From Pierre.Cox at ias.u-psud.fr Tue Apr 2 08:55:09 2002 From: Pierre.Cox at ias.u-psud.fr (Pierre.Cox at ias.u-psud.fr) Date: Tue, 2 Apr 2002 15:55:09 +0200 (MET DST) Subject: [asac]Draft of ASAC Report In-Reply-To: <200203290844.DAA25233@polaris.cv.nrao.edu> Message-ID: Dear All: This is to inform you on a few issues re the written report of the ASAC face-to-face meeting. I will send to you in a next message the draft section on the RSC together with recommendations. In order to be able to incorporate your comments, suggestions and remarks in the current draft I suggest that you send them directly to me (with a copy to Geoff). I will take care of iterating and editing the new version of the draft report. Since the Executive Summary should be send to the ACC members next Friday April 5th, I would appreciate if you could send me your comments on section 1 of the report by friday April 5th morning (CET) at the latest. The comments on the other sections of the report can be received until Saturday April 6th in the morning (CET) at the latest. I will make the needed corrections on saturday and send the new version to Geoff for final iteration. The final version of the ASAC report will be send out to the ACC members on Tuesday, April 9th. Tomorrow at the teleconf, we will have a discussion on the ASAC report. Today, the ESAC discussed the report during a teleconf and I propose to give a summary of the main points which were raised during this discussion. In advance, thank you for your efforts. With best regards, Pierre From Pierre.Cox at ias.u-psud.fr Tue Apr 2 10:46:32 2002 From: Pierre.Cox at ias.u-psud.fr (Pierre.Cox at ias.u-psud.fr) Date: Tue, 2 Apr 2002 17:46:32 +0200 (MET DST) Subject: [asac]Draft of ASAC Report: section on RSC In-Reply-To: Message-ID: Dear All: Please find hereafter a first draft of the section 12 `Regional Support Centers'. I apologize for the slight delay in sending this to you, but I just returned back from Japan yesterday. With best regards, Pierre **************************************************************** \section{Regional Support Centers} \label{rsc} In the October 2001 ASAC report, the roles of the Science Operations Center (SOC) and the Regional Support Centers (RSCs) were discussed. It was recommended that there should be `a single SOC, operated by the ALMA observatory, where the pipeline produces and stores the official archive' and that the RSCs `should be responsible for the support of the observer, from proposal preparation through data reduction and analysis'. Further study and discussion were recommended on the core functionality of the RSCs and on the number of RSCs that are needed. The ASAC has considered the issues of the RSCs further and we report here on the conclusions based on the various discussions which were held in the partner communities. The need for a RSC has been recognized as being a critical aspect in the success of ALMA through the support of the astronomical community at large and in the scientific return of the project. The main problem with interferometry is that it is a `cultural change' for most astronomers, so that assistance is essential for any new user. Astronomers therefore need support in the same time zone, and new users need physical access to a Centre. There should thus be one RSC for each partner community. Even experienced observers need to top-up their knowledge and talk to a team of people who are experts users in the instrument. The interaction of `ALMA-qualified' astronomers with the ALMA users will also be essential to develop tools and strategies for the best use of ALMA. Therefore it is important that such a Centre has close interactions with the instrument and the Operation Centre in Chile but also with the Project. The Centre should also provide easy access to the Data Archive. The discussions led to strongly convergent views on the core functions of the RSC. These are the core functions that each RSC should have, to be distinguished from additional functions that different partners may add. It is the functions themselves, rather than the particular means to realize them, that we discuss here; the means may differ among the partners. These are the core functions that we have identified, in order of importance: \begin{enumerate} \item Providing user support for