Mid-Infrared Imaging of the Einstein Cross QSO

Eric Agol , Stuart Wyithe, Barbara Jones, Omer Blaes, Chris Fluke, PASA, 18 (2), in press.
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Observations

To monitor the infrared bump requires monitoring at

$\lambda > 2.7 \mu$m (beyond the 1 micron dip), so we utilized the Long Wavelength Spectrometer on Keck. Observations were taken on 28 July, 1999 and 25-26 September 1999 in the 11.7 and 8.9 $\mu$m filters, as reported in Agol et al. (2000), as well as a new observation on 7 November 2000 in the 11.7 $\mu$m filter for 65 minutes total time and 28 minutes on source. There was a great improvement in signal-to-noise between 1999 and 2000 due to eliminating pattern noise and increasing observing efficiency. The table shows the fraction of the total flux contained in each image for the two sets of observations:

Table 1: Source fluxes.
Date $\lambda$ A B C D
25-26/9/99 11.7 & 8.9 $\mu$m 0.27 +- 0.02 0.30 +- 0.02 0.16 +- 0.02 0.27 +- 0.02
7/11/00 11.7 $\mu$m 0.250+-0.015 0.277+-0.015 0.180+-0.015 0.293+-0.015
4/8/99 V-band 0.39 0.11 0.41 0.10

The optical data were taken from Wozniak et al. (2000), and corrected for extinction. The analysis of the 1999 data is described in Agol et al. (2000). The 2000 data had Poisson errors since the pattern noise was eliminated.

Next Section: The Infrared Source is
Title/Abstract Page: Mid-Infrared Imaging of the
Previous Section: Microlensing in the Einstein
Contents Page: Volume 18, Number 2

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