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Writing Proposals and Scheduling

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European Radio Interferometry Summer School 2011 Rimini, Italy Writing Proposals and Scheduling Tuomas Savolainen Max-Planck-Institut f. Radioastronomie – PowerPoint PPT presentation

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Title: Writing Proposals and Scheduling


1
Writing Proposals and Scheduling
European Radio Interferometry Summer School 2011
Rimini, Italy
  • Tuomas Savolainen
  • Max-Planck-Institut f. Radioastronomie

2
Outline
  • Designing an experiment
  • Scientific idea
  • Feasibility study
  • Choosing the array and its configuration
  • Some useful tools for planning
  • Writing a (good) observing time proposal
  • Scientific justification some dos and donts
  • Technical part
  • Proposal submission tools
  • Schedule / observing file preparation
  • An example of a VLBI schedule

3
Designing an experiment
4
Designing an experiment
  • Begin with a scientific idea
  • This is the fun part, but remember that the aim
    must be clear.
  • Make a proper literature search has someone
    already done the job?
  • Use ADS, CDS, NED and observatory archives
  • Check data from different surveys
  • Make a list of targets
  • You may need to revise this after checking the
    feasibility
  • Which array to choose?

5
Select a (trial) array
  • Are the sources observable from the array
    location?
  • Note the increased atmospheric noise for
    low-elevation sources
  • Continuum or spectral line?
  • Which band? (Check the source velocity for line
    observations)
  • Are multiple bands needed? Simultaneously?
    Frequency agility of the telescopes?
  • If observing lines, what is the required spectral
    resolution? Is your planned setup supported by
    the correlator?
  • What is the required angular resolution?
  • ?min??/Bmax
  • What is the largest scale of structure?
  • ?max??/Bmin

6
Image courtesy of NRAO/IAU
7
Freq.
ALMA
GMVA
gt 100 GHz
VLBA
PdB
ATCA
EVLA
eMERLIN
gt 1 GHz
EVN
LBA
Westerbork
lt 1 GHz
GMRT
Angular resolution
LOFAR
arcmin
arcsec
milliarcsec
8
Evaluate feasibility
  •  

9
Evaluate feasibility
  • Need a wide field of view?
  • Avoid time-average smearing -gt need short
    correlator integration time
  • Avoid bandwidth smearing -gt need high spectral
    resolution
  • Larger than the primary beam -gt multiple
    pointings, mosaicing
  • Note that this can generate a lot of data, so
    spend a moment thinking how you are going to
    handle it

Bandwidth smearing. Cotton (1999)
10
Evaluate feasibility
  • Calibration strategy
  • Phase calibrators / phase-reference sources (see
    Bob Campbells talk)
  • Special needs
  • Astrometry
  • Polarimetry (antenna leagake terms, EVPA)
  • Scheduling constraints
  • Fixed or dynamic?
  • Need for dry atmosphere (at high freq.) or quiet
    ionosphere (at low freq.)?
  • Sun limits
  • Coordinated observations with other instruments

Cas A
Image courtesy of NRAO/IAU
Does the chosen array/configuration/strategy
pass? If yes, go and write a proposal. Otherwise
start over.
11
Note about VLBI Selecting telescopes
  • Depending on the required angular resolution,
    sensitivity, and observing band one may choose
    EVN (multiple telescope choices), eVLBI, VLBA,
    HSA, GMVA, LBA or global VLBI
  • Check the (u,v) coverage!

Examples of EVN (u,v) coverages
12
Archives
  • Check the telescope archive for earlier
    observations of your sources
  • Need to re-observe?
  • Augment existing data instead starting from
    scratch?
  • Use to justify feasibility
  • EVN archive.jive.nl
  • VLA, VLBA archive.nrao.edu
  • MERLIN www.merlin.ac.uk/archive
  • GMRT ncra.tifr.res.in/gmrtarchive/
  • WSRT www.astron.nl/wsrt-archive/php/
  • ATCA atoa.atnf.csiro.au/

13
Some useful tools and links
  • EVN sensitivity calculator www.evlbi.org/cgi-bin/
    EVNcalc
  • ALMA sensitivity calculator almascience.eso.org/c
    all-for-proposals/sensitivity-calculator
  • EVLA exposure calculator science.nrao.edu/facilit
    ies/evla/calibration-and-tools/exposure/evlaExpoCa
    lc.jnlp
  • ATCA observing tools www.narrabri.atnf.csiro.au/o
    bserving/tools
  • Sched (useful for planning VLBI experiments)
    www.aoc.nrao.edu/cwalker/sched/

