Archeops Data Analysis Meeting
Friday 22nd October 1999

Next Meeting in Toulouse 26 November 19999



  •  Nabila Aghanim
  •  Alexandre Amblard
  •  Eric Aubourg
  •  Jim Bartlett
  •  Alain Blanchard
  •  Francois Bouchet
  •  Alexandre Bourrachot
  •  Francois Couchot
  •  Jacques Delabrouille
  •  F.-Xavier Desert
  •  Xavier Dupac
  •  Philippe Filliatre
  •  Ken Ganga
  •  Martin Giard
  •  Yannick Giraud-Heraud
  •  Jean-Christophe Hamilton
  •  Jean Kaplan
  •  Philippe Marty
  •  Fabrice Naraghi
  •  Michel Piat
  •  Daniel Santos
  •  Jean-Charles Vanel
  •  Didier Vibert
  •  Dominique Yvon



    Dear Archeops Collaborators,
    Here is some information about the upcoming Archeops Data Analysis Meeting. In order to prepare, we have some questions. PLEASE respond to the questions marked with '***' as soon as possible:

    *** Who will be coming? We need to know the number of people who will
    *** be here in order to make the preparations.

    *** Any other suggestions?

    *** If you have questions, please contact Xavier Desert (about the
    *** content of the meeting) or Jacques Delabrouille (about College de
    *** France logistics).

    === Logistical Information ===

    Date    : Friday, October 22, 1999
    Time    : 10 AM
    Location: College de France
              First Floor Conference Room, Building F
              (See below for directions)

    Directions: We believe that most people know how to get to the College de France. It is at the intersection of Rue Saint Jacques and Rue des Ecoles, in the 5th arrondissement in Paris. Once there, go in through
    the main entrance and tell the guards that you're here for an "Archeops" meeting at "PCC" and they will contact us to bring you to the meeting.

    For a map of the area and some other information (mostly for the non-French), see the web page

    === Outline of Agenda ===

    Morning  :

     The goal of the morning session will be to present what people have done thus far.

    *** Who would like to present something? In order to make the
    *** schedule, we need to know how many speakers there will be. The
    *** format will be very simple. We will try to organize things in the
    *** following groups, but additions and changes are always
    *** possible. If you are going to present something, please give us a
    *** sentence or two describing it, and tell us where you think it
    *** belongs in the list below.
    *** Each participant should prepare 2-3 transparents for a short
    *** presentation (5-10 minutes) of routine(s) that (s)he makes available
    *** to the Archeops collaboration. This should contain
    *** - goal of the routine (or set of)
    *** - language, and dependencies : e.g. C code need such_and_such library
    *** - algorithm
    *** - input-output
    *** - one example
    *** A simple postscript file could be sent to me just before the meeting
    *** to be posted in the software repository and on the web

    Data Extraction and Documentation
      Archiving (data, software, papers, etc.)

     Instrument Characterization
      Focal Plane

     Data Characterization

     Data Reduction
      Removing Drifts

      Stellar Sensor


     The afternoon session will be an open discussion of what was presented in the Morning session, as well as a discussion of what needs to be done, and how it should be organized and scheduled and assigned to people. Possible topics will include:

     Goals of First Iteration of Data Processing
      Accurate Boresight Pointing
      Focal Plane
      Beam Shapes
      Relative and Absolute Calibration
      See suggestions for many tasks below

     Format of Deliverables
      Software Repository and Packaging
      Documentation, Paper Preparations
      Data, Filters, etc.

     Data Analysis
      Likelihood Analyses

      What is the most critical task?
      Will there be conflicts when others have to return to the lab for
       the next flight?
      At the following meeting, we should have a first cut at maps and

     Possible Inclusion of new Collaborators
      - Stompor, Borrill & Balbi, suggested by Shaul Hanany from U.
      - Rome people (Vittorio & DeGasperis suggested by Paolo de Bernardis)
    on map projection softwares and C_l estimates.

    Ken Ganga, Jacques Delabrouille, Francois Bouchet,
    F.-Xavier D\'esert
    Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53,
    414 rue de la piscine, 38041 Grenoble Cedex 9  FRANCE
    Tel:  (+33) 4 7663 5512, Fax :     (+33) 4 7644 8821

    Some Thoughts On The Many Tasks We Need To Do

    Document and Archive Raw Data
      To Tape
      To Disk? On the Web?
      Obtain Flight Log
                Data Tapes
                Web-Based Log Book

    Extract Raw Data to something easily used (called it "Extracted Data")
      Extract Data
      Store extracted data on easily accessed disk
      Document and Archive Extracted Data
      Document and Archive Data Extraction Code (RCS? CVS?)

    Characterize Time Stream (Extracted) Data
      Visually Inspect Data
        Make plots
        Flag obviously bad data
          Log and Flag Obviously Bad Data
            How much is flagged?
          Find Explanations for Obviously Bad Data
            (is it in the Log?)
      Statistically Inspect Data
        Power Spectra
         PRODUCT: Estimate of noise level, 1/f knees, etc. as a function of
        Log and Flag statistically bad data
          How much is flagged?
        Find Explanations for Statistically Bad Data
          (is it in the Log?)
        Inspect Data in various Coordinates
          In Time
            Find Missing Data and Flag it (add new, flagged points?)
            Experimental variations?
            Changes in Responsivity?
              Changes in Noise?
          In Azimuth
            Earth Shine?
          In Elevation
        Characterize Time-Constants/Filters
          From Planets
          From Point Sources?
          From First Principles?
      Document and Archive Inspection Code and Flags

    Reconstruct Pointing
      With Galaxy
       PRODUCTS: Rough azimuth estimates (good to 1/2 deg.) with
                  associated sample numbers
                 Rough estimate of the elevation, assumed to be constant
      With Planets
       PRODUCTS: Focal Plane Map, with offsets in both elevation and azimuth
                 Beam Maps
      With Star Sensor

    Make Beam Maps/Focal Plane Map
      From Time Stream with Jupiter
      Compare with Saturn in Time Stream
      From Maps with Jupiter
      Compare with Saturn in Maps
      Other Sources/Galaxy?

    Reduce Time Stream Data
      Flag Cosmic Rays
        By Hand
        By Computer
      Flag Planet Sightings
      Remove Atmosphere and Drifts
        Correlate with high-frequency channels
        Use FFT or some other filter?
        Using cross-linking (best done iteratively with Map-making)
      Deconvolve Time Constants
      Document and Archive Time Stream Code

    Map Making
      Using simple binning
        Make error estimates
      Using complicated, "optimal" matrix methods
        Make noise covariance matrix
      Best done iteratively with time-stream reduction
      "Jack-knife" data
        In time

    Analyze Maps
      Investigate Noise properties
        Histogram of noise
        Check covariances
        Check Gaussianity
      Correlate with foregrounds
          Cross-check with planets
        Point sources?
        Vary galactic cuts and make custom cuts
      Characterize CMB
        Make correlation function.
        Make power spectrum with FFT methods
        Make power spectrum with likelihood methods
          Account for dipole/foreground removal
        Fit power spectrum to CMB power spectra
        Fit data directly to CMB power spectra
        "Jack-knife" data
          In time
          On Sky
          In Azimuth