From ewine at strw.leidenuniv.nl Thu Mar 1 08:19:24 2001 From: ewine at strw.leidenuniv.nl (Ewine van Dishoeck) Date: Thu, 1 Mar 2001 14:19:24 +0100 Subject: [asac] copy of letter/NSF budget Message-ID: <200103011319.OAA17852@nitrogen.strw.LeidenUniv.nl> Dear ASAC members, Below please find a copy of the final version of our letter as sent to the ACC early this morning European time. Thanks to everyone for their constructive inputs, and especially to Christine for improving the flow of the sentences. Yesterday night, the bad news about the NSF budget for FY2002 was released, including the lack of any new starts in FY2002. A copy of the message from Paul Vanden Bout to the NRAO staff is included below. As Paul states, the community will need to work together with NRAO to inform the Federal government of the importance of ALMA and the need to get at least continued D&D funding for 2002 to keep ALMA moving forward. The consequences for the project is obviously something we will need to discuss further in our March 14 telecon. With best wishes, Ewine ----------------------------------------------------------------------------- To: ALMA Coordinating Committee From: ALMA Science Advisory Committee February 28, 2001 Dear ACC members, In early February 2001, the ASAC learned with dismay of further financial pressures on the ALMA project that could impose a budget limit of $663M on the three-partner project. At its previous meeting in Berkeley in September 2000, the ASAC (including informally its new Japanese members) outlined a plan for the enhanced ALMA. This plan included: a new compact array (the ACA), which would enable new science and enhance the capability for wide field imaging; a suite of ten receivers, which would enable a rich astronomical program over all of the available millimeter/submillimeter atmospheric bands; and an enhanced correlator, which would significantly increase the speed and sensitivity of the system. In October 2000, we learned of a proposed 10% cut in the budget, and we began planning to discuss accommodation of that reduction during our February 23-24 2001 meeting in Florence. With the proposed further reduction, the new budget limit of $663M results in only a modest increase over the original $552M budget of the combined European/American partners, despite the joining of our Japanese colleagues in the project. Further, some of this increase must go to the additional overhead of a larger organisation. Since the observing time is now divided three ways, the advantage to each of the partners of combining the LMSA/LSA/MMA projects is considerably diluted. The impact on the science program from this proposed further reduction is considerable, as little more than the ACA and one additional receiver band (band 10, for a total complement of five receiver bands) can be added. The ASAC has become convinced of the importance of the ACA through imaging simulations presented at the Florence meeting. At the 10% cut level, a total of 8-10 receivers could be included in addition to the ACA. With the proposed 20% cut, the loss of bands 1, 4, and 8 eliminates substantial and important science. Band 1 at a wavelength of 7 mm offers unique capability for studying large scale structures forming in the denser parts of the early universe and for investigating the innermost parts of disks forming around young stars. It would bring a whole new user community - the microwave background astronomers - to ALMA. Band 4 at 2 mm is important for the study of the formation of massive stars, in particular as signatures of distant (early) galaxy formation. It is also rich in molecular lines which are important for astrochemistry. Band 8 at 0.6 mm contains significant continuum emission from newly forming low mass stars and the emission from ubiquitous atomic carbon in nearby galaxies, important for galactic structure studies. In addition, the loss of the next generation correlator implies a decrease in observing speed for some of the highest ranked scientific programs by up to a factor of two. Together with the loss of the receiver bands, this implies a substantial decrease in the opportunities for serendipitous spectral discoveries. ALMA is a unique project, the first true world observatory and the only major telescope planned in the next few decades at millimeter and submillimeter wavelengths. This plan for a single instrument stands in sharp contrast to the situation in ground-based optical and infrared astronomy, where there are many instruments in both the public and the private sector, including the dual Gemini 8 m telescopes, the Japanese Subaru telescope, the VLT system of ESO, and the dual 10 m Keck telescopes. The ALMA project is the top priority major new initiative in astronomy in many countries. It is an exciting new instrument, full of the promise to answer many fundamental questions in astrophysics. It deserves the fullest support. Sincerely, The ALMA Scientific Advisory Committee ----------------------------------------------------------------------------- MESSAGE TO NRAO STAFF The U.S. Office of Management and Budget released today the budgetary outline of the FY 2002 requests for federal agencies and programs that President Bush will send to Congress [see http://www.gpo.gov/usbudget/index.html]. This plan includes a request for the NSF that would increase its FY 2002 funding by only 1% relative to the FY 2001 appropriation. Targeted increases for a very few NSF Divisions would consume this modest increase, and more, and would leave all other NSF activities, including Astronomy, to share a proposed FY 2002 funding level less than that realized in FY01. In addition to the unfortunate consequences for virtually all of NSF science, no new starts for NSF facilities are proposed in FY 02. Beyond the implications for Observatory operating funds, the lack of new starts is particularly regrettable for the NRAO because it appears to mean that the construction phase of ALMA will not begin in FY 2002 as had been anticipated. Clearly, the absence of new starts is not specifically focused on ALMA. Rather, it reflects the President's desire to freeze agency programs for a time while he and his staff can review the plans, organization, progress and priorities of current initiatives. However, in the specific case of ALMA this order has the consequence of