[mmaimcal]ALMA Design Reference Science Plan
Al Wootten
awootten at nrao.edu
Wed Jul 2 11:58:30 EDT 2003
Dear ANASAC or Imaging and Calibration member:
The ALMA Science IPT has formulated an outline for an ALMA Design
Reference Science Plan. We solicit you comments and help in putting
this together. In particular, if you would like to aid us in
translating the ALMA science case into more finely detailed
specifications of what three years of ALMA observing with the full 64
element array would look like, please let us know. In particular, if
you would like to contribute specifications for ALMA experiments falling
into one of the subtheme areas below, please let us know.
-Clear skies, Al
*****************************************************************************
Outline ALMA Design Reference Science Plan
===========================================
EvD, SG, AW, update June 28, 2003
Goal: to provide a prototype suite of high-priority ALMA projects that
could be carried out in 3 years of full ALMA operations. This Design
Reference Science Plan (DRSP) serves as a quantitative reference for
developing the science operations plan, for performing imaging
simulations, for software design, and for other applications within
the ALMA project. Specifically, it can be used to:
- allow cross-checking of the ALMA specifications against "real"
experiments
- allow a first look at the time distribution for
- configurations
- frequencies
- experimental difficulty (fraction of projects that are pushing
ALMA specs)
- start developing observing strategies
- derive "use-cases" for the Computing IPT
- be ready in case some ALMA rescoping is required, or in case some
ALMA
specifications cannot be met.
Disclaimer: This plan, when written, will contain a representative set
of high-priority projects to be carried out by ALMA in a number of
different research areas, as envisaged by researchers currently active
in (sub)millimeter astronomy. However, since the scientific goals will
evolve over time, the actual 3 yr observing plan of ALMA by 2012 may
be quite different from this ALMA Design Reference Science Plan. The
DRSP is therefore a living document, to be reviewed and updated
periodically. Although an effort has been made to cover all subjects
and to include some of the most challenging projects, it is unlikely
to include all types of science that will be possible with ALMA. This
plan does NOT form the basis for any definition of ALMA early science
observing programs nor any `key', `large' or `legacy-type' programs.
This plan does not not apply to "Early Science Operations" when less
than 64 antenna's are available and where a different observing
strategy is needed (at least up to 32 antenna's). It considers only
the baseline ALMA project with Bands 3, 6, 7 and 9, but includes the
option to indicate whether the project would benefit from the ACA.
The DSRP should include the types of projects mentioned in the
"Science examples for calibration" document by Guilloteau et al.
How to develop the DRSP
=======================
DEADLINE FOR FIRST DRAFTS AUGUST 15, 2003
1. Science themes: take headings from the European science case
submitted to ESO council in late 1999. See:
http://www.eso.org/projects/alma/science/alma-science.pdf
This gives 4 themes and 21 sub-themes. Each sub-theme has a leader who
can enlist the help of other scientists in the community (preferably
ESAC/ANASAG) for help. Several names have been listed; the sub-theme
leader should contact them. Those with * have not yet been confirmed
or been contacted. Keep the number of people involved relatively
small to speed up the process and convergence. The sub-theme leaders
provide input to the overall theme leader, who makes an initial
coordination and balance of the programs in his/her theme, especially
in cases of large "oversubscriptions".
(Sub-)leaders should not feel obliged to follow precisely the science
described in the ESO document; it is just a starting point.
==============================================================================
Topic Leader Others
------------------------------------------------------------------------------
Theme 1: Galaxies and Cosmology [Leader: Guilloteau]
-------------------------------
1.1 The high-redshift universe Guilloteau Cox*,
Carilli*,Shaver,
Isaak
1.2 Gravitational lenses Shaver
1.3 Quasar absorption lines Lucas*
1.4 SZ with ALMA Hasegawa
1.5 Gas in galactic nuclei Carilli* Hasegawa
1.6 The AGN engine Carilli* Hasegawa
1.7 Galaxies in the local universe Wilson Turner*,
Tatematsu,Isaak
1.8 ALMA and the Magellanic Clouds Aalto*
Viallefond*,Rubio*,Tatem.
