Characterization of the New Mauna Kea IR Filter Set

Preliminary results on the calibration and color terms of the new Mauna Kea IR filter set have been determined from a small data set obtained on 12 March 1999 using NSFCam at the 0.15 arcsec plate scale. The plot below presents the difference between the new filter set (MK) and the standard JHKK' filter set as a function of IR color for 5 stars (4 UKIRT faint standards and an A0V star). JPEG plots and ascii files of the transmission profiles for the MK filters are also available.

New MK IR Filter Set


The relationships between the new filters and the old ones can be summarized as follows:

J (MK) - J = 0.142 (± 0.013) - 0.073 (± 0.030) * (J-K)
H (MK) - H = -0.213 (± 0.016)
K (MK) - K = -0.081 (± 0.026) - 0.054 (± 0.139) * (H-K)
K'(MK) - K' = -0.287 (± 0.024) - 0.073 (± 0.131) * (H-K)

The color terms for the K and K' filters are only marginally significant (less than 75% probability for the K filter and less than 90% probability for the K' filter, as determined from an F test). A weighted mean of the data for these two filters yields:

K (MK) - K = -0.087 (± 0.020)
K'(MK) - K' = -0.293 (± 0.021)


The mean offsets agree well with those expected based on inspection of the transmission curves of the two sets of filters. The values given above imply that the new H filter yields a 20% increase in throughput over the current H filter in NSFCam, while the new K and K' filters yield increases in throughput of about 10 and 30 percent respectively.

We have additional data sets and will provide updates to this page as these data are reduced and analyzed.

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Maintained by Bobby Bus (sjb@irtf.ifa.hawaii.edu)