From soliver at nrao.edu Tue Oct 14 18:11:39 2003 From: soliver at nrao.edu (Stacy Oliver) Date: Tue, 14 Oct 2003 15:11:39 -0700 Subject: [asac][almanews] ALMA Memo 461 Released Message-ID: <002301c392a0$24278be0$8edbc5ce@MOONSHINE> ALMA MEMO #461 The Amplitude Calibration System revisited S.Guilloteau (IRAM / ESO) A.Bacmann (ESO) 2003-09-16 Keywords: Amplitude Calibration, Receiver Saturation Different strategies of use of a semi-transparent device combined with two temperature loads for calibration are explored. It is shown that a system with an ambient load, a hot (100 Celsius or so) load, and a semi-transparent grid with 50 % transmission allows to reach a 1 % accuracy on the receiver gain even in presence of saturation. The best precision requires a device which offers the 5 major combinations: Sky, Sky+Ambient, Sky+Hot, Ambient, Hot. If saturation is negligible, the system can be used as a standard dual load calibration device, with better accuracy. View a pdf version of ALMA Memo #461. http://www.alma.nrao.edu/memos/html-memos/alma461/memo461.pdf _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From soliver at nrao.edu Tue Oct 14 18:12:50 2003 From: soliver at nrao.edu (Stacy Oliver) Date: Tue, 14 Oct 2003 15:12:50 -0700 Subject: [asac][almanews] ALMA Memo 478 Released Message-ID: <002401c392a0$4e42a900$8edbc5ce@MOONSHINE> ALMA MEMO #478 Distance to Possible Calibration Sources as a Function of Frequency for ALMA Bryan Butler National Radio Astronomy Observatory 2003-10-07 The assumption that so-called "fast switching" calibration will always be done by observing a calibrator at 90 GHz is examined. It is found that it may be better to observe the calibrator at the same frequency as the target, since suitable calibration sources may be just as close at higher frequencies as they are at 90 GHz (all roughly 1? for continuum bandwidths). In the end it will depend on the characteristics of the sources (size, mostly). Observing the calibrator at 90 GHz will require an additional calibration to be performed on fairly short timescales (of order minutes) to calibrate the relative complex gain between the target and calibrator frequency, since the electronics will change between scans. This extra calibration is not required if calibrator and target are observed at the same frequency. In addition, observing the calibrator at the same frequency as the target removes the requirement of having very accurate atmospheric modelling in order to transfer the phase and amplitude from calibrator frequency to target frequency (especially problematic in regions of dispersion near strong telluric lines). Because of the uncertainty in the sizes of the sources, it is not recommended to change the current paradigm of calibrating at 90 GHz, but the option of calibrating at the target frequency should be kept in mind, and exercised if it turns out that the sources considered herein are appropriate to use as calibrators (small enough). View a pdf version of ALMA Memo #478. http://www.alma.nrao.edu/memos/html-memos/alma478/memo478.pdf _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From soliver at nrao.edu Wed Oct 15 12:44:50 2003 From: soliver at nrao.edu (Stacy Oliver) Date: Wed, 15 Oct 2003 09:44:50 -0700 Subject: [asac][almanews] ALMA Memo 337 Released Message-ID: <001601c3933b$a6f1bdc0$8edbc5ce@MOONSHINE> ALMA MEMO #337 Development of Frequency Multiplier Technology for ALMA Kamaljeet S. Saini 2003-01-01 Keywords: Frequency Multiplier, Planar Integrated Frequency Multiplier, Doubler, Tripler, MMIC, Integrated Capacitor, Integrated Spiral Inductor, Amplitude Noise, Phase Noise, Noise Transmission Matrix This ALMA memo, also published as a dissertation at the University of Virginia in January 2003 (UVA Science & Engineering Library call number Diss. Engr. 2003.S24), presents a novel GaAs on Quartz based approach toward larger band-width Schottky diode frequency multipliers and reports the first fully integrable frequency multiplier based on this composite substrate is reported. This technology was developed as a low cost solution for meeting the ALMA frequency multiplier requirement up to about 400 GHz. This technology has since then been commercially applied to design and build frequency triplers for the first local oscillator chains for ALMA bands 6 and 7. The memo also describes other contemporary state-of-the-art frequency multiplier technologies and provides a comprehensive up to date survey of existing frequency multiplier designs together with their measured performances from published literature. View a pdf version of ALMA