Workgroup B

Notes of Activities

Applications

• SWARP input to Sextractor
  • http://terapix.iap.fr/rubrique.php?id_rubrique=49
  • SWarp is a program that resamples and co-adds together FITS images using any arbitrary astrometric projection defined in the WCS standard

• R makes images for input to Moviemaker
  • http://www.r-project.org
  • R is a language and environment for statistical computing and graphics
  • it provides a wide variety of statistical (linear and nonlinear modelling, classical statistical tests, time-series analysis, classification, clustering, ...) and graphical techniques, and is highly extensible.
  • The S language is often the vehicle of choice for research in statistical methodology, and R provides an Open Source route to participation in that activity.
  • we can use R as library of mathematical functions

Data

• SWIRE and/or SDSS not WFS (projection problems)

Theory

• Laurie supply halo data to feed into R?

Services

• SIAP, VOTable, CEA

Issues

• Dave and Robert working on using R with CEA?
• Paul gave demo of a CEA server installation
• Paul made SWARP into a CEA application
  • Example workflow: swarp-2.wf
• Nic grabbed sample SDSS DR3 http://casjobs.sdss.org/vo/DR3SIAP/SIAP.asmx/getSiapInfo?&FORMAT=image/fits&BANDPASS=i& optical image frames and (with David) edited and successfully submitted a workflow to coadd frames with SWARP and saved to myspace
• David mosaiced the separate image files within a SWARP workflow
  • TO DO: input a smaller test mosaic having just 2 image frames to sextractor
• Laurie working with Robert to visualise clustering in simulated dark matter halo data using R

Outcomes

1. SWARP was successfuly deployed - and is now available as an application for use in a workflow.
2. Image data from HST was acquired and processed through SWARP
3. Next step to feed this into Sextractor - script for this was begun
   • SWARP output image

1. R was successfully deployed
2. Theory data (results from a dark matter cluster simulation) were loaded into MySpace and fed into the R application
3. An R script was run on this theory input data - a k-mean cluster finder algorithm was applied - results returned to MySpace
   • cluster-wf: graphics showing the workflow used
   • R output graphic: graphic showing the output from the workflow

Key Points for Future Work

Technical Issues and Limitations

• MySpace upload file size limit of 10-12MB is too small - many image files are >128MB already
• ACS images are 80Mb but after SWARP algorithm is run the output file is of order 400Mb which is too large to handle at present
• Swarp interface - editing the input file list always give an end point with a blank new file name box - this gets passed as an extra null parameter to Swarp which then fails. So now - we have to save the workflow, download it, edit it to remove the spurious extra filename parameter, and then reload it to myspace before running.
• system topology - Leicester outage stopped all work - no myspace, registry.
• speed of system - especially at login - this takes ages
• general user interface
• finding what data there is at a point
• some services didn't work as advertised - e.g. the siap to dss failed - maybe due to IPv6 issues?
• minor bug when logging into my space from Top Cat: username is auto filled in but using name on pc rather than AG username. Would like to remember as AG username in future?

Resources

• Science cases

-- NicholasWalton - 14 Jul 2005