Control File Keyword Reference

This page documents every control file keyword recognized by fourfit4. Keywords are grouped by their function in the processing pipeline.

Supported reflects current HOPS4 implementation status. EHT / VGOS indicates which experiment type requires the keyword (EHT, VGOS, or BOTH).

Conditional Statements

Conditional blocks allow control file statements to be applied selectively based on baseline, station, source, or scan properties.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
else		BOTH	No		Never implemented in the original fourfit
if	list of strings	BOTH	Yes	MHO_ControlConditionEvaluator and MHO_ControlFileParser

Labeling Operators

Labeling operators assign identifiers (channel labels, sampler indices, polarization labels) to the data. They execute first in the operator pipeline, before any calibration is applied.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
chan_ids	channel_names: string, channel_frequencies: list of floats	BOTH	Yes	MHO_ChannelLabeler
python_labeling	module_path: string, function_name: string, [override_priority: float]	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON; priority 0.2
samplers	fixed-length list of strings	BOTH (VGOS mainly)	Yes	MHO_SamplerLabeler
swap_pol_labels	pol1: string, pol2: string	BOTH	Yes	MHO_PolarizationRelabeler / MHO_PolarizationRelabelerBuilder	priority 0.1

Flagging and Selection

These keywords mark or exclude data based on quality criteria, spectral notches, passband limits, or time/frequency selection.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
dc_block	true | false	BOTH	Yes	MHO_DCBlock	Needs testing (check XP spectrum agains ff3)
freqs	logical-intersection list of strings	BOTH	Yes	MHO_DataSelectionBuilder and MHO_SelectRepack	We need to debug the case where freqs selects down to just 1 channel
min_weight	float	BOTH	Yes		Not fully tested, appears to be working
notch_comb	offset: float, period: float, width: float	BOTH	Yes	MHO_NotchComb / MHO_NotchCombBuilder	priority 4.5
notches	list of floats	BOTH	Yes	MHO_Notches	SNR agrees with fourfit3, more testing needed
passband	list of floats	BOTH	Yes	MHO_Passband	SNR agrees with fourfit3, more testing needed
python_flagging	module_path: string, function_name: string, [override_priority: float]	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON; priority 2.9
skip	true | false	BOTH	Yes
start	integer	BOTH	Yes	MHO_DataSelectionBuilder and MHO_SelectRepack	integer sec within scan selection enabled, minute-past-the-hour is not supported
stop	integer	BOTH	Yes	MHO_DataSelectionBuilder and MHO_SelectRepack	integer sec within scan selection enabled, minute-past-the-hour is not supported