Memo #337. http://www.alma.nrao.edu/memos/html-memos/alma337/memo337.pdf Download a zipped postscript version of ALMA Memo #337. http://www.alma.nrao.edu/memos/html-memos/alma337/memo337.zip _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From soliver at nrao.edu Wed Oct 29 17:24:38 2003 From: soliver at nrao.edu (Stacy Oliver) Date: Wed, 29 Oct 2003 15:24:38 -0700 Subject: [asac][almanews] ALMA Memo 472 Released Message-ID: <004101c39e6b$70a50ca0$8edbc5ce@MOONSHINE> ALMA MEMO #472 AIPS++ Reuse Analysis Test: Report on Phase I A. Kemball, K. Golap, G. Moellenbrock (NRAO) R. Lucas, D. Broguiere (IRAM) 2003-09-10 Keywords: Software, Off-line, Science, Calibration, Imaging This report describes the results of testing to assess the ability of AIPS++ to be adapted to the needs of the ALMA reduction software. Specifically: 1) how can AIPS++ be adapted to reduce data of an instrument for which it was not designed, 2) how long is the learning curve for developers who have sufficient experience in the processing of millimeter data, but no experience at all of the AIPS++ programming environment, and 3) can we perform an end-to-end experiment on actual, real-life millimeter-wave spectroscopic data? This report describes the course of implementation for these tests and the final results and conclusions. View a pdf version of ALMA Memo #472. http://www.alma.nrao.edu/memos/html-memos/alma472/memo472.pdf _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From soliver at nrao.edu Wed Oct 29 17:24:51 2003 From: soliver at nrao.edu (Stacy Oliver) Date: Wed, 29 Oct 2003 15:24:51 -0700 Subject: [asac][almanews] ALMA Memo 473 Released Message-ID: <004601c39e6b$788187f0$8edbc5ce@MOONSHINE> ALMA MEMO #473 AIPS++ Reuse Analysis Test: Report on Phase II J. Pety1,2, A. Baker3, A. Coulais2, F. Gueth1, D. Shepherd4, L. Testi5, C. Wilson6 Support by D. Broguiere1, K. Golap2, R. Lucas1, G. Moellenbrock4, W. Young4 1 IRAM (France), 2 LERMA, Observatoire de Paris (France) 3 MPE, Garching (Germany), 4 NRAO (USA) 5 INAF - Osservatorio Astrofisico di Arcetri (Italy), 6 McMaster University (Canada) 2003-03-10 Keywords: Offine, Software, Science, Calibration, Imaging The "AIPS++ Reuse Analysis Test" has been designed to address the ability of AIPS++ to be adapted to the needs of the ALMA reduction software. It has been divided into three parts: Phase I Implementation of PdBI (Plateau de Bure Interferometer) calibration engines inside AIPS++; Phase II Test of the calibration extensions implemented in Phase I and of the native AIPS++ capabilities (in particular, imaging capabilities) on a fair sample of PdBI data sets by a panel of testers outside the AIPS++ team; Phase III Benchmarking of AIPS++ on ALMA-size data sets using the calibration extensions implemented in Phase I. This report addresses every aspect linked to Phase II. Section 2 details the findings on the test charge as seen from Phase II. Section 3 is a collection of recommendations to the AIPS++ project. These findings and recommendations follow naturally from the experience gained during Phase II, which is summarized in Appendix A. In all sections of this appendix, the text gives only the mean of a response sample whose dispersion is sometimes large. We thus encourage the reader to go through all the questionnaires available in Appendices B through H, to obtain an idea of the full range of feedback. View a pdf version of ALMA Memo #473. http://www.alma.nrao.edu/memos/html-memos/alma473/memo473.pdf _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From soliver at nrao.edu Wed Oct 29 17:24:53 2003 From: soliver at nrao.edu (Stacy Oliver) Date: Wed, 29 Oct 2003 15:24:53 -0700 Subject: [asac][almanews] ALMA Memo 474 Released Message-ID: <004701c39e6b$79bf5f20$8edbc5ce@MOONSHINE> ALMA MEMO #474 IRAM/AIPS++ Test: Phase III R. Lucas, D. Broguiere (IRAM) K. Golap, J. McMullin (NRAO) R. Rusk (DRAO) 2003-09-10 Keywords: Software, Off-line, Benchmark This document reports on computing performance issues on millimeter-wave, ALMA-sized data sets. This is the first step in monitoring the AIPS++ performance on realistic data sets which will be used for testing the off-line processing requirements. The results of this test are being used as a guide for future development, identifying the areas where work is most needed. Subsequent benchmark testing will be pursued via the ALMA benchmark program at http:shiraz.drao.nrc.ca:8080/AlmaDRPBenchmarks/. View a pdf version of ALMA Memo #474. http://www.alma.nrao.edu/memos/html-memos/alma474/memo474.pdf _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews