The miscellaneous module¶
The miscellaneous module defines various miscellaneous functions used in Rapthor.
Module that holds miscellaneous functions and classes
- rapthor.lib.miscellaneous.angular_separation(position1, position2)¶
Compute the angular separation between two RADec coordinates.
- Parameters:
- position1tuple of float
The first (RA, Dec) coordinates in degrees.
- position2tuple of float
The second (RA, Dec) coordinates in degrees.
- Returns:
- separationastropy.units.Quantity
The angular separation between the two positions, in degrees by default.
- rapthor.lib.miscellaneous.approx_equal(x, y, *args, **kwargs)¶
Return True if x and y are approximately equal, otherwise False
If x and y are floats, return True if y is within either absolute error tol or relative error rel of x. You can disable either the absolute or relative check by passing None as tol or rel (but not both).
- Parameters:
- xfloat
First value to be compared
- yfloat
Second value to be compared
- rapthor.lib.miscellaneous.calc_theoretical_noise(obs_list, w_factor=1.5, use_lotss_estimate=False)¶
Return the expected theoretical image noise for a dataset. For convenience, the total unflagged fraction is also returned.
Note: by default, the calculations follow those of SKA Memo 113 (see https://arxiv.org/abs/1308.4267) and assume no tapering. International stations are not included. A alternvate estimate can be made for LOFAR data following Shimwell et. al (2022, A&A, 659, A1), where the noise in LOFAR images was found to behave as follows (for an 8 hour, 48 MHz observation):
noise = A×cos(90-elevation)^−2.0, where A is 62 μJy beam−1
- Parameters:
- obs_listlist of Observation objects
List of the Observation objects that make up the full dataset
- w_factorfloat, optional
Factor for increase of noise due to the weighting scheme used in imaging (typically ranges from 1.3 - 2)
- use_lotss_estimatebool, optional
If True, the empirical LoTSS noise estimate from Shimwell et. al (2022) is used instead of the one from SKA Memo 113
- Returns:
- noisefloat
Estimate of the expected theoretical noise in Jy/beam
- unflagged_fractionfloat
The total unflagged fraction of the input data
- rapthor.lib.miscellaneous.convert_mjd2mvt(mjd_sec)¶
Converts MJD to casacore MVTime
- Parameters:
- mjd_secfloat
MJD time in seconds
- Returns:
- mvtimestr
Casacore MVTime string
- rapthor.lib.miscellaneous.convert_mvt2mjd(mvt_str)¶
Converts casacore MVTime to MJD
- Parameters:
- mvt_strstr
MVTime time
- Returns:
- mjdtimefloat
MJD time in seconds
- rapthor.lib.miscellaneous.dec2ddmmss(deg, as_string=False)¶
Convert Dec coordinate (in degrees) to DD MM SS.S
- Parameters:
- degfloat
The Dec coordinate in degrees
- as_stringbool
If True, return the Dec as a string with ‘d’, ‘m’, and ‘s’ as the separators. E.g.: ‘12d23m13.4s’. If False, return a tuple of (DD, MM, SS.S, sign)
- Returns:
- ddmmsstuple of (int, int, float, int) or string
A tuple of (DD, MM, SS.S, sign) or a string as ‘DDdMMmSS.Ss’
- rapthor.lib.miscellaneous.find_unflagged_fraction(ms_file, start_time, end_time)¶
Finds the fraction of data that is unflagged for an MS file in the given time range
- Parameters:
- ms_filestr
Filename of input MS
- start_timefloat
MJD time in seconds for start of time range
- end_timefloat
MJD time in seconds for end of time range
- Returns:
- unflagged_fractionfloat
Fraction of unflagged data
- rapthor.lib.miscellaneous.get_flagged_solution_fraction(h5file, solsetname='sol000')¶
Get flagged fraction for solutions in given H5parm
- Parameters:
- h5filestr
Filename of input h5parm file
- solsetnamestr, optional
The solution set name to use. The flagged fraction is calculated over all solution tables in the given solution set
- Returns:
- flagged_fractionfloat
Flagged fraction
- rapthor.lib.miscellaneous.get_max_spectral_terms(skymodel_file)¶
Get the maximum number of spectral terms (including the zeroth term) in a sky model
- Parameters:
- skymodel_filestr
Input sky model filename
- Returns:
- ntermsint
Maximum number of spectral terms
- rapthor.lib.miscellaneous.get_reference_station(soltab, max_ind=None)¶
Return the index of the station with the lowest fraction of flagged solutions
- Parameters:
- soltablosoto solution table object
The input solution table
- max_indint, optional
The maximum station index to use when choosing the reference station. The reference station will be drawn from the first max_ind stations. If None, all stations are considered.
