Processing SMA Data
1.2 m Telescopes

What's in the SMA raw data directory?

When taking interferometer data, the SMA records data in a set of files all contained in a single directory. Below is a description of the files you will find in your data directory. For a more complete description including data type, structure, and attributes, click here.

antennas This file contains the X, Y and Z coordinates of each antenna, in meters. The coordinate system is defined, with these letters, in Thompson, Moran and Swenson's text "Interferometry and Synthesis in Radio Astronomy" (Chapter 4, page 87 in the 2nd Edition). This file is only written to once when the data directory is opened.
autoCorrelations (SWARM only) This file contains the autocorrelation spectra from the SWARM correlator.
bl_read This file contains the baseline information. There is one fixed-length record written per receiver per sideband per baseline per scan. The order of the loops writing out these records is: 'receiver, sideband, polarization, baseline'. For most tracks receiver and polarization only have a single value, and the loops collapse to 'sideband, baseline'
codes_read The header blocks that comprise the header information for each scan generally only contain integer index 'code' values for the values. This file contains the associated string and description related to each code.
codeVersion This file contains the dates at which certain critical pieces of the online software were compiled. It is intended to help track bug fixes that need to be applied to certain data sets.
eng_read This file contains fixed-length records for engineering data - e.g. integration ID, pointing offsets. One record is written for each antenna.
in_read This file contains scan header information e.g. source, project code, integration number, track ID, azimuth and elevation. It consists of fixed-length records, with one record written for each scan.
modeInfo An ASCII file containing two integers on a single line. The first integer specifies the number of active receivers ("1" or "2"), the second integer specifies the bandwidth, in GHz ("2" or "4").
plot_me_5_rx{n} There is one of these files for each active receiver. This file is is used by corrPlotter to produce the "mir display".
projectInfo This file simply contains the name of the project PI. It exists only to help track the data through our retrieval system.
sch_read This is the file that actually contains the visibility data. Unlike most of the files containing binary data, the records in this file are of wildly varying length, depending upon the resolution of the spectrometer band. There is one record written for each scan, and it contains the packed visibility data for all chunks and the pseudocontinuum channels.
sp_read This file contains the header information for each individual spectral band of data. A spectral band can be either a correlator chunk or the pseudo-continuum channel.
SMAshLog_{YYYYMMDD_HHMMSS} This file contains all of the SMAsh commands which were issued while the array was using this directory to store data. In some cases there may be more than one of these files in the directory.
tsys_read This file contains the system temperature information. It holds all the Tsys measurements we have for each antenna, along with the IF frequency ranges overwhich those Tsys measurements were acquired.
we_read This file contains antenna status flags, and weather information for each scan. For the 11 element arrays, element 0 contains observatory-wide values, and the other elemets contain the values measured at the individual antennas.