Currently no linearity correction is applied to the INGRID data. Therefore, select carefully your exposure time so that the level of counts of the sky and your sources is below ~12000 ADU.
NOTE: Each point in the figure above was obtained by
averaging a set of
seven dome flats, obtained via the 'multrun' command, each set having a
fixed exposure time. Two series of such sets were taken so that the
exposure time of each multrun was increasing through the first,
decreasing through the second. Moreover, the two series were mixed up
(1s,16s,3s,14s ... 4s,13s,2s,15s) in order to average out any possible
influences of the lamp's intensity variations on the global trend of
the
curve. However, each single data point could still be affected by these
variations, and the peaks in the normalized flux at low counts might be
due to this.
The linearity has not changed since November 2001 (last measurement
done in November 2005).
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Last Updated: 11 August 2006
Samantha Rix, srix@ing.iac.es |