interrupting a program that has its international agreement forged, its design and development phase milestones achieved, and its recommendations from the NSF oversight body all in place for FY 2002 construction. Given the high importance of the ALMA scientific program, the timing of the restriction against FY 2002 new starts for the ALMA Project is extremely unfortunate. The President's FY 2002 budget will be under review and discussion in Congress for the next several months. During this time, we intend to work with the community to inform the Federal government of the importance of ALMA and of the need for the project to move to construction expeditiously. At the same time, we will work to preserve the momentum of the project at the NRAO and internationally by securing adequate FY02 funding for a fifth year of design and development should it not be possible for construction to begin in FY 2002. Another item of note to astronomy in the FY 2002 Budget Plan is the announcement that NASA and NSF are to form a Blue Ribbon Commission to consider the pros and cons of giving NASA the responsibility for all astronomy, both ground- and space-based. The Commission is to report by September 1, 2001. Paul Vanden Bout 28 February 2001 From cwhite at NRAO.EDU Mon Mar 5 15:41:39 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Mon, 05 Mar 2001 15:41:39 -0500 Subject: [asac] [almanews] ALMA Memos 349, 350, and 351 Released Message-ID: <3AA3FA03.82B72075@nrao.edu> ALMA Memo #349 Fibre-Optic Link Design of the Atacama IF Data Transfer System Roshene McCool February 2001 This report examines the designs for two possible data links for IF signal transfer from the ALMA antennas to the data correlator. The first design is for the case where the correlator is located on the array site. The second design is for the case where the correlator is located at or near San Pedro, perhaps some 70km away, by fibre, from the array site. The main focus of the report is the technical feasibility or otherwise of the options. The report also provides some of the information from which the better option, from a systems point of view, can be selected. No estimates of costs are provided. Proper costings will be provided in a forthcoming companion report together with recommendations of actual components. This part of the whole is being released so that the ALMA community can assess the technical arguments which justify a necessary but modest increase in costs for IF data transfer. View a PDF version of ALMA Memo #349 http://www.alma.nrao.edu/memos/html-memos/alma349/memo349.pdf Download a postscript version of ALMA Memo #349 http://www.alma.nrao.edu/memos/html-memos/alma349/memo349.ps ------------------------------------------------------------------------- ALMA Memo #350 Feasibility Study of the Enhanced Correlator for 3-way ALMA I. Sachiko K. Okumura, Yoshihiro Chikada, Munetake Momose, and Satoru Iguchi February 2001 Here we report the feasibility study of the enhanced correlator proposed by Japan for 3-way ALMA. First we briefly review the scientific significance of the enhanced correlator, which does NOT depend on the correlator architecture. Then we describe the proposal of a high-performance FX correlator system for an enhanced correlator of 3-way ALMA. This FX correlator system always realizes both super-high spectral-resolution ( < 0.1km/s at 40GHz ) and wideband ( > 700km/s at 850GHz ) observations simultaneously up to 850GHz for each 2GHz baseband of the ALMA IF system. This FX system consists of 1024 x 1024 - FFT parts, 4-bit cross-correlation parts, and control parts. Re-quantization and flexible frequency-channel smoothing is newly installed. Re-quantization reduces the lines of connection between F and X parts compared with the previous FX system. Flexible frequency-channel smoothing makes the output frequency channels from 524288(=512 x 1024) to 8192 per baseband and eliminates the fear that the large amount of frequency channels might increase the costs of post-detection computing and archiving. Realization of this correlator system will allow us to make breakthrough in both sub-millimeter line and continuum observations with 3-way ALMA. We present the detailed specifications, block diagrams, estimated hardware size and power consumption of the high-performance FX correlator system. Preliminary plan for its implementation to the 3-way ALMA is also commented. View a PDF version of ALMA Memo #350 http://www.alma.nrao.edu/memos/html-memos/alma350/memo350.pdf ------------------------------------------------------------------------- ALMA Memo #351 275-370 GHz DSB and SSB Waveguide Mixers Employing a Tuned Nb/Al-AlOx/Nb SIS Tunnel Junction A. Navarrini and B. Lazareff February 2001 We discuss the design and optimisation of two full height waveguide SIS mixers for astronomical applications both covering the 275-370 GHz frequency band: a Double Side Band (DSB) and a Single Side Band (SSB) mixer. The expected SSB receiver noise temperature referred to the mixer input are in the range 23-35 K for the DSB and 25-38 K for SSB mixer. A 30 % operating bandwidth can be achieved in the DSB case by using an "end-loaded" tuning stub to tune out the junction capacitance of 75 fF (junction size 1 ?m2) followed by two quarter-wave transformer sections. A similar operating bandwidth is obtained in the SSB mixer by using a parallel tuning inductor with a radial microstrip stub. Single junctions are mounted on a 80 mm thick quartz which stretches only part way across the waveguide. In the SSB mixer the image rejection is obtained using a mechanically rugged noncontacting backshort with a circular cross-section which can be moved inside a circular waveguide. Both mixers have a 4 GHz IF passband and a central IF frequency of 6 GHz. A stability criterion for intrinsically DSB and SSB mixers under typical operating conditions has been derived. We have shown that when an inductive series matching structure is used to compensate the junction capacitance, the SSB mixer cannot be operated over a wide frequency range in a stable way. An inductive parallel matching structure allows us to fulfil the necessary conditions of stability. Receiver performance has been optimised for both mixers in order to guarantee a low mixer noise temperature while maintaining adequate gain and stable operations over the