- Returns:
- ref_indint
Index of the reference station
- rapthor.lib.miscellaneous.make_template_image(image_name, reference_ra_deg, reference_dec_deg, ximsize=512, yimsize=512, cellsize_deg=0.000417, freqs=None, times=None, antennas=None, aterm_type='tec', fill_val=0)¶
Make a blank FITS image and save it to disk
- Parameters:
- image_namestr
Filename of output image
- reference_ra_degfloat
RA for center of output mask image
- reference_dec_degfloat
Dec for center of output mask image
- imsizeint, optional
Size of output image
- cellsize_degfloat, optional
Size of a pixel in degrees
- freqslist, optional
Frequencies to use to construct extra axes (for IDG a-term images)
- timeslist, optional
Times to use to construct extra axes (for IDG a-term images)
- antennaslist, optional
Antennas to use to construct extra axes (for IDG a-term images)
- aterm_typestr, optional
One of ‘tec’ or ‘gain’
- fill_valint, optional
Value with which to fill the data
- rapthor.lib.miscellaneous.nproc()¶
Return the number of CPU cores _available_ to the current process, similar to what the Linux nproc command does. This can be less than the total number of CPU cores in the machine. NOTE: This function uses os.sched_getaffinity(), which is not available on every OS. Use multiprocessing.cpu_count() as fall-back.
- rapthor.lib.miscellaneous.ra2hhmmss(deg, as_string=False)¶
Convert RA coordinate (in degrees) to HH MM SS.S
- Parameters:
- degfloat
The RA coordinate in degrees
- as_stringbool
If True, return the RA as a string with ‘h’, ‘m’, and ‘s’ as the separators. E.g.: ‘12h23m13.4s’ If False, return a tuple of (HH, MM, SS.S)
- Returns:
- hhmmsstuple of (int, int, float) or string
A tuple of (HH, MM, SS.S) or a string as ‘HHhMMmSS.Ss’
- rapthor.lib.miscellaneous.remove_soltabs(solset, soltabnames)¶
Remove H5parm soltabs from a solset
Note: the H5parm must be opened with readonly = False
- Parameters:
- solsetlosoto solution set object
The solution set from which to remove soltabs
- soltabnameslist
Names of soltabs to remove
- rapthor.lib.miscellaneous.rename_skymodel_patches(skymodel, order_dec='high_to_low', order_ra='high_to_low', dec_bin_width=2.0)¶
Rename the patches in the input sky model according to the given scheme
Note: the patches are first binned by Dec and then sorted by RA within each bin. The patch names start from “Patch_1” and increase first by RA and then by Dec, ordered either with increasing or decreasing RA and Dec as given by the order_dec and order_ra args
- Parameters:
- skymodelLSMTool skymodel.SkyModel object
Input sky model
- order_decstr, optional
- The scheme to use for ordering:
‘high_to_low’: patches increase with decreasing Dec
‘low_to_high’: patches increase with increasing Dec
- order_rastr, optional
Same as order_dec, but for RA
- dec_bin_widthfloat, optional
Bin width in degrees for the Dec values
- rapthor.lib.miscellaneous.string2bool(invar)¶
Converts a string to a bool
- Parameters:
- invarstr
String to be converted
- Returns:
- resultbool
Converted bool
- rapthor.lib.miscellaneous.string2list(invar)¶
Converts a string to a list
- Parameters:
- invarstr
String to be converted
- Returns:
- resultlist
Converted list