pypeit.spectrographs.keck_kcwi module

Implements KCWI-specific functions.

class pypeit.spectrographs.keck_kcwi.KeckKCWISpectrograph[source]

Bases: Spectrograph

Child to handle Keck/KCWI specific code

Todo

Need to apply spectral flexure and heliocentric correction to waveimg

bpm(filename, det, shape=None, msbias=None)[source]

Generate a default bad-pixel mask.

Even though they are both optional, either the precise shape for the image (shape) or an example file that can be read to get the shape (filename using get_image_shape()) must be provided.

Parameters

filename (str or None) – An example file to use to get the image shape.
det (int) – 1-indexed detector number to use when getting the image shape from the example file.
shape (tuple, optional) – Processed image shape Required if filename is None Ignored if filename is not None
msbias (numpy.ndarray, optional) – Processed bias frame used to identify bad pixels. This is ignored for KCWI.

Returns

An integer array with a masked value set to 1 and an unmasked value set to 0. All values are set to 0.

Return type

numpy.ndarray

calc_pattern_freq(frame, rawdatasec_img, oscansec_img, hdu)[source]

Calculate the pattern frequency using the overscan region that covers the overscan and data sections. Using a larger range allows the frequency to be pinned down with high accuracy.

NOTE: The amplifiers are arranged as follows:

(0,ny) ——— (nx,ny)

| 3 | 4 |
———
| 1 | 2 |

(0,0) ——— (nx, 0)

Todo

PATTERN FREQUENCY ALGORITHM HAS NOT BEEN TESTED WHEN BINNING != 1x1

Parameters

frame (numpy.ndarray) – Raw data frame to be used to estimate the pattern frequency.
rawdatasec_img (numpy.ndarray) – Array the same shape as frame, used as a mask to identify the data pixels (0 is no data, non-zero values indicate the amplifier number).
oscansec_img (numpy.ndarray) – Array the same shape as frame, used as a mask to identify the overscan pixels (0 is no data, non-zero values indicate the amplifier number).
hdu (astropy.io.fits.HDUList) – Opened fits file.

Returns

patt_freqs – List of pattern frequencies.

Return type

list

camera = 'KCWI': Name of the spectrograph camera or arm. This is used by specdb, so use that naming convention

check_frame_type(ftype, fitstbl, exprng=None)[source]

Check for frames of the provided type.

Parameters

ftype (str) – Type of frame to check. Must be a valid frame type; see frame-type Definitions.
fitstbl (astropy.table.Table) – The table with the metadata for one or more frames to check.
exprng (list, optional) – Range in the allowed exposure time for a frame of type ftype. See pypeit.core.framematch.check_frame_exptime().

Returns

Boolean array with the flags selecting the exposures in fitstbl that are ftype type frames.

Return type

numpy.ndarray

comment = 'Supported setups: BM, BH2; see :doc:`keck_kcwi`': A brief comment or description regarding PypeIt usage with this spectrograph.

compound_meta(headarr, meta_key)[source]

Methods to generate metadata requiring interpretation of the header data, instead of simply reading the value of a header card.

Parameters

headarr (list) – List of astropy.io.fits.Header objects.
meta_key (str) – Metadata keyword to construct.

Returns

Metadata value read from the header(s).

Return type

object

config_specific_par(scifile, inp_par=None)[source]

Modify the PypeIt parameters to hard-wired values used for specific instrument configurations.

Parameters

scifile (str) – File to use when determining the configuration and how to adjust the input parameters.
inp_par (ParSet, optional) – Parameter set used for the full run of PypeIt. If None, use default_pypeit_par().

Returns

The PypeIt parameter set adjusted for configuration specific parameter values.

Return type

ParSet

configuration_keys()[source]

Return the metadata keys that define a unique instrument configuration.

This list is used by PypeItMetaData to identify the unique configurations among the list of frames read for a given reduction.

Returns: List of keywords of data pulled from file headers and used to constuct the PypeItMetaData object.
Return type: list

classmethod default_pypeit_par()[source]

Return the default parameters to use for this instrument.

Returns: Parameters required by all of PypeIt methods.
Return type: PypeItPar

fit_2d_det_response(det_resp, gpmask)[source]

Perform a 2D model fit to the KCWI detector response. A few different setups were inspected (BH2 & BM with different grating angles), and a very similar response pattern was found for all setups, indicating that this structure is something to do with the detector. The starting parameters and functional form are assumed to be sufficient for all setups.

Parameters

det_resp (numpy.ndarray) – An image of the flatfield structure.
gpmask (numpy.ndarray) – Good pixel mask (True=good), the same shape as ff_struct.

Returns

A model fit to the flatfield structure.

Return type

numpy.ndarray

get_datacube_bins(slitlength, minmax, num_wave)[source]

Calculate the bin edges to be used when making a datacube.

Parameters

slitlength (int) – Length of the slit in pixels
minmax (numpy.ndarray) – An array with the minimum and maximum pixel locations on each slit relative to the reference location (usually the centre of the slit). Shape must be \((N_{\rm slits},2)\), and is typically the array returned by get_radec_image().
num_wave (int) –

Number of wavelength steps. Given by::
int(round((wavemax-wavemin)/delta_wave))

:param tuple: Three 1D numpy.ndarray providing the bins to use :param when constructing a histogram of the spec2d files. The elements: :param are \(: :type are :math:\): x,y,lambda

get_detector_par(det, hdu=None)[source]

Return metadata for the selected detector.

