The xsh_mflat recipe

xsh_mflat

Synopsis

Create the master flat and the orders edges traces table frames

Description

This recipe creates the master flat and the orders edges traces table frames.

Input Frames :

  • [UVB] A set of n RAW frames (Format = RAW, n>=3, Tag = FLAT_D2_mode_UVB, mode=SLIT/IFU)

  • [UVB] A set of n RAW frames (Format = RAW, n>=3, Tag = FLAT_QTH_mode_UVB)

  • [VIS] A set of n RAW frames (Format = RAW, n>=3, Tag = FLAT_mode_VIS)

  • [NIR] A set of n x n RAW frames ((Format = RAW, n>=3, Tag = FLAT_mode_NIR_ON, FLAT_mode_NIR_OFF)

  • A spectral format table (Format = PRE, Tag = SPECTRAL_FORMAT_TAB_arm)

  • An order table (Format = TABLE, Tag = ORDER_TAB_CENTR_arm)

  • [UVB,VIS] A master bias (Format = PRE, Tag = MASTER_BIAS_arm)

  • [OPTIONAL] A map of reference bad pixel (Format = QUP,RAW, Tag = BP_MAP_RP_arm)

  • [OPTIONAL] A map of non linear pixel (Format = QUP,RAW, Tag = BP_MAP_NL_arm)

  • [OPTIONAL,UVB,VIS] A master dark (Format = PRE, Tag = MASTER_DARK_arm)

Products :

  • An updated order table with edge UP and edge LOW (Format = TABLE, TAG = ORDER_TAB_EDGES_mode_arm)

  • A master flat (Format = PRE, PRO.CATG = MASTER_FLAT_mode_arm)

  • The inter-order background frame (Format = PRE, PRO.CATG = MFLAT_BACK_mode_arm)

  • The inter-order background sampling points grid table (Format = PRE, PRO.CATG = MFLAT_GRID_BACK_mode_arm)

Prepare the flat frames.

Stack and sigma clip all the flat frames.

Subtract master bias.

Subtract master dark.

Detect order edge.

Subtract background.

Create the Master Flat.

Constructor

cpl.Recipe("xsh_mflat")

Create an object for the recipe xsh_mflat.

import cpl
xsh_mflat = cpl.Recipe("xsh_mflat")

Parameters

xsh_mflat.param.keep_temp

If ‘no’, temporary files are deleted. (str; default: ‘no’) [default=”no”].

xsh_mflat.param.debug_level

Additional xshooter debug level. One of ‘none’, ‘low’, ‘medium’, ‘high’ (str; default: ‘none’) [default=”none”].

xsh_mflat.param.time_stamp

Add timestamp to product file name. (bool; default: False) [default=False].

xsh_mflat.param.decode_bp

Integer representation of the bits to be considered bad when decoding the bad pixel mask pixel values. Most frequent codes relevant for the user: 0: good pixel, 8: pick-up noise, 16: cosmic-ray removed, 32: cosmic-ray unremoved, 128: calibration file defect, 256: hot pixel, 512: dark pixel, 4096: A/D converted saturation, 32768: non linear pixel, 1048576: extrapolated flux in NIR, 4194304: Interpolated flux during extraction. (int; default: 2144337919) [default=2144337919].

xsh_mflat.param.pre_overscan_corr

pre-overscan correction. 0: no correction 1: mean overscan correction 2: mean prescan correction 3: (mean pre+mean overscan)/2 correction (int; default: 1) [default=1].

xsh_mflat.param.stack_method

Method used to build master frame. (str; default: ‘median’) [default=”median”].

xsh_mflat.param.klow

Kappa used to clip low level values, when method is set to ‘mean’ (float; default: 5.0) [default=5.0].

xsh_mflat.param.khigh

Kappa used to clip high level values, when method is set to ‘mean’ (float; default: 5.0) [default=5.0].

xsh_mflat.param.detectorder_edges_search_win_hsize

During extraction the local spatial profile (=cross-order) of the spectrum is determined by collapsing the 2-dimensional spectrum along the dispersion axis. This parameter defines the half size of the region across which the spectrum is collapsed. This parameter affects flagged pixels interpolation. In case of spectrum gaps the recommended optimal value is: (size_of_gap [nm]/(2*size_of_pixel [nm])+1) (int; default: 50) [default=50].

