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Pipeline code for KCor
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Names for new occulters #368

Closed bberkeyU closed 5 months ago

bberkeyU commented 6 months ago

The new occulters have arrived. In the drawings, these occulters are named T1, T2, T3.

What names should we use for the fits headers? During eclipse prep/eclipse obs, I think we are going to use the T2 occulter so we need to agree on the names and get them into the kcor epochs.spec.cfg file.

Following our old scheme T2 might be OC-T2 but this doesn't give a data user any concept of the diameter in arcseconds.

There is a new issue #369 that creates a new naming scheme, consistent with this naming, for the older occulters.

Tasks

jburkepile commented 6 months ago

The original occulter names had the diameter in arcsec based on the effective focal length of the Jenoptik lens. I put a Jira ticket in last month asking the IG to measure the effective focal length of the Optimax lens currently in K-Cor. We don't have that yet.

I suggest we go with the physical diameter of the occulters in mm. I have taken the average of the vendor (OPTX) and the DFS diameter measurements and converted them to mm to get:

Occulter Size [mm]
T1 19.950 +/- 0.009 [mm]
T2 19.702 +/- 0.005 [mm]
T3 19.486 +/- 0.005 [mm]

I suggest we name them by their physical sizes and then add a keyword for the effective focal length (EFL) of the objective lens we are using.

New occulter names and please change the comment:

OC-T1-19.950    / ID occulter, diameter in mm
OC-T2-19.702    / ID occulter, diameter in mm
OC-T3-19.486    / ID occulter, diameter in mm

Mike - Are you okay with this change in the name?

We can later add a keyword for the effective focal length (EFL) of the objective lens we are using once we get the Optimax EFL from the IG.

mgalloy commented 6 months ago

For the pipeline, as long as the first 8 characters are unique amongst the possible occulted names, the names don't matter.

mgalloy commented 6 months ago

Before we implement #369, I need sizes in arcseconds for the new occulters (assuming the current objective lens).

bberkeyU commented 5 months ago

Changing of the Kcor header comments is harder than ucomp; because they are hard coded. I would like to delay changing the comment until we confirm we will only be using the new occulter or until we get more stable power so I can upgrade the whole fits keyword system to be scribable.

mgalloy commented 5 months ago

Calculating the size in arcseconds using the formula:

occulter_radius_in_arcseconds = 206264.8 * (occulter_diameter_in_mm / 2.0) / focal_length
                              = 103132.4 * occulter_diameter_in_mm / focal_length

Using differentials to compute the error in this size:

d_occulter_radius_in_arcseconds = 103132.4 * (focal_length * d_occulter_diameter_in_mm - occulter_diameter_in_mm * d_focal_length) / focal_length^2

where d_focal_length is 0.2 mm and d_occulter_diameter_in_mm is found along with diameters in the table above.

Occulter Diameter [mm] Error [mm] Size [arcseconds] Error [arcsec]
T1 19.95 0.009 1019.317 0.359
T2 19.702 0.005 1006.646 0.156
T3 19.486 0.005 995.610 0.157

So I'm reporting all the sizes in arcseconds to +/- 0.1 arcseconds.

jburkepile commented 5 months ago

How about reporting:

mgalloy commented 5 months ago

The pipeline is now using the following comments:

Occulter OCCLTRID comment
OC-991.6 ID occulter, radius in arcsec
OC-1018.9 ID occulter, radius in arcsec
OC-1006.9 ID occulter, radius in arcsec
OC-1 ID occulter, equivalent to OC-1006.9
OC-1017.0 ID occulter, tapered, radius in arcsec
OC-T1-19.950 ID occulter, tapered, diameter in mm
OC-T2-19.702 ID occulter, tapered, diameter in mm
OC-T3-19.486 ID occulter, tapered, diameter in mm