==== Science imaging template METIS_img_n_obs_GenericChopNod ====

=== Procedure for METIS_img_n_obs_GenericChopNod ===
 
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Setup imager|
  * Move ''IMG-N PP1 FILT'' to selected filter
  * Set detector parameters (total exposure time, readout mode, cube mode T/F). The system will set the DIT/NDIT combination depending on the background levels.
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Start science exposures|
  * This templates performs chopping (using the CFO-PP2 chopper) between the target and a sky position. Additionally, it performs nodding, switching from one field to another by offsetting the telescope. Nodding allows to correct for optical path residuals that remain after chopping. This template enhances the flexibility of nodding offsets, and allows the user to specify them in a list of relative offset positions. 
  * Set the chopper parameters (''chop-pattern/positions'', ''chop frequency'')
  * Set the number of chopping cycles (moving through all defined chop positions) using the parameter ''NChopCycles''
  * Set the nodding parameters (list of offsets)
  * Set the number of nodding cycles using the parameter ''NNodCycles''
  * At each offset position start science exposures with DIT/NDIT. 
  * Read-out and save individual exposures, or co-added frames, depending on the ''cube mode'' T/F keyword.

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End science exposures|
  * Return telescope and chopper back to the initial position. 
  * Collect headers
  * Merge into one or more data cubes
  * Go back to Setup Imager until target observations are finished (single OB). For example, to observe in a different filter.
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===Parameters for METIS_img_n_obs_GenericChopNod ===

^Parameter             ^Hidden     ^Range (default)            ^Label^  
|DPR CATG              |yes        |SCIENCE TEST (SCIENCE) |Data product category|
|DPR TECH              |yes        |IMAGE (IMAGE)                 |Data product technique|
|DPR TYPE              |yes        |OBJECT SKY STD PSF-CALIBRATOR (OBJECT)|Data product type|                      
|DET2 DIT               |yes         |0..TBD (NODEFAULT)         |IMG-N Detector integration time (DIT)|
|DET2 NDIT              |yes         |1..TBD (NODEFAULT)         |IMG-N Number of Integrations (NDIT)|
|DET2 NCORRS NAME       |no         |TBD                         |IMG-N Readout mode|
|DET2 CUBE MODE        |yes         |T F (Y)                    |Toggle cube mode| 
|INS OPTI13 NAME         |no         |N1 N2 PAH8.6 PAH8.6_ref PAH11.25 PAH11.25_ref [NeII] [NeII]_ref [SIV] [SIV]_ref N3 (N1)                |IMG-N Filter name|
|INS OPTI14 NAME         |no         |OPEN ND1 ND2 ND3 ND4 (OPEN)                  |IMG-N Neutral density filter|
|SEQ TIME               |no         |0..TBD (NODEFAULT)         |Total integration time (sec)|
|SEQ NCHOPCYCLES       |no         |0..TBD (NODEFAULT)         |Number of chopping cycles|
|SEQ NNODCYCLES       |no         |0..TBD (NODEFAULT)         |Number of nodding cycles|
|SEQ RETURN            |no         |T F (T)                    |Return to origin?|
|SEQ CFO CHOP FREQ         |yes        |0..5 (1)                        |Chopping frequency|
|SEQ CFO CHOP XPOS       |no         |TBD (NODEFAULT)          |Chopper x position|
|SEQ CFO CHOP YPOS       |no         |TBD (NODEFAULT)           |Chopper y position|
|SEQ OFFSET1 LIST |no |TBD (NODEFAULT) |List of X or RA offsets (arcsec)|
|SEQ OFFSET2 LIST |no |TBD (NODEFAULT) |List of Y or DEC offsets (arcsec)|

Notes: 
  * It is not yet clear what will be the standard chopping pattern, it will possibly be a 3-point pattern instead of the "classical" 2-point pattern. This will require parameters to define the chopper positions, instead of the chopper throw/angle combination. These keywords should be updated once the "main" chopping pattern is decided. 


