J/AJ/112/241 Spectral irradiance calibration. VI. (Cohen+ 1996)
Spectral irradiance calibration in the infrared. VI.
3-35 um spectra of three southern standard stars
Cohen M., Witteborn F.C., Bregman J.D., Wooden D.H., Salama A., Metcalfe L.
<Astron. J. 112, 241 (1996)>
=1996AJ....112..241C 1996AJ....112..241C
ADC_Keywords: Spectra, infrared ; Stars, standard
Abstract:
We present three new absolutely calibrated continuous stellar spectra
from 3 to 35um, constructed as far as possible from actual observed
spectral fragments taken from the Kuiper Airborne Observatory (KAO),
and the IRAS Low Resolution Spectrometer (LRS). These stars - alpha1
Cen, alpha TrA, and epsilon Car - augment our previous archive of
complete absolutely calibrated spectra for northern K and M giants.
All these spectra have a common calibration pedigree. The wavelength
coverage is ideal for calibration of many existing and proposed
ground-based, airborne, and satellite sensors. KAO and IRAS data in
the 15-30 um range suggest that the spectra of cool giants are close
to Rayleigh-Jeans slopes. Our observations of alpha1 Cen, absolutely
calibrated via our adopted Sirius model, indicate an angular diameter
in very good agreement with values in the literature, demonstrating
"closure" of the set of spectra within our absolute framework. We
compare our observed alpha1 Cen spectrum with a published grid of
theoretical models from Kurucz, and adopt a plausible theoretical
shape, that fits our spectrum, as a secondary reference spectrum in
the southern sky.
Objects:
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RA (2000) DE Designation(s)
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14 40 00.8 -60 50 42 alpha1 Cen = HD 128620 = HR 5459
16 48 39.6 -69 01 38 alpha TrA = HD 150798 = HR 6217
08 22 31.0 -59 30 35 epsilon Car = HD 71129/30 = HR 3307
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File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 55 2316 alp1 Cen composite spectrum
table3.dat 55 621 alp TrA composite spectrum
table4.dat 55 524 eps Car composite spectrum
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See also:
J/AJ/110/275 : IR spectra of standard stars (Cohen+ 1995)
J/AJ/112/2274 : Spectral irradiance calibration. VII. (Cohen+ 1996)
Byte-by-byte Description of file: table?.dat
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Bytes Format Units Label Explanations
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1-11 E11.4 um Lambda Wavelength
12-22 E11.4 W/cm2/um Irrad Irradiance
23-33 E11.4 W/cm2/um Utotal Total uncertainty
34-44 E11.4 % Ulocal Local bias
45-55 E11.4 % Uglobal Global bias
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Photometry actually used to construct the spectrum
------------------------------------------------------------------------------
Star Name FWHM Mag.±Unc. Eff Wvl Eff Wvl F-lam Source
(Vega) (star) W/cm2/um
(um) (um)
------------------------------------------------------------------------------
alp1 Cen SAAO-L 0.5648 -1.559 0.015 3.475 3.450 3.00E-14 Carter 1994
alp1 Cen ESO-L 0.6509 -1.552 0.021 3.768 3.768 2.18E-14 Engels+ 1981
alp1 Cen ESO-M 0.5418 -1.437 0.028 4.748 4.759 7.95E-15 Engels+ 1981
alp1 Cen ESO-N1 0.8954 -1.557 0.023 8.394 8.394 9.68E-16 Bouchet+ 1989
alp1 Cen ESO-N2 1.2949 -1.553 0.026 9.886 9.853 5.06E-16 Bouchet+ 1989
alp TrA SAAO-L 0.5648 -1.338 0.008 3.475 3.463 2.45E-14 Carter 1994
eps Car SAAO-L 0.5648 -1.914 0.016 3.475 3.464 4.16E-14 Carter 1994
------------------------------------------------------------------------------
References:
Bouchet et al., 1989A&AS...80..379B 1989A&AS...80..379B
Carter 1994, priv. comm.
Engels et al., 1981A&AS...45....5E 1981A&AS...45....5E
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Spectral fragments and portions of these actually used in observed spectrum
("used" may include combination with other data where overlaps occur)
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Star Fragment Ref. Total range Start and stop Average resolving
(um) wavelengths (um) power
---------------------------------------------------------------------------
alp1 Cen KAO-NIR 1 3.04- 5.53 3.04- 5.53 160
alp1 Cen KAO-5--9 2 5.07- 9.28 5.07- 9.28 190
alp1 Cen KAO-8--13 3 8.80-13.07 ..... 250
alp1 Cen LRS 4 7.67-22.74 7.67-11.55 30
alp1 Cen KAO-Si:Bi 5 15.00-18.51 ..... 80
alp1 Cen KAO-Si:P 6 19.48-27.20 ..... 180
alp1 Cen LONG 7 1.25-35.00 12.20-35.00 --
alp TrA KAO-NIR 1 2.90- 5.51 2.90- 4.87 160
alp TrA KAO-5-9 2 4.94- 9.36 4.94- 8.97 190
alp TrA KAO-8-13 3 8.80-13.08 ..... 250
alp TrA LRS 4 7.67-22.74 7.67-12.59 30
alp TrA KAO-Si:Bi 5 15.00-18.51 ..... 80
alp TrA KAO-Si:P 6 21.90-27.08 ..... 180
alp TrA LONG 8 1.25-35.00 11.00-35.00 --
eps Car KAO-NIR 1 2.90- 5.50 2.90- 4.87 160
eps Car KAO-5-9 2 4.94- 9.30 4.94- 8.41 190
eps Car KAO-8-13 3 8.80-13.22 ..... 250
eps Car LRS 4 7.67-22.74 7.67-17.98 30
eps Car KAO-Si:Bi 5 15.87-18.53 ..... 80
eps Car KAO-Si:P 6 21.90-27.20 ..... 180
eps Car LONG 9 1.25-35.00 11.00-35.00 --
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References:
1,5,6: HIFOGS data of April 10 & 12, 1993 KAO flights
[alp1 Cen/alp CMa] for table2
[alp TrA/alp1 Cen] and [alp TrA/alp CMa] for table3
[eps Car/[alp1 Cen] and [eps Car/alp CMa] for table4.
