Efficiency QCs

[marcolandoni]

Here below the relevant QCs for the efficiency group

• efficiency:
  1. Relative efficiency for UVB arm, range 5100A - 5300
  2. EFFMON template .. was observation started under photometric conditions?
  3. median star counts in arm at given range
  4. Chromatic efficiency plot for UVB arm; the values trended in plot are marked. The plot is constituted from the following wavelength ranges: 5670A, a point each circa 200 angstroms (chromatic efficiency)

-flat_response:

1. For each calibration flat lamp: D2 current response / reference response = a + b * (lam - lam0)

On 2015-10-25, the first flux standard star was acquired with the effmon template, meaning this observation was acquired under strict photometric conditions. The calibration product 'response function' from that date serves as a reference in the following. It is marked by a vertical red bar in the history plot.

The master response function once generated as a weighted and clean mean of response functions for the purpose to flux calibrate XSHOOTER science observations (internal data producs = IDPs) is a representative response function for a given time range. The comparison between the reference response function (from 2015-10-25, ARCFILE=XSHOO.2015-10-26T01:23...) and the current response function as well as the comparison between the master response and the current response is parameterized via

current(lambda) / reference(lambda) = a + b * (lambda - lambda_0 )

current(lambda) / master(lambda) = a + b * ( lambda - lambda_0 )

where lambda_0 is the center wavelength of the considered wavelength range, parameter a is the relative overall flux of the spectrum, corresponding to atmospheric variations and parameter b is a first order chromatic deviation (the slope between the reference(/master) and the current).

This plot shows both parameters a and b, of which parameter b is the important one.

On 2015-10-25, there is a=1 and b=0 by definition. The response function is a flat-fielded efficiency, hence the response function depends on the spectral shape of the flat field lamp, on long-term changes as well as on exchanges of the lamp. For this reason, dates of lamp exchanges are marked by blue vertical bars.

[thespacedoctor]

UVB XShooter Page

VIS XShooter Page

NIR XShooter Page

[thespacedoctor]

FYI I added '3. median star counts in arm at given range' to the list above