observing proposals, data reduction beyond the pipeline products, and archival research; \item Providing feedback from the user to the project on performance; \item Hosting a copy of the ALMA Archive or a link to it. \end{enumerate} \noindent We note that the role in supporting archival research overlaps to some degree with the role of Virtual Observatories and the interaction between the RSC and these VOs needs to be defined. Whether each RSC has a physical copy of the archive or merely provides a link is a matter of implementation. Various communities have considered other functions to be important (e.g., financial support for the US community, software development for the Canadian community), but the core functions listed above have been agreed to be the common denominator. Other aspects, which could be supported by the communities own resources outside the ALMA projecs, include, e.g.: \begin{itemize} \item Software development \& maintenance beyond the nominal operations \item Interferometric data handling \& new techniques \item Support for special projects such as public surveys with limited time-priority, legacy programs or projects which cannot be handled with the pipeline \item Organisation of post-docs (ALMA Fellowship), training program \& interferometry schools \end{itemize} \noindent These non-core functions or development activities will depend on the community. Finally, the ASAC reiterates that it is crucial that the RSCs are operated with an international and collaborative spirit leading to close interactions between the RSCs for the benefit of the astronomical community at large. From k.tatematsu at nao.ac.jp Wed Apr 3 02:56:21 2002 From: k.tatematsu at nao.ac.jp (K. Tatematsu) Date: Wed, 03 Apr 2002 16:56:21 +0900 Subject: [asac]Re: Draft of ASAC Report: section on RSC In-Reply-To: References: Message-ID: <5.0.2.7.2.20020403154614.069e9298@133.40.7.95> Dear Pierre, and ASAC members, At 17:46 02/04/02 +0200, Pierre.Cox at ias.u-psud.fr wrote: >We note that the role in supporting archival research overlaps to some degree >with the role of Virtual Observatories and the interaction between the RSC >and these VOs needs to be defined. Whether each RSC has a physical copy of the >archive or merely provides a link is a matter of implementation. Various >communities have considered other functions to be important (e.g., financial >support for the US community, software development for the Canadian community), >but the core functions listed above have been agreed to be the common >denominator. I have a comment on the sentence "Whether each RSC has a physical copy of the archive or merely provides a link is a matter of implementation." # Although I said the same in the face-to-face meeting, I am afraid that most of you # did not understand my comment. Let's think about doing archival astronomy by using VO. Ten years later, we will have local ALMA archive (physical or link) and Subaru archive in Tokyo. If you believe in Moore's law in computing, the network speed will be of order 100-1000 times faster than the present day in 10 years. So, local network speed (within NAOJ and directly connected universities) would be of order Tbps (now 1-10Gbps), while global network between Tokyo and Chile (or USA or Europe) would be of order Gbps (now 1-10 Mbps). Some astronomer may try to do VO astronomy (without using pre-existing simple catalogues) to get brand-new result by cross-correlation. We assume that he/she likes to cross-correlate the ALMA and Subaru database. You know that yearly ALMA data amount can be of order 1 PB, and the archive is very large in size. If the ALMA archive is physical in Japan, cross-correlation on network is very fast on Tbps network. On the other hand, if the ALMA-J archive is just a link to Chile main archive, cross-correlation is 1000 times slower, because it uses Gbps line. Even for a USA archive researcher has benefit from high-speed link between the ALMA-J physical archive and Subaru archive. Cross-correlation will need high-speed network between archives, while the result can be sent to USA even on slower Gbps line because the data size of cross-correlation is much smaller. Here, I assume that cross-correlation is not CPU-power bound (e.g. position of two data archive is well determined, and image matching is not necessary ...) I feel that whether the local archive is physical or just a link is not an implementation issue but more serious if we mind how quick we can get scientific result. Or, you can wait for 1000 times longer time... If I miss the point, please let me know it. Cheers, Ken From guillote at iram.fr Wed Apr 3 08:09:37 2002 From: guillote at iram.fr (Stephane Guilloteau) Date: Wed, 3 Apr 2002 15:09:37 +0200 Subject: [asac]Re: Draft of ASAC Report: section on RSC Message-ID: <00b101c1db10$cf42b660$eefc30c1@pctcp72.iram.fr> Dear Ken, I agree with your conclusion, i.e. that a local implementation is likely to be much faster than just a portal to the archive. However, I believe we should leave the issue opened, and still state that the choice between a "physical copy or a link is a matter of LOCAL implementation". Some RSC(s) may elect to have a physical copy, other(s) to have just a link. This could be a choice of the respective user communities. Admittedly, if you can afford it, a physical copy probably offers a better solution to a strongly concentrated community like in Japan. In Europe, the situation is different, and it is yet another case in North America where networks are much more powerful. Stephane -----Original Message----- From: K. Tatematsu To: asac at NRAO.EDU Date: Wednesday, April 03, 2002 9:59 AM Subject: [asac]Re: Draft of ASAC Report: section on RSC >Dear Pierre, and ASAC members, > >At 17:46 02/04/02 +0200, Pierre.Cox at ias.u-psud.fr wrote: >>We note that the role in supporting archival research overlaps to some degree >>with the role of Virtual Observatories and the interaction between the RSC >>and these VOs needs to be defined. Whether each RSC has a physical copy of the >>archive or merely provides a link is a matter of implementation. Various >>communities have considered other functions to be important (e.g., financial >>support for the US community, software development for the Canadian community), >>but the core functions listed above have been agreed to be the common >>denominator. > >I have a comment on the sentence "Whether each RSC has a physical copy of the >archive or merely provides a link is a matter of implementation." ># Although I said the same in the face-to-face meeting, I am afraid that >most of you ># did not understand my comment. > >Let's think about doing archival astronomy by using VO. >Ten years later, we will have local ALMA archive (physical or link) and >Subaru archive in Tokyo. >If you believe in Moore's law in computing, the network speed will be of >order 100-1000 >times faster than the present day in 10 years. >So, local network speed (within NAOJ and directly connected universities) >would be of order Tbps (now 1-10Gbps), while global network >between Tokyo and Chile (or USA or Europe) would be of order Gbps (now >1-10 Mbps). > >Some astronomer may try to do VO astronomy (without using pre-existing simple >catalogues) to get brand-new result by cross-correlation. >We assume that he/she likes to cross-correlate the ALMA and Subaru database. >You know that yearly ALMA data amount can be >of order 1 PB, and the archive is very large in size. > >If the ALMA archive is physical in Japan, cross-correlation on network is >very fast on Tbps >network. On the other hand, if the ALMA-J archive is just a link to Chile main >archive, cross-correlation is 1000 times slower, because it uses Gbps line. > >Even for a USA archive researcher has benefit from high-speed link between >the ALMA-J physical archive and Subaru archive. Cross-correlation >will need high-speed network between archives, while the result >can be sent to USA even on slower Gbps line because the data size of >cross-correlation is much smaller. > >Here, I assume that cross-correlation is not CPU-power bound >(e.g. position of two data archive is well determined, and image matching >is not necessary >...) > >I feel that whether the local archive is physical or just a link is not an >implementation >issue but more serious if we mind how quick we can get scientific result. >Or, you can wait for 1000 times longer time... > >If I miss the point, please let me know it. > >Cheers, >Ken > > > > > >_______________________________________________ >Asac mailing list >Asac at listmgr.cv.nrao.edu >http://listmgr.cv.nrao.edu/mailman/listinfo/asac > From jsr