whole frequency band of interest. View a PDF version of ALMA Memo #351 http://www.alma.nrao.edu/memos/html-memos/alma351/memo351.pdf ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From cwhite at NRAO.EDU Thu Mar 8 15:06:48 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Thu, 08 Mar 2001 15:06:48 -0500 Subject: [asac] ASAC Meeting Teleconference Info Message-ID: <3AA7E658.8ACFACC8@nrao.edu> CALL DATE: MAR-14-2001 (Wednesday) CALL TIME: 10:15 AM EASTERN TIME (15:15 UT) USA Toll Free Number: 888-323-2716 USA Toll Number: +1-712-271-0629 PASSCODE: ALMA LEADER: Mr Al Wootten -- Carolyn White National Radio Astronomy Observatory 520 Edgemont Road Charlottesville, VA 22903 804-296-0224 Fax: 804-296-0278 From cwhite at NRAO.EDU Fri Mar 9 08:31:44 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Fri, 9 Mar 2001 08:31:44 -0500 (EST) Subject: [asac] [almanews] ALMA Memo 352 Released Message-ID: ALMA Memo No. 352 Design and Development of 183 GHz Water Vapour Radiometers R. Hills(MRAO), H. Gibson(MRAO/SAO), J. Richer(MRAO), H. Smith(MRAO), V. Belitsky(OSO/Chalmers), R. Booth(OSO/Chalmers), D. Urbain(OSO/Chalmers) March 06, 2001 This memo describes the plans for the development of the prototype 183 GHz radiometers for ALMA. It is planned that such radiometers will be used to correct for the phase errors introduced by water vapour in the atmosphere. One radiometer will be mounted on each of the antennas and will provide real-time measurements of the brightness temperature of the atmosphere at frequencies near the 183 GHz emission line of water. These measurements will be used to estimate the path fluctuations that are caused by the variations in the amount of water vapour along the line of sight from each antenna. Even on a good site corrections for these fluctuations will be needed for much of the time, especially at ALMA higher frequency bands and on long baselines. A substantial amount of work on the design of the radiometers has already been carried out, so this document contains a description of the instruments to be built, at the level of a conceptual design. Two radiometers of somewhat different designs, but with most components in common, will be built and tested. The intention is to develop a cost-effective and reliable final design suitable for production in quantity. It is expected that the prototype radiometers constructed here will subsequently be used for tests in the field, both to sort out compatibility issues with the rest of the ALMA system and to develop the phase-correction techniques further. The project is being carried out as a collaboration between Chalmers and MRAO. View a pdf version of ALMA Memo 352: http://www.alma.nrao.edu/memos/html-memos/alma352/memo352.pdf Download a postscript version of ALMA Memo 352 http://www.alma.nrao.edu/memos/html-memos/alma352/memo352.ps ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From tetsuo.hasegawa at nao.ac.jp Tue Mar 13 03:53:50 2001 From: tetsuo.hasegawa at nao.ac.jp (Tetsuo Hasegawa) Date: Tue, 13 Mar 2001 17:53:50 +0900 Subject: [asac] ASAC topic Message-ID: Dear Ewine and Geoff, As Yasuo Fukui is now travelling, I propose a topic for the coming ASAC telecon tomorrow. Before the Florence meeting, ASAC has been asked by ALG on the priority among the enhancements enabled by Japanese participation under a 10% cut (see the attached pdf document). At the beginning of the Florence meeting, we are told that ACC now wants ASAC to think about the priorities under 20% cut. We tried to do so in the course of the meeting, with a very miserable mood, and managed to squeeze out some choice. We did not have time and energy in Florence to think of the 10% case. At the same time, ASAC have sent a letter to ACC to think the 20% cut over again. The above sequence of events means that we still need to make a prioritization for the 10% cut constraint. I would like to present a model supported by Japanese ASAC members as follows. We believe that it greatly enhances the scientific capability of ALMA in many ways while staying within the budgetary constraints set by the 10% cut. We want to hear the ASAC thoughts on Wednesday. Net new resource assumed $140M (under 10% cut, overhead of ALG-estimated $50M removed; see the pdf document) 1) Add 2 receiver bands (Bands 8 and 10): $30M 2) Build ACA with 6 bands: $70M 3) Build the enhanced correlator: $35M -------------------- Total: $135M *adding 1 or 2 receiver bands (Bands 4 and 1): +$10 to 20M *give up 2SB capability: -$20M (estimate of cost reduction being made at Nobeyama) *refinements of the estimate of "overheads" -------------- next part -------------- A non-text attachment was scrubbed... Name: ALMA_cost_3way.pdf Type: application/pdf Size: 6482 bytes Desc: not available URL: -------------- next part -------------- _______________________________________________________________ !!! My e-mail address has changed !!! Tetsuo HASEGAWA, D. Sc. ALMA-J Project Scientist Professor, National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan Phone +81-422-34-3843 / FAX +81-422-34-3764 _______________________________________________________________ From guillote at iram.fr Tue Mar 13 12:37:42 2001 From: guillote at iram.fr (Stephane Guilloteau) Date: Tue, 13 Mar 2001 18:37:42 +0100 Subject: [asac] ASAC topic Message-ID: <002701c0abe4$4f1763c0$cafc30c1@pctcp72.iram.fr> Dear Tetsuo, I think we should definitely discuss the Enhanced Correlator case further. However, the costing has you presented it is incomplete because it does not take into account the induced costs on the Data Processing & Archiving. Since the enhanced correlator may produce 16 times more channel on average than the baseline correlator, real-time processing will be significantly more heavy, and thus more costly. This should be estimated and included in the "Enhanced Correlator" additional cost. Concerning the Archiving, the task is more complex, since it depends on the archiving requirements. There is first a scientific issue on how many channels should be archived, and then a costing excercise to be done later. Altogether, these extra costs may amount to 5 to 10 M$, perhaps even more, i.e. may cost us one or more frequency band... I believe it perfectly OK for the ASAC to indicate priorities even if the exact costing is not known in advance, but the ASAC should nevertheless be aware of the