2137 RIC FCa : ADI post-processing recipe

[astronomyk]

See MET-2137, MET-2238

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RIX: 2137:

"ADI images" -> could you define it (e.g. images taken in pupil tracking mode), otherwise it is confusing with images after or before the ADI subtraction (post-ADI is used, maybe use pre-ADI?).

"the centroid of the central source is determined": is it with QACITS ? (is the running frequency of QACITS matching the DIT?)

"The median PSF": to avoid confusion please use for instance "the temporal median of the coronagraphic image cube" (you can also add hereafter called median psf if preferred)

Raw contrast: how is it computed ? (the contrast curve and throughput computations are explained later in the paragraph).

Raw and post-ADI contrast curves, and throughput curves: are the azimuthal inhomogeneities included in the computation ? How are these estimations are affected by a bright companion ? Does the pipeline take this into account somehow ?

The term 'PSF subtraction' is also confusing, and called later speckle subtraction... maybe use 'coronagraphic image model subtraction' or 'ADI subtraction' ?

Fig. 50, the subtraction of the median seems included in the co-added image product: shouldn't the arrows be connected before (before subtraction box and at derotated image) 

RIX answers:

"ADI images" -> could you define it (e.g. images taken in pupil tracking mode), otherwise it is confusing with images after or before the ADI subtraction (post-ADI is used, maybe use pre-ADI?).

Will make textual correction to DRLD here to better define ADI images.

"the centroid of the central source is determined": is it with QACITS ? (is the running frequency of QACITS matching the DIT?)

For focal plane coronagraphs the QACITS telemetry will tell us both the star and focal plane mask positions, if properly working at <0.01 lambda/D precision and offset. Have to talk to HCI team to see what the update speed is and whether it is synchronized. For pupil plane coronagraphs we need to crosscorrelate non-saturated parts of the PSF with a reference template to find the centroids.

"The median PSF": to avoid confusion please use for instance "the temporal median of the coronagraphic image cube" (you can also add hereafter called median psf if preferred)

Will make textual correction here to clarify along which dimension the median is taken.

Raw contrast: how is it computed ? (the contrast curve and throughput computations are explained later in the paragraph).

Will add explanation here for the calculation of the raw contrast with the normalization with the level of the off-axis PSF reference.

Raw and post-ADI contrast curves, and throughput curves: are the azimuthal inhomogeneities included in the computation ? How are these estimations are affected by a bright companion ? Does the pipeline take this into account somehow ?

What do you mean with azimuthal inhomogeneities ? candidates and visual companions ? At the moment candidates are not masked in the contrast curves. Need to talk to HCI team / you to see if this needs to be included.

The term 'PSF subtraction' is also confusing, and called later speckle subtraction... maybe use 'coronagraphic image model subtraction' or 'ADI subtraction' ?

Will clarify this in the text

Fig. 50, the subtraction of the median seems included in the co-added image product: shouldn't the arrows be connected before (before subtraction box and at derotated image)

We generate both outputs with / without median subtraction after derotation. We need to keep the non-derotated cube in memory to allow both outputs to be regenerated. It is difficult to represent this in such a workflow.

The action item 2238 only describes additional quantiles for the contrast curve but the other issues should also be tackled for completeness.

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Todo:

• add option to set percentile for contrast curves
• reread section and make textual corrections to clarify PSF subtraction, ADI images and definition of raw contrast / 5 sigma contrast

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Made the textual corrections apart from the percentile option for the contrast curves. Need to talk to reviewer about that.