing.
  • Antenna based calibrations: amplitude and phase closure
  • Atmospheric and instrumental phase characteristics
  • Tsys and Jy/K
  • Pointing
  • correlator calibration techniques.

10:30 am-noon Laptop tutorial data reduction and analysis of student data

12 - 1 pm Lunch at the CARMA site

1pm Bandpass Calibration with example (John)

1-2 pm Special Topics In Mapping (Melvyn)

  • The missing short spacing problem;
    • importance for getting correct answers for spectral index, etc;
    • negative sidelobes due to extended structure;
    • filling in missing spacings with larger single dish or Ekers-Rots scheme
  • Mosaicing: setting up grid files, linear and nonlinear mosaicing schemes
  • Heterogeneous array imaging

2-2:30 pm Correlator Tour (James)

Insert lost Mel lecture here?

2:30-6pm Calibration and analysis of student projects (all)

  • Students prepare observing scripts, reduce and analyze data.

6pm Dinner at the CARMA site

Evening - Group Photo (all)

DAY 4: Thursday 16 July 2009

7am-8am Breakfast at CARMA Site or OVRO Kitchen

9-10 am CARMA Hardware Lecture 2 - Local Oscillators, Phaselocks (Dick)

  • Review system block diagram, heterodyne system, local oscillator
  • Independent oscillators, 100 GHz, synchronized to fraction of one cycle over periods of hours (sounds hard)
  • Basic phaselock: mix with reference, low pass filter, generate correction voltage; keeps phase relationship fixed
  • CARMA phaselock chain; synthesizer, YIG, Gunn, 10 MHz, 50 MHz
  • Fiber system; linelength correction
  • Lobe rotation
    • compute differential doppler shift due to earth's rotation for 100 GHz signal incident on 2 antennas 10-m apart: 0.24 Hz
    • lobe rotators
  • interferometer response for a double sideband conversion system
  • need to offset freq of 1st LO as well as insert delays
    • can be understood as removing differential doppler shift due to earth's rotation
  • Phaselocks; the LO system
  • Cable length measurement system
  • Phase switching; Walsh functions
  • Sideband separation by phase switching;
    • note that only signals common to an antenna pair can be separated; noise appears in both sidebands
  • Fiber optic hardware

10:00am - noon Students reduce and analyze data

12 - 1 pm Lunch at the CARMA site

1 - 2 pm Combining Single dish and interferometric data (Melvyn)

2 - 2:30 pm CARMA Future Plans (Douglas)

2:30 - 6pm Students reduce and analyze data, work on presentations

6pm Dinner at the CARMA site.

Student projects observed on CARMA array overnight.

DAY 5: Friday 17 July 2009

7am-8am Breakfast at CARMA Site or OVRO Kitchen

9:00-10:00 am CARMA Hardware Lecture 3 - Correlator; Software Control (James)

  • review system block diagram
  • correlator is detector and spectrometer for the array
  • XF vs FX
  • delays, 2nd LO lobe rotation, sideband separation
  • correlator modes
  • FPGA's
  • noise source
  • basic architecture of computer control system, CAN nodes

10:00-12 Student Presentations

  • Each observing team will give a 5-10 minute presentation on their project

12 - 1 pm Lunch at the CARMA site

1-2 pm Array Reconfiguration (John)

  • moving the antennas and calibrating a new array configuration
  • finding new pad coordinates
  • finding pointing offsets.
  • finding the delay centers
  • radio and optical pointing
  • finding a baseline

2-4 pm Student Presentations continued

4-6 pm Analysis of student data and work on memo contributions

6 pm. Dinner at the CARMA site

  • Drink Beer (provided :-)
  • Decide on destination of hike.

Student projects observed on CARMA array overnight.

DAY 6: Saturday 18 July 2009

Group Hike, destination TBD.

Student projects observed on CARMA array all day and overnight (volunteer observer needed)

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