Data Flow

This page outlines the steps the data take from detector to archive.

Six computers are needed to operate both MODS: there is one Linux data server per channel, called mods1blue, mods1red, mods2blue, mods2red, and one Linux instrument server per MODS, called mods1 or mods2. There is one live spare in the computer room B that can be configured as either a data or instrument server (check whether one or two).

For a given channel, in this case MODS1 Blue:

1. azcam software running on mods1blue interfaces with the Archon controller and reads the detector. The data are stored in multi-extension FITS files, where extensions 1, 2, 3 and 4, named IM1, IM2, IM3 and IM4, hold the data from the four quadrants, Q3, Q4, Q1 and Q2, respectively, and extension 5 is a binary table which stores the Archon controller hardware status at the start of the exposure. See the Data Files section of the Detector page for more details on the Archon ADC to quadrant mapping. These raw MEF files are stored in /data/mods1b on mods1blue.
2. The raw MEF files are then NFS-copied to the instrument server, mods1. The dataMan agent running on mods1 processes the raw data to create an overscan-subtracted, trimmed and merged image which it writes to a 6th extension, called MERGED. dataMan also updates/corrects certain header keywords/values. These files are stored on the instrument server in /data/mods1b, and
3. they are copied to newdata (/lbt/data/new) which is NFS-mounted on the instrument server, mods1. The observing tools, modsDisp and modsAlign, use the MERGED 6th extension.
4. From newdata, the files are copied to the appropriate UT-date directory in the mountain repository (/lbt/data/repository/YYYYMMDD) and then on to the Tucson repository and to the IA2-managed archive (archive.lbto.org) from which investigators will retrieve their data.

Please see the Archive page for information on how to retrieve your data from the Archive, how to retrieve associated calibrations and a listing of data reduction scripts and pipelines.