UIST Imaging
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Imaging: Zeropoints
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Nominal zeropoints for a 5 arcsecond aperture at an airmass of 1.0 are
given below. A larger field stop was installed in February 2003 leading
to less vignetting at L' and M', and larger zeropoints. An ARC controller
with a different gain was installed in Oct. 2006, resulting in a difference
in zero points.
Note
that the zeropoint is a function of airmass, can vary from night to night,
and will be smaller than these values if the seeing is very poor.
| Filter |
Zeropoint mag |
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Oct 2002-Feb 2003 |
Mar 2003-Oct 2006
Larger Field Stop |
29 Oct 2006 - May 2008
(New controller) |
June 2008 - Present
(row-reset in thermal) |
| J | 21.12 | 21.15 | 22.37 | 22.37 |
| H | 21.47 | 21.50 | 22.62 | 22.62 |
| K | 20.77 | 20.80 | 21.84 | 21.84 |
| L' | 19.40 | 19.50 | 20.50 | 20.51 |
| M' | 17.13 | 17.29 | 18.29 | 18.33 |
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