science_products.rst

Science Products

The following sections describe the format and contents of each of the Roman ASDF science products.

Uncalibrated raw data: uncal

Exposure raw data products are designated by a file name suffix of "uncal." These files usually contain only the raw detector pixel values from an exposure, with the addition of meta data associated with the exposure. The resultantdq array is an optional array used to flag missing data in the data Formatting process.

data array		Data Type	Units	Dimensions
data	Required	uint16	DN	nresultants x nrows x ncols
amp33	Required	uint16	DN	nresultants x 4096 x 128
resultantdq	Optional	uint8	N/A	nresultants x nrows x ncols

• data: 3-D data array containing the raw pixel values. The first two dimensions are equal to the size of the detector readout, with the data from multiple resultants stored along the 3rd axis.
• amp33: This is the reference output from a dedicated SCA Output that reads additional Reference Pixels on the SCA that are separate from the full-frame array read out by the Science Outputs. This Output is active in parallel with either the 32 Science Outputs or the 1 Guide Window Output.
• resultantdq: An array that flags the location of any missing data discovered in the data formatting process.

Ramp data: ramp

As raw data progress through the romancal.pipeline.ExposurePipeline <exposure_pipeline> pipeline they are stored internally in a ~romancal.datamodels.RampModel. This type of data model is serialized to a ramp type ASDF file on disk. The original detector pixel values are converted from integer to floating-point data type. An ERR array and two types of data quality arrays are also added to the product. The ASDF file layout is as follows:

data array		Data Type	Units	Dimensions
data	Required	float32	DN	nresultants x nrows x ncols
pixeldq	Required	uint32	N/A	nrows x ncols
groupdq	Required	uint8	N/A	nresultants x nrows x ncols
err	Required	float32	DN	nresultants x nrows x ncols
amp33	Required	uint16	DN	nresultants x 4096 x 128
border_ref_pix_left	Required	float32	DN	nresultants x 4096 x 4
border_ref_pix_right	Required	float32	DN	nresultants x 4096 x 4
border_ref_pix_top	Required	float32	DN	nresultants x 4 x 4096
border_ref_pix_bottom	Required	float32	DN	nresultants x 4 x 4096

• data: 3-D data array containing the pixel values. The first two dimensions are equal to the size of the detector readout, with the data from multiple resultants stored along the 3rd axis.
• pixeldq: 2-D data array containing DQ flags that apply to all groups and all resultants for a given pixel (e.g. a hot pixel is hot in all groups and resultants).
• groupdq: 3-D data array containing DQ flags that pertain to individual reads within an exposure, such as the point at which a pixel becomes saturated within a given exposure.
• err: 3-D data array containing uncertainty estimates.
• amp33: Amp 33 reference pixel data.
• border_ref_pix_left: Copy of original border reference pixels, on left (from viewers perspective).
• border_ref_pix_right: Copy of original border reference pixels, on right (from viewers perspective).
• border_ref_pix_top: Copy of original border reference pixels, on the top (from viewers perspective).
• border_ref_pix_bottom: Copy of original border reference pixels, on the bottom (from viewers perspective).

Note

The reference pixels that are on the outer border of the science array are copied to these storage arrays (border_ref_pixel<position>) at the dq_init step but are retained in the science array until being trimmed at the ramp fitting step.

Calibrated data: cal

The cal products are the result of runnng the romancal.pipeline.ExposurePipeline <exposure_pipeline> and yields an ~romancal.datamodels.ImageModel`2-D. Single exposure calibrated products contain many of the same arrays as the previous products. The calibrated products are the result of an average over all integrations (cal`).

data array		Data Type	Units	Dimensions
data	Required	float32	e-/ s	nrows x ncols
dq	Required	uint32	N/A	nrows x ncols
err	Required	float32	e-/ s	nrows x ncols
var_poisson	Required	float32	(e-/ s)2	nrows x ncols
var_rnoise	Required	float32	(e-/ s)2	nrows x ncols
var_flat	Required	float32	(e-/ s)2	nrows x ncols
amp33	Required	uint16	DN	nresultants x 4096 x 128
border_ref_pix_left	Required	float32	DN	nresultants x 4096 x 4
border_ref_pix_right	Required	float32	DN	nresultants x 4096 x 4
border_ref_pix_top	Required	float32	DN	nresultants x 4 x 4096
border_ref_pix_bottom	Required	float32	DN	nresultants x 4 x 4096

• data: 2-D data array containing the calibrated pixel values.
• err: 2-D data array containing uncertainty estimates for each pixel. These values are based on the combined VAR_POISSON and VAR_RNOISE data (see below), given as standard deviation.
• dq: 2-D data array containing DQ flags for each pixel.
• var_poisson: 2-D data array containing the variance estimate for each pixel, based on Poisson noise only.
• var_rnoise: 2-D data array containing the variance estimate for each pixel, based on read noise only.
• var_flat: 2-D data array containing the variance estimate for each pixel, based on uncertainty in the flat-field.
• amp33: Amp 33 reference pixel data.
• border_ref_pix_left: Copy of original border reference pixels, on left (from viewers perspective).
• border_ref_pix_right: Copy of original border reference pixels, on right (from viewers perspective).
• border_ref_pix_top: Copy of original border reference pixels, on the top (from viewers perspective).
• border_ref_pix_bottom: Copy of original border reference pixels, on the bottom (from viewers perspective).