==== Science imaging coronagraphy template METIS_img_n_cvc_obs_AutoChop ====

=== Procedure for METIS_img_n_cvc_obs_AutoChop ===
 
++++
Setup imager|
  * Move ''IMG-N PP1 FILT'' to selected filter
  * Remove the neutral density filter (located in one of the wheels in IMG-N PP1)
  * 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. 
++++
++++
Start science exposures|

  * This templates performs chopping (using the CFO-PP2 chopper) between the three VPM masks. The positions are pre-defined by the locations of the three VPM masks sitting in the CFO-FP2. The exact centering of the star at the three positions is performed during the acquisition, and the chopper parameters (chop-throw and angle) are calculated. The chopping is always performed between the centers of the two (out of three) side-by-side VPMs in VPM-N1/N2 (sequence B-A-B-A…, followed by B-C-B-C…).
  * Set the number of chopping cycles (chopped pairs of images) using the parameter NChopCycles.
  * At each position start science exposures with DIT/NDIT. 
  * Every ~10 min, the chopper is used to move the star to a separation of >20 λ/D from the VPM-N2 centre, but still well within VPM-N2’s footprint. Unsaturated PSF measurements are obtained (while chopping), using an ND filter if needed. Chop subtraction is applied to obtain sky-subtracted PSF measurements. The user can specify the offset value for the off-axis PSF measurement, or stick to the default value (to be optimized during commissioning).
  * Use chopper to place the star back close to the VPM-N2 centre (centring accurate to within ~1 λ/D). In case of bright stars, an ND should be used.
  * Close the QACITS loop.
  * Read-out and save individual exposures, or co-added frames, depending on the ''cube mode'' T/F keyword.

++++
++++
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.

++++

===Parameters for METIS_img_n_cvc_obs_AutoChop ===


^Parameter             ^Hidden     ^Range (default)            ^Label^  
|DPR CATG              |yes        |SCIENCE TEST (SCIENCE) |Data product category|
|DPR TECH              |yes        |IMAGE,CVC (IMAGE,CVC)                 |Data product technique|
|DPR TYPE              |yes        |OBJECT SKY (OBJECT)|Data product type|                      
|DET2 NCORRS NAME       |no         |TBD                         |IMG-N Readout mode|
|DET2 CUBE MODE        |yes         |T F (T)                    |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 (OPEN)                  |IMG-N Neutral density filter|
|SEQ TIME OBJECT       |no         |0..TBD (NODEFAULT)         |Total integration time on OBJECT position (sec)|
|SEQ TIME PSF       |no         |0..TBD (NODEFAULT)         |Total integration time on off-axis PSF position (sec)|
|SEQ DET2 DIT OBJECT       |yes         |0..TBD (NODEFAULT)         |DIT on OBJECT positions|
|SEQ DET2 NDIT OBJECT       |yes         |1..1000 (NODEFAULT)       |NDIT on OBJECT positions|
|SEQ DET2 DIT PSF       |yes         |0..TBD (NODEFAULT)         |DIT on off-axis PSF positions|
|SEQ DET2 NDIT PSF       |yes         |1..1000 (NODEFAULT)       |NDIT on off-axis PSF positions|
|SEQ NCHOPCYCLES       |no         |0..TBD (NODEFAULT)         |Number of chopping cycles|
|SEQ RETURN            |no         |T F (T)                    |Return to origin?|
|SEQ CFO CHOP POSANG       |yes        |0..360 (0)             |Chopper position angle|
|SEQ CFO CHOP THROW        |yes        |0..5 (2.5)             |Chop throw|
|SEQ CFO CHOP FREQ         |yes        |0..5 (1)               |Chopping frequency|
|SEQ PSFOFFSET AZ      |no         |0..TBD (TBD)               |Azimuth offset to PSF reference position|
|SEQ PSFOFFSET ALT     |no         |0..TBD (TBD)               |Altitude offset to PSF reference position|