Files generated during Orac-dr imaging data reduction have suffices denoting the processing step
that created them. This appendix contains a list with short descriptions of what they mean. Most will
be removed once a recipe has finished using them. So you will probably only see these files if you list
the contents of directory $ORAC_DATA_OUT while the pipeline is running, or you interrupt the pipeline
with CTRL/C, or something has gone wrong with the the recipe and pipeline has aborted, or you have
commented out the ‘_TIDY’ primitive from the recipe, or you have set the ORAC_KEEP environment
variable to 1.
| Suffix | Stands for | Description |
| _adu | ADU | Multiplied by the exposure time to convert the units to ADU (Michelle) |
| _bc | Bias Corrected | Residual bias variations removed (ISAAC) |
| _bgl | BackGround Limited | Whether or not each pixel is background limited, i.e. Poisson noise exceeds the read noise |
| _bp | Bad Pixel | Co-added with the bad-pixel mask |
| _bpc | Bad Pixel Cumulative | Cumulative bad-pixel mask (UIST) |
| _bpd | Bad Pixel Data | Thresholded bias or dark frame for bad-pixel mask creation (UIST) |
| _cl | CLone | Modifiable copy of IRCAM raw data |
| _db | De-Biassed | The bias is actually zero, but it sets up various Ccdpack ancillary data for later processing |
| _dcb | Differenced Chop Beams | The difference of the A- and B-beam signals of nodded data, as used by NOD_CHOP recipes |
| _dk | DarK | Dark subtracted |
| _dp | Differenced Pair | The difference of successive frames in a NOD recipe |
| _dta | Distortion Transfomation Applied | Resampled for field distortion |
| _ess | E-beam Sky Subtracted | Polarimetry target e-beam after sky subtraction |
| _ff | Flat Field | Divided by the flat field |
| _fm | Flat Masked | This has the flagged deviant pixels detected by the initial flat-field creation restored after object masking |
| _fpm | Fabry-Perot Masked | After a mask is applied to exclude regions beyond the circle transmitted by the Fabry-Perot etalon. |
| _md | Masked Deviants | Deviant pixels from the neighbourhood (usually 3 σ in 15×15-pixel region) flagged as bad |
| _nl | Non-Linearity | The standard non-linearity correction has been applied (IRCAM only) |
| _nm | Normalised to Mode | Normalised masked frames combined to make the flat field |
| _om | Objects Masked | This has sources masked with bad values so that they do not bias the self flat field |
| _oss | O-beam Sky Subtracted | Polarimetry target o-beam after sky subtraction |
| Suffix | Stands for | Description |
| _qm | Quadrant Masked | One of the quadrants is masked with bad pixels, created in QUADRANT_JITTER |
| _pov | POisson Variance | Poisson variance added |
| _raw | Raw copy | Copy of the raw data, but in output directory and has history recording enabled |
| _rnv | Read Noise Variance | Variance created containing the readnoise |
| _ss | Sky Subtracted | Global or local sky subtraction applied |
| _th | THresholded | Non-physical values set to bad |
| _trn | TRaNsform | The transformed or resampled data immediately prior to making a mosaic |
| _xpr | X PRofile | Median of each row (ISAAC) |
| _ypr | Y PRofile | Median of each column (ISAAC) |
| Suffix | Stands for | Description |
| _An | A beam Negative | Extracted negative A-beam source and region from chopped and nodded mosaic |
| _Ap | A beam Positive | Extracted positive A-beam source and region from chopped and nodded mosaic |
| _Bn | B beam Negative | Extracted negative B-beam source and region from chopped and nodded mosaic |
| _Bp | B beam Positive | Extracted Positive B-beam source and region from chopped and nodded mosaic |
| _cab | Combined A & B beams | Combined positive and negative images extracted from chopped and nodded mosaic |
| _cpc | Column-Profile Corrected | Removed column pattern, likely arising from pickup |
| _fb | Filled Bad pixels | Bad pixels in the mosaic are filled using smooth function of the neighbouring good pixels |
| _I | Intensity | Polarisation intensity |
| _mos | Mosaic | Final mosaic |
| _P | Percentage | Percentage polarisation |
| _PI | Polarisation Intensity |
|
| _Q | Stokes Q | Stokes Q parameter |
| _qcab | Quality Combining A & B beams | Quality map from combining positive and negative images extracted from chopped and nodded mosaic |
| _rpc | Row-Profile Corrected | Removed row pattern, say due to bias variations |
| _scab | Smoothed Combined A & B beams | Block-smoothed combined positive and negative images extracted from chopped and nodded mosaic |
| _sp | Stokes Parameters | Data cube of Stokes parameters |
| _TH | THeta | Polarisation angle |
| _U | Stokes U | Stokes U parameter |
| _w | Wavelength | Fabry-Perot mosaic from different wavelengths |
| _xpr | X PRofile | Median of each row of the mosaic |
| _ypr | Y PRofile | Median of each column of the mosaic |
The following frame suffices were present prior to version 3.0 of Orac-dr.
| Suffix | Stands for | Description |
| _dg | De-Glitched | Bad pixels replaced by median of neighbours |
| _sbp | Substitute Bad Pixels | Bad pixels replaced (needed for PISA) |
| _sc | SCaled | Data scaled to lie within the range of values allowed by PISA for the object masking |
The following mosaic suffices were present prior to version 3.0 of Orac-dr.
| Suffix | Stands for | Description |
| _mu | Mosaic (Unfiltered) | Intermediate mosaic (could contain bad/hot pixels) |