== P3.18	Atmospheric calibration and absolute flux calibration == 

- **Phase**		:	3  
- **Status**		: 	Draft	 
- **Category**	: 	Nighttime testing (functionality and operability) (C5) + Nighttime calibration (C6)
- **Recurrence**	: 	once at commissioning and then for each LSS observation.
- **Duration**	: 	4 hours

**Description**
- Atmospheric calibration to remove telluric atmospheric features from the stellar spectrum and get absolute flux calibration per spectral resolution element. 

**Prerequisites**
- Authorize SHARK-NIR on the SX side.
- Atmospheric conditions: AO working conditions.
- Bad pixel map, Background or Dark, Flat-field, wavelength calibration. 

**Procedure**
- Observe the spectrum of a featureless (standard) star at a similar airmass to that of the science target.

**Templates**
- SHARKNIR_lss_cal_RemoveTelluric (not released)
- SHARKNIR_lss_cal_AbsoluteFlux (not released)

**Success criteria**
- Better than 10% for absolute flux calibration and average residuals from telluric removal.

**Notes**
- Same as activity 7.4 in AD4

**LBTO support**
- AO support

**Date performed and by whom**