at mrao.cam.ac.uk Wed Apr 3 08:51:51 2002 From: jsr at mrao.cam.ac.uk (John Richer) Date: Wed, 03 Apr 2002 14:51:51 +0100 Subject: [asac]Re: Draft of ASAC Report: section on RSC In-Reply-To: <5.0.2.7.2.20020403154614.069e9298@133.40.7.95> (k.tatematsu@nao.ac.jp) References: <5.0.2.7.2.20020403154614.069e9298@133.40.7.95> Message-ID: Dear Ken, This is an interesting point, but can't be quite right I think. It argues that any two data archives which are to be compared in some sense (not sure exactly is meant by cross correlation here) must be on an ultra-fast local network, i.e. be co-located. Obviously, co-location of the data will lead to faster data mining. However, if one accepts that the ALMA and the Subaru archive must be co-located for archival research, you are forced to accept that you must have a physical copy of *every* relevant Petabyte-scale archive at the same location - Sloan, VISTA, VLT, Gemini, ... One paradigm of the VO and the Grid is data-location independence. Geographically distributed archives are 'federated' through special software, allowing access from anywhere on the planet. This works because for most applications, one does not need to complete petabyte-scale 'cross correlations': one is interested for example in selecting all sources in the northern sky with SLOAN magnitudes below 20 which have ALMA 350 GHz fluxes greater than 5 mJy. The actual data volume transmitted over the global networks needed to do this is much smaller than the raw-data archive sizes. Of course, I agree you can find applications where a true petabyte times petabyte correlation is required: but I think in practice these are rare, and the VO is not designed to handle these in general. If these applications are important, then the world needs a 'physical' VO - a single machine room with all the astronomy archives sent to to it. John -- John Richer Astrophysics Group, Cavendish Lab, Madingley Road, Cambridge CB3 0HE http://www.mrao.cam.ac.uk/~jsr Tel: +44-1223-337246 Fax: +44-1223-354599 From k.tatematsu at nao.ac.jp Wed Apr 3 11:16:36 2002 From: k.tatematsu at nao.ac.jp (K. Tatematsu) Date: Thu, 04 Apr 2002 01:16:36 +0900 Subject: [asac]Re: Draft of ASAC Report: section on RSC In-Reply-To: References: <5.0.2.7.2.20020403154614.069e9298@133.40.7.95> <5.0.2.7.2.20020403154614.069e9298@133.40.7.95> Message-ID: <5.0.2.7.2.20020404002934.0448e3b0@133.40.7.95> Dear Stephane and John, thank you for your reply. At 14:51 02/04/03 +0100, John Richer wrote: >One paradigm of the VO and the Grid is data-location independence. Yes, I admit that my argument does not match the location-independent paradigm. >Geographically distributed archives are 'federated' through special >software, allowing access from anywhere on the planet. This works >because for most applications, one does not need to complete >petabyte-scale 'cross correlations': one is interested for example in >selecting all sources in the northern sky with SLOAN magnitudes below >20 which have ALMA 350 GHz fluxes greater than 5 mJy. The actual data >volume transmitted over the global networks needed to do this is much >smaller than the raw-data archive sizes. Yes, it is true if we can put almost all essential information into a compact-enough catalog. It is not difficult to make a point source catalog from two dimensional images at a few or several optical-IR bands. However, the millimeter and submillimeter data often contain irregular shaped diffuse emission also having irregular velocity structure in three dimensions. My concern is how we can build such catalogue(s) efficiently. If it is OK, it would not be necessary to consult the raw data for cross correlation and the network speed requirement depends on compression efficiency of the calatogue. Now, I feel that I should stop here. Sorry for confusion. With best regards, Ken From nje at bubba.as.utexas.edu Wed Apr 3 11:22:40 2002 From: nje at bubba.as.utexas.edu (Neal Evans) Date: Wed, 3 Apr 2002 10:22:40 -0600 (CST) Subject: [asac]Re: Draft of ASAC Report: section on RSC Message-ID: <200204031622.g33GMeW14842@bubba.as.utexas.edu> Hi all, Ken made an interesting point. I just read an interesting article last night that Tim Cornwell pointed me towards. It compares various "Moore's Laws". Everything is not scaling in the same way. For the present, disk