Software
- Test software
- Missing science specifications
5 Partners P. vanden Bout)
- - Spain wishes to join the ALMA project, by agreement with the ECC
- - Canada to join through the US. Official within a year
- - Japan (M. Ishiguru)
- 3-way partnership not possible at present
- Resolution drafted for ACC Nov 12 meeting:
- - to establish a joint scientific and technical working
group
- - to use best efforts to obtain approval and funding
- - to continue to work towards formal agreement on
enhanced project.
If no fast agreement possible, Japan will join later and make
unique contribution, with new capabilities (e.g. enlargement
of ALMA? array of small antennas? large single antenna?)
Maximize benefit by keeping close contact between ALMA and
Japan.
Good progress being made in Japan: 17 M$ - Prototype FX
correlator - 10-m antenna - high frequency receiver (800 GHz)
with array junctions.
6 Antenna status (P. Napier)
- June 1999 - 4 US proposals
- July 1999 - 6 European proposals
- Initial evaluation completed.
- Now in final discussions with companies to make coordinated
US/European contract awards. Cost within reach. Fixed price contracts.
Likely 24 month delivery rather than 21. Recommendation on two
successful companies in about 2 weeks. Contracts in 6 weeks.
- Surface accuracy 25 microns OK. Adding stability spec. Reset panels
every 5 years.
- Pointing. 0.6 arcsec offset. 2 arcsec absolute. Difficult but doable.
- Fast motion 3/6 deg/sec el/az. Acceleration 12/24 deg/sec/sec el/az.
- Not major cost driver. (but maintenance and lifetime unclear)
- Solar spec seem to be within reach, using machined grooves.
7 LO PDR summary (J. Payne)
- First "joint" PDR
- 3 options considered, option II being the baseline (approved)
- I Conventional
- II Photonic over fibers at about 100 GHz with multipliers
at each telescope
- III Pure photonic - no multipliers
- Phase noise independent of frequency up to 50 GHz (measured)
- Round trip pathlength correction tested up to 25 km at 25 GHz.
- NTT photodetector purchased, tried, tested at 100 GHz, and works!
- Calibration scheme using pure photonic LO.
- Recommend to focus on production plan.
8 Joint Receiver Development Group (J. Payne)
- Issues for science advice:
- Construction priority for frequency bands.
- confirm first production receivers are 115, 230 or 345, and
650 GHz. The issue of 230 vs 345 GHz needs to be revisited
by the new SAC. The US MAC favored 345 because it is in
the range of optimum frequency for dust emission and it
provides a reasonable intermediate step between 115 and 650
GHz.
- 30-45 GHz band?
- Circular polarization requirement. At specific frequencies ?
requirements for 183 GHz phase monitoring (field, optical axis
alignment, etc)
- total power stability spec
- nutating subreflector required?
- requirement for amplitude calibration accuracy
- Confirm the following specifications for switching frequencies
- - frequency switched 10 Hz, 50 MHz maximum switch
- - frequency changing in one freq band 1.5 seconds or less
- - frequency changing from the 3mm band to any other band
in 1.5 seconds or less.
9 30-45 GHz Band (A. Wootten, S. Myers)
- Scientific arguments for 30-45 GHz band (CMB fluctuations, S-Z
effect, low-J CO lines at high redshift, low excitation heavier
molecules with wide FOV, solar active regions (flare location), etc)
Need to know implications for system design
10 Miscellaneous issues (all)
- Priority among frequency bands: (1) 100 GHz; (2) and (3) to be
further discussed
- Polarization should be available as a standard mode. Need
specifications.
- Longest baselines (> 10 km): scientific need, surface brightness
sensitivity (Menten), topological constraints on site to be determined
- Short spacing recovery: simulations required
11 Status of WBS (R. Kurz)
- Management/administration (Brown/Kurz)
- Site development (Gordon/Hofstadt)
- Antennas (Napier/Andersen)
- Receivers (Payne/Wild)
- LO (Sramek/Wild/Guesten)
- IF/transmission (Sramek/Baudry)
- Correlator (Webber/Baudry)
- Computing/software (Glendenning/Raffi)
- System engineering & integration (Emerson/Guilloteau)
- Science (Wootten/Guilloteau)
- Details in document, 1st draft next week
12 New SAC advisory committee (R. Brown)
- Role:
- advice to both the ACC and Executive Committee
- address specific science issues, both directly and through
experts in community
liason with the project teams. Specifications and Goals.
- Two-way information for best science/technology tradeoffs
provide information to the community
serve as ambassadors for the project
- Composition:
- not too big; N/2 = 8 as an upper limit
- small enough to be effective, large enough to provide effective
- interaction with the community
- have external representatives, both geographic and topic
- membership remains constant through Phase 1
- Meetings:
- Monthly teleconference
- Twice a year face to face meetings
- easily accessible web pages
13 Recommendations on ALMA SAC
The US and European representation on the SAC is proposed as follows:
- US: 8 members + 3 ex-officio (US project scientist, Canada rep, Science & Technology liason)
- Europe: 8 members (the present 6 plus 2 additions) + 3 ex-officio
(European project scientist, Spainish rep, ESO rep (P. Shaver))
- Japan and Chile: Suitable arrangements should be made to include
imput from representatives of Japan and Chile.
- Interim Coordinator: N. Evans
Meetings:
-
Teleconference once a month. (2nd Tuesday of each month;
5 pm CET, 11am Eastern, 8am California). First teleconference
on the Tuesday following the Nov 12 ACC meeting, i.e. November
16th.
First face-to-face meeting near February 2000, or US break
(mid-march).
14 Other issues
- Form a joint Science & System group. SAC to recommend what should be
covered in that group.
- Brief discussion of several issues: polarization, long baselines,
configuration & topology, accuracy of LO settings at highest
frequencies, nutating subreflector, 30-45 GHz band (need for
engineering information, cost implications), frequency bands
(incl. 215-290 GHz), Zeeman splitting, correlator dump rate, first
and second generation specifications.