Infrared standards for ISO

Hammersley, P. L.; Muizon, M. Jourdain de; Kessler, Martin; Bouchet, P.; Joseph, R. D.; Habing, H. J.; Salama, A.; Metcalfe, L.

doi:10.1051/aas:1998380

Cited by 18 publications

(26 citation statements)

References 10 publications

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“…(MSX ) Price et al (2004); ( DIR) Smith et al (2004); ( H ) Hammersley et al (1998); (S) Selby et al (1988); (IRAS ) Beichman et al (1988); ( T ) Tokunaga (1984).…”

Section: New Calibrated Reference Spectramentioning

confidence: 99%

“…We have combined the moderate-resolution 2.36-35 m spectra (k /Ák $ 400) obtained by the SWS (Leech et al 2003) on ISO with the best photometry available on Cohen et al's secondary and tertiary standards, which we reference to the rescaled absolute infrared spectrum of Sirius, to create absolutely calibrated moderateresolution spectra for 33 stars, 29 of which are in the Cohen et al calibration network. The highest quality photometry was from MSX, the Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE ), and Hammersley et al (1998). MSX and DIRBE were space-based experiments, and therefore, atmospheric effects do not affect their measurements.…”

Section: New Calibrated Reference Spectramentioning

confidence: 99%

“…A mean relative spectral response for the spectrometer was determined from the SWS observations of a small number of Cohen et al primary and secondary standards, as well as other stars with model atmosphere spectra. The relative response thus derived was scaled to absolute values with calibrated photometry obtained by the ISO program for that purpose ( Hammersley et al 1998;Hammersley & 4 See http://www.iso.vilspa.esa.es/users/expl _ lib/ISO/wwwcal /. Strecker et al (1979); ( HW ) Hinkle et al (1995), Wallace & Hinkle (1996; (S) SWS (Sloan et al 2003); (CVF ) ISOCAM CVF ); (A) autoshape (see text).…”

Section: Rationalizing the Sws Spectrometrymentioning

confidence: 99%

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Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars

Engelke

Price²,

Kraemer³

2006

Astron J

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We have increased the spectral resolution and accuracy of the absolute infrared spectral flux for a subset of stellar standards created by Cohen and his collaborators in previous papers in this series. We combined the moderateresolution (k/Ák $ 400) spectroscopy obtained on infrared standard stars by the Short Wavelength Spectrometer on the Infrared Space Observatory with high-quality photometry that is tied to our recent absolute calibration from the Midcourse Space Experiment. New spectra were created for 33 stars, 9 of which are Cohen et al. secondary standards and another 20 of which are tertiary standards for which Cohen adopted spectral templates. The effective temperatures and angular diameters for the stars are derived from the absolute spectra and compare favorably with independent measures of these quantities in the literature. The present spectra display systematic differences with those of Cohen and colleagues in that they have 4%-7% lower fluxes in the 1-4 m spectral region. Our spectra remove the A-K star calibration bias recently noted in the calibration of the Spitzer Space Telescope camera.

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“…(MSX ) Price et al (2004); ( DIR) Smith et al (2004); ( H ) Hammersley et al (1998); (S) Selby et al (1988); (IRAS ) Beichman et al (1988); ( T ) Tokunaga (1984).…”

Section: New Calibrated Reference Spectramentioning

confidence: 99%

Section: New Calibrated Reference Spectramentioning

confidence: 99%

Section: Rationalizing the Sws Spectrometrymentioning

confidence: 99%

See 1 more Smart Citation

Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars

Engelke

Price²,

Kraemer³

2006

Astron J

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“…In preparation of the PACS in-flight photometric calibration, secondary standard source lists with stars described in Cohen et al (1996), Hammersley et al (1998), and Gordon et al (2007) were prepared by the PACS Instrument Control Centre (ICC) team. Depending on the source visibility during the Herschel mission, a subset of sources from these lists were observed to cover the flux range from 0.5 -2.5 Jy down to 2 -10 mJy over the three photometer wavelengths 70, 100, and 160 µm.…”

Section: Source Selectionmentioning

confidence: 99%

Herschel-PACS photometry of faint stars for sensitivity performance assessment and establishment of faint FIR primary photometric standards

