Processing SMA Data
Reading SMA Data into CASA
- Using pyuvdata (ALPHA VERSION)
- Using MIR mir2ms (BETA VERSION)
- Using MIR autofits (RECOMMENDED)
- Using sma2casa.py (NO LONGER SUPPORTED)
1. Using pyuvdata
IMPORTANT An alpha version of pyuvdata is available on the RTDC. We encourage users to make use of this and report any issues to firstname.lastname@example.org.
Pyuvdata is a python interface to interferometric datasets. It allows the conversion of datasets from one format to another with multiple data formats supported. Here we give the example of converting SMA data from raw MIRIAD format to UVFITS and CASA measurement sets.
2. Using MIR mir2ms
IMPORTANT A beta version of
mir2ms is available with MIR.
mir2ms is a MIR task that converts a raw (uncalibrated) SMA dataset directly to CASA measurment set in IDL.
We encourage users to report any issues to Charlie Qi (email@example.com).
The script comes packaged with the June 2021 version of MIR. This is available on the RTDC or you can find it on the MIR github page sma-mir.
[Oct 2021] Header informaion on the gunnLO is currently incompatible with
mir2ms; there is a work-around described below. Currently only a single receiver is supported.
Create a .pro script in your current working directory; in this example it has been named mymir.pro (remember that the filename must match the name given to the 'pro' in the first line of the file). There are two required tasks in this file - applying the Tsys correction and fixing the problem data header. You can optionally provide instructions to perform some basic data cleaning (e.g. flagging pointing scans & spikes). The mymir.pro script should follow this template.
As part of the routine,
autofits (see 'Using MIR autofits' below) to generate UVFITS files per source, sideband, and chunk. Unlike
mir2ms opens your local version of CASA then imports and concetenates the UVFITS files automatically.
WARNING This routine creates over 200 temporary files and directories in your cwd which will require ~ 5x the disk space of the input data directory.
mir2ms in MIR.
IDL> mir2ms, dir='210808_13:37:36', rx=230, /mymir, outname='210808_133736'
Then wait a long time. When the script has finished, exit IDL and you will find the temporary files have been deleted. You will be left with an outname_rx.ms directory in your cwd along with IDL and CASA log files.
3. Using MIR autofits
This option converts data already calibrated in MIR to CASA measurement set format. The data are written out in UVFITS format from MIR, then the provided script must used to import it to CASA.
3. Using sma2casa.py
BE AWARE: This routine converts raw, uncalibrated SMA only. It is untested with newer versions of CASA and should not be considered reliable. A new routine for converting raw SMA data is under development.
Two python scripts are used for the conversion - sma2casa.py and smaImportfix.py. This section describes the most common use case, but a more detailed description, including a full list of options, can be found at sma2casa Details.