Theme 2: Star and planet formation [Leader: Wootten]
------------------------------------
2.1 Initial conditions of star formation Wootten Bacmann, Pety, Myers*,
Mardones*
2.2 Young stellar objects Richer
Bachi*,Mart-Pint.*,Gueth*,
Wright, di Francesco
2.3 Chemistry of star-forming regions van Dish Wootten,Schilke*,Tatem,
Wright
2.4 Protoplanetary disks Dutrey
Testi,Guilloteau,Mundy*,
Saito
Theme 3: Stars and their evolution [Leader: TBD]
------------------------------------
3.1 The Sun Benz
3.2 Mm continuum from stars ? Osten
3.3 Circumstellar envelopes Cernicharo* Lucas*
3.4 Post-AGB sources Cernicharo* Cox*
3.5 Supernovae Tatematsu Rupen
3.6 Gamma ray bursts Hasegawa Frail
Theme 4: Solar system [Leader: Butler]
-----------------------
(to be re-organzed by Bryan)
4.1 Planetary atmospheres Gurwell*
4.2 Asteroids and comets Butler Bockelee-Morvan*
4.3 Extrasolar planets ?
--------------------------------------------------------------------------
* To be contacted/confirmed
Wilson / Crutcher* to contribute to description polarization
observations, which are part of the various sub-themes.
2. Priorities and available time: the different science (sub)themes
need to be prioritized and assigned certain fractions of the total
time (3 yr). This task is most appropriate for the ASAC together with
the project scientists. As a starting point the following division
over the themes is proposed, based on the ALMA Level 1 science drivers
and proposal pressure at other telescopes in this wavelength
range. Assuming 100% observing efficiency 24 hr/day for 3 yr leads to
(numbers will likely be scaled down afterwards for typical
"weather/downtime" of 20%):
Theme 1: Galaxies and Cosmology: 40% = 14.4 months = 10500 hr
Theme 2: Star and Planet Formation: 30% = 10.8 months = 7880 hr
Theme 3: Stars and their evolution: 20% = 7.2 months = 5250 hr
Theme 4: Solar system: 10% = 3.6 months = 2620 hr
This should give the leaders of the various sub-themes a rough
indication of the scope of the programs they should aim for. Some
subtopics, e.g. 1.1 and 2.4, will likely require more than 1/7
respectively 1/4 of the available time in those themes. Based on the
first draft of the DSRP and "time pressure" to reach primary science
goals, the numbers can be re-adjusted in subsequent iterations by the
ASAC/PS.
3. Time estimates: one set of sensitivities needs to be used for
integration time calculations. Take those that are now on the ESO
ALMA Web at:
http://www.eso.org/projects/alma/science/bin/sensitivity.html
which are based on ALMA memo 393.
4. Write observing proposal: for each subtheme, leaders should provide
1. Name of program and authors
2. One short paragraph with science goal(s)
3. Number of sources (e.g., 1 deep field of 4'x4', 50 YSO's,
300 T Tauri stars with disks, ...; do NOT
list individual sources or your "pet object",
except in special cases like LMC, Cen A,
HDFS)
4. Coordinates:
4.1. Rough RA and DEC (e.g., 30 sources in Taurus, 30 in Oph, 20
in Cha,
30 in Lupus)
Indicate if there is significant clustering in a particular RA/DEC
range
(e.g. if objects in one particular RA range take 90% of the time)
4.2. Moving target: yes/no (e.g. comet, planet, ...)
4.3. Time critical: yes/no (e.g. SN, GRB, ...)
5. Spatial scales:
5.1. Angular resolution (arcsec):
5.2. Range of spatial scales/FOV (arcsec):
(optional: indicate whether single-field, small mosaic,
wide-field mosaic...)
5.3. Single dish total power data: yes/no
5.4. ACA: yes/no
5.5. Subarrays: yes/no
6. Frequencies:
6.1. Receiver band: Band 3, 6, 7, or 9
6.2. Lines and Frequencies (GHz):
(approximate; do NOT go into detail of
correlator set-up but indicate whether multi-line or single
line;
apply redshift correction yourself; for multi-line observations
in a single band requiring different frequency settings,
indicate e.g. "3 frequency settings in Band 7" without
specifying
each frequency (or give dummies: 340., 350., 360. GHz). For
projects
of high-z sources with a range of redshifts, specify e.g.
