Bias Image¶
- Mode:
Bias
- Usage:
Offline, Online
- Key:
MegaraBIAS_IMAGE
- Product:
MasterBias
- Recipe:
- Recipe input:
- Recipe result:
Before the Analog-to-Digital conversion is performed a pedestal (electronic) level is added to all images obtained with the MEGARA CCD. This is a standard procedure in CCD imaging and spectroscopy applications for Astronomy and is intended to minimize the ADC errors produced when very low analog values are converted to DUs.
Requirements of the mode¶
The sequence for this observing mode should include the actions to calibrate the pedestal level of the detectors and associated control electronics by taking images with null integration time. This mode requires having the shutter closed and to readout the detector in a series of exposures with null integration time, being this series the bias image set.
Procedure¶
The frames in the observed block are stacked together using the median of them as the final result. The variance of the result frame is computed using two different methods. The first method computes the variance across the pixels in the different frames stacked. The second method computes the variance in each channel in the result frame.
Products¶
Bias image sets are to be obtained both as part of the activities related to the verification of the instrument status and for processing data for scientific exploitation.
Recipe, inputs and results¶
- class megaradrp.recipes.calibration.bias.BiasRecipe(*args, **kwargs)¶
Process BIAS images and create a MASTER_BIAS product.
This recipe process a set of bias images obtained in Bias Image mode and returns a combined product image, trimmed to the physical size of the detector.
See also
megaradrp.types.MasterBias
description of the MasterBias product
Notes
Images are corrected from overscan and trimmed to the physical size of the detector. Then, they corrected from Bad Pixel Mask, if the BPM is available, Finally, images are stacked using the median.
- class BiasRecipeInput(*args, **kwds)¶
BiasRecipeInput documentation.
- Attributes:
- master_bpmMasterBPM, requirement, optional
Master Bad Pixel Mask
- methodstr, requirement, optional, default=median
Combination method
- method_kwargsdict, requirement, optional
Arguments for combination method
- obresultObservationResultType, requirement
Observation Result
- class BiasRecipeResult(*args, **kwds)¶
BiasRecipeResult documentation.
- Attributes:
- master_biasMasterBias, product
- RecipeInput¶
alias of
BiasRecipeInput
- RecipeResult¶
alias of
BiasRecipeResult
- run(rinput)¶
Execute the recipe.
- Parameters:
- rinputBiasRecipe.RecipeInput
- Returns:
- BiasRecipe.RecipeResult
- set_base_headers(hdr)¶
Set metadata in FITS headers.