Arguments

The jump step has many optional arguments that can be set by the user. The details for each are listed below.

Parameters for Baseline Cosmic Ray Jump Detection

  • --rejection_threshold: A floating-point value that sets the sigma threshold for jump detection. In the code, sigma is determined using the read noise from the read noise reference file and the Poisson noise (based on the median difference between samples and the gain reference file). Note that any noise source beyond these two that may be present in the data will lead to an increase in the false positive rate and thus may require an increase in the value of this parameter. The default value of 4.0 for the rejection threshold will yield 6200 false positives for every million pixels, if the noise model is correct.

  • --three_group_rejection_threshold: Cosmic ray sigma rejection threshold for ramps having 3 groups. This is a floating-point value with default value of 6.0, and minimum of 0.0.

  • --four_group_rejection_threshold: Cosmic ray sigma rejection threshold for ramps having 4 groups. This is a floating-point value with default value of 5.0, and minimum of 0.0.

  • --maximum_cores: The number of available cores that will be used for multi-processing in this step. The default value is ‘1’, which does not use multi-processing. The other options are either an integer, ‘quarter’, ‘half’, or ‘all’. Note that these fractions refer to the total available cores and on most CPUs these include physical and virtual cores. The clock time for the step is reduced almost linearly by the number of physical cores used on all machines. For example, on an Intel CPU with six real cores and six virtual cores, setting maximum_cores to ‘half’ results in a decrease of a factor of six in the clock time for the step to run. Depending on the system, the clock time can also decrease even more with maximum_cores is set to ‘all’. Setting the number of cores to an integer can be useful when running on machines with a large number of cores where the user is limited in how many cores they can use. Note that, currently, snowball and shower detection does not use multiprocessing.

  • --flag_4_neighbors: If set to True (default is True) it will cause the four perpendicular neighbors of all detected jumps to also be flagged as a jump. This is needed because of the inter-pixel capacitance (IPC), which causes a small jump in the neighbors. The small jump might be below the rejection threshold, but will affect the slope determination of the pixel. The step will take about 40% longer to run when this is set to True.

  • --max_jump_to_flag_neighbors: A floating point value in units of sigma that limits the flagging of neighbors. Any jump above this cutoff will not have its neighbors flagged. The concept is that the jumps in neighbors will be above the rejection threshold and thus be flagged as primary jumps. The default value is 200.

  • --min_jump_to_flag_neighbors: A floating point value in units of sigma that limits the flagging of neighbors of marginal detections. Any primary jump below this value will not have its neighbors flagged. The goal is to prevent flagging jumps that would be too small to significantly affect the slope determination. The default value is 10.

Parameters that affect after jump Flagging

After a jump of at least ‘after_jump_flag_dn1’ DN, groups up to ‘after_jump_flag_time1’ seconds will also be flagged as jumps. That pair of arguments is defined as:

  • --after_jump_flag_dn1: A floating point value in units of DN

  • --after_jump_flag_time1: A floating point value in units of seconds

A second threshold and time can also be set: after a jump of at least ‘after_jump_flag_dn2’ DN, groups up to ‘after_jump_flag_time2’ seconds will also be flagged as jumps. That pair of arguments is defined as:

  • --after_jump_flag_dn2: A floating point value in units of DN

  • --after_jump_flag_time2: A floating point value in units of seconds

Parameters that affect Near-IR Snowball Flagging

  • --expand_large_events: A boolean parameter that controls whether the jump step will expand the number of pixels that are flagged around large cosmic ray events. These are know as “snowballs” in the near-infrared detectors and “showers” for the MIRI detectors. In general, this should be set to True.

  • --min_jump_area: The minimum number of contiguous pixels needed to trigger the expanded flagging of large cosmic rays events.

  • --min_sat_area: The minimum number of saturated pixels required to meet “sat_required_snowball”.

  • --expand_factor: A multiplicative factor applied to the enclosing ellipse for snowballs. This larger area will have all pixels flagged as having a jump.

  • --use_ellipses: deprecated

  • --sat_required_snowball: A boolean value that if True requires that there are saturated pixels within the enclosed jump circle.

  • --min_sat_radius_extend: The minimum radius of the saturated core of a snowball required to for the radius of the saturated core to be extended.

  • --sat_expand: Number of pixels to add to the radius of the saturated core of snowballs

  • --edge_size: The distance from the edge of the detector where saturated cores are not required for snowball detection

  • --mask_snowball_core_next_int: Turns on/off the flagging of saturated cores of snowballs in the next integration

  • --snowball_time_masked_next_int: Controls the total time that the saturated cores of snowballs are flagged in the next integration.

Parameters that affect MIRI Shower Flagging

  • --find_showers: Turn on the detection of showers for the MIRI detectors

  • --extend_snr_threshold: The SNR minimum for the detection of faint extended showers in MIRI

  • --extend_min_area: The required minimum area of extended emission after convolution for the detection of showers in MIRI

  • --extend_inner_radius: The inner radius of the ring_2D_kernel that is used for the detection of extended emission in showers

  • --extend_outer_radius: The outer radius of the Ring2DKernal that is used for the detection of extended emission in showers

  • --extend_ellipse_expand_ratio: Multiplicative factor to expand the radius of the ellipse fit to the detected extended emission in MIRI showers

  • --time_masked_after_shower: Number of seconds to flag groups as jump after a detected extended emission in MIRI showers

  • --min_diffs_single_pass: The minimum number of differences to switch to flagging all outliers at once

  • --max_shower_amplitude: The maximum allowable amplitude for MIRI showers in DN/s

Parameter that affects both Snowball and Shower flagging

  • --max_extended_radius: The maximum extension of the jump and saturation that will be flagged for showers or snowballs

Parameters that affect Sigma Clipping

  • --minimum_groups: The minimum number of groups to run the jump step with sigma clipping

  • --minimum_sigclip_groups: The minimum number of groups to switch the jump detection to use sigma clipping

  • --only_use_ints: If true the sigma clipping is applied only for a given group across all ints. If not, all groups from all ints are used for the sigma clipping.