"6 frequency settings in Band 3". Apply redshift correction
yourself)
6.3. Spectral resolution (km/s):
6.4. Bandwidth or spectral coverage (km/s or GHz):
7. Continuum flux density:
7.1. Typical value (Jy):
(take average value of set of objects)
(optional: provide range of fluxes for set of objects)
7.2. Required continuum rms (Jy or K):
7.3. Dynamic range within image:
(from 7.1 and 7.2, but also indicate whether e.g. weak objects
next to bright objects)
8. Line intensity:
8.1. Typical value (K or Jy):
(take average value of set of objects)
(optional: provide range of values for set of objects)
8.2. Required rms per channel (K or Jy):
8.3. Spectral dynamic range:
9. Polarization: yes/no (optional)
9.1. Required Stokes
9.2. Total polarized flux density (Jy)
9.3. Required polarization rms and/or dynamic range
9.4. Polarization fidelity
10. Integration time for each observing mode/receiver setting (hr):
11. Total integration time for program (hr):
12. Comments on observing strategy (e.g. line surveys, Target of
Opportunity, Sun, ...): (optional)
Example from Al Wootten:
========================
1. Name: Infall toward protostars
Authors: A. Wootten, ....
2. Science goal: Detect molecular line absorption against the
continuum of a disk surrounding a protostar. The program is based on
the detection of formaldehyde at 1.3 mm in IRAS4A by Di Francesco et
al. 2001, ApJ 562, 770. Using IRAM, they detected H$_2$CO absorption
at 1.3 mm of $T_b = 10$ K against a continuum of 3000 mJy with a
velocity resolution of 0.16 km/s. This provides the best evidence for
infall, but it is currently only possible for the few brightest
sources. To generalize the result and to study the infall velocity
field in detail, we would like to do similar experiments on 30 sources
with 10 times weaker disks with a velocity resolution of 0.05 km/s.
3. Number of sources: 30
4. Coordinates:
4.1. 10 sources in Oph (RA=16:30, DEC=-24)
10 sources in Perseus (RA=03, DEC=+30)
10 sources distributed over sky (RA=any, DEC=any visible)
4.2. Moving target: no
4.3. Time critical: no
5. Spatial scales:
5.1. Angular resolution: 0.5"
5.2. Range of spatial scales/FOV: 11"x8"
5.3. Single dish: yes
5.4. ACA: yes
5.5. Subarrays: no
6. Frequencies:
6.1. Receiver band: Band 6
6.2. Line: H2CO 3_12 - 2_11
Frequency: 226 GHz
6.3. Spectral resolution (km/s): 0.05 km/s
6.4. Spectral coverage (km/s or GHz): 20 km/s
7. Continuum flux density:
7.1. Typical value: O.3 Jy
7.2. Continuum peak value: 0.3 Jy
7.3. Required continuum rms: 0.0002 K
7.4. Dynamic range in image:
8. Line intensity:
8.1. Typical value: 0.03 Jy
8.2. Required rms per channel: 0.1 K
8.3. Spectral dynamic range: 20
9. Polarization: no
10. Integration time per setting: 30 x 10 hrs
11. Total integration time for program: 300 hr
Note 1: since this is a substantial amount of time, may want to reconsider
fluxes of typical sources, number of sources, choice of line, linewidth,
etc.
Note 2: for projects having more than one frequency setting, items 6-10 need
to be repeated for each setting. For multi-line/chemistry surveys, these
can be grouped per band, by simply stating "5 frequency settings in Band 6"
etc.
*****************************************************************************
Copy of some Science IPT e-mail exchange; for your information
-------------------------------------------------------------
June 29, 2003
Dear Science IPT members,
Thanks to many of you for your detailed comments on the DRSP. Below
are responses to the points raised in the e-mail discussions. Please
remember that it is essential to keep this exercise as SIMPLE as
possible initially; we can always add further complications and
options after we have established the basic structure.
