Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observing faint targets with MIDI at the VLTI -- The MIDI AGN Large
  Programme experience   In order to put MIDI/VLTI observations of AGNs on a significant statistical
basis, the number of objects had to be increased dramatically from the few
prominent bright cases to over 20. For this, correlated fluxes as faint as ~
150 mJy need to be observed, calibrated and their errors be estimated reliably.
We have developed new data reduction methods for the coherent estimation of
correlated fluxes with the Expert Work Station (EWS). They increase the
signal/noise of the reduced correlated fluxes by decreasing the jitter in the
group delay estimation. While correlation losses cannot be fully avoided for
the weakest objects even with the improved routines, we have developed a method
to simulate observations of weak targets and can now detect --- and correct for
--- such losses. We have analyzed all sources of error that are relevant for
the observations of weak targets. Apart from the photon-noise error, that is
usually quoted, there is an additional error from the uncertainty in the
calibration (i.e. the conversion factor). With the improved data reduction,
calibration and error estimation, we can consistently and reproducibly observe
fluxes as weak as ~ 150 mJy with an uncertainty of ~ 15 % under average
conditions.

13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org