From tdumonde at nrao.edu Mon Dec 2 09:29:50 2002 From: tdumonde at nrao.edu (Tatiana DuMonde) Date: Mon, 02 Dec 2002 09:29:50 -0500 Subject: [alma_na] ALMA NA DH meeting Message-ID: <3DEB6E5E.9090506@nrao.edu> Just a quick reminder that there will be an ALMA NA DH meeting today at 1pm EST. The phone number for this meeting will be: 434-984-0244. Hope to hear from you all there. Sincerely, Tatiana From soliver at nrao.edu Thu Dec 5 16:34:31 2002 From: soliver at nrao.edu (Stacy Oliver) Date: Thu, 5 Dec 2002 14:34:31 -0700 Subject: [alma_na] [almanews] ALMA Memos 437 Released Message-ID: ALMA MEMO #437 Miniature, Modular Heat Sinks for ALMA Cryostats D. Koller, J. Effland, A. R. Kerr, K. Crady and F. Johnson (NRAO) 2002/12/02 Keywords: miniature heat sink, cryogenic electronics, thermal measurements Proposed receiver cartridges for ALMA may utilize up to 96 wires for SIS mixer bias, IF amplifier bias, thermometry and other functions [1]. To reduce heating of the mixer block and minimize the load on the 4 K refrigerator stage, heat sinks will be required on the 80 K, 12 K and 4 K stages. The present concept for the receiver cartridges requires disassembly of each thermal stage to effect repairs. Heat sinks utilizing connectors simplify disassembly, thus improving the mean time to repair. The large number of wires and connections will require a simple, reliable heat sink capable of being mass-produced for the expected 64 receiver cartridges. The main body of this report describes two different heat sink designs utilizing Nanonics "Dualobe" connectors configured in a modular arrangement for simple installation in receiver cryostats. In Appendix B, a simpler but less effective heat sink is described. The measured thermal performance of all the heat sinks is presented. View a pdf version of ALMA Memo #437. http://alma.aoc.nrao.edu/memos/html-memos/alma437/memo437.pdf Download a postscript version of ALMA Memo #437. http://alma.aoc.nrao.edu/memos/html-memos/alma437/memo437.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From soliver at nrao.edu Fri Dec 6 17:28:26 2002 From: soliver at nrao.edu (Stacy Oliver) Date: Fri, 6 Dec 2002 15:28:26 -0700 Subject: [alma_na] [almanews] ALMA Memos 442 Released Message-ID: ALMA MEMO #442 The Intensity Calibration Framework for HIFI Volker Ossenkopf, (SRON Groningen) 2002/12/05 Keywords: Calibration Existing schemes for the calibration of radio-astronomical observations are insufficient for the application in forthcoming space missions with heterodyne systems like HIFI. Many of the approximations used are not valid for systems with large IF frequencies and they are too rough for the desired calibration accuracy of a few percent. Moreover, they do not exploit the full capabilities of instruments with two thermal load for the bandpass calibration. We propose a new calibration scheme for the planning and reduction of HIFI observations, taking advantage of the lack of an atmosphere and correcting for the effects of standing waves in the combined observation of lines and continuum with HIFI. The new calibration scheme uses a separate OFF measurement to determine the properties of standing waves between the subreflector and the receiver. Two different effects are corrected. Standing wave ripples are removed from the continuum level providing the spectral baseline of the observations and the modulation of the line strengths by standing waves is corrected in the absolute line calibration. However, at high frequencies the standing wave correction imposes severe constraints on the integration time for the OFF measurement. A reasonable use of the standing-wave calibration is thus only possible if the standing wave pattern is stable over long time scales. We have also provided an accurate estimate of the error budget of the calibration allowing to put clear limits on the accuracy of the different instrumental parameters required to achieve a given intensity calibration accuracy. View a pdf version of ALMA Memo #442. http://alma.aoc.nrao.edu/memos/html-memos/alma442/memo442.pdf Download a postscript version of ALMA Memo #442. http://alma.aoc.nrao.edu/memos/html-memos/alma442/memo442.ps _______________________________________________ Almanews mailing list Almanews at listmgr.cv.nrao.edu http://listmgr.cv.nrao.edu/mailman/listinfo/almanews From tdumonde at nrao.edu Mon Dec 9 09:20:00 2002 From: tdumonde at nrao.edu (Tatiana DuMonde) Date: Mon, 09 Dec 2002 09:20:00 -0500 Subject: [alma_na] JAO/IPT meeting Message-ID: <3DF4A690.7030003@nrao.edu> There will be a JAO/IPT meeting today at 1530 UTC (10:30 EST). For those in CV, ER conference room # 311 will be used. The phone number for the meeting is the following: 434-296-7082. Please excuse the lateness of this message. Sincerely, Tatiana From mrafal at nrao.edu Fri Dec 13 15:08:20 2002 From: mrafal at nrao.edu (Marc D. Rafal) Date: Fri, 13 Dec 2002 15:08:20 -0500 Subject: [alma_na] NA Telecon Message-ID: <008c01c2a2e3$61dffba0$d8e883c0@bruno> I will be traveling west on Monday so we will NOT have a North American Telecon. I will figure out a time later in the week to reschedule it. Marc -------------- next part -------------- An HTML attachment was scrubbed... URL: From jbauer at nrao.edu Fri Dec 20 10:25:27 2002 From: jbauer at nrao.edu (Janet Bauer) Date: Fri, 20 Dec 2002 10:25:27 -0500 Subject: [alma_na] JAO/IPT Meeting on Monday, 23rd December Message-ID: <3E033667.6090808@nrao.edu> There will be a meeting on Monday, 23rd December at 1530 UT. Please dial 434.296.7082.