Status
SMA Data Reduction
September 2026
Known Issues
Flux calibration
There have been issues with the flux scaling routines in CASA for some SMA calibrators. CASA's setjy task may run successfully but produce an inappropriate or inaccurate flux model for some sources, particularly those without suitable CASA models or solar system objects with significant structure. These values may also differ significantly from the fluxes previously used in MIR. Users should visit the sma-data-reduction GitHub repository which contains calibration scripts with work-arounds for this problem.
Polarization
Conversion with pyuvdata outside of CASA still does not provide calibrated polarization products. Users may request the data in CASA measurement set format for the purposes of inspection, but will not be able to perform the necessary calibration steps. For help calibrating polarization data contact smarequester@cfa.harvard.edu.
Doppler tracking
Data taken between 4th April, 2011 and 3rd April, 2019 were affected by an error related to Doppler-tracking of data, which will affect spectral line measurements of features smaller than 1 km/sec in width. The error in question blurred out data over a velocity width of up to 0.8 km/sec, with a small overall blue-shifting of the line emission by approximately 0.3 km/sec. If you are using MIR, the routine 'uti_hayshft_fix' can be used to correct this error.
Updates & Info
Tsys application
Tsys application is an option in pyuvdata. If the Tsys is applied the resulting visibilities will be scaled to produce uncalibrated values in Jy. If Tsys calibration is not requested be warned that the Tsys information has not been propagated to the measurement set and is essentially lost. To correct for the atmosphere, you will need to use a gain calibrator.
Shared risk data
Data between 200801 and 200119 include shared risk data where the two new chunks s5 and s6 were added. These 2 chunks will cover the bottom 4GHz of the LSB and the top 4GHz of the USB. These chunks were undergoing commissioning so the data should be carefully checked before being used for any science purposes.
Documentation
Data reduction documentation is currently being expanded. Visit the RTDC webpages and report any problems or queries to holly.thomas@sao.si.edu.