storage is getting cheaper much faster than access (bandwidth). So it probably does make sense to have lots of copies of the archive that are held "locally." However, it is still an implementation decision that should be made based on analysis of issues like this by people who understand them better than I do. What the ASAC should say is that we want fast access and the RSCs should provide it. Then they can figure out the best way to do it at the time. Cheers, Neal From soliver at NRAO.EDU Wed Apr 3 12:57:58 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Wed, 3 Apr 2002 10:57:58 -0700 Subject: [asac][almanews] ALMA Memo 416 Released Message-ID: ALMA Memo #416 The Relative Sensitivity of Full-Wave and Half-Wave Detectors in Radio Astronomy A. R. Thompson (NRAO) and D. T. Emerson (NRAO) 02/04/03 Keywords: sensitivity, linear detectors, square-law detectors, half-wave, full-wave The sensitivity in the measurement of Guassian noise power using a half-wave detector can suffer degradation relative to that of a full-wave detector, in cases where the bandwidth if the input waveform is not small compared to the center frequency. There are two physical mechanisms that suggest a basis for this effect. The half-wave detector responds to only half of the input waveform, resulting in possible loss of information. Also, in the half-wave detector a component of the input spectrum feeds through the diode and adds to the noise that is subsequenctly filtered by averaging at the detector output. This feedthrough component does not occur in full-wave detectors. The phenomena are examined using an analytic method developed by Nuttall (1986), and also by numerical simulation. The results for both linear and square-law characteristics are considered, and formulas and graphs for estimating the magnitude of the effects are given. View a pdf version of ALMA Memo 416. http://www.alma.nrao.edu/memos/html-memos/alma416/memo416.pdf Download a postscript version of ALMA Memo 416. http://www.alma.nrao.edu/memos/html-memos/alma416/memo416.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From tetsuo.hasegawa at nao.ac.jp Wed Apr 3 23:23:59 2002 From: tetsuo.hasegawa at nao.ac.jp (Tetsuo Hasegawa) Date: Thu, 4 Apr 2002 13:23:59 +0900 Subject: [asac]Draft of ASAC Report In-Reply-To: References: Message-ID: Dear Pierre, Thank you for sending the draft on Japanese participation. It is perfect as it is, and we do not see any need for addition. With best, Tetsuo -- _______________________________________________________________ Tetsuo HASEGAWA, D. Sc. ALMA-J Project Scientist Professor, National Astronomical Observatory of Japan 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan Phone +81-422-34-3780 / FAX +81-422-34-3764 _______________________________________________________________ From Pierre.Cox at ias.u-psud.fr Wed Apr 3 23:53:33 2002 From: Pierre.Cox at ias.u-psud.fr (Pierre.Cox at ias.u-psud.fr) Date: Thu, 4 Apr 2002 06:53:33 +0200 (MET DST) Subject: [asac]Draft of ASAC Report: section on 3-way project Message-ID: Dear All: Please find hereafter a draft of the section 'Toward a three-way Project' which was missing in the draft report of the ASAC face-to-face meeting report. Comments welcome. Best regards, Pierre \section{Toward a three-way Project} \label{3way} The enhancements to the ALMA Project resulting from a participation of Japan in the Project are so valuable from a scientific point of view that all efforts should be made to allow Japan to become a full partner in a future 3-way ALMA Project. These enhancements include the ACA, the missing six receiver bands, and the Second Generation Correlator. In addition, the experience of the Japanese community, in particular with ASTE, will be a valuable asset to ALMA. During the meeting, M. Ishiguro presented areas of Japanese interest in ALMA, which include: Antennae, frontends for Bands 10 and 4, the photonic LO system, a High Speed Sampler, the Second Generation Correlator together with a contribution to the infrastructure and computing. The ASAC notes that in order to make an extension to a three-way partnership possible, a certain flexibility needs to be kept in the Project, since Japan cannot be counted on to provide all the enhancements. Receiver Band 1, for example, would work with HEMT amplifiers for which