possible cost consequences of the priorities. Stephane -----Original Message----- From: Tetsuo Hasegawa To: asac at NRAO.EDU Cc: lmsa-pro at nro.nao.ac.jp ; lmsa-shoi at nro.nao.ac.jp Date: Tuesday, March 13, 2001 9:58 AM Subject: [asac] ASAC topic >Dear Ewine and Geoff, > >As Yasuo Fukui is now travelling, I propose a topic for the coming ASAC >telecon tomorrow. > >Before the Florence meeting, ASAC has been asked by ALG on the priority >among the enhancements enabled by Japanese participation under a 10% cut >(see the attached pdf document). At the beginning of the Florence meeting, >we are told that ACC now wants ASAC to think about the priorities under 20% >cut. We tried to do so in the course of the meeting, with a very miserable >mood, and managed to squeeze out some choice. We did not have time and >energy in Florence to think of the 10% case. At the same time, ASAC have >sent a letter to ACC to think the 20% cut over again. > >The above sequence of events means that we still need to make a >prioritization for the 10% cut constraint. I would like to present a model >supported by Japanese ASAC members as follows. We believe that it greatly >enhances the scientific capability of ALMA in many ways while staying within >the budgetary constraints set by the 10% cut. We want to hear the ASAC >thoughts on Wednesday. > >Net new resource assumed $140M (under 10% cut, overhead of ALG-estimated >$50M removed; see the pdf document) > > >1) Add 2 receiver bands (Bands 8 and 10): $30M >2) Build ACA with 6 bands: $70M >3) Build the enhanced correlator: $35M >-------------------- >Total: $135M > > >*adding 1 or 2 receiver bands (Bands 4 and 1): +$10 to 20M >*give up 2SB capability: -$20M (estimate of cost reduction being made at >Nobeyama) >*refinements of the estimate of "overheads" > From awootten at NRAO.EDU Tue Mar 13 16:02:11 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Tue, 13 Mar 2001 16:02:11 -0500 (EST) Subject: [asac] Phone no. Message-ID: <200103132102.QAA27341@polaris.cv.nrao.edu> AUDIO ACCESS INFORMATION: ========================== CALL DATE: MAR-14-2001 (Wednesday) CALL TIME: 10:15 AM EASTERN TIME USA Toll Free Number: 888-323-2716 USA Toll Number: +1-712-271-0629 PASSCODE: ALMA LEADER: Mr Al Wootten From cwhite at NRAO.EDU Tue Mar 13 16:36:07 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Tue, 13 Mar 2001 16:36:07 -0500 (EST) Subject: [asac] [almanews] MMAOC 2001 Report Message-ID: I am pleased to pass along the report of The Millimeter Array Oversight Committee (MMAOC). The MMAOC, a panel charged by the NSF to review progress and planning for the US portion of ALMA (formerly the MMA Project), has strongly urged the Foundation to commit to construction. Based on a detailed two-day review in February, the committee concluded that "the ALMA project is ready to start construction and we recommend that NSF approve ALMA to move to Phase II. The ALMA team is more than ready for ALMA construction." The committee further noted: The project has made impressive technical progress and is meeting the goals for Phase I ... NRAO is to be commended for remarkable technical and managerial progress. They have initiated implementation of all of the recommendations we requested at our last meeting, and moved the project from a scientific dream to a realistic plan for an observatory ... NRAO has made rapid progress in all areas, including technical tasks, project management, and also international coordination ... they have succeeded admirably in the Design and Development Phase (Phase I). Key accomplishments of the ALMA team include: * Completion of the Work Breakdown Structure (WBS) enumerating all tasks for the project, * Completion of the budget organized according to the WBS, * Completion of a schedule leading to full deployment in 2009, * Completion of an international plan allocating work elements to the US and Europe, * Establishment of an Earned Value system, showing progress along the plan and calculating the performance for both cost and schedule, * Awarding contracts (one NRAO, one ESO) for antenna prototypes, for delivery late this year, * Production of advanced cryogenically cooled receivers, meeting the specifications for ALMA, * Design of a suitable correlator chip, that meets the ALMA requirements, The full text of the MMAOC report can be found at the following link: http://www.alma.nrao.edu/docs/mmaoc2001.pdf Marc Rafal Project Manager ALMA-US ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From awootten at NRAO.EDU Tue Mar 13 17:37:28 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Tue, 13 Mar 2001 17:37:28 -0500 (EST) Subject: [asac] Draft Agenda Message-ID: <200103132237.RAA00303@polaris.cv.nrao.edu> Folks, A draft of the agenda is available at: http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacmar01agenda.html The text of the report is not yet available for linking to this page, but I expect it to be available soon and I will link it at the time at which I receive it. Clear skies, Al From awootten at NRAO.EDU Wed Mar 14 09:40:13 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Wed, 14 Mar 2001 09:40:13 -0500 (EST) Subject: [asac] ASAC Report Message-ID: <200103141440.JAA18408@polaris.cv.nrao.edu> Folks: The ASAC report from Jack is linked to the agenda for today, or directly at: http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacreportfeb01.ps Apparently the mailer did not recognize his email as a valid one, and sent this to me rather than distribution. Then it bounced for me as too long a message! Sorry this is tardy owing to these problems. Enjoy. Clear skies, Al From wilson at physics.mcmaster.ca Wed Mar 14 13:09:37 2001 From: wilson at physics.mcmaster.ca (Christine Wilson) Date: Wed, 14 Mar 2001 13:09:37 -0500 (EST) Subject: [asac] comments on report Message-ID: Hi, Jack, Here are my comments on the draft of the ASAC report. I've put the substantial ones at the top and the typos etc. at the end. Chris MAJOR COMMENTS As I mentioned in the telecon, I'm worried that the momentum is building quickly towards a project with a 20% cut to the contributions of North America and Europe. I think it's important that our report comes out strongly and clearly against such a cut. One way to do this would be to have a section in the report where we collect together all the issues regarding the 20% cut; at