Instrument Throughput, Atmospheric Extinction, Filter Transformation

Zero Points

The instrument evolution is currently being monitored via the pipeline produced PAF files. The zero point trends in the J, H, and Ks filters since July 2006 can be found here.

For previous data about the zero point evolution please refer to this page.

Atmospheric Extinction

Date \ Filter J H K Ks
La Silla Folklore 0.08 0.06 0.11  
Oct 1998 0.10 0.04   0.05
Mar 2000 0.08 0.03   0.05
May 2004 0.070 0.023   0.045
Dec 2005 0.07 0.03   0.03
Jul 2010 0.077 0.035   0.047
May 2011 0.066 0.037   0.069
May 2012 0.089 0.045   0.070
Oct 2012 0.066 0.026   0.069
More details, including uncertainties, are available here for: May 2004, July 2010, May 2011, May 2012, and Oct 2012.

Filter Transformation

In the following, lower case refer to SOFI instrumental magnitudes' corrected for atmospheric extinction and upper case letters refer to tabulated magnitudes in the Persson et al. list of standards. Stars in the J-Ks colour range 0.24 to 1.28 were used to derive the following relationships.

J-j=-0.007(J-K)+23.15, fit residual 0.013 magnitudes
H-h=-0.022(J-K)+22.98, fit residual 0.009 magnitudes
Ks-ks=0.023(J-K)+22.38, fit residual 0.013 magnitudes
K-ks=-0.005(J-K)+22.39, fit residual 0.017 magnitudes

Spectroscopic Mode

Counts are in electrons per second per Angstrom for a 15th magnitude A0 star at Zenith.
 

Date \ Grism-Wavelength Blue 10500 Blue 12000 Blue 13000 Blue 15000 Red 16000 Red 17000 Red 22000 Red 23000 Red 24000
March 1998 4.5 3.8 2.9 1.9 1.7 1.6 1.1 0.83 0.61


Last Modification: 2012-10-04, V.D. Ivanov

 
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