From awootten at NRAO.EDU Mon Nov 5 12:21:23 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Mon, 5 Nov 2001 12:21:23 -0500 (EST) Subject: [asac] Meeting Weds 7 November 2001 Message-ID: <200111051721.MAA16048@polaris.cv.nrao.edu> Folks: The dial-in information CALL DATE: NOV-07-2001 (Wednesday) CALL TIME: 09:30 AM EASTERN TIME = 1430 Universal Time DURATION: 1 hr USA Toll Free Number: 888-677-1819 USA Toll Number: +1-212-287-1630 PASSCODE: 28599 LEADER: Mr Geoff Blake An agenda has been posted at: http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacnov01agenda.html I will unfortunately be en route to another meeting and cannot attend. Clear skies, Al From soliver at tuc.nrao.edu Wed Nov 14 18:18:20 2001 From: soliver at tuc.nrao.edu (Stacy Oliver) Date: Wed, 14 Nov 2001 16:18:20 -0700 Subject: [asac] [almanews] ALMA Memo 397 Released Message-ID: ALMA Memo #397 Proposed Quartz Vacuum Window Designs for ALMA Bands 3 - 10 Daniel Koller, A. R. Kerr, G. A. Ediss (NRAO) 2001-11-13 Keywords: quartz crystal low-loss vacuum windows, antireflection layers This memo describes the design of Z-cut crystal quartz vacuum windows with plastic antireflection layers for ALMA Bands 3 through 10. The windows can be made using readily available materials and proven construction techniques. Model calculations for each of the bands are presented showing the expected reflection loss and total insertion loss. View a pdf version of ALMA Memo 397. http://www.alma.nrao.edu/memos/html-memos/alma397/memo397.pdf Download a ps version of ALMA Memo 397. http://www.alma.nrao.edu/memos/html-memos/alma397/memo397.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 soliver at tuc.nrao.edu Tue Nov 20 12:36:09 2001 From: soliver at tuc.nrao.edu (Stacy Oliver) Date: Tue, 20 Nov 2001 10:36:09 -0700 Subject: [asac] [almanews] ALMA Memo 398 and 399 Released Message-ID: ALMA Memo #398 Impact of ACA on the Wide-Field Imaging Capabilities of ALMA J. Pety, F. Gueth and S. Guilloteau (IRAM) 2001-11-18 Keywords: mosaicing, wide field imaging, ALMA simulator This document presents the imaging simulations performed at IRAM to study the importance of the ALMA Compact Array (ACA) on the wide field imaging performances of ALMA. The simulations are based on a fast, approximate but sufficiently accurate method. The image reconstruction is based on two new CLEAN-based deconvolution methods for mosaics. The effects of i) pointing errors, ii) amplitude calibration errors and iii) atmospheric phase noise have been systematically studied. The effect of a poor knowledge of the primary beams has also been studied. Finally we investigated the impact of variations of the deconvolution parameters. A large number of simulations have been performed, using several test images. This allowed us to disentangle artifacts due to particular random sampling of the errors from the genuine, average impact of these errors on all images. We find that adding ACA observations improves the image quality of ALMA in some types of images. More importantly, ACA provides robust results, when ALMA fails in presence of some type of errors, or on some images. One of the two new deconvolution techniques requires only a very moderate increase in computing time to include the ACA data. View a pdf version of ALMA Memo 398. http://www.alma.nrao.edu/memos/html-memos/alma398/memo398.pdf Download a zipped ps version of ALMA Memo 398. http://www.alma.nrao.edu/memos/html-memos/alma398/memo398.zip ---------------------------------------------------------------------------- ------------------------- ALMA Memo #399 Millimeter Wave Generation Using a Uni-Traveling-Carrier Photodiode T. Noguchi, A. Ueda, H.Iwashita, S. Takano, Y. Sekimoto, M. Ishiguro, T. Ishibashi, H. Ito, and T. Nagatsuma 2001-11-19 Keywords : photomixer, photodiode, millimeter-wave generation We have designed a new photomixer using a uni-traveling carrier photodiode (UTC-PD) for generation of W-band radiation. The UTC-PD is integrated on a InP chip with DC and RF circuits and the chip is mounted upside down on a fused quartz substrate which is placed in a microstrip channel across a quarter-height W-band waveguide. A simple cross-shaped microstrip-waveguide transition printed on the quartz substrate is used to couple power into the waveguide. From the simulation it is found that this microstrip-waveguide transition can give better than -15 dB return loss over 75--120 GHz. The UTC-PD is irradiated by combined two lasers from the back side of the InP chip. We have successfully produced difference-frequency radiation at 100 GHz with a power level of 1 mW by the photomixer. View a pdf version of ALMA Memo 399. http://www.alma.nrao.edu/memos/html-memos/alma399/memo399.