Klaas

Balog

Nielbock

et al. 2018

A&A

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Aims. Our aims are to determine flux densities and their photometric accuracy for a set of seventeen stars that range in flux from intermediately bright ( 2.5 Jy) to faint ( 5 mJy) in the far-infrared (FIR). We also aim to derive signal-to-noise dependence with flux and time, and compare the results with predictions from the Herschel exposure-time calculation tool. Methods. We obtain aperture photometry from Herschel-PACS high-pass-filtered scan maps and chop/nod observations of the faint stars. The issues of detection limits and sky confusion noise are addressed by comparison of the field-of-view at different wavelengths, by multi-aperture photometry, by special processing of the maps to preserve extended emission, and with the help of large-scale absolute sky brightness maps from AKARI. This photometry is compared with flux-density predictions based on photospheric models for these stars. We obtain a robust noise estimate by fitting the flux distribution per map pixel histogram for the area around the stars, scaling it for the applied aperture size and correcting for noise correlation.Results. For 15 stars we obtain reliable photometry in at least one PACS filter, and for 11 stars we achieve this in all three PACS filters (70, 100, 160 µm). Faintest fluxes, for which the photometry still has good quality, are about 10 -20 mJy with scan map photometry. The photometry of seven stars is consistent with models or flux predictions for pure photospheric emission, making them good primary standard candidates. Two stars exhibit source-intrinsic far-infrared excess: β Gem (Pollux), being the host star of a confirmed Jupiter-size exoplanet, due to emission of an associated dust disk, and η Dra due to dust emission in a binary system with a K1 dwarf. The investigation of the 160 µm sky background and environment of four sources reveals significant sky confusion prohibiting the determination of an accurate stellar flux at this wavelength. As a good model approximation, for nine stars we obtain scaling factors of the continuum flux models of four PACS fiducial standards with the same or quite similar spectral type. We can verify a linear dependence of signal-to-noise ratio (S/N) with flux and with square root of time over significant ranges. At 160 µm the latter relation is, however, affected by confusion noise. Conclusions. The PACS faint star sample has allowed a comprehensive sensitivity assessment of the PACS photometer. Accurate photometry allows us to establish a set of five FIR primary standard candidates, namely α Ari, ε Lep, ω Cap, HD 41047 and 42 Dra, which are 2 -20 times fainter than the faintest PACS fiducial standard (γ Dra) with absolute accuracy of <6%. For three of these primary standard candidates, essential stellar parameters are known, meaning that a dedicated flux model code may be run.

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“…10). Figure 10 also plots the IRAS LRS and PSC data and different photometric data points collected from the ISO Ground Based Preparatory Programme (GBPP) 4 as obtained by Hammersley et al (1998) and Hammersley & Jourdain de Muizon (2003). For the Marcs atmosphere spectra, stellar parameters as determined by Decin et al (2003a) were used as input parameters.…”

Section: Comparison Between Different Ir Stellar Reference Sedsmentioning

confidence: 99%

Theoretical model atmosphere spectra used for the calibration of infrared instruments

Decin

Eriksson

2007

A&A

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Context. One of the key ingredients in establishing the relation between input signal and output flux from a spectrometer is accurate determination of the spectrophotometric calibration. In the case of spectrometers onboard satellites, the accuracy of this part of the calibration pedigree is ultimately linked to the accuracy of the set of reference spectral energy distributions (SEDs) that the spectrophotometric calibration is built on. Aims. In this paper, we deal with the spectrophotometric calibration of infrared (IR) spectrometers onboard satellites in the 2 to 200 µm wavelength range. We aim at comparing the different reference SEDs used for the IR spectrophotometric calibration. The emphasis is on the reference SEDs of stellar standards with spectral type later than A0, with special focus on the theoretical model atmosphere spectra. Methods. Using the MARCS model atmosphere code, spectral reference SEDs were constructed for a set of IR stellar standards (A dwarfs, solar analogs, G9-M0 giants). A detailed error analysis was performed to estimate proper uncertainties on the predicted flux values. Results. It is shown that the uncertainty on the predicted fluxes can be as high as 10%, but in case high-resolution observational optical or near-IR data are available, and IR excess can be excluded, the uncertainty on medium-resolution SEDs can be reduced to 1-2% in the near-IR, to ∼3% in the mid-IR, and to ∼5% in the far-IR. Moreover, it is argued that theoretical stellar atmosphere spectra are at the moment the best representations for the IR fluxes of cool stellar standards. Conclusions. When aiming at a determination of the spectrophotometric calibration of IR spectrometers better than 3%, effort should be put into constructing an appropriate set of stellar reference SEDs based on theoretical atmosphere spectra for some 15 standard stars with spectral types between A0 V and M0 III.

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Infrared standards for ISO

Cited by 18 publications

References 10 publications

Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars

Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars

Herschel-PACS photometry of faint stars for sensitivity performance assessment and establishment of faint FIR primary photometric standards

Theoretical model atmosphere spectra used for the calibration of infrared instruments

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