14
Writing an observing proposal
15
Observing time proposal
  • Common user instruments usually announce a call
    for proposals two or three times per year
  • ToOs are accepted any time
  • Different over-subscription factors at different
    observatories and at different LST ranges
    sometimes it pays off to know these
  • A typical proposal has three parts
  • Cover sheet (includes the source list and is
    nowadays usually generated by a web-based
    proposal submission tool)
  • Scientific justification
  • Technical justification

16
Scientific justification some dos and donts
  • A good scientific justification is
  • Clear and concise
  • Includes the necessary background material needed
    to understand the scientific goal but not more
  • Clearly explains how the scientific goal is
    achieved by making the proposed observations
  • It is a good idea to
  • Use (clear!) figures
  • Try to avoid
  • Unnecessary repetition
  • Too many buzzwords

17
Scientific justification some dos and donts
  • Telescope program committees hate to see
  • Poorly justified sample sizes
  • Why do you want to observe 10 sources? Why not 5
    or 100?
  • Fishing trips
  • We would like to observe this source to see if
    there is something interesting there.
  • Old hats unnecessary repeating of old
    experiments
  • Vague claims
  • No clear logical path from the observations to
    the astrophysical goal advertised by the
    proposers.
  • Non-scientific (i.e. political) arguments
  • Proposer not adhering to the given page limit!

18
Technical part
  • Justify the requested observing time
  • required rms noise
  • required (u,v) coverage
  • time needed for calibrators
  • Check that the required dynamic range is
    achievable
  • If non-standard setups or a very stringent
    scheduling is needed, it is a good idea to
    consult the observatory staff beforehand it may
    turn out that what you are requesting is in fact
    impossible to do.

19
Proposal submission tools
  • Electronic submission via web-based tools is now
    the norm (an exception is for example IRAM PdB)
  • Different tools for different observatories
  • EVN, WSRT, eMERLIN NorthStar (proposal.jive.nl)
  • VLBA, EVLA NRAO PST (my.nrao.edu)
  • ALMA Observing tool (download from
    www.almascience.org)
  • ATCA (opal.atnf.csiro.au)
  • Usually possible to modify the proposal until DL
    Submit early, modify and re-submit!

20
Scheduling an observation
21
Scheduling
  • After the acceptance of the proposal
  • Preparation of the required observing files using
    observatory-specific tools
  • Observatory staff checks the observing files and
    schedules the observations (either on a fixed
    date or dynamically)
  • Observing file contains
  • Array configuration
  • Receiver setups
  • Correlator setup
  • Scans of targets and calibrators
  • Constraints for dynamic scheduling
  • Can have a lot of details
  • Pay attention to
  • Visibility of the targets and calibrators and
    their separation on the sky
  • Duty cycles
  • Be extra careful if using non-standard receiver
    setups.
  • Be sure to observe all the required calibrators
    (flux, phase, polarization leakage and evpa,
    bandpass, fringe finder in VLBI observations)

22
OPT for EVLA
  • Log in at e2e.nrao.edu

23
Sched for VLBI observations
  • VLBI observing file (schedule) is prepared with a
    program called Sched, which makes control files
    for all the individual telescopes
    (www.aoc.nrao.edu/cwalker/sched/)
  • Sched handles automatically a lot of things like
    calculating the slewing times of different
    telescopes
  • Since VLBI telescopes are distributed around the
    world, your source transits at different times at
    different telescopes sites. The schedule has to
    match the allocated UT slot, which corresponds to
    the requested GST range. Use sched to check
    source uptimes already when planning the
    experiment.
  • If preparing VLBI schedule for the first time,
    seek help from an experienced user.
  • Remember to schedule strong and compact
    fringe-finder sources several times during the
    observation. Try to schedule these when they are
    observable from all the antennas.
  • Send ltobscodegt.key file to the observatory staff

24
Sched for VLBI observations
25
Sched for VLBI observations
26
Future proposal deadlines
  • WSRT Sep 15 2011
  • IRAM PdB Sep 22 2011
  • EVN Oct 1 2011
  • ATCA Dec 15 2011
  • GMRT Jan 15 2012
  • EVLA, VLBA, GMVA Feb 1 2012
  • ALMA spring 2012
  • GOOD LUCK WITH PROPOSAL PREPARATION!
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