Calibration Operators

Calibration operators apply phase, delay, and amplitude corrections to the visibility data. Execution order within this category is determined by the operator priority value.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
adhoc_file	string	EHT	Yes	MHO_AdhocPhaseCorrection	Tested for USB
adhoc_file_chans	string	EHT	Yes	MHO_AdhocPhaseCorrection	Tested for USB
adhoc_flag_file	flag_file: string	EHT	Yes	MHO_AdhocFlagging	Tested for USB
adhoc_period	float	EHT	Yes	MHO_AdhocPhaseCorrection	Tested for USB
adhoc_phase	algorithm_type: string	EHT	Yes	MHO_AdhocPhaseCorrection	Tested for USB
adhoc_poly	list of floats	EHT	Yes	MHO_AdhocPhaseCorrection	Tested for USB
adhoc_tref	float	EHT	Yes	MHO_AdhocPhaseCorrection	Tested for USB
delay_offs	channel_names: string, pc_delays: list of floats	BOTH	Yes	MHO_ManualChannelDelayCorrection
delay_offs_l	channel_names: string, pc_delays: list of floats	BOTH	Yes	MHO_ManualChannelDelayCorrection	Needs further testing! – phase_shift compensation for VGOS not yet implemented
delay_offs_r	channel_names: string, pc_delays: list of floats	BOTH	Yes	MHO_ManualChannelDelayCorrection	Needs further testing! – phase_shift compensation for VGOS not yet implemented
delay_offs_x	channel_names: string, pc_delays: list of floats	BOTH	Yes	MHO_ManualChannelDelayCorrection	Needs further testing! – phase_shift compensation for VGOS not yet implemented
delay_offs_y	channel_names: string, pc_delays: list of floats	BOTH	Yes	MHO_ManualChannelDelayCorrection	Needs further testing! – phase_shift compensation for VGOS not yet implemented
mount_type	string	EHT	Yes		Supports apply field rotation to R/L pols for cassegrain, and nasmyth left/right telescopes, needs testing!
pc_delay_l	float	BOTH	Yes	MHO_ManualPolDelayCorrection	Needs further testing!
pc_delay_r	float	BOTH	Yes	MHO_ManualPolDelayCorrection	Needs further testing!
pc_delay_x	float	BOTH	Yes	MHO_ManualPolDelayCorrection	Needs further testing!
pc_delay_y	float	BOTH	Yes	MHO_ManualPolDelayCorrection	Needs further testing!
pc_mode	string	VGOS (multitone) BOTH (manual)	Yes		manual pc supported, multitone implemented (but only tested on LSB data!)
pc_period	integer	BOTH	Yes
pc_phase_offset_l	float	BOTH	Yes	MHO_ManualPolPhaseCorrection	Needs further testing!
pc_phase_offset_r	float	BOTH	Yes	MHO_ManualPolPhaseCorrection	Needs further testing!
pc_phase_offset_x	float	BOTH	Yes	MHO_ManualPolPhaseCorrection	Needs further testing!
pc_phase_offset_y	float	BOTH	Yes	MHO_ManualPolPhaseCorrection	Needs further testing!
pc_phases	channel_names: string, pc_phases: list of floats	BOTH	Yes	MHO_ManualPolPhaseCorrection
pc_phases_l	channel_names: string, pc_phases: list of floats	BOTH	Yes	MHO_ManualChannelPhaseCorrection	Tested for LSB/USB but not DSB
pc_phases_r	channel_names: string, pc_phases: list of floats	BOTH	Yes	MHO_ManualChannelPhaseCorrection	Tested for LSB/USB but not DSB
pc_phases_x	channel_names: string, pc_phases: list of floats	BOTH	Yes	MHO_ManualChannelPhaseCorrection	Tested for LSB/USB but not DSB
pc_phases_y	channel_names: string, pc_phases: list of floats	BOTH	Yes	MHO_ManualChannelPhaseCorrection	Tested for LSB/USB but not DSB
python_calibration	module_path: string, function_name: string, [override_priority: float]	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON; priority 3.9
python_finalize	module_path: string, function_name: string, [override_priority: float]	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON; priority 9.9
station_delay	float	BOTH	Yes	MHO_StationDelayCorrection	delay is applied directly to visibilities (note that the implementation is not the same as ff3, where it is applied during pc_delay amb resoluiton)

Fringe Fitter Parameters

These parameters control the fringe-fitting search: delay and delay-rate windows, coherence time, reference frequency, phase calibration mode, and related station-specific settings.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
dr_win	list of floats	BOTH	Yes		Needs testing
est_pc_manual	integer	BOTH	Yes	MHO_EstimatePCManual	Needs additional testing (there may be a bug in the HOPS3 implmentation w.r.t to channel label mapping)
gen_cf_record	true | false	BOTH	Yes		always true (however we may want to allow the CF to be discarded too). AEN request – provide option to store CF with comments as well
lsb_offset	float	BOTH	Yes	This is a double-side band data feature
mb_win	list of floats	BOTH	Yes		Needs testing
mbd_anchor	string	BOTH	Yes
optimize_closure	true | false	BOTH	Yes
ref_freq	float	BOTH	Yes	MHO_DelayRate, MHO_InterpolateFringePeak, MHO_ComputePlotData	Need to document everywhere this field is used
sb_win	list of floats	BOTH	Yes		Needs testing
spectral_line	true | false	EHT	No, still in testing		Read via /control/fit/spectral_line
spectral_line_freq_win	list of floats	EHT	No, still in testing		Read via /control/fit/spectral_line_freq_win
t_cohere	float	EHT?	Yes	MBDelaySearch (and OpenMP/CUDA) extensions	This is passed as a parameter, which triggers the associated behavior in MBDelaySearch, it is not a standalone operator
weak_channel	float	BOTH	Yes

