J/AJ/161/177 Spitzer IRAC photometry of 36 JWST calibration stars (Krick+, 2021)
Spitzer IRAC photometry of JWST calibration stars.
Krick J.E., Lowrance P., Carey S., Laine S., Grillmair C., Van Dyk S.D.,
Glaccum W.J., Ingalls J.G., Rieke G., Hora J.L., Fazio G.G., Gordon K.D.,
Bohlin R.C.
<Astron. J., 161, 177-177 (2021)>
=2021AJ....161..177K 2021AJ....161..177K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, standard; Photometry, infrared; Spectral types
Keywords: Photometric standard stars; Infrared photometry; Flux calibration
Abstract:
We present infrared photometry of all 36 potential JWST calibrators
for which there is archival Spitzer IRAC data. This photometry can
then be used to inform the stellar models necessary to provide
absolute calibration for all JWST instruments. We describe in detail
the steps necessary to measure IRAC photometry from archive retrieval
to photometric corrections. To validate our photometry, we examine the
distribution of uncertainties from all detections in all four IRAC
channels as well as compare the photometry and its uncertainties to
those from models, ALLWISE, and the literature. Seventy-five percent
of our detections have standard deviations per star of all
observations within each channel of less than 3%. The median standard
deviations are 1.2%, 1.3%, 1.1%, and 1.9% in 3.6-8.0, respectively. We
find less than 8% standard deviations in differences of our photometry
with ALLWISE and excellent agreement with literature values (less than
3% difference), lending credence to our measured fluxes. JWST is
poised to do groundbreaking science, and accurate calibration and
cross-calibration with other missions will be part of the
underpinnings of that science.
Description:
We use publicly available data from the Spitzer Heritage Archive 5
(SHA) available on the NASA/IPAC Infrared Science Archive (IRSA).
The Infrared Array Camera (IRAC) was operational on the Spitzer Space
Telescope from 2003 to 2020 with four broad mid-infrared bands with
response covering 3.15-9.25um. The James Webb Space Telescope (JWST)
is currently scheduled to launch in 2021 and will observe from 0.6 to
28.3um. This paper provides high-precision IRAC fluxes, where
available, at 3.6, 4.5, 5.8, and 8.0um (also denoted ch1-ch4,
respectively).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 36 *JWST calibrators observed with Spitzer IRAC
table3.dat 80 36 Measured IRAC fluxes for JWST calibrators
table5.dat 16 391 IRAC channel 1 full array average instrument
response curve
table6.dat 16 401 IRAC channel 2 full array average instrument
response curve
table7.dat 16 311 IRAC channel 3 full array average instrument
response curve
table8.dat 16 311 IRAC channel 4 full array average instrument
response curve
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Note on table1.dat : This list is drawn from the James Webb Space
Telescope User Documentation on Absolute Flux Calibration,
https://jwst-docs.stsci.edu/data-processing-and-calibration-files
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See also:
J/AJ/132/1445 : Standard calibration stars infrared spectra (Engelke+, 2006)
J/ApJ/790/53 : Photometric data of HD 209458b (Zellem+, 2014)
J/AJ/150/204 : Spectroscopy of standard stars (Joner+, 2015)
http://jwst-docs.stsci.edu/ : JWST User Documentation homepage
http://irsa.ipac.caltech.edu/ : NASA/IPAC Infrared science archive homepage
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Calibrator star name
13- 14 I2 h RAh [0/22] Hour of Right Ascension from SIMBAD (J2000)
16- 17 I2 min RAm Minute of Right Ascension from SIMBAD (J2000)
19- 23 F5.2 s RAs Second of Right Ascension from SIMBAD (J2000)
25- 25 A1 --- DE- [-/+] Sign of the Declination from SIMBAD (J2000)
26- 27 I2 deg DEd Degree of Declination from SIMBAD (J2000)
29- 30 I2 arcmin DEm Arcminute of Declination from SIMBAD (J2000)
32- 35 F4.1 arcsec DEs Arcsecond of Declination from SIMBAD (J2000)
37- 41 A5 --- SpT Spectral Type
43- 47 F5.2 mag Vmag [4.29/16.7] V-band magnitude
49- 53 F5.2 mag Kmag [4.19/15.5] K-band magnitude
55- 58 F4.2 mag AV [0/0.26]? Extinction, V-band
60- 74 A15 --- OName Other or Alternative names
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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 Calibrator star name
13- 19 F7.2 mJy F3.6 [0.14/7387]? mean 3.6um flux
21- 24 F4.2 % e_F3.6 [0.5/5.3]? Standard deviation for F3.6
26- 29 I4 --- NF3.6 [4/7082]? Number of F3.6um measurements
31- 37 F7.2 mJy F4.5 [0.11/3659]? mean 4.5um flux
39- 42 F4.2 % e_F4.5 [0.7/7.6]? Standard deviation for F4.5
44- 47 I4 --- NF4.5 [5/7516]? Number of F4.5um measurements
49- 54 F6.2 mJy F5.8 [0.8/970]? mean 5.8um flux
56- 59 F4.2 % e_F5.8 [0.3/8.8]? Standard deviation for F5.8
61- 63 I3 --- NF5.8 [5/725]? Number of F5.8um measurements
65- 70 F6.2 mJy F8.0 [0.45/627]? mean 8.0um flux
72- 76 F5.2 % e_F8.0 [0.4/14]? Standard deviation for F8.0
78- 80 I3 --- NF8.0 [4/738]? Number of F8.0um measurements
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Byte-by-byte Description of file: table[5678].dat
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Bytes Format Units Label Explanations
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1- 7 F7.5 um Wave Wavelength in microns
9- 16 F8.6 -- Response Instrument response in electrons/photon (1)
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Note (1): See https://irsa.ipac.caltech.edu/data/SPITZER/docs/irac/
calibrationfiles/spectralresponse/ for a description of the IRAC
instrument response curves and the use of these data
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 02-Aug-2021