the moment they are in various places throughout the report. Although this might paraphrase our letter to the ACC somewhat, I think it's important that our report (which will eventually be public) spells the issues out. In the last sentence of the section on management structure, you might check with people like Bob Brown and so on that it is OK to say that we intend to have a continuing upgrades budget. I got the impression at the meeting that this money WAS proposed in the NSF budget, but was sort of hidden as operations and not identified as upgrades. We should certainly talk about the scientific NEED for such funds, and that is done later in the document. The whole second paragraph of the configurations section was not discussed at the ASAC meeting, because the PDR had yet to take place. I think we should remove this section from our report and put it in the minutes of today's telecon. In the section on Frequency Bands, unless our letter to the ACC is going to be made public by posting on the web page, we should make sure the essential contents are included in our report. On page 4, we talk about possibly postponing Band 10 and bringing up one of the other bands instead. I'm not sure we want to say this, it seems a bit dangerous to talk about substituting one band for another. I think that sentence could just be removed. In the section on Total Power Stability, it might make sense to add the polarization justification here (from page 13). Similarly, we might want to move the section on page 5 on Calibration Accuracy to the section on Calibration (on page 15). (Calibration is not only fragmente in the project, it's fragmented in our report!) On page 8, maybe I'm just still confused about the correlators, but I have a question. Does the reprogramming of the baseline correlator give you the same total efficiency as the Future or Enhanced correlator, albeit with many fewer channels and some restriction on total bandwidth? If so, it would be nice to say so CLEARLY in our report. Still on page 8, if we expect the correlator plans and costs by only September 2002, then we ought to specify frequent reports as to their progress. I see this situation as rather like the configuration issue; we start off with two competing designs and, if we're lucky, they will converge to something better than either initial design. In the polarization section on page 12, I think it's important to explore the issue of rotating some receivers by 45 degrees a little bit more. In particular, the Receiver group could be asked to see whether band 7 could be rotated without impacting the optics etc. Someone else could look into whether the 45 degree phase rotator would in fact be inexpensive and low-noise. Perhaps this is something for the polarimetry group (when it is set up) to focus on. MINOR COMMENTS/TYPOS - the report should list the members (present and absent) and other people who were present - in the Status report section: "major design AND development activities in Japan." - the formatting is rather incoherent at the moment; some parts are sectioned and others not. - in "Towards 3-way partnership": "The issue of the 20% CUT was discussed ..."; also I would remove "the" in front of ALMA in that paragraph. - in "Configurations", first sentences has "the the"; later down that paragraph, "The committee WAS very impressed ..." - I think the first paragraph on the correlators has too much detail - you have % that are mis-TeXed on: page 7, second paragraph; two in page 13, first paragraph - I would prefer not to refer to web pages, which may change or disappear, in our report. On page 7, instead of refering to the Table, perhaps we could give a couple of examples of how tradeoff in capacity for efficiency works; similarly, if the report on the Japanese FX design is available in the memo series, we should refer to it there. - pg 8, I would substitute "considered" or "compared" for "pondered" -pg 11, remove "the" in front of ALMA - pg 11, what does "a phase-difference measurement" mean? - pg 12, I wouldn't discuss the widgets, since we're not considering it. From ishiguro at nro.nao.ac.jp Wed Mar 14 14:35:14 2001 From: ishiguro at nro.nao.ac.jp (Masato Ishiguro) Date: Thu, 15 Mar 2001 04:35:14 +0900 Subject: [asac] comments on report Message-ID: <000801c0acbd$e506d300$c2dc2885@ishigu-v.mtk.nao.ac.jp> Dear Jack, Just a short comment on the LO(page 5) in the draft ASAC report. 1) the NTT PIN photodiode LO source -> the photomixer developed by NAOJ using the NTT UTC-PD 2) The development of photonic LO is inside the ALMA project as agreed in the last ALMA photonic meeting in Tokyo. Masato From cwhite at NRAO.EDU Wed Mar 14 15:50:08 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Wed, 14 Mar 2001 15:50:08 -0500 (EST) Subject: [asac] [almanews] ALMA Memo No. 353 Released Message-ID: ALMA Memo No.353 Investigation of suppression of sidelobes by simple displacement of clustered groups of regularly spaced antennas Steven Heddle March 2001 A means of suppressing beam sidelobes by simple displacements of subgroups of regularly spaced antennas is proposed and investigated. Previous experiments in the optical domain suggest that this should be possible, and the principle is developed first by analogy and then by a simple analysis to encompass the radio astronomical situation. Considering the specific example of a hexagonal array with the additional constraint of compactness, some improvement over a completely regularly placed configuration is demonstrated. An analysis suggests why the improvement is less than that hoped for. Alternative optimization methods yield compact arrays with lower sidelobes, but the principle outlined here may prove useful in other configurations. View a PDF version of ALMA Memo #353. http://www.alma.nrao.edu/memos/html-memos/alma353/memo353.pdf Download a postscript version of ALMA Memo #353. http://www.alma.nrao.edu/memos/html-memos/alma353/memo353.ps ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From tetsuo.hasegawa at nao.ac.jp Thu Mar 15 04:38:44 2001 From: tetsuo.hasegawa at nao.ac.jp (Tetsuo Hasegawa) Date: Thu, 15 Mar 2001 18:38:44 +0900 Subject: [asac] comments on report In-Reply-To: Message-ID: Dear Christine, At 1:09 PM -0500 01.3.14, Christine Wilson wrote: > On page 8, maybe I'm just still confused about the correlators, but I have a > question. Does the reprogramming of the baseline correlator give you the same > total efficiency as the Future or Enhanced correlator, albeit with many fewer > channels and some restriction on total bandwidth? If so, it would be nice to > say so CLEARLY in our report. My colleagues, i.e., Chikada, Okumura, and Iguchi here in Japan, tell me that your understanding is correct. If we sacrifice the number of IF lines by half, we would have a room to reprogram the baseline correlator to improve the efficiency from 0.88 to 0.98. In this case, we regain 10% of the sinsitivity PER CHANNEL, but we lose 50% of the bandwidth. We can enjoy this 10% gain in a limited case of spectral line observations over a sacrifice of the continuum sensitivity and/or opportunity of multiple line mapping. This is the limit posed by the absolute amount of the hardware of the baseline correlator, and a substantial improvement is possible with the enhanced/future correlator. In revising the corresponding part of the ASAC report, this reservation should also be stated. With best, Tetsuo _______________________________________________________________ !!! My e-mail address has changed !!! Tetsuo HASEGAWA, D. Sc. ALMA-J Project Scientist Professor, National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan Phone +81-422-34-3843 / FAX +81-422-34-3764 _______________________________________________________________ From bachiller at oan.es Thu Mar 15 07:23:57 2001 From: bachiller at oan.es (Rafael Bachiller) Date: Thu, 15 Mar 2001 13:23:57 +0100 Subject: [asac] comments on report In-Reply-To: Your message of "Wed, 14 Mar 2001 13:09:37 EST." References: Message-ID: <200103151124.MAA03207@baal.oan.es> Dear Christine, After recent discussions with Al and Stephane the points you raised on the correlator became clear, so I was at the point of suggesting changes to improve the correlator section. I also agree with removing references to web pages which can be too ephemeral. Best regards, Rafael From awootten at NRAO.EDU Thu Mar 15 10:00:43 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Thu, 15 Mar 2001 10:00:43 -0500 (EST) Subject: [asac] comments on report In-Reply-To: References: Message-ID: <200103151500.KAA24760@polaris.cv.nrao.edu> Hi, Chris Some comments on your comments... "On page 8, maybe I'm just still confused about the correlators, but I have a question. Does the reprogramming of the baseline correlator give you the same total efficiency as the Future or Enhanced correlator, albeit with many fewer channels and some restriction on total bandwidth? If so, it would be nice to say so CLEARLY in our report. " Well, there will be differences in the tenths to one per cent range between the reprogrammed baseline correlator and the Future and Enhanced Correlators in the higher resolution lower bandwidth modes which depend upon the details of the sampling, FIR filtering, etc. but yes the number of channels and bandwidth gets halved more or less (details depend on things such as the number of wires, etc), as calculated by Ray for the table I presented. This will be presented as a memo soon. I've contributed to the confusion, I'm afraid, by dribbling this information out before the memo was written. Additionally, of course, the ability to record data at a maximum rate of something like 60 MB/s will limit the ability to make full use of many additional channels. This limit should be relaxed as Moore's law enables us to record more and more data in the future. I see I left this in my outbox too long and Hasegawa has already commented on it! "Still on page 8, if we expect the correlator plans and costs by only September 2002, then we ought to specify frequent reports as to their progress. I see this situation as rather like the configuration issue; we start off with two competing designs and, if we're lucky, they will converge to something better than either initial design." And the ASAC should examine the 'big picture' of data recording, archiving and reduction procedures in parallel with consideration of the higher data rates from baseline/future/enhanced correlator designs. Some of this should begin with next month's discussion. "In the polarization section on page 12, I think it's important to explore the issue of rotating some receivers by 45 degrees a little bit more. In particular, the Receiver group could be asked to see whether band 7 could be rotated without impacting the optics etc. Someone else could look into whether the 45 degree phase rotator would in fact be inexpensive and low-noise. Perhaps this is something for the polarimetry group (when it is set up) to focus on." The receivers and optics are a package and no mechanical rotation whatsoever is possible. Some receivers may be installed at a 45 degree angle; this is the only option. The ASAC could charge the JRDG to consider the issue of the phase rotator in collaboration with the polarimetry group. Clear skies, Al From tetsuo.hasegawa at nao.ac.jp Thu Mar 15 15:33:26 2001 From: tetsuo.hasegawa at nao.ac.jp (Tetsuo Hasegawa) Date: Fri, 16 Mar 2001 05:33:26 +0900 Subject: [asac] comments on report In-Reply-To: Message-ID: Dear Christine, Rafael, and other ASAC colleagues, At 1:09 PM -0500 01.3.14, Christine Wilson wrote: > - I would prefer not to refer to web pages, which may change or > disappear, in our report. On page 7, instead of refering to the Table, > perhaps we could give a couple of examples of how tradeoff in capacity > for efficiency works; similarly, if the report on the Japanese FX design > is available in the memo series, we should refer to it there. At 1:23 PM +0100 01.3.15, Rafael Bachiller wrote: > After recent discussions with Al and Stephane the points you raised > on the correlator became clear, so I was at the point of suggesting > changes to improve the correlator section. I also agree with removing > references to web pages which can be too ephemeral. The report of the feasibility study of the Japanese FX correlator is available as ALMA Memo#350. For those who are interested, its digest version (5 pages, pdf) distributed at Florence can be downloaded from http://www.nro.nao.ac.jp/~sokumura/eALMAcorr/FeasibilityASAC-abs3.pdf Tetsuo _______________________________________________________________ !!! My e-mail address has changed !!! Tetsuo HASEGAWA, D. Sc. ALMA-J Project Scientist