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 Mon Nov 26 13:22:26 2001 From: awootten at NRAO.EDU (Al Wootten) Date: Mon, 26 Nov 2001 13:22:26 -0500 (EST) Subject: [asac] Draft minutes last meeting Message-ID: <200111261822.NAA09602@polaris.cv.nrao.edu> Next meeting will be: CALL DATE: DEC-05-2001 (Wednesday) CALL TIME: 09:30 AM EASTERN TIME DURATION: 1 hr USA Toll Free Number: 888-469-0509 USA Toll Number: +1-312-470-0141 PASSCODE: 44628 LEADER: Dr Al Wootten Peter produced draft minutes of the last meeting, which I will circulate here for your information. Please submit agenda items for the next meeting to Geoff and to Pierre asap. Remember to email your preferences for the next face to face meeting as requested in item 4. The International Astronomical Observatories in Chile Workshop on Galactic Star Formation Across the Stellar Mass Spectrum (Chile, March 2002) http://www.ctio.noao.edu/workshop2002/ -------------------------------------------------------------------------= ---------------------------------- ALMA Science Advisory Committee Teleconference, 7 November 2001 Draft Minutes Participants: R. Bachiller, G. Blake, R. Brown, P. Cox, R. Crutcher, N. Evans, Y. Fukui, S. Guilloteau, M. Gurwell, T. Hasegawa, M. Ishiguro, R. Kurz, J. Mangum, H. Matsuo, N. Nakai, J. Richer, S. Sakamoto, P. Shaver, K. Tatematsu, E. van Dishoeck, S. Yamamoto The proposed agenda was adopted, and the minutes of the previous meeting were accepted. 1. U.S. Funding Status R. Brown announced that the construction of ALMA has been effectively approved: $12.5 million has been allocated in FY 2002 =93for construction=94. The overall budget package still has to be passed by th= e House and Senate and signed by the President; these steps should take place imminently, and appear virtually certain. The ASAC congratulated the Project on this crucial milestone for ALMA. 2. Status of Japan M. Ishiguro summarized the recent developments in Japan. The R & D budget proposal had been submitted to the Ministry of Finance over the summer. The Ministry of Finance has since said that it would be difficult to secure the full budget, and asked NAOJ to consider participating at a lower level. M. Ishiguro said that even then Japan would be able to do a considerable part of the project. Japan wants to make its best efforts to participate, and there are continuing discussions with the Ministry of Finance. The years 2002/2003 are currently categorized as R & D for ALMA in Japan; an amount of about $13-15 million should be available, and there are good prospects for the 12-meter prototype. The main construction budget will start in 2004, and for that plans will have to be made a year from now. The ACC strongly supports Japanese participation, even at a level less than one-third of the total. 3. Results of ACC Meeting, Status of ASAC Charter R. Kurz started by saying that in Europe, the current plan is for final project approval in June 2002, although a decision as early as December is still possible. He summarized the current status of the project, in the light of the above developments and the recent meetings in Washington. The focus will be on the baseline bilateral project, led by the original ACC and AEC, while maintaining close communication and coordination with Japan. In the latter context, the E-ACC will still exist and will meet about once per year, and the ALG will be resurrected to provide relevant input. The ASAC will continue with the same full composition it has currently, and the chair and vice-chair will rotate between the European and North American partners. The AEC has been asked by the ACC to