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Keck-DataReductionPipelines / KCWI_DRP

KCWI python DRP
BSD 3-Clause "New" or "Revised" License
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Implement zeroth order reduction #100

Open scizen9 opened 2 years ago

scizen9 commented 2 years ago

Add infrastructure and primitives to handle KCWI zeroth order data reductions using algorithms from IDL pipeline.

With the new guider, this may be used to verify acquisition and should be an option.

It will require a short flat field exposure in the afternoon calibrations in zeroth order for both channels.

The red channel mechanism rotations are much faster than the blue channel, so at night it is likely that this will be done with the red channel only.

scizen9 commented 2 years ago

So looking at the commissioning data from 2017-04-12, I see that zeroth order is a misnomer. There is no grating installed and it is literally direct imaging with no disperser at all. This could be a problem, since removing and installing a grating could be costly time-wise. The relevant data are in the table below, which includes camera angles and encoder positions. The headers show the following encoder values for the articulation stage:

BARTANG =              -1.2199 / Blue Articulation Stage Angle (deg)            
BARTENC =               155291 / Blue Articulation Stage Encoder Value  
kb170412_00149.fits (TBO/1,1/1/10/ 1/   1.2 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.856) 13.370:        /  FeAr/FlatA

kb170412_00150.fits (TBO/1,1/1/10/ 1/   1.2 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.856) 13.370:        /  FeAr/FinBars

kb170412_00151.fits (TBO/1,1/1/10/ 1/   1.2 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.856) 13.370:        /  FeAr/TPat

kb170412_00152.fits (TBO/1,1/1/10/ 1/   1.2 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.856) 13.370:        /  ThAr/TPat

kb170412_00153.fits (TBO/1,1/1/10/ 1/   1.2 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.856) 13.370:        /  ThAr/FinBars

kb170412_00200.fits (TBO/1,1/1/10/ 1/   2.0 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.801) 1.050:        /     -/M3 - core

kb170412_00201.fits (TBO/1,1/1/10/ 1/   1.5 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.801) 1.060:        /     -/M3 - core

kb170412_00202.fits (TBO/1,1/1/10/ 1/   0.5 s), (Sma/KBlue/None/  Aligned dg/   0.0/  Sky/ 60.1 dg), ( -1.2/Open/-1.801) 1.060:        /     -/M3 - core
scizen9 commented 2 years ago

After a discussion with Matt, he informed me that zeroth order can be obtained using the following prescription:

  1. Configure grating for standard 1st order spectrum
  2. Once obtained, send camera angle to zero.

I recommend that we obtain a data set for the BL grating this way (just flats, but use an arclamp [ThAr?]) to test this out. Exposure times should be of order 1 or 2 seconds. I recommend checking the image and be sure to avoid saturation. Also, Matt suggested that we should tweak the angle such that the slices do not straddle an amplifier boundary. That way we can read out in quad mode and it will be good and fast.

Let's make a plan to acquire a data set and I'd like to be vnc'd in and eavesdropping.