Warning

Many of the necessary detector parameters are read from the file header, meaning the hdu argument is effectively required for KCWI. The optional use of hdu is only viable for automatically generated documentation.

Parameters

det (int) – 1-indexed detector number.
hdu (astropy.io.fits.HDUList, optional) – The open fits file with the raw image of interest.

Returns

Object with the detector metadata.

Return type

DetectorContainer

get_lamps_status(headarr)[source]

Return a string containing the information on the lamp status.

Parameters: headarr (list) – A list of 1 or more astropy.io.fits.Header objects.
Returns: A string that uniquely represents the lamp status.
Return type: str

get_rawimage(raw_file, det)[source]

Read a raw KCWI data frame

NOTE: The amplifiers are arranged as follows:

(0,ny) ——— (nx,ny)

| 3 | 4 |
———
| 1 | 2 |

(0,0) ——— (nx, 0)

Parameters

raw_file (str) – File to read
det (int) – 1-indexed detector to read

Returns

detector_par (pypeit.images.detector_container.DetectorContainer) – Detector metadata parameters.
raw_img (numpy.ndarray) – Raw image for this detector.
hdu (astropy.io.fits.HDUList) – Opened fits file
exptime (float) – Exposure time read from the file header
rawdatasec_img (numpy.ndarray) – Data (Science) section of the detector as provided by setting the (1-indexed) number of the amplifier used to read each detector pixel. Pixels unassociated with any amplifier are set to 0.
oscansec_img (numpy.ndarray) – Overscan section of the detector as provided by setting the (1-indexed) number of the amplifier used to read each detector pixel. Pixels unassociated with any amplifier are set to 0.

get_wcs(hdr, slits, platescale, wave0, dwv, spatial_scale=None)[source]

Construct/Read a World-Coordinate System for a frame.

Parameters

hdr (astropy.io.fits.Header) – The header of the raw frame. The information in this header will be extracted and returned as a WCS.
slits (SlitTraceSet) – Slit traces.
platescale (float) – The platescale of an unbinned pixel in arcsec/pixel (e.g. detector.platescale). See also ‘spatial_scale’
wave0 (float) – The wavelength zeropoint.
dwv (float) – Change in wavelength per spectral pixel.
spatial_scale (float, None, optional) – The spatial scale (units=arcsec/pixel) of the WCS to be used. This variable is fixed, and is independent of the binning. If spatial_scale is set, it will be used for the spatial size of the WCS and the platescale will be ignored. If None, then the platescale will be used.

Returns

The world-coordinate system.

Return type

astropy.wcs.wcs.WCS

header_name = 'KCWI': Name of the spectrograph camera or arm from the Header. Usually the INSTRUME card.

init_meta()[source]

Define how metadata are derived from the spectrograph files.

That is, this associates the PypeIt-specific metadata keywords with the instrument-specific header cards using meta.

static is_nasmask(hdr)[source]

Determine if a frame used nod-and-shuffle.

Parameters: hdr (astropy.io.fits.Header) – The header of the raw frame.
Returns: True if NAS used.
Return type: bool

lamps(fitstbl, status)[source]

Check the lamp status.

Parameters

fitstbl (astropy.table.Table) – The table with the fits header meta data.
status (str) – The status to check. Can be 'off', 'arcs', or 'dome'.

Returns

A boolean array selecting fits files that meet the selected lamp status.

Return type

numpy.ndarray

Raises

ValueError – Raised if the status is not one of the valid options.

name = 'keck_kcwi': The name of the spectrograph. See Spectrographs for the currently supported spectrographs.

ndet = 1: Number of detectors for this instrument.

pypeit_file_keys()[source]

Define the list of keys to be output into a standard PypeIt file.

Returns: The list of keywords in the relevant PypeItMetaData instance to print to the PypeIt Reduction File.
Return type: list

pypeline = 'IFU': String used to select the general pipeline approach for this spectrograph.

raw_header_cards()[source]

Return additional raw header cards to be propagated in downstream output files for configuration identification.

The list of raw data FITS keywords should be those used to populate the configuration_keys() or are used in config_specific_par() for a particular spectrograph, if different from the name of the PypeIt metadata keyword.

This list is used by subheader_for_spec() to include additional FITS keywords in downstream output files.

Returns: List of keywords from the raw data files that should be propagated in output files.
Return type: list

supported = True: Flag that PypeIt code base has been sufficiently tested with data from this spectrograph that it is officially supported by the development team.

telescope = Parameter Value Default Type Callable ---------------------------------------------------------------- name KECK KECK str False longitude -155.47833333333335 None int, float False latitude 19.828333333333333 None int, float False elevation 4160.000000000756 None int, float False fratio 15 None int, float False diameter 10 None int, float False eff_aperture 72.3674 None int, float False : Instance of TelescopePar providing telescope-specific metadata.

url = 'https://www2.keck.hawaii.edu/inst/kcwi/': Reference url