From lucas at iram.fr Sat Sep 1 09:41:31 2001 From: lucas at iram.fr (Robert Lucas) Date: Sat, 01 Sep 2001 15:41:31 +0200 Subject: [asac] Data Processing requirements Message-ID: <3B90E58B.4B132DD3@iraux2.iram.fr> To ASAC Members: There are links to two new documents on the SSR home page (http://iram.fr/%7Elucas/almassr/, under "Working Documents"): Both are draft documents (not yet reviewed in the Computer Group). 2001 Sep 1 : Draft Pipeline requirements 2001 Sep 1 : Draft Off-Line Data Processing Requirements Happy reading! Comments welcome! Robert Lucas -- Robert LUCAS, Institut de Radioastronomie Millimetrique 300 rue de la Piscine, F-38406 St Martin d'Heres Cedex (FRANCE) Tel +33 (0)4 76 82 49 42 Fax +33 (0)4 76 51 59 38 E-mail: mailto:lucas at iram.fr http://iram.fr/~lucas/ From soliver at tuc.nrao.edu Tue Sep 4 13:29:25 2001 From: soliver at tuc.nrao.edu (Stacy Oliver) Date: Tue, 4 Sep 2001 10:29:25 -0700 Subject: [asac] [almanews] ALMA Memos 389 and 390 Released Message-ID: ALMA Memo #389 Radio Interferometer Array Point Spread Functions I. Theory and Statistics David Woody Owens Valley Radio Observatory 2001-08-31 Keywords: radio interferometers, configurations, point spread function This paper relates the optical definition of the PSF to radio interferometer arrays. The statistical properties of the PSF including the effect of missing UV data are derived as a function of the number of antennas and array magnification, defined as the ratio of the primary beam width from an individual element to the synthesized beam width. The effect of earth rotation synthesis on the PSF is also calculated and the merits of various configuration strategies are discussed in terms of their PSFs. The concept of a pseudo-random array is introduced as an array whose large-scale average distribution matches an idealized continuous antenna distribution. The small-scale difference between the actual discrete distribution and the idealized continuous distribution produces far sidelobes in the PSF. It is shown that the statistical distribution of the sidelobes, s, of pseudo-random arrays of N antennas with sparse UV coverage is given by P(s)=N*exp(-N*s). The average sidelobe is ~1/N and the standard deviation is also ~1/N. Note that the single antenna measurements are included in the formulation of the PSF used in this work. The expected peak sidelobe for a pseudo-random array with a magnification mag is smax~2*ln(mag)/N and it is predicted that optimization can reduce the peak sidelobe to smax~2*[ln(mag)-ln(N)]/N. Pseudo-random arrays provide a benchmark against which proposed configurations can be compared. View a pdf version of ALMA Memo 389. http://www.alma.nrao.edu/memos/html-memos/alma389/memo389.pdf ____________________________________________________________________________ ______________________________________________ ALMA Memo #390 Radio Interferometer Array Point Spread Functions II. Evaluation and Optimization David Woody Owens Valley Radio Observatory 2001-08-31 Keywords: radio interferometers, configurations, point spread function The PSF of several sample arrays, including pseudo-random and circular arrays, are evaluated. The distribution of sidelobes is shown to closely follow the theoretical distribution derived in the companion paper [1]. An optimization procedure is developed that produces configurations with peak sidelobes close to the expected limit given in [1] and with a smooth progression from small peaks near the center of the PSF and the largest peaks at the edge of the primary beam. Plotting the peak sidelobe as a function of the radial distance from the center of the PSF is shown to be very useful for evaluating the PSF. The optimized arrays provide a benchmark against which other configurations can be compared. View a pdf version of ALMA Memo 390. http://www.alma.nrao.edu/memos/html-memos/alma390/memo390.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 awootten at NRAO.EDU Tue Sep 4 15:26:18 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Tue, 4 Sep 2001 15:26:18 -0400 (EDT) Subject: [asac] Reading material In-Reply-To: References: <200108311526.LAA29665@polaris.cv.nrao.edu> Message-ID: <200109041926.PAA06851@polaris.cv.nrao.edu> Dear ASAC members: The reading list for the ASAC meeting has been updated and some bad links repaired. Receiver information from W. Wild has been added today. A very complete site reading list from Radford was also added. Some adjustments to the agenda are pending and will be in place tomorrow. Clear skies, Al From awootten at NRAO.EDU Wed Sep 5 15:55:26 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Wed, 5 Sep 2001 