Professor, National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan Phone +81-422-34-3843 / FAX +81-422-34-3764 _______________________________________________________________ From awootten at NRAO.EDU Mon Mar 19 11:26:27 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Mon, 19 Mar 2001 11:26:27 -0500 (EST) Subject: [asac] Report of the Florence ASAC Meeting, February 2001 Message-ID: <200103191626.LAA04825@polaris.cv.nrao.edu> Folks Jack sent me this report which I received this morning. The final, or perhaps nearly final, version of the report is at: http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacreportfeb01.ps Please send comments ASAP and no later than Wednesday morning. Clear skies, Al From awootten at NRAO.EDU Thu Mar 22 10:12:14 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Thu, 22 Mar 2001 10:12:14 -0500 (EST) Subject: [asac] Final Report of the ASAC Meeting 23-24 February 2001 Message-ID: <200103221512.KAA02074@polaris.cv.nrao.edu> Folks: The final report of the ASAC Committee has been prepared by Chairman Jack Welch. This version supercedes previous versions. I have placed it at (postscript) http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacreportfeb01.ps or as (Adobe Acrobat 4.0) http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacreportfeb01.pdf It will eventually appear under its own link at the ASAC WWW page on the ALMA web site. Much thanks to Jack and to the Committee for the work they have put into this report and for the guidance they have provided for the coming months. Clear skies, Al From cwhite at NRAO.EDU Fri Mar 23 15:11:51 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Fri, 23 Mar 2001 15:11:51 -0500 (EST) Subject: [asac] [almanews] ALMA Memos 354, 355, and 356 Released Message-ID: ALMA Memo 356 Reliability of Nanonics Dualobe Connectors J.E. Effland (NRAO) 03/22/01 Miniature connectors manufactured by Nanonics Corporation (http://www.nanonics.com/dualobe.html) are being used on ALMA mixers in development at NRAO?s Central Development Lab. These ?Dualobe? connectors have been selected for a number of spacecraft programs, which affirms their reliability. Connector pin damage from misalignment during connection, which occurred on previous NRAO mixer bias connectors, is minimized because the plastic insulator must be engaged before the pins contact their receptacles This report provides reliability information obtained from Nanonics for their Dualobe connectors. A section summarizing a visit to Ball Aerospace, who is using hundreds of these Nanonics connectors, is also included. View a PDF version of ALMA Memo #356. http://www.alma.nrao.edu/memos/html-memos/alma356/memo356.pdf View a html version of ALMA Memo #356 http://www.alma.nrao.edu/memos/html-memos/alma356/memo356.html Download a postscript version of ALMA Memo #356. http://www.alma.nrao.edu/memos/html-memos/alma356/memo356.ps ----------------------------------------------------------------- ALMA Memo 355 Design of the ALMA's Compact Configuration with the Road Design First L. Kogan At the recent PDR of the ALMA configurations (Grenoble, February 26-27, 2001) the committee selected the best brightness sensitivity as a main criterion of the compact configuration design. The best brightness sensitivity is equivalent to the most wide synthesized beam or the smallest size of the array configuration. The self shadowing of antennas requires some minimum spacing between antennas. During reconfiguration each antenna has to be accessible by the transporter. And this make even more requirement to the spacing between antennas. So it looks like that the problem of achievement of the best brightness sensitivity is equivalent to the problem of minimizing area of the road inside of the array. The previous designs of the compact configuration were leaving the road problem to the end. At the same time the road requirement can destroy the original good configuration. That is why I suggest to design the road with minimum area at the beginning and then design the configuration itself considering the roads as a topography constrain. Such an approach can be considered as a complete design because the road area is minimized since the beginning and therefore the brightness sensitivity is maximized. Optimization of the side lobes can be carried out by the standard procedure at AIPS (task CONFI) using the road constrain as a topography constrain. The road file has to be created at the standard Butler's format used for the site topography. At this memo I give several examples of the roads and relevant configurations. The synthesized beam widths are compared with ideal hexagon configuration beam. One of the configurations has the beam width very close to the ideal hexagon configuration of the given spacing. View a PDF version of ALMA Memo #355. http://www.alma.nrao.edu/memos/html-memos/alma355/memo355.pdf Download a postscript version of ALMA Memo #355. http://www.alma.nrao.edu/memos/html-memos/alma355/memo355.ps --------------------------------------------------------------------- ALMA Memo #354 Choices of Antenna Size and Number for the Atacama Compact Array Wm. J. Welch The lack of large scale structure in array maps is the result of the hole in the center of the visibility plane that arises because the smallest spacing between antennas is limited to one antenna diameter. Visibility data may be extracted for a region in the center of the hole from a single antenna map made with one array antennas. This can be accomplished by Fourier transforming the map and dividing out the transform of the gain function to produce the visibility. If a mosaic of pointings is obtained with the array in its interferometric mode, this data set allows extrapolation of the visibilities inward from the edge of the hole. This can be done by a similar procedure in which the same gain function is divided from the observed visibilities to obtain visibilities within the edge of the hole. From the overlap, a complete map may be constructed. Pointing errors spoil this procedure. The effect of the pointing errors is to produce phase and amplitude errors in the visibilities that increase toward the overlap region from both the origin and the edge of the hole. This is doubly bad, because the transforms of the gain functions also tend toward zero in the overlap region and the data errors are amplified