have an updated bilateral project plan ready by 1 February 2002 ($552 million total). It is essential to proceed with the International Project Office, and to implement the IPTs, as soon as possible. At its meeting the ACC expressed its appreciation for the considerable work by the ASAC on the enhancements for the trilateral project, the operations plan, and other inputs. The ACC has not made decisions on the operations plan yet, and will need continuing ASAC input. The antenna procurement issues were briefly discussed, and also the access to the land in Chile, for which legal opinion has recently been obtained. G. Blake called for comments on the current ASAC Charter, as this is intended for review by the ACC in its December teleconference. 4. Next ASAC Face-to-Face Meeting Y. Fukui proposed that the next ASAC face-to-face meeting take place in Tokyo or Nagoya on 19-20 March 2002, with an ALMA Science Day to follow on the 21st. Another possibility may be one week earlier (12-14 March). ASAC members were asked to e-mail their preferences to all three Chairs/Vice Chairs: G. Blake, P. Cox, and Y. Fukui. 5. Ongoing investigations: Simulations, Operations S. Guilloteau said that the report on the ACA would be ready as an ALMA memo by the end of the week. The simulator will be made generally available. He also said that configuration studies were needed to make sure that the ACA could be accommodated. New studies have started on single dish observing techniques, and a report on these is expected by the end of the month. On Operations, Neal Evans raised the question of how to move forward. Issues could include the RSCs, and the ALMA TAC. P. Cox mentioned that a meeting on the European RSC is scheduled to take place in Paris on 7 December, and G. Blake said that he would discuss steps for the North American RSC with C. Wilson. Concerning the TAC, it was proposed to collect information on TACs from other facilities, as a starting point for discussion. As mentioned above, the ACC just =93took note=94 of the A= SAC recommendations on operations, and would like continuing ASAC input. 6. AOB P. Shaver conveyed the good news that Karl Menten has made significant progress in the last few weeks, and ASAC members are encouraged to send e-mail message to Karl via his secretary Edith Fingas (efingas at mpifr-bonn.mpg.de). 7. Next teleconference The next ASAC teleconference will take place on Wednesday 5 December at 14:30 UT. From soliver at tuc.nrao.edu Wed Nov 28 15:27:57 2001 From: soliver at tuc.nrao.edu (Stacy Oliver) Date: Wed, 28 Nov 2001 13:27:57 -0700 Subject: [asac] [almanews] ALMA Memo 396 Released Message-ID: ALMA Memo #396 A Photonic MM-Wave Reference and Local Oscillator Source P. G. Huggard & B. N. Ellison (Rutherford Appleton Laboratory, Chilton) P. Shen, N. J. Gomes & P. A. Davies (University of Kent, Canterbury) W. P. Shillue, A. Vaccari, W. Grammer & J. M Payne(NRAO, Tucson) 2001-11-21 Keywords: photomixer, photodiode, millimetre-wave generation We report further progress on the development of a photonic mm-wave waveguide source suitable for application as a phase reference and as a local oscillator. The mm-wave power was generated in a W-band waveguide mount by the beating of two 1.55 ?m laser beams in a modified commercial photodiode. Maximum optical to mm-wave power conversion efficiency of 1.8% was measured at 75 GHz, where an input power of +10 dBm yielded a non-saturated output power of -7.5 dBm. Measured output powers fell approximately as frequency^(-4) above 100 GHz, decreasing from about -10 dBm at 100 GHz to -40 dBm at 625 GHz. We remark that the mount is non-optimised for frequencies above 110 GHz, and so these measurements are a lower limit on the available power. View a pdf version of ALMA Memo 396. http://www.alma.nrao.edu/memos/html-memos/alma396/memo396.pdf Download a zipped postscript version of ALMA Memo 396. http://www.alma.nrao.edu/memos/html-memos/alma396/memo396.zip ============================================================================= ALMAnews is a broadcast service. To unsubscribe, send an e-mail message to majordomo at nrao.edu with "unsubscribe almanews" in the message body.