Exposure Level Processing

Class:

romancal.pipeline.ExposurePipeline

Alias:

exposure_pipeline

The ExposurePipeline applies detector-level corrections to given exposure types (imaging, prism, and grism.). It is applied to one exposure at a time. It is sometimes referred to as “ramps-to-slopes” processing, because the input raw data are in the form of ramps containing accumulating counts from the non-destructive detector readouts and the output is a corrected countrate (slope) image.

The list of steps applied by the ExposurePipeline pipeline is shown in the table below.

Step	WFI-Image	WFI-Prism	WFI-Grism
dq_init	✓	✓	✓
saturation	✓	✓	✓
linearity	✓	✓	✓
dark_current	✓	✓	✓
jump	✓	✓	✓
ramp_fitting	✓	✓	✓
assign_wcs	✓	✓	✓
flatfield	✓
photom	✓
source_detection	✓
tweakreg	✓

Arguments

The exposure pipeline has an optional argument:

--use_ramp_jump_detection  boolean  default=True

When set to True, the pipeline will perform jump detection as a part of the ramp fitting step. The data at this stage of the pipeline are still in the form of the original 3D ramps ( ngroups x ncols x nrows ) and have had all of the detector-level correction steps applied to it, up to but not including the detection and flagging of Cosmic-Ray (CR) hits within each ramp (integration). For this case the jump module in ramp_fitting will update the dq array with the CR hits (jumps) that are identified in the step.

Inputs

3D raw data

Data model:

RampModel

File suffix:

_uncal

The input to the ExposurePipeline is a single raw exposure, e.g. “r0008308002010007027_06311_0019_WFI01_uncal.asdf”, which contains the original raw data from all of the detector readouts in the exposure ( ngroups x ncols x nrows ).

Note that in the operational environment, the input will be in the form of a RawScienceModel, which only contains the 3D array of detector pixel values, along with some optional extensions. When such a file is loaded into the pipeline, it is immediately converted into a RampModel, and has all additional data arrays for errors and Data Quality flags created and initialized to zero.

Outputs

2D Image model

Data model:

ImageModel

File suffix:

_cal

Result of applying all pipeline steps up through the tweakreg step is to produce calibrated data with the image wcs aligned to Gaia, and is 2D image data, which will have one less data dimensions as the input raw 3D data ( ngroups x ncols x nrows ). In addition to being a 2-dimensional image the output from the pipeline has the reference pixels removed from the edges of the science array.