J/AJ/164/161 IRS calibration to IRAC: 61 IRS standard stars (Kraemer+, 2022)
Tying Spitzer's IRS Calibration to IRAC; Observations of IRS Standard Stars.
Kraemer K.E., Engelke C.W., Renger B.A., Sloan G.C.
<Astron. J., 164, 161 (2022)>
=2022AJ....164..161K 2022AJ....164..161K
ADC_Keywords: Stars, standard; Stars, K-type; Stars, A-type;
Photometry, infrared; Spectral types
Keywords: Infrared photometry ; Photometric standard stars ; Flux
calibration ; Spectrophotometry ; Spectrophotometric standards
Abstract:
We present 3.6 and 4.5µm photometry for a set of 61 standard stars
observed by Spitzer's Infrared Spectrograph (IRS). The photometry was
obtained with the Infrared Array Camera (IRAC) on Spitzer in order to
help tie the calibration of IRAC and the IRS, which had been anchored
to the calibration of the Multiband Infrared Photometer for Spitzer.
The wavelength range of the IRS data only slightly overlaps with the
IRAC 4.5µm band and not at all with the 3.6µm band. Therefore,
we generated synthetic spectra from spectral templates of stars with
the same spectral types and luminosity classes as our sample stars,
normalized to the IRS data at 6-7µm, and compared those to the
observed photometry. The new IRAC observations of IRS standard stars
demonstrate that the two instruments are calibrated to within 1% of
each other.
Description:
The Spitzer's Infrared Spectrograph (IRS) instrument team observed
several dozen calibration sources over the course of the mission,
primarily K-giants and A-dwarfs, along with bright stars and very red
sources such as galaxies. We selected the set of K-giants and A-dwarfs
described by Sloan+, 2015, J/AJ/149/11. We also included several
fainter K-giants and solar analogs that were added to the calibration
list later in the mission.
Most of the observations were made under Program 12059 in 2015-2016,
with 11 additional stars observed under Program 14221 in 2019.
Thirteen stars were observed twice because the temperature of the
4.5µm array was unstable due to an Infrared Array Camera
(IRAC/Spacecraft) Communications anomaly from 2015 November 27 to
December 14, the time of the first observations (S.Carey 2016,
private communication).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 28 *Observations: A dwarfs and solar analogs
table2.dat 70 48 *Observations: K giants
table3.dat 45 76 Observed Photometry
table4.dat 50 68 Observed to synthetic flux ratios
table6.dat 78 22 HD 165459 calibration photometry
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Note on table1.dat: See text regarding the luminosity class of lambda
Tel. Note that some stars were observed twice and thus the first few
columns are repeated.
Note on table2.dat: Some stars were observed twice and thus the first
few columns are repeated.
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See also:
B/pastel : The PASTEL catalogue (Soubiran+, 2016-)
J/AJ/110/275 : IR spectra of standard stars (Cohen+ 1995)
J/PASP/110/863 : A Stellar Spectral Flux Library; 1150 - 25000 A (Pickles 1998)
J/AJ/132/1445 : Standard calibration stars infrared spectra (Engelke+, 2006)
J/AJ/135/2245 : Absolute spectrum of Sun and Vega for 0.2-30um (Rieke+, 2008)
J/AJ/149/11 : Spectra of candidate standard stars in mid-IR (Sloan+, 2015)
J/AJ/161/177 : Spitzer IRAC photo of 36 JWST calibration stars (Krick+, 2021)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star Name
13- 14 I2 h RAh [2/22] Hour of Right Ascension (J2000)
16- 17 I2 min RAm Minute of Right Ascension (J2000)
19- 23 F5.2 s RAs Second of Right Ascension (J2000)
25 A1 --- DE- [±] Sign of the Declination (J2000)
26- 27 I2 deg DEd Degreee of Declination (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination (J2000)
32- 35 F4.1 arcsec DEs Arcsecond of Declination (J2000)
37- 43 A7 --- SpType Spectral Type
45- 48 I4 yr Obs.Y Observation Date; year
50- 52 A3 "month" Obs.M Observation Date; month
54- 55 I2 d Obs.D Observation Date; day
57- 64 I8 --- AOR [58130432/68759040] AOR Key
66- 70 F5.3 s Tint [0.02/0.4] Integration Time
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star name
13- 20 I8 --- AOR [58130432/68759040] AOR Key
22- 27 F6.3 Jy Flux3.6 [0.13/12.9] Flux density at 3.6 micron
29- 33 F5.3 Jy e_Flux3.6 [0.001/0.2] Uncertainty in Fluxd3.6
35- 39 F5.3 Jy Flux4.5 [0.07/7.13] Flux density at 4.5 micron
41- 45 F5.3 Jy e_Flux4.5 [0.001/0.1] Uncertainty in Flux4.5
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Star name (1)
14- 19 F6.3 Jy Flux3.6o [0.13/12.9] Oberved flux density at 3.6micron
21- 26 F6.3 Jy Flux3.6s [0.12/12.5] Synthetic flux density at
3.6 micron
28- 32 F5.3 --- obs/synth3.6 [0.91/1.06] Flux3.6o/Flux3.6s
34- 38 F5.3 Jy Flux4.5o [0.07/7.13] Observed flux density at 4.5micron
40- 44 F5.3 Jy Flux4.5s [0.07/7.26] Synthetic flux density at
4.5 micron
46- 50 F5.3 --- obs/synth4.5 [0.91/1.04] Flux4.5o/Flux4.5s
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Note (1): Labels "v1" and "v2" in the names refer to photometry from the
first and second measurements for the 13 stars which were observed
twice. Those for HD165459 are for the three integration times, 0.02,
0.1, and 0.4sec
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 8 I8 --- AOR [57825280/60630528] AOR
10- 14 F5.3 mag mag3.6 [6.62/6.64] Brightness at 3.6 micron
16- 20 F5.3 mag e_mag3.6 [0.002] uncertainty in mag3.6
22- 26 F5.3 Jy Flux3.6 [0.62/0.63] Flux density at 3.6 micron
28- 32 F5.3 Jy e_Flux3.6 [0.001] Uncertainty in fluxdens3.6
34- 38 F5.3 mag Dmag3.6 [0.03/0.05] Delta from nominal in mag at
3.6 micron (1)
40- 43 F4.1 % Dpc3.6 [-3.7/-2.9] Delta from nominal in percent
at 3.6 micron
45- 49 F5.3 mag mag4.5 [6.6/6.7] Brightness at 4.5 micron
51- 55 F5.3 mag e_mag4.5 [0.002] Uncertainty in mag4.5
57- 61 F5.3 Jy Flux4.5 [0.4/0.41] Flux density at 4.5 micron
63- 67 F5.3 Jy e_Flux4.5 [0.001] Uncertainty in fluxdens4.5
69- 73 F5.3 mag Dmag4.5 [0.03/0.04] Delta from nominal in mag at
4.5 micron
75- 78 F4.1 % Dpc4.5 [-3.6/-2.7] Delta from nominal in percent at
4.5 micron
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Note (1): Nominal values are 6.593mag and 0.648Jy at 3.6micron;
and 6.575mag and 0.521Jy at 4.5micron
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 24-Nov-2022