xsh_mflat.param.detectorder_edges_flux_thresh

Threshold in relative flux (compared to the central flux) below which the order edges are defined (float; default: 0.4) [default=0.4].

xsh_mflat.param.detectorder_min_sn

Minimum signal-to-noise ratio at the centroid of the orders (60 for SLIT-UVB,VIS,NIR, 20 for IFU-UVB,VIS, 4 for IFU-NIR (float; default: -1.0) [default=-1.0].

xsh_mflat.param.detectorder_min_order_size_x

Minimum order size in pixels along X direction [60 for UVB,VIS, 40 for NIR] (int; default: -1) [default=-1].

xsh_mflat.param.detectorder_chunk_half_size

Half size in pixels of the chunks in Y direction (int; default: 1) [default=1].

xsh_mflat.param.detectorder_slitlet_low_factor

Factor for slitlet on lower edge slitlet (IFU) (float; default: 1.0) [default=1.0].

xsh_mflat.param.detectorder_slitlet_up_factor

Factor for slitlet on upper edge (IFU) (float; default: 1.0) [default=1.0].

xsh_mflat.param.detectorder_fixed_slice

If true the size of slitlet is fixed (IFU) (bool; default: True) [default=True].

xsh_mflat.param.detectorder_slice_trace_method

method adopted for IFU slice tracing (‘fixed’ for SLIT and ‘sobel’ for IFU): (str; default: ‘auto’) [default=”auto”].

xsh_mflat.param.detectorder_qc_mode

If true allows one to skip edge detection on orders below detectorder- min-sn (oly for QC mode, not to be set by normal users) (bool; default: False) [default=False].

xsh_mflat.param.detectorder_d2_min_sn

minimum signal noise ratio in D2 lamp frame in order (float; default: 60.0) [default=60.0].

xsh_mflat.param.background_edges_margin

X margin to order edge to define background sampling points (int; default: 1) [default=1].

xsh_mflat.param.background_poly_deg_y

Poly mode fit deg along Y. (int; default: 9) [default=9].

xsh_mflat.param.background_poly_deg_x

Poly mode fit deg along X. (int; default: 9) [default=9].

xsh_mflat.param.background_poly_kappa

Poly mode kappa value of kappa-sigma-clip outliers removal. (float; default: 10.0) [default=10.0].

The following code snippet shows the default settings for the available parameters.

import cpl
xsh_mflat = cpl.Recipe("xsh_mflat")

xsh_mflat.param.keep_temp = "no"
xsh_mflat.param.debug_level = "none"
xsh_mflat.param.time_stamp = False
xsh_mflat.param.decode_bp = 2144337919
xsh_mflat.param.pre_overscan_corr = 1
xsh_mflat.param.stack_method = "median"
xsh_mflat.param.klow = 5.0
xsh_mflat.param.khigh = 5.0
xsh_mflat.param.detectorder_edges_search_win_hsize = 50
xsh_mflat.param.detectorder_edges_flux_thresh = 0.4
xsh_mflat.param.detectorder_min_sn = -1.0
xsh_mflat.param.detectorder_min_order_size_x = -1
xsh_mflat.param.detectorder_chunk_half_size = 1
xsh_mflat.param.detectorder_slitlet_low_factor = 1.0
xsh_mflat.param.detectorder_slitlet_up_factor = 1.0
xsh_mflat.param.detectorder_fixed_slice = True
xsh_mflat.param.detectorder_slice_trace_method = "auto"
xsh_mflat.param.detectorder_qc_mode = False
xsh_mflat.param.detectorder_d2_min_sn = 60.0
xsh_mflat.param.background_edges_margin = 1
xsh_mflat.param.background_poly_deg_y = 9
xsh_mflat.param.background_poly_deg_x = 9
xsh_mflat.param.background_poly_kappa = 10.0

You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:

import cpl
xsh_mflat = cpl.Recipe("xsh_mflat")
[...]
res = xsh_mflat( ..., param = {"keep_temp":"no", "debug_level":"none"})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

Please report any problems to P.Goldoni, L.Guglielmi, R. Haigron, F. Royer, D. Bramich, A. Modigliani. Alternatively, you may send a report to the ESO User Support Department.