there is no real expertise in Japan and the Second Generation Correlator has been envisioned as a European-Japanese collaboration. All decisions which are not time critical, i.e. which do not lead to a delay in the two-way project, should be postponed until the situation of Japan is clear. In particular, a single antenna type is of prime importance for the overall performance of the array, and we emphasize that the selection process should be based on the evaluation of all three prototypes, provided the current schedule is kept. We refer to the recommendation for a single antenna type in the antenna section of this document. From soliver at NRAO.EDU Fri Apr 5 16:20:23 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Fri, 5 Apr 2002 14:20:23 -0700 Subject: [asac][almanews] ALMA Memos 415 and 418 Released Message-ID: ALMA MEMO #415 Phase Correction using Submillimeter Atmospheric Continuum Emission S.Matsushita (CfA/SMA), H.Matsuo (NAOJ), M.C.Wiedner (CfA/SMA), J.R.Pardo (Consejo Superior de Investigaciones Cientificas/CalTech) 2002/04 Keywords: Atmospheric Effects, Calibration, Phase Correction We discuss a phase correction method using total power from submillimeter/millimeter SIS receivers. The discussion is based on FTS measurements and model calculations of submillimeter/millimeter atmospheric emission under various weather conditions. Liquid water in the atmosphere (cloud or fog) limits the phase correction accuracy using the total power measurements. Comparison between millimeter and submillimeter total power phase correctionshows that the sensitivity requirement is more easily met at submillimeterwavelengths under good atmospheric conditions (precipitable water vapor[pwv] < 1 mm), and the phase correction error due to liquid water is muchless at these wavelengths. Simultaneous operation of millimeter and submillimeter receivers will further reduce the phase correction error appreciably. View a pdf version of ALMA Memo #415. http://www.alma.nrao.edu/memos/html-memos/alma415/memo415.pdf Download a postscript version of ALMA Memo #415. http://www.alma.nrao.edu/memos/html-memos/alma415/memo415.ps ____________________________________________________________________________ ________ ALMA MEMO #418 GEOTECHNICAL STUDY, CHAJNANTOR SITE, 2002 CAMPAIGN, II REGION, CHILE Geo Ambiental Consultores Ltda. 2002/03 The present report is written by Geo Ambiental Consultores Ltda. for the European Southern Observatory and summarizes the findings at the Chajnantor Site of the so called Cerro Chasc?n Science Preserve. At this site, a total of 22 borings were drilled between January 6 and January 24 of year 2002 to help in the geotechnical characterization for the development of the Atacama Large Millimeter Array (ALMA) project. ** Please note: Figure 11 is currently not included. It will be added to the document as soon as it becomes available. View a pdf version of ALMA Memo #418. http://www.alma.nrao.edu/memos/html-memos/alma418/memo418.pdf Download a postscript version of ALMA Memo #418. http://www.alma.nrao.edu/memos/html-memos/alma418/memo418.ps Download a zipped postscript version of ALMA Memo #418. http://www.alma.nrao.edu/memos/html-memos/alma418/memo418.zip _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From awootten at NRAO.EDU Mon Apr 8 15:38:39 2002 From: awootten at NRAO.EDU (Al Wootten) Date: Mon, 8 Apr 2002 15:38:39 -0400 (EDT) Subject: [asac]Dates of face-to-face meeting Message-ID: <200204081938.PAA04482@polaris.cv.nrao.edu> Folks One of my action items from the telecon last week is to canvass the ASAC on dates for the fall face-to-face meeting. I have put several options together, please vote your 1 2 3 preference. I'll present the results for acceptance or modification at the next telecon. _____Option A. Monday Sept 9: Visit Vertex antenna pm Tues-Weds Sept 10-11,meeting Sept 12. fly out _____Option B. Saturday Sept 7: Visit Vertex antenna pm Sept 8-9, meeting Sept 10 fly out to next meeting or home _____Option C. Thurs Sept 12: Visit Vertex antenna pm Fri-Sat Sept. 13-14, meeting Sept 15 fly out I have put my notes from the telecon on the WWW at URL http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacapr02minutes.html Note that owing to various holidays the next meeting will be on Thursday 2 May at 1300 UT. I have attached links to the ASAC Report circulated today to the ACC to the proto-minutes. Congratulations and thanks to you all for your timely work on this. 