We are excited to get this DSRP "on the road" as soon as possible, and
urge the leaders of the various (sub)sections to get to work. The time
schedule is:
~Aug 10: Deadline to be set by theme leaders to receive input from
subthemes for initial coordination
Aug 15: Deadline for proposals from (sub)themes
Sep 1: First analysis by Project Scientists complete
Sep 5-6: Presentation to ASAC
Sep 22: Semi-final document sent to all contributors for review
Oct. 1: Comments due
Oct 15: Delivery of document to project
Note that we have to strictly adhere to this time schedule because of
the timing of the ASAC meeting and because several other IPTs need the
DRSP input urgently. Be prepared to give progress reports at the next
Science IPT telecons....
Looking forward to your input by August 15 (or preferably earlier!),
Ewine, Al and Stephane
**************************************************************************
Comments and recommendations on issues raised in e-mails:
========================================================
1. Form/Lay-out: an offical cover sheet/proposal form is premature at
this stage and not needed for our current purposes. A simple Latex
template will be circulated in July for everyone's use. For the
moment, please proceed in simple ascii following the outline given
below.
2. Parameters: several people have suggested to have primary
parameters (to be provided by the proposers) and secondary or tertiary
parameters (which can be derived afterwards). This is a O.K. in
principle, but in practice it turns out that some secondary parameters
(in particular integration time, see below) are best provided by the
proposer. Some secondary parameters have been included as "optional"
in the template. The DSRP experience will help to provide input to the
SSR/computing IPT which parameters are best taken as primary in the
ObservingTool.
3. Time estimates: please use the ESO time calculator for all time
estimates, which is based on ALMA memo 393. Since the actual receiver
and antenna performance will not be known until the first antenna's
are installed on the Chajnantor site, this "simple-minded" estimate is
more than adequate at this stage. It is more relevant for this
exercise that we all use the SAME time estimator. The times should be
calculated by the "proposers" themselves, NOT afterwards from the
rms. As noted by Stephane and Jerome, only those people intimately
involved in the science can make the necessary trade-off between
sensitivity, number of targets and time. Experience with previous
"DRM" or "guaranteed time" programs on space missions has shown the
same: use integration time rather than rms or S/N to define the scope
of your program; otherwise, it would require too much "back and forth"
interaction between the project and the proposers. The project can
always re-check or re-calculate integration times afterwards if there
are major changes in receiver specifications etc.
4. Stringency: this parameter does not need to be provided by the
proposer but can be evaluated afterwards. It is therefore left out for
now. It would be great if Mark can make a tool by September.
5. Coordinates: precise RA and DEC of individual targets are NOT
needed at this stage. Rough indications are sufficient. For example:
program wants to observe 50 YSO's: 10 in Taurus (+04, +25), 10 in
Perseus (+03, +30), 10 in Oph (+16:30, -24), etc.
6. Polarization: most people seem to favor polarization integrated
with the different science topics rather than as a separate
topic. Accordingly, no separate subtopic on polarization has been
added, but Christine Wilson and Dick Crutcher will be asked to provide
input and/or review polarization projects.
7. People involved: leaders are free to invite people from the
community to participate in the DSRP. Several volunteers have been
suggested and listed. This would be a great way to get some people
from the community involved in ALMA. On the other hand, in the
interest of making rapid progress and converging on a coherent DSRP,
it may be best to keep the "teams" relatively small, at most 4-5
people per subtopic. Leaders should take a broad view and make sure
that their team focusses on the main science drivers for ALMA, not on
`pet-projects' of individuals.
8. Science case: keep as short as possible. One paragraph should be
enough!
9. Disclaimer: a note has been added that this DSRP does in NO WAY
form the basis for any `claims' on targets or programs for early
science observing or for any `key'/`legacy-type' programs (if ALMA
would decide to have such programs).
10. Time "allocation": a rough starting division of time over the
different subjects is proposed, based on the ALMA Level 1 science
drivers and proposal pressure at other telescopes in this wavelength
range.
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