The enhanced Agenda
from last month's meeting is available.
Action Items Science IPT telecon March 11, 2003
- Polarization widget:
Christine to e-mail to polarization experts to ask input on central
frequency. This has been done, and comments have been received from
several people (to be posted on the mmimcal web page?). The project
scientists will make a recommendation, to be reviewed by the ASAC.
Al to ask Steve Myers whether wider bandwidths can be used, using the
methods developed at lower frequency by Carlstrom et al.
- Single antenna design:
Scientific areas which benefit most from a single design (i.e. exactly
same beam pattern etc.) are polarization and mosaicing, but the
scientific loss if the antenna's are not identical is hard to quantify.
Operational costs will undoubtedly be higher if there are two types of
antennas, which will impact science indirectly by leaving less money
for other science-related items. This was thought to be a very serious
concern. All to send to Stephane a summary of their comments. Stephane
to transmit these concerns to the JAO.
- Fast switching tests:
Marc Holdaway's updated note to be posted on mmaimcal. Please send
somments in the next week.
- Site:
Lars-Ake et al. to submit memo in the next weeks on error analysis on
water vapor and delay from 183 GHz data following Delgado's work.
New weather data from Cerro Negro considered to be interesting to
obtain advanced warning of weather changes (~30 min up wind), but not
high priority to work on. Suggestion is to look first at differences
between Chajnantor and down wind (e.g. Pampa La Bola) as test, and also
at new report from Sarazin on satellite data.
- Calibration:
See minutes from telecon February 7. Dual load tests show rapid
variations with time and temperature. First semi-transparent vane tests
to occur in early May. New absolute calibration scheme by Jack Welch
considered interesting, if it can be done at 90 GHz rather than 30 GHz.
Stephane has made a revised plan, and Bryan and Stephane to pursue this
further. All to send comments to Stephane on plan.
- Configuration:
Stephane confirms that compact array should be designed to 15.15m and
urges John to submit document to ALMAEDM. The reconfiguration sequence
can be a separate document to ALMAEDM.
Mark to continue optimizing Y+ array with fewer additional stations
(more pads in common with John's array) along the lines outlined in the
telecon, i.e., reasonable compromise between highest angular resolution
and acceptable sidelobes.
- SSR:
Most urgent here is the question from Steve Scott about the data rates
for the enhanced correlator. All science IPT members to review Steve's
notes and send comments to project scientists in the next week. Main
question is whether the proposed increase in the AVERAGE data rate from
4 to 8 MB/s is O.K. This would mean that any project which needs a
higher average data rate has to specify it at the proposal stage.
Please think about this from the perspective of the science you would
like to do, e.g. line surveys, high-redshift CO blind searches which use
the full bandwidth at relatively high spectral resolution, ....
- Imaging:
Jerome Pety reported that the Japanese simulations are progressing well
and that transfer of expertise has been successful. See the PS plot of
(image and uv plane) fidelities as a function of the SNR for the m51ha
test image on
http://www.cv.nrao.edu/~awootten/mmaimcal/scipt11feb03.html. From the
fidelity definition, fidelity values will always be lower than the SNR.
Here the SNR is defined as the Image peak intensity / theoretical
noise, where the theoretical noise is deduced from the integration time
and Tsys . The interpretation of the results is not obvious. Indeed,
depending on the image properties (for instance its dynamic) the number
of pixels whose intensity is below (i.e. not detected) or above (i.e.
detected) the noise for a given SNR ( may vary a lot. This effect will
affect a lot the median fidelities computed in the image plane.
The question from Jerome to the Science IPT is: what is the range of
SNR that is expected for real science cases for such simulated images?
More specifically:
"What typical range of SNR can be expected to access to the scientific
goals for each of the standard images used in the memo #398 about ACA
simulations ?"
All to send comments to the project scientists in the next week.
The NA Imaging and Calibration Group has held several meetings; agendas
for those may be examined at:
- SSR fast data rate (John, Ewine)
- Operations/Design Reference Mission working group
To be covered in normal agenda:
-
Site:
document by Nyman et al. to be circulated
- Calibration: comments on new
calibration plan
comments on "science examples" document
- Configuration: final version compact array
to be submitted ***DONE***
optimization of Y+ array
-
SSR:
summary of AIPS++ review + response circulated ***DONE***
AIPS++ testing Phase II + II circulated ***DONE***
- Calibration (Bryan, Stephane)
- MILESTONES: all leaders of level 3 milestones with
March deadlines to
report on status
- new calibration plan
- science examples for calibration
- Brief reports from other subgroups:
- others (outreach, ...)
- configurations (Y+: Holdaway; antenna moves:
Conway)
- SSR (Lucas)
- site (Nyman)
- imaging (Gueth)
- Project news/updates;
Calendar
ALMA Board met, signed agreement.
Software IPT Preliminary Design Review
will be held in Tucson 18-20 March 2003.
AMAC Meeting 24-25 March
Socorro
ASAC Face-to-face Meeting 2-3 April 2003 in Grenoble, France at
IRAM.
May 26/27 ALMA Board face-to-face (Europe)
ALMA Week 2 June Victoria
Several of the below items were also discussed at length during the
recent mmaimcal and calibration telecons, but it is important to have
the input and comments of the entire science IPT before recommendations
are made to the project/ASAC.
See ImCal
and Calibration
for background information on some of the above items.
- Polarization widget: central frequency? See material at ImCal,
above. (Stephane/Al)
- Scientific benefits of a single antenna design. See Report.
(Stephane/Al)
- Fast switching tests. See material at ImCal, above. (Mark
Holdaway)
Reports from Subgroups
- SSR: fast data rate: have we reached a conclusion? Mel
Wright's comments. "We would like input from the Science IPT before
making this proposal and hope that you will help us. I have attached a
document (EnhancedCorrelator.pdf)
that attempts to make some assumptions to distill out reasonable
constants in the data rate equation. If these are accepted at face
value, the main unknown in the average data rate is the number of
channels. The second attachment (DataRates.pdf)
is our previous request for a rate increase. It contains more
background material and examples that are not duplicated in the newer
document."
Calibration telecon 2003-Feb-07; the minutes
are available. Note particularly the calibration scheme proposed by
Jack Welch, and a
modification of it proposed by Stephane Guilloteau.