there. For the homogeneous array, the effects of even small errors in pointing are severe. The use of an array of smaller antennas provides a better overlap in the central hole, and reduces the effects of pointing errors. The smaller the compact array antennas, the better is the overlap, but more antennas are required and calibration becomes more difficult. A reasonable compromise would be 6m, half the 12m diameter diameter and a traditional choice. For the compact array to contribute a point source sensitivity that matches that of the more closely spaced 12m antennas, the necessary number of small antennas is approximately $(12/D_c)\times$6, where $D_c$ is the diameter of the compact array antenna. As an example, the compact D array of the 10 BIMA antennas shows reasonably good overlap with Kogan's (1998) 12m D array. View a PDF version of ALMA Memo #354. http://www.alma.nrao.edu/memos/html-memos/alma354/memo354.pdf Download a postscript version of ALMA Memo #354. http://www.alma.nrao.edu/memos/html-memos/alma354/memo354.ps ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From cwhite at NRAO.EDU Tue Mar 27 14:13:26 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Tue, 27 Mar 2001 14:13:26 -0500 (EST) Subject: [asac] [almanews] ALMA Memo 357 and Memo 358 Released Message-ID: ALMA Memo 357 Sideband Calibration of Millimeter-Wave Receivers A. R. Kerr, S.-K. Pan and J. E. Effland 2001-Mar-27 Unless the sideband ratio of a heterodyne receiver is close to the ideal value (less than ~ 0.1 dB for a double-sideband receiver, greater than ~ 20 dB for a sideband-separating receiver), a significant correction is required to the single-sideband receiver noise temperature deduced from the Y-factor measured using broadband hot and cold loads. If, in addition, there is significant conversion gain from one or more of the higher harmonic sidebands, nfLO +/- fIF (n = 2, 3,...), that must also be taken into account when evaluating the sideband ratio and the single-sideband receiver noise temperature. In principle, the sideband ratio of a receiver can be measured by injecting CW signals of known relative amplitudes into the upper and lower sidebands and measuring the IF response to each. At millimeter wavelengths, however, it is difficult to determine with sufficient accuracy the relative amplitudes of two low level RF signals separated in frequency by twice the IF (2fIF = 8?24 GHz in the case of ALMA receivers). This note shows that the image rejection of a sideband-separating mixer can be measured accurately using CW test signals in the upper and lower sidebands, even when the relative power levels of the test signals are not known. This allows accurate determination of the upper- and lower-sideband gains and the single-sideband noise temperature of a sideband-separating receiver, even if it has poor image rejection. In contrast, there is no simple and accurate way to determine the sideband ratio and SSB sensitivity of a DSB receiver. This has implications for ALMA?s single-dish mode of operation, in which sideband separation using LO phase switching is not possible, but high SSB measurement accuracy is required. View a PDF version of ALMA Memo #357 http://www.alma.nrao.edu/memos/html-memos/alma357/memo357.pdf Download a postscript version of ALMA Memo #357 http://www.alma.nrao.edu/memos/html-memos/alma357/memo357.ps -------------------------------------------------------------------- ALMA Memo 358 OBSERVING Melvyn Wright (Radio Astronomy Laboratory, University of California, Berkeley) 2001-Mar-23 This memo proposes an entity which provides an integrated description for dynamically scheduled observations. The ``observing object'' is created from the observing proposal and used throughout the observing and data reduction process. It is archived and provides a self contained and complete record of the data. View a PDF version of ALMA Memo #358 http://www.alma.nrao.edu/memos/html-memos/alma358/memo358.pdf Download a postscript version of ALMA Memo #358 http://www.alma.nrao.edu/memos/html-memos/alma358/memo358.ps ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From cwhite at NRAO.EDU Thu Mar 29 13:41:11 2001 From: cwhite at NRAO.EDU (Carolyn White) Date: Thu, 29 Mar 2001 13:41:11 -0500 (EST) Subject: [asac] [almanews] ALMA Memo 359 Released Message-ID: ALMA Memo 359 Optics Study for ALMA Receivers James Lamb March 2001 The design of the receiver optics plays a crucial part in the ultimate sensitivity of the ALMA array. We present some general design concepts to guide the development of the optical layout of the final receivers. Relevant properties of materials used in the optical path are examined, and various types of optical elements are discussed. General principles of high efficiency optical train designs are presented. In general, simple systems are advocated, with minimal truncation losses. The areas which have the greatest uncertainty are the windows and infrared filters where the trade-offs between the RF losses, infrared blocking, pressure resistance and gas permeability have to be carefully considered. A sample design for Band 3 is given. View a PDF version of ALMA Memo #359 http://www.alma.nrao.edu/memos/html-memos/alma359/memo359.pdf Download a postscript version of ALMA Memo #359 http://www.alma.nrao.edu/memos/html-memos/alma359/memo359.ps ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body. From awootten at NRAO.EDU Thu Mar 29 17:24:43 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Thu, 29 Mar 2001 17:24:43 -0500 (EST) Subject: [asac] Next teleconference APR-12-2001 (Thursday) Message-ID: <200103292224.RAA24017@polaris.cv.nrao.edu> Folks: For your advance information: AUDIO ACCESS INFORMATION: ========================== CALL DATE: APR-12-2001 (Thursday) CALL TIME: 10:15 AM EASTERN DAYLIGHT TIME USA Toll Free Number: 888-791-2132 USA Toll Number: +1-415-228-4574 PASSCODE: ALMA LEADER: Mr Al Wootten Clear skies, Al +--------------------------------------------------------+ | Alwyn Wootten (http://www.cv.nrao.edu/~awootten/) | | Project Scientist, Atacama Large Millimeter Array/US | | Astronomer, National Radio Astronomy Observatory | | 520 Edgemont Road, Charlottesville, VA 22903-2475, USA | | (804)-296-0329 voice Help us build The ALMA| | (804)-296-0278 FAX {> {> {> {> | +----------------------------------^-----^-----^-----^---+