15:55:26 -0400 (EDT) Subject: [asac] Face to face meeting Message-ID: <200109051955.PAA05153@polaris.cv.nrao.edu> Folks: Please excuse this mailing if you are not going to the meeting; it is expeditious to send this to lists rather than cobble a special list. Some revisions have been made to the agendas. For plans on return to Santiago please visit: http://alma.sc.eso.org/visitors_stgo.html I have updated and corrected poor links on the receiver reading material. Contributions from Dick Crutcher and Jack Welch have been added to the ACA Examples page. Rafael Bachiller has revised the ASAC Correlator Guidelines in response to the query from the Correlator meeting. Please see this on the page. Weather forecast for Saturday: Calama (Sat-Mon) high 70 low 50 F clear. San Pedro will be somewhat cooler than Calama Chajnantor high 32 low 15 F clear and windy. Santiago high 60 low 40 F clear. Please pack appropriate clothing--layers are useful. The site can be very dusty. It has been suggested that a plastic bag might be useful to bring along to shield items in your suitcase from the dusty ones post-Chajnantor. Continental electrial adapters are appropriate for laptops, etc. Clear skies, Al From leo at das.uchile.cl Wed Sep 5 16:13:44 2001 From: leo at das.uchile.cl (Leonardo Bronfman) Date: Wed, 5 Sep 2001 16:13:44 -0400 (CST) Subject: [asac] contact Message-ID: <200109052013.QAA00253@radio.das.uchile.cl> Dear ASAC members, For your arrival in Santiago the days prior to the visit to San Pedro, your contact in case of trouble is Andrea Lagarini, at ESO office, phone 463-3113. I will leave Santiago early on September 7th. Best regards Leo From leo at das.uchile.cl Thu Sep 6 12:15:34 2001 From: leo at das.uchile.cl (Leonardo Bronfman) Date: Thu, 6 Sep 2001 12:15:34 -0400 (CST) Subject: [asac] Re: presentation tool In-Reply-To: from "Tetsuo Hasegawa" at Sep 06, 2001 05:49:14 AM Message-ID: <200109061615.MAA15512@radio.das.uchile.cl> Dear Tetsuo, yes, there is such a projector to be connected at Cerro Calan for the ASAC and at the Science day Best regards Leo > > Dear Leo, > > One quick question: > Is a LCD projector (to be connected with my PowerBook) available for the > presentation at ASAC and at the Science Day? > Of course, I will bring transparencies for the overhead projector as well. > > See you soon. > > 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 awootten at NRAO.EDU Fri Sep 7 10:28:17 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Fri, 07 Sep 2001 10:28:17 -0400 Subject: [asac] Mark Holdaway's New Results Message-ID: <3B98D980.D5376DF2@nrao.edu> Should any of the ASAC members still be stationed near their printers, I'd like to bring to their attention Mark Holdaway's new results on the ACA. Look at his homepage: http://www.tuc.nrao.edu/~mholdawa/ where the first item is the new writeup, in postscript. See you all in Chile; I will have some copies with me. Clear skies, Al -------------- next part -------------- An HTML attachment was scrubbed... URL: From seiichi at nro.nao.ac.jp Mon Sep 17 23:01:25 2001 From: seiichi at nro.nao.ac.jp (Seiichi Sakamoto) Date: Tue, 18 Sep 2001 12:01:25 +0900 Subject: [asac] Enhanced sciences with ACA? Message-ID: Dear ASAC members: In the Santiago face-to-face meeting, relatively high priority was assigned to ACA based on rather vague feeling. This is potentially of severe concern to ALMA, because the full scope of the enhancement may be threatened if we fail to present strong science cases for ALMA+SD+ACA that cannot be realized with ALMA+SD. Here I summarize some of my comments/concerns and TBDs on the science cases for ACA in the following. I hope this helps a bit to finalize the ASAC report. Any comments and corrections are welcome. (1) General comments/concerns: - Mass and motion of the objects are two of the most important parameters in observational astrophysics. How ACA is related to these parameters? Accurate imaging does not mean robust extraction of mass distribution. What is the importance of extremely high fidelity images probed by molecules other than molecular hydrogen? - What fraction of ALMA users really takes advantages of the extremely high fidelity of ALMA+SD+ACA? Is it of higher priority than to ensure routine high fidelity imaging with ALMA+SD to all users? - How easily will we lose the gain achieved with ACA by degrading the SD observations or by inappropriate deconvolution algorisms? (2) Line ratios: - In multi-line analyses, ambiguity of chemical abundances, complexity of the objects, unmatched synthesized beams, inhomogeneity of physical conditions in the synthesized beam, and robustness of the model used (e.g., LVG) often limit the robustness of conclusions. We should evaluate what level of fidelity is necessary/sufficient for this kind of analyses, and what level of fidelity can be achieved for realistic cases (noise for realistic integration times and source strengths). - We should explain why extremely high fidelity is preferred rather than number of bands (or number of observable lines) that also enhances ability of multi-line observations. (3) Arm-to-interarm contrast: - Fidelity of images at extremely high level may not be the limiting factor that controls conclusions. The arms of spiral galaxies are not always well-defined, and identification of arms may limit the robustness. The situation becomes more difficult for flocculent galaxies. We should examine if different researchers independently obtain consistent value of the arm-to-interarm contrast with sample images to the accuracy of current interest. - Uncertainty due to ambiguous luminosity-mass conversion may also play a major role. (4) Mass spectrum of clouds and cores: - Ken Tatematsu's analysis at the face-to-face meeting clearly demonstrated that ALMA+SD already realizes enough fidelity for this purpose. In realistic cases, complexity of the objects (cloud/clump overlapping, irregular structure, etc.) and robustness of simple finding algorisms (e.g., CLUMPFIND) may limit the results. - Uncertainty due to ambiguous luminosity-mass conversion may also play a role. - We should find other cases in which extremely high fidelity is needed. (5) Polarization: - Polarization study seems among which ACA might play a role. We need examples that clearly demonstrate this. We should be sure that ACA supports polarization capability under severe budgetary constraints if we are to stress this science case. (6) Submillimeter observations: - Smaller diameter of ACA antenna may be suitable for submillimeter observations. However, current situation suggests that submillimeter receivers that enable submillimeter observations may be competitive with ACA. We should justify why we prefer ACA rather than Band 8 if we are to stress this science case. - If we are to stress this science case, optimization of the array diameter, number of antenna, and configuration may be needed, because the current optimization is based on imaging capability. With best, Seiichi ========================================== Seiichi Sakamoto ------------------------------------------ ALMA-Japan Project Office National Astronomical Observatory of Japan Osawa, Mitaka, Tokyo 181-8588, Japan phone: +81-422-34-3843 fax: +81-422-34-3764 e-mail: seiichi at nro.nao.ac.jp URL: http://www.nro.nao.ac.jp/~seiichi ------------------------------------------ From ewine at strw.leidenuniv.nl Tue Sep 18 03:57:06 2001 From: ewine at strw.leidenuniv.nl (Ewine van Dishoeck) Date: Tue, 18 Sep 2001 09:57:06 +0200 Subject: [asac] ASAC report: timeline Message-ID: <200109180757.f8I7v6I27176@hydrogen.strw.leidenuniv.nl> Dear ASAC members, I trust that you got back safely to your homes, even a few days late. Many thanks again to all of you for staying focussed under these difficult circumstances, and for contributing to our productive ASAC meeting and the ALMA science day. I enclose below the timeline for the report, together with the people responsible for the various sections. Please keep to these deadlines, since the schedule is tight. Remember that the next telecon is on WEDNESDAY October 10, at the usual time. With best regards, Ewine *************************************************************************** Schedule ASAC report: ==================== - Copies viewgraphs, powerpoint presentations -> Ewine a.s.a.p. (see also e-mail Peter Shaver) - First drafts sections -> Ewine Sept. 24 - First complete draft -> ASAC Oct. 3 - Comments ASAC -> Ewine Oct. 9 - Final report to E-ACC Oct. 15 Schedule Science Cases for enhancements (Appendix ~10 p. + figures): ======================================= - ACA science case -> Ewine Sept. 29 - Complete draft -> ASAC Oct. 8 - Comments ASAC -> Ewine Oct. 11 - Final report to E-ACC Oct. 15 *************************************************************************** Sections: ========= - Project status, management (from minutes) - Site issues, configuration: Booth, Bronfman, Sakamoto - ACA simulations, science: Cox, Crutcher, Hasegawa, Welch - Correlator: Bachiller, Scoville, Yamamoto - Operations: Evans, Fukui, Wilson - Software: Benz, Gurwell, Tatematsu - Calibration, WVR: Matsuo, Richer, Wilson - Polarization: Crutcher - Receivers: Blake, vD, Nakai - Antennae, test interferometer: Fukui, Walmsley, Welch - ASTE, APEX: Kawabe/Yamamoto, Schilke