N A W G ======= NRAO Algorithms Working Group Meeting - PRELIMINARY AGENDA Date: 2006-03-08 (Wednesday) Time: 1300 MST = 1500 EST Video Hub: CV-conf (others call in) Rooms: SOC317/CV311/GB241/TUCN525 Audio Toll-Free number (in US): 866-791-0515 Participant Passcode: 4329509 =============================================================================== The NAWG: I would like to invite you to attend and participate in the eleventh NRAO Algorithms Working Group (NAWG) meeting on Wednesday 8 March 2006. The goal of these meetings is to have a general forum to discuss data-processing algorithms related issues of interest to scientists and software folks alike (independent of development platform or package). This is in response to the pressures of planning for the EVLA hard problems like wide-field/wide-band imaging as well as thinking about problems for ALMA and GBT. It is meant to be as observatory-wide as possible and I'm trying to solicit some participants from the various sites. These meetings are meant to be mostly informal discussion with some scheduled presentations ("Main Events") on algorithmic research and/or implementation topics. If you wish to participate and also want to speak on a topic let me know (or just show up either in person or via video/audio)! These meetings are scheduled for the 2nd Wednesday each month (in the NAUG meeting slot in the calendar). =============================================================================== Agenda: Send items for inclusion to smyers 1. Organizational issues o request for contributed talks for future meetings! 2. Project-related (ALMA, EVLA, GBT, VLBA, &c.) issues o EVLA Memo 102 (02/2006) "Monte Carlo Methods for Bayesian Image Reconstruction and Analysis in Radio Astronomy" Urvashi R. V. & T.J. Cornwell http://www.aoc.nrao.edu/evla/geninfo/memoseries/evlamemo102.pdf 3. ***Main Event*** - Presentations and Discussion Items ******************************************************************* A pair of short talks by Gianfranco Gentile and Joe Hembold (UNM) on the use of spherical harmonic transforms in interferometry for ultra-wide-field imaging. --- "Spherical harmonics and wide field imaging" Gianfranco Gentile, Joe Helmboldt, Sudhakar Prasad (UNM) Abstract: I will introduce the approach of representing the sky brightness in terms of spherical harmonics and how this can be in principle used to create images from interferometric measurements. This could be an alternative approach to other wide-field imaging techniques such as faceting and the w-projection method. PPT and PDF available at: ftp://neoastro.phys.unm.edu/pub/ggentile/ --- "Spherical Harmonic Interferometric Imaging: Implementation" Joe Helmboldt, Gianfraco Gentile, and Sudhakar Prasad (UNM) Abstract: By representing the surface brightness of the sky in terms of spherical harmonics, one can arrive at a relation between the spatial coherence function measured by an interferometer and the spherical harmonic transform of the brightness distribution. However, there are several practical concerns one must address in order to use this to produce images using actual interferometric data. These involve 1) the determination of the largest value of l for which one needs to compute the spherical harmonic transform of the brightness distribution, 2) the computation of spherical harmonics for large (up to 100,000) values of l, and 3) the optimal technique to use to convert visibilities into values of the spherical harmonic transform for pairs of l and m values. These issues and our current efforts to address them will be discussed. PDF will be available before the talk at: http://astronomy.nmsu.edu/helmbold/sh_imaging.pdf ******************************************************************* 4. Future events (please sign up!) o Convolutional mosaicing (Myers, Golap, Bhatnagar) 5. Relevant reading: o Links to Jan 2006 URSI talks: Session J2 Friday Jan 6 2006 New Interferometric Calibration Techniques Organizer: M. Wright - Mark Holdaway's talk on fast-switching for ALMA http://www.aoc.nrao.edu/~smyers/aips++/talks/HoldawayURSI06jan06.pdf Session J3 Friday Jan 6 2006 Challenges and New Algorithms for Interferometric Imaging Organizer: S. Myers - Sanjay's talk on high-dynamic range imaging http://www.aoc.nrao.edu/~smyers/aips++/talks/BhatnagarURSI06jan06.pdf - Urvashi's talk on wide-band continuum imaging (see below) http://www.aoc.nrao.edu/~smyers/aips++/talks/UrvashiURSI06jan06.pdf - Crystal's talk on submillimeter imaging (SMA & ALMA) http://www.aoc.nrao.edu/~smyers/aips++/talks/BroganURSI06jan06.pdf o Online Conference Proceedings: - "SKA Wide-Field Imaging Workshop", Dwingeloo, NL, 22-24 June 2005 http://www.skatelescope.org/pages/news/Wrksp20220605.htm - "ALMA and SZ", Paris, 7-8 April 2005 http://www.dstu.univ-montp2.fr/alma/sz.html - "First RadioNET Software Forum", Jodrell Bank, 1-3 March 2005 http://www.radionet-eu.org/rnwiki/ProceedingsFirstSoftwareForumMeeting o Paper & Memos: - Beyond the isoplanatic patch in the VLA Low-frequency Sky Survey (W.D. Cotton et al.) Abstract: http://link.aip.org/link/%3FPSISDG/5489/180/1 - Solving for the Antenna Based Pointing Errors (Bhatnagar, Cornwell & Golap) http://www.aoc.nrao.edu/evla/geninfo/memoseries/evlamemo84.pdf - EVLA and SKA Computing Costs for Wide Field Imaging (Cornwell) http://www.aoc.nrao.edu/evla/geninfo/memoseries/evlamemo77.pdf - W Projection: A New Algorithm for Non-Coplanar Baselines (Cornwell, Golap, Bhatnagar) http://www.aoc.nrao.edu/evla/geninfo/memoseries/evlamemo67.pdf - W-projection paper draft: http://www.atnf.csiro.au/people/tim.cornwell/wproj-paper.pdf - Effects of Atmospheric Emission Fluctuations and Gain Fluctuations on Continuum Total Power Observations with ALMA (Holdaway) http://www.mma.nrao.edu/memos/html-memos/abstracts/abs490.html http://www.mma.nrao.edu/memos/html-memos/alma490/memo490.pdf o Algorithms etc. FFTs: http://www.fftw.org/links.html FFTs on the Sphere: http://www.cs.dartmouth.edu/~rockmore/fft.html http://www.cs.dartmouth.edu/~geelong/sphere/ HEALPIX: http://healpix.jpl.nasa.gov/ Fast convolution on the sphere: http://arxiv.org/abs/astro-ph/0008227 o Post-processing requirements: - ALMA Offline Data Processing Requirements http://www.alma.nrao.edu/development/computing/docs/joint/0018/ALMAoffline-sw-18.pdf - EVLA Offline Data Processing Requirements http://www.aoc.nrao.edu/~smyers/evla/evla_offline.pdf o GBT: - GBT Software Review Agenda & Presentations http://wiki.gb.nrao.edu/bin/view/Software/ReviewAgenda2004 - GBT Standard Observing Modes http://wiki.gb.nrao.edu/bin/view/Observing/StandardObservingModes 6. Upcoming meetings and deadlines: o 2006 Jan 4-7 URSI Meeting (w/Algorithms session), Boulder, CO ******************************************************************* o NAWG Website: http://www.aoc.nrao.edu/~smyers/nawg/ *******************************************************************