J/AJ/157/107 GALEX spectral database correction with IUE SEDs (Bohlin+, 2019)
A correction for GALEX spectroscopic UV flux distributions from comparisons
with CALSPEC and IUE.
Bohlin R.C., Bianchi L.
<Astron. J., 157, 107-107 (2019)>
=2019AJ....157..107B 2019AJ....157..107B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, white dwarf ; Spectra, ultraviolet
Keywords: stars: atmospheres - stars: fundamental parameters -
techniques: spectroscopic - ultraviolet: stars
Abstract:
The CALSPEC database of absolute spectral energy distributions (SEDs)
from the Hubble Space Telescope is based on pure hydrogen model atmosphere
calculations for three unreddened white dwarf stars and represents the
current UV flux calibration standard with a precision approaching 1%
for well observed stars. Following our previous work to correct
International Ultraviolet Explorer (IUE) fluxes, this paper provides
an average correction for the Galaxy Evolution Explorer (GALEX) spectral
database that places GALEX fluxes on the current CALSPEC scale. Our
correction is derived by comparing GALEX spectroscopic flux distributions
with CALSPEC and corrected IUE SEDs. This recalibration is relevant
for any project based on GALEX archival spectroscopic data, e.g., UV
or multi-wavelength analyses, correlating GALEX spectra with other existing
or future databases, and planning of new observations. The recalibration
will be applied to our planned catalog of corrected GALEX SEDs.
Description:
The GALEX spacecraft was launched on 2003 April 28 and had 10 yr of
success in obtaining broadband UV photometry at effective wavelengths
of 1539 (FUV) and 2316 Å (NUV), in addition to spectrophotometry with
a CaF2 grism that is sampled at 3.5 Å intervals from 1300 to 3000 Å.
The spectral resolution is 8 Å in the FUV second order and 20 Å in
the NUV first order with a gap near 1820 Å between the FUV and NUV
ranges (Morrissey et al. 2007ApJS..173..682M 2007ApJS..173..682M).
Both the CALSPEC and IUE (http://archive.stsci.edu/iue/) data sets are
compared with GALEX (http://galex.stsci.edu/GR6/) spectral flux
distributions in preparation for a recalibration and publication of
the relatively unexploited 125564 GALEX prism spectra, which comprise
a homogeneous set fainter and tenfold larger than the IUE sample
(Bianchi et al. 2018Ap&SS.363...56B 2018Ap&SS.363...56B; Bianchi et al. 2019, in preparation).
Our new database will facilitate future use of GALEX spectra for a
variety of purposes.
Each GALEX match is verified during both sets of comparisons, i.e.,
with the few overlapping CALSPEC stars and with several IUE SEDs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 88 18 Spectra used for the IUE/GALEX comparison
table3.dat 16 35 Multiplicative correction for GALEX fluxes
table4.dat 81 17682 IUE SEDs for 18 stars
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See also:
J/ApJS/119/207 : IUE echelle spectra of hot white dwarfs (Holberg+, 1998)
J/ApJS/147/145 : IUE low-dispersion spectra of white dwarfs (Holberg+, 2003)
J/A+A/596/A49 : Synthetic GALEX photometry for IUE sources
(Beitia-Antero+, 2016)
J/AJ/155/162 : Comparison of IUE and CALSPEC SEDs for 6 WDs (Bohlin+, 2018)
http://archive.stsci.edu/prepds/galex-fluxcal/ : Online version of this paper
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Star Stellar identifier
12- 13 I2 h RAh Hour of Right Ascension (J2000)
15- 16 I2 min RAm Minute of Right Ascension (J2000)
18- 21 F4.1 s RAs Second of Right Ascension (J2000)
23 A1 --- DE- Sign of the Declination (J2000)
24- 25 I2 deg DEd Degree of Declination (J2000)
27- 28 I2 arcmin DEm Arcminute of Declination (J2000)
30- 31 I2 arcsec DEs Arcsecond of Declination (J2000)