2,3: HIFOGS data of April 7, 1993 KAO flight
[alp1 Cen/alp CMa] for table2
[alp TrA/alp1 Cen] and [alp TrA/alp CMa] for table3
[eps Car/[alp1 Cen] and [eps Car/alp CMa] for table4.
The 5-9 um spectral ratio is additionally confirmed by
HIFOGS data of July 22, 1994 KAO flight from Australia.
4: LRS raw data extracted from "LRSVAX" Groningen archive at NASA-Ames
7: Engelke Fn. used for T=5770K and ang. diam. of 8.66 mas (see Lydon et
al. (1993ApJ...413..390L 1993ApJ...413..390L) and Demarque et al. (1986ApJ...300..773D 1986ApJ...300..773D));
we rescaled this to 8.59mas. This Engelke Function was locked to the
photometrically scaled LRS spectrum by splicing and used to replace
the observations from 12.20um. An error of 2.0% in EFn. due to effective
temperature uncertainty was input for this fragment.
8: Engelke Fn. used for T=4140K and ang. diam. of 12.40 mas
(Harper 1992MNRAS.256...37H 1992MNRAS.256...37H); we rescaled this to 9.55 mas. This
Engelke Function was locked to the photometrically scaled LRS spectrum
by splicing and used to replace the observations from 11.00 um. An
error of 2.6% in EFn. due to effective temperature uncertainty was
input for this fragment.
9: Engelke Fn. used for T=4064K (Pasquini & Brocato 1992A&A...266..340P 1992A&A...266..340P),
and we guessed an ang. diam. of 12.50mas; we rescaled this to 12.67mas.
This Engelke Function was locked to the photometrically scaled LRS
spectrum by splicing and used to replace the observations from
11.00um. An error of 2.6% in EFn. due to effective temperature
uncertainty was input for this fragment.
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Information on splices and biases incurred
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Star Process Factor ±Bias (%)
determined
--------------------------------------------------------------
alp1 Cen NIR cf. photometry 0.796 1.31
alp1 Cen LRS blue/red bias -- 0.09
alp1 Cen LRS cf. photometry 0.778 2.07
alp1 Cen 5-9 joint splice to NIR and LRS 0.995 0.16
alp1 Cen Engelke Fn. splice to LRS 0.989 0.38
alp TrA KAO-NIR cf. photometry 1.004 0.74
alp TrA KAO-5--9 splice to NIR 1.050 0.14
alp TrA LRS blue/red bias -- 0.06
alp TrA LRS splice to KAO 1.009 0.40
alp TrA Engelke Fn. splice to LRS 0.593 0.78
eps Car KAO-NIR cf. photometry 1.051 1.49
eps Car KAO-5--9 splice to NIR 1.082 0.57
eps Car LRS blue/red bias -- 0.07
eps Car LRS splice to KAO 0.989 0.73
eps Car Engelke Fn. splice to LRS 0.956 0.58
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Notes:
1. Composite spectra are NOT tabulated at equal intervals of the wavelength,
but rather at the wavelengths of the original model.
2. In most cases "total uncertainty" is the error term most appropriate to
use. It is the standard deviation of the spectral irradiance and includes
the local and global biases. Local and global biases are given as a
percent of the irradiance. The global bias does not contribute error to
flux ratios or color measurements, and may, in those cases, be removed
(in the RSS sense) from the total error.
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Origin: AAS CD-ROM series, Volume 7, 1996 Lee Brotzman [ADS] 03-Oct-1996
References:
Cohen M. et al., Paper I, 1992AJ....104.1650C 1992AJ....104.1650C
Cohen M. et al., Paper II, 1992AJ....104.2030C 1992AJ....104.2030C
Cohen M., Paper III, 1992AJ....104.2045C 1992AJ....104.2045C
Cohen M. et al., Paper IV, 1995AJ....110..275C 1995AJ....110..275C, Cat. J/AJ/110/275
Cohen M. and Davies J.K., Paper V, 1995MNRAS.276..715C 1995MNRAS.276..715C
Cohen M. et al., Paper VII, 1996AJ....112.2274C 1996AJ....112.2274C
(End) [CDS] 30-Jan-1997