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 | | (434)-296-0329 voice Help us build The ALMA| | (434)-296-0278 FAX {> {> {> {> | +----------------------------------^-----^-----^-----^---+ From awootten at NRAO.EDU Mon Apr 8 15:59:19 2002 From: awootten at NRAO.EDU (Al Wootten) Date: Mon, 8 Apr 2002 15:59:19 -0400 (EDT) Subject: [asac]Option D and E Message-ID: <200204081959.PAA05280@polaris.cv.nrao.edu> Folks, I had thought I had covered all proposed options but obviously not. I've already had requests for other options. Here are two more which have been suggested in the past few minutes. _____Option D. Sun Sept 15: Visit Vertex antenna pm Mon-Tues Sept. 16-17, meeting Sept 18 fly out _____Option E. Friday Sept 6: Visit Vertex antenna pm Sept 7-8, meeting Sept 9 fly out to next meeting or home 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 | | (434)-296-0329 voice Help us build The ALMA| | (434)-296-0278 FAX {> {> {> {> | +----------------------------------^-----^-----^-----^---+ From soliver at NRAO.EDU Fri Apr 12 16:12:42 2002 From: soliver at NRAO.EDU (Stacy Oliver) Date: Fri, 12 Apr 2002 13:12:42 -0700 Subject: [asac][almanews] ALMA Memos 419 Released Message-ID: ALMA MEMO #419 THE Y+ LONG-BASELINE CONFIGURATION TO ACHIEVE HIGH RESOLUTION WITH ALMA Angel Ot?rola (ESO) & Mark A. Holdaway (NRAO) 04/12/2002 Keywords: Y+, configuration, resolution, roads, pads The ALMA array configuration design has been split into a compact array, an extended array, and a ?zoom? spiral array which aims to connect them. The currently accepted extended array is a 14 km ring around Chasc?n. Based on Fourier plane coverage, resolution, operations, engineering, and environmental arguments, we present an alternative to the extended configuration: a Y-shaped set of zooming configurations, which naturaly grows out of the spiral zoom configurations. This set of preliminary configurations indicates a savings of about 20 km in roads and cables, and 35 fewer pads compared to the current ring design. It has smoothly varying resolution, which permits the observer to tailor the resolution to his requirements. Reconfiguration is much smoother with the Y configuration than the 14 km diameter ring. The most extended Y configuration obtains the same resolution as the 14 km ring array. However, in order to achieve these advantages, together with the highest possible resolution for the ALMA interferometer, we need to explore the possibility of extending the Science Preserve by at least two kilometres to the west of its current western boundary. View a pdf version of ALMA Memo #419. http://www.alma.nrao.edu/memos/html-memos/alma419/memo419.pdf Download a postscript version of ALMA Memo #419. http://www.alma.nrao.edu/memos/html-memos/alma419/memo419.ps Download a zipped postscript version of ALMA Memo #419. http://www.alma.nrao.edu/memos/html-memos/alma419/memo419.zip _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From jmangum at tuc.nrao.edu Wed Apr 17 17:15:25 2002 From: jmangum at tuc.nrao.edu (Jeff Mangum) Date: Wed, 17 Apr 2002 14:15:25 -0700 Subject: [asac]ALMA Week Calibration meeting agenda Message-ID: <15549.58861.41799.755637@pisco.tuc.nrao.edu> Hello, An agenda for the ALMA Week Calibration meeting can be found at http://www.tuc.nrao.edu/~jmangum/alma/calibration.shtml. Apologies if you receive this message multiple times. Please let me know if you would like to suggest changes to this agenda. Cheers, Jeff Mangum From awootten at NRAO.EDU Tue Apr 30 14:39:10 2002 From: awootten at NRAO.EDU (Al Wootten) Date: Tue, 30 Apr 2002 14:39:10 -0400 (EDT) Subject: [asac]Meeting 2 May 2002 Message-ID: <200204301839.OAA22521@polaris.cv.nrao.edu> Folks, CALL TIME: 09:00 AM EASTERN TIME 1300 Universal Time CALL DATE: MAY-02-2002 (Thursday) DURATION: 1 hr USA Toll Free #:888-324-3184 International #: +1-712-271-3820 PASSCODE: 50537 LEADER: Al Wootten The AEC will postpone its telecon, normally held at this hour, by a few minutes in order to be present for new business item (1) on the agenda. Agenda with hyperlinks, etc. may be found at: http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacmay02agenda.html Clear skies, Al