soxs_mdark

Every raw CCD image contains counts resulting from a ‘dark current’, electrons released due to the thermal effects in the CCD material. For both the UVB-VIS (< 0.00012 \(\rm{e^{-}/s/pixel}\)) and NIR detectors (< 0.005 \(\rm{e^{-}/s/pixel}\)), the dark current is almost negligible. Not all pixels will have the same dark current, with some pixels having a higher-than-typical current. These are so-called ‘hot-pixels’, and these must be identified and recorded (using the create_noise_map utility).

The purpose of the soxs_mdark recipe is to generate a master-dark frame used to remove flux attributed to the dark current from other frames.

Input

Table 50 Input files for the soxs_mdark recipe. The files are typically passed to the soxs_mdark recipe via a set-of-file (sof) file listing one file per line.

Data Type	Content	Related OB	Min. Frame Count
FITS images	raw dark frames (exposures with identical exposure time and detectors readout parameters).	SOXS_gen_cal_VISDark, SOXS_gen_cal_NIRDark, SOXS_img_cal_Dark	3

Table 51 Ancillary (static) files required by the soxs_mdark recipe. These files are packaged with and shipped with the code.

Data Type	Content
FITS images	Default bad-pixel map

Parameters

Table 52 The soxs_mdark recipe parameters.

Parameter	Description	Type	Entry Point	Related Util
frame_clipping_sigma	number of \(\sigma\) from the median frame flux beyond which pixel is added to the bad-pixel mask	float	settings file	clip_and_stack
frame_clipping_iterations	number of \(\sigma\)-clipping iterations to perform when adding pixels to the bad-pixel mask	int	settings file	clip_and_stack
stacked_clipping_sigma	number of \(\sigma\) deviations from the median pixel flux beyond which pixel is excluded from stack	float	settings file	clip_and_stack
stacked_clipping_iterations	number of \(\sigma\)-clipping iterations to perform before stacking	int	settings file	clip_and_stack

Method

The raw dark frames are stacked together (using the clip_and_stack utility) into master-dark frames and, in the process, clipping rogue pixels from the individual raw frames and reducing the read-noise contribution. The algorithm used in the soxs_mdark recipe is shown in Fig. 36.

Fig. 36 The soxs-mdark recipe algorithm.

Output

Table 53 Output files for the soxs_mdark recipe and their respective ESO PRO keywords.

Label	Content	Data Type	PRO CATG	PRO TYPE	PRO TECH
MDARK	Master dark frame (frame containing typical dark-current flux accumulated over the exposure time of the input frames)	FITS image	DARK_<ARM>	REDUCED	IMAGE

QC Metrics

Table 54 Quality Control metrics calculated in the soxs_mdark recipe.

Label	Description	Unit	Acceptable Range
HOTPIX FRAC	Fraction of hot pixels	-	-
MDARK MEDIAN	Median flux level of master dark	electrons	NIR: [-15, 50]
HOTPIX NUM	Number of hot pixels	-	-
RAW RON	RON in single DARK	electrons	NIR: [0,30]

Recipe API

class soxs_mdark(log, settings=False, inputFrames=[], verbose=False, overwrite=False, command=False, debug=False, turnOffMP=False)

Bases: soxspipe.recipes.base_recipe.base_recipe

The soxs_mdark recipe generates a master-dark frame used to remove flux attributed to the dark current from other frames.

Key Arguments

• log – logger

• settings – the settings dictionary

• inputFrames – input fits frames. Can be a directory, a set-of-files (SOF) file or a list of fits frame paths.

• verbose – verbose. True or False. Default False

• overwrite – overwrite the product file if it already exists. Default False

• command – the command called to run the recipe

• debug – debug mode. True or False. Default False

• turnOffMP – turn off multiprocessing. True or False. Default False. If True, multiprocessing will be turned off and the recipe will run in serial. This is useful for debugging.

Usage

from soxspipe.recipes import soxs_mdark
mdarkFrame = soxs_mdark(
    log=log,
    settings=settings,
    inputFrames=fileList,
    verbose=False,
    overwrite=False
).produce_product()

Initialization

clean_up(forceFail=False)

clip_and_stack(frames, recipe, ignore_input_masks=False, post_stack_clipping=True)

detrend(inputFrame, master_bias=False, dark=False, master_flat=False, order_table=False)

flag_poor_data()

get_recipe_settings()

prepare_frames(save=False)

produce_product()

generate a master dark frame

Return:

• productPath – the path to master dark frame

qc_median_flux_level(frame, frameType='MBIAS', frameName='master bias', medianFlux=False)

qc_ron(frameType=False, frameName=False, masterFrame=False, rawRon=False, masterRon=False)

report_output(rformat='stdout')

subtract_mean_flux_level(rawFrame)

update_fits_keywords(frame, rawFrames=False)

verify_input_frames()

verify input frame match those required by the soxs_mdark recipe

If the fits files conform to the required input for the recipe, everything will pass silently; otherwise, an exception will be raised.

xsh2soxs(frame)