Spectral Irradiance Calibration in the Infrared. XIII. “Supertemplates” and On-Orbit Calibrators for the SIRTF Infrared Array Camera

Martin Cohen1; S. T. Megeath2; Peter L. Hammersley3; Fabiola Martín-Luis3; John Stauffer4

摘要

We describe the technique that will be used to develop a set of on-orbit calibrators for the Infrared Array Camera (IRAC) and demonstrate the validity of the method for stars with spectral types either K0–M0 III or A0–A5 V. For application to SIRTF, the approach is intended to operate with all available optical, near-infrared (NIR), and mid-infrared (MIR) photometry and to yield complete absolute spectra from UV to MIR. One set of stars is picked from Landolt's extensive network of optical (UBVRI) calibrators, the other from the Carter-Meadows set of faint IR standards. Traceability to the "Cohen-Walker-Witteborn" framework of absolute photometry and stellar spectra is assured. The method is based on the use of either "supertemplates," which represent the intrinsic shapes of the spectra of K0–M0 III stars from far-UV (1150 ?) to MIR (35 μm) wavelengths, or Kurucz synthetic spectra for A0–A5 V stars. Each supertemplate or Kurucz model is reddened according to the individual star's extinction and is normalized using available characterized optical photometry. This paper tests our capability to predict NIR (JHK) magnitudes using supertemplates or models constrained by Hipparcos/Tycho or precision ground-based optical data. We provide absolutely calibrated 0.275–35.00 μm spectra of 33 Landolt and Carter-Meadows optical standard stars to demonstrate the viability of this technique, and to offer a set of IR calibrators 100–1000 times fainter than those we have previously published. As an indication of what we can expect for actual IRAC calibration stars, we have calculated the absolute uncertainties associated with predicting the IRAC magnitudes for the faintest cool giant and hot dwarf in this new set of calibration stars.

机译：我们描述了将用于为红外阵列相机（IRAC）开发一套在轨校准器的技术，并论证了该方法对光谱类型为K0–M0 III或A0–A5 V的恒星的有效性。对于SIRTF，该方法旨在与所有可用的光学，近红外（NIR）和中红外（MIR）光度法一起使用，并产生从UV到MIR的完整绝对光谱。一组恒星是从Landolt广泛的光学（UBVRI）校准器网络中选取的，另一组是从Carter-Meadows一套微弱的IR标准中选取的。可以追溯到绝对光度法和恒星光谱的“ Cohen-Walker-Witteborn”框架。该方法基于“超级模板”的使用，“超级模板”表示从远紫外线（1150？）到中红外（35μm）波长的K0–M0 III星的光谱的固有形状，或代表A0–3的Kurucz合成光谱的形状。 A5 V星。每个超级模板或Kurucz模型都根据单个恒星的灭光而变红，并使用可用的特征光学光度法进行归一化。本文测试了我们使用受Hipparcos / Tycho约束或基于地面的精确光学数据约束的超级模板或模型预测NIR（JHK）幅度的能力。我们提供33颗Landolt和Carter-Meadows光学标准星的经过绝对校准的0.275–35.00μm光谱，以证明该技术的可行性，并提供一组比我们先前发布的红外校准器弱100–1000倍的红外校准器。为了说明我们对实际IRAC校准星的期望，我们已经计算出了与预测这套新的校准星中最微弱的冷巨星和热矮星的IRAC大小相关的绝对不确定性。

Spectral Irradiance Calibration in the Infrared. XIII. “Supertemplates” and On-Orbit Calibrators for the SIRTF Infrared Array Camera

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