33- 37 F5.2 10-15W/m2/nm SWP [0.17/13.4] IUE/short-wavelength prime
(SWP) stellar flux in the 1539Å region
(FUV) (in 10-13erg/s/cm2/Å)
39- 40 I2 --- o_SWP [1/17] Number of IUE/SWP observations
42- 45 F4.2 10-15W/m2/nm LW [0.12/3.3] IUE/long wavelength (LW) stellar
flux in the 2316Å region (NUV)
(in 10-13erg/s/cm2/Å)
47- 48 I2 --- o_LW [1/13] Number of IUE/LW observations
50- 88 A39 --- GALEX GALEX spectral data idenfifier(s)
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 0.1nm Wave [1300/3000] Wavelength (Å)
6- 10 F5.3 --- Cor [0.926/1.098] Correction
12- 16 F5.3 --- e_Cor [0.006/0.032]? Uncertainty in Cor
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Star Stellar identifier (1)
12- 18 F7.2 0.1nm Wave [1152.26/3346.83] Wavelength (Å)
20- 29 E10.3 ct/s CRate [-0.006778/2.379] Net count rate
31- 40 E10.3 cW/m2/nm Flux [-1.378e-13/3.582e-12] Flux
(in erg/s/cm2/Å)
42- 51 E10.3 ct/s Bkg [-0.06255/0.5961] Background count rate
53- 61 E9.3 cW/m2/nm e_Flux [0/2.508e-13] The 1σ uncertainty in Flux
(in erg/s/cm2/Å)
63- 66 F4.1 --- Nobs [1/17] Number of observations
68- 75 F8.1 s Exp [221.1/101399] Total exposure time
77- 81 F5.2 % rms [0/99] rms scatter
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Note (1): For each source the first line gives the identifiers used to construct
the short-wavelength prime (SWP) portion of the spectrum. The second line
gives the identifiers used to construct the long wavelength (LW) portion of
the spectrum. The LWP is generally used but for a few sources a third line
gives the identifiers of the LWR identifiers used. In all cases the large
aperture identifiers are given first and followed by the small aperture
identifiers, if any:
BPM16274 = Lswp21856 Lswp21857 Eswp21894 Eswp22961 Lswp22962 Lswp22988
Lswp22989;
BPM16274 = Llwp02450 Llwp02477 Llwp02503 Llwp03313 Llwp03314 Elwp03340;
SK194 = Lswp42507 Lswp42508;
SK194 = Llwp21282 Llwp21283;
SK196 = Eswp50741 Lswp51722;
SK196 = Llwp28821 Llwp28822;
GD50 = Lswp11304 Lswp28886 Mswp29858 Lswp29859 Lswp31974 Sswp13381
Sswp31975 Sswp28886;
GD50 = Llwp09689 Mlwp09690 Llwp10125;
HZ4 = Lswp21836 Lswp24733 Lswp24747;
HZ4 = Llwp02458 Llwp02476 Llwp02489 Llwp06520;
LB227 = Lswp21837 Lswp21855 Eswp21872 Eswp24752 Lswp30007;
LB227 = Llwp05058 Elwp06521 Llwp06535 Elwp06536 Llwp09834 Llwp09835
Llwp09847;
HZ2 = Eswp24736 Lswp24737 Lswp24738 Lswp24739 Lswp30013;
HZ2 = Llwp05062 Llwp05063 Llwp05064 Llwp05076 Llwp09848;
WD0416-550 = Lswp33106;
WD0416-550 = Llwp12872;
HG7-233 = Lswp33108;
HG7-233 = Llwp12875;
GD108 = Lswp23160 Lswp30803 Mswp30804;
GD108 = Llwp03485 Elwp08369 Mlwp10606;
HZ21 = Lswp01378 Lswp07457 Mswp07525 Mswp11277 Lswp19142 Lswp19143
Eswp21844 Lswp21850 Lswp22712 Lswp22713 Lswp22940 Lswp22941
Lswp22942 Lswp22974 Eswp22975 Lswp22987 Lswp31286;
HZ21 = Llwp02467 Llwp02471 Llwp03143 Llwp03144 Elwp03302 Llwp03303
Llwp03325 Llwp03326 Llwp03339;
HZ21 = Llwr01330 Llwr06461 Mlwr06515 Llwr15154;
FEIGE59 = Lswp28203 Lswp28204;
FEIGE59 = Llwp08074 Llwp08075;
GD153 = Eswp07448 Lswp11295 Lswp23219 Lswp40920 Lswp40921 Eswp40931
Eswp40932 Lswp41421 Eswp41422 Eswp41423 Sswp23219;
GD153 = Llwp02736 Llwp19816 Llwp19817 Llwp19834 Llwp19835 Elwp20184
Elwp20185 Llwp20186;
GD153 = Llwr06453 Llwr09905;
Q1302-102 = Lswp03569 Eswp17228 Eswp17229 Lswp17230 Lswp28749 Lswp28750
Lswp28751;
Q1302-102 = Llwp08732 Elwp08734 Llwp08735;
Q1302-102 = Llwr03143;
LDS749b = Lswp14127 Eswp14656 Eswp32001 Lswp36148;
LDS749b = Llwp11804 Llwp11805;
LDS749b = Llwr10753 Llwr11248;
StHA190 = Lswp39690 Eswp47698 Sswp47698;
StHA190 = Llwp18852;
G93-48 = Lswp28469 Lswp28470 Mswp28471;
G93-48 = Llwp08367 Llwp08368 Mlwp09688;
L791-40 = Lswp17278 Lswp15491;
L791-40 = Llwr12151 Llwr11956.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 05-Jun-2019