VGOS-Only Parameters

These parameters are specific to VGOS (geodetic) broadband observations, including ionospheric correction, sampler delays, and tone masking.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
ion_npts	integer	VGOS	Yes
ion_smooth	true | false	VGOS	Yes
ion_win	list of floats	VGOS	Yes
ionosphere	float	VGOS	Yes		value read in and mapped to station ID
mixed_pol_yshift90	true | false	VGOS/Mixedmode	Yes
pc_amp_hcode	float	VGOS	Yes
pc_tonemask	channel_names: string, tone_masks: ?	VGOS	Yes		Make sure this works with USB data too
sampler_delay_l	list of floats	VGOS	Yes
sampler_delay_r	list of floats	VGOS	Yes
sampler_delay_x	list of floats	VGOS	Yes
sampler_delay_y	list of floats	VGOS	Yes

Global Configuration Parameters

Global configuration parameters affect overall pipeline behavior and are not specific to a single baseline or station.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
adhoc_amp	float	BOTH	Yes
plot_backend	string	BOTH	Yes
python_custom_plot	module_path: string, function_name: string	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON

Python Extension Operators

Python extension operators invoke user-supplied Python functions at specific points in the pipeline (pre-fit, post-fit, calibration, flagging, labeling, finalization, and custom plotting). See the Python Plugin User Guide for details.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
python_postfit	module_path: string, function_name: string, [override_priority: float]	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON; priority 8.9
python_prefit	module_path: string, function_name: string, [override_priority: float]	BOTH	Yes	MHO_PythonOperatorBuilder	Requires build with HOPS_ENABLE_EMBEDDED_PYTHON=ON; priority 7.9

Deprecated / Not Supported

The following keywords are parsed for backward compatibility but are not implemented in HOPS4. They will be silently ignored or rejected.

Keyword	Format	EHT / VGOS	Supported	Implementation Class	Notes
avxplopt			No		reserved, not implemented
avxpzoom			No		reserved, not implemented
dec_offset	deprecated	BOTH	No		this keyword is parsed in c-lib, but does nothing
fmatch_bw_pct		BOTH	No
gates	deprecated	BOTH	No		part of frequency switching mode feature
index	deprecated		No		MK4 correlator specific
interpolator		BOTH	deprecated	MHO_InterpolateFringePeak	‘simul’ only, iterate is not implemented
max_parity			No
pc_freqs		BOTH	No
period	deprecated	BOTH	No		part of frequency switching mode feature
plot_data_dir		BOTH	No		Generally speaking this operator is not needed in hops4 as the plot data is already fully output
ra_offset	deprecated	BOTH	No		this keyword is parsed in c-lib, but does nothing
switched	deprecated		No		part of frequency switching mode feature
use_samples	true | false	BOTH	No		Normalizes data according to sampler statistics (This a mark4 correlator only feature)
vbp_coeffs			No		reserved, not yet implemented
vbp_correct			No		reserved, not yet implemented
vbp_file			No		reserved, not yet implemented
vbp_fit			No		reserved, not yet implemented
x_crc	`keep’ or `discard’		deprecated
x_slip_sync	`keep’		deprecated
y_crc	`keep’ or `discard’		deprecated
y_slip_sync	`keep’		deprecated