J/ApJ/872/199 Candidate spectrophotometric standard DA WDs (Calamida+, 2019)
Photometry and spectroscopy of faint candidate spectrophotometric standard DA
white dwarfs.
Calamida A., Matheson T., Saha A., Olszewski E., Narayan G., Claver J.,
Shanahan C., Holberg J., Axelrod T., Bohlin R., Stubbs C.W., Deustua S.,
Hubeny I., Mackenty J., Points S., Rest A., Sabbi E.
<Astrophys. J., 872, 199 (2019)>
=2019ApJ...872..199C 2019ApJ...872..199C
ADC_Keywords: Stars, white dwarf; Photometry, HST; Spectra, optical;
Spectral types; Stars, distances; Photometry, ugriz; Ultraviolet
Keywords: methods: observational ; standards ; stars: fundamental parameters ;
techniques: photometric ; techniques: spectroscopic ; white dwarfs
Abstract:
We present precise photometry and spectroscopy for 23 candidate
spectrophotometric standard white dwarfs. The selected stars are
distributed in the Northern hemisphere and around the celestial
equator, and are all fainter than r∼16.5mag. This network of stars,
when established as standards and together with the three Hubble Space
Telescope primary CALSPEC white dwarfs, will provide a set of
spectrophotometric standards to directly calibrate data products to
better than 1%. In future deep photometric surveys and facilities,
these new faint standard white dwarfs will have enough signal-to-noise
ratio to be measured accurately while still avoiding saturation. They
will also fall within the dynamic range of large telescopes and their
instruments for the foreseeable future. This paper discusses the
provenance of the observational data for our candidate standard stars.
Description:
Photometric data discussed in this investigation were collected with
the WFC3 UVIS and IR cameras on board the HST during Cycle 20 and 22
(proposals GO-12967 and GO-13711, PI: Saha). Observations were taken
in five filters in Cycle 20, namely F336W, F475W, F625W, F775W, F160W.
In Cycle 22 the near-UV filter F275W was added.
Nine of the candidate DA white dwarfs (DAWDs) are distributed along
the celestial equator and were observed in both Cycle 20 and Cycle 22,
while the other 14 DAWDs and the three HST primary CALSPEC standards
were observed only in Cycle 22. Table 4 lists the log of the
observations for Cycle 20 and 22.
Observations span a time interval of about 1yr for Cycle 20 (2012
November until 2013 September) and about 1.3yr for Cycle 22 (2014
September until 2016 January).
The final magnitudes for the 23 candidate spectrophotometric standard
DAWDs and the HST primary CALSPEC WDs are listed in Table 9.
We used two different facilities to obtain spectra of our standard
star candidates.
As part of the HST photometry proposal, we were awarded Gemini/GMOS
time. This amounted to 43hr from Cycle 20 (split over Gemini semesters
2013A and 2013B) and 28.1hr from Cycle 22 (split over Gemini semesters
2015A and 2015B). The final spectra are continuous from 3500 to 6360Å.
Alternate spectra were obtained in 2015 at the Multiple Mirror
Telescope (MMT) with the Blue Channel spectrograph (wavelength
coverage from 3400 to 8400Å).
Details of the observations with both facilities are presented in
Table 5.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 138 26 List of properties of the HST primary CALSPEC
standards and the 23 candidate spectrophotometric
standard DAWDs
table2.dat 105 26 Pan-STARRS1 photometry for the candidate
spectrophotometric standard DA white dwarfs
table3.dat 92 26 GAIA DR2 photometry for the candidate
spectrophotometric standard DA white dwarfs
table4.dat 114 742 Log of the observations collected with the Wide
Field Camera 3 (WFC3) on board the Hubble Space
Telescope (HST) during cycles 20 and 22
table5.dat 108 45 Log of the spectroscopic observations
table9.dat 115 81 Photometry in the WFC3 UVIS and IR filters for the
3 HST primary CALSPEC standards and the 23
candidate standard DAWDs in the AB photometric
system
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
B/wd : Spectroscopically identified white dwarfs (McCook+, 2014)
III/116 : Spectrophotometric Standards (Massey+ 1988)
III/235 : Spectroscopically Identified White Dwarfs (McCook+, 2008)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/AJ/132/1221 : VJHK and SDSS photometry of DA white dwarfs (Holberg+, 2006)
J/AJ/135/1239 : Spectral distances to DA white dwarfs (Holberg+, 2008)
J/AJ/135/1598 : Optical spectroscopy of type Ia supernovae (Matheson+, 2008)
J/A+A/505/441 : UVES/VLT spectra of white dwarfs (Koester+, 2009)
J/ApJ/743/138 : Spectroscopic survey of bright white dwarfs (Gianninas+, 2011)
J/MNRAS/417/1210 : DA-white dwarfs from SDSS and UKIDSS (Girven+, 2011)
J/ApJS/204/5 : SDSS DR7 white dwarf catalog (Kleinman+, 2013)
J/A+A/560/A106 : NLTE spectral analysis of white dwarf G191-B2B (Rauch+, 2013)
J/A+A/568/A22 : Joint analysis of the SDSS-II and SNLS SNe Ia (Betoule+, 2014)
J/ApJS/231/1 : Hot DA WDs grid of synthetic spectra (Levenhagen+, 2017)
J/MNRAS/469/2102 : White dwarf population from the SDSS DR12 (Anguiano+, 2017)
J/AJ/155/162 : Comparison of IUE and CALSPEC SEDs for 6 WDs (Bohlin+, 2018)
J/AJ/157/229 : CALSPEC: WFC3 infrared grism spectrophotometry (Bohlin+, 2019)
http://www.stsci.edu/hst/instrumentation/
reference-data-for-calibration-and-tools/astronomical-catalogs/calspec :
CALSPEC HST data
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- Name Star name
28- 50 A23 --- AName Alternative name
52- 53 I2 h RAh Hour of right ascension (J2000) (1)
55- 56 I2 min RAm Minute of right ascension (J2000)
58- 63 F6.3 s RAs Second of right ascension (J2000)
65 A1 --- DE- Sign of declination (J2000) (1)
66- 67 I2 deg DEd Degree of declination (J2000) (1)
69- 70 I2 arcmin DEm Arcminute of declination (J2000)
72- 77 F6.3 arcsec DEs Arcsecond of declination (J2000)
79- 85 F7.3 mas/yr pmRA [-38.5/77] Proper motion in RA (1)
87- 91 F5.3 mas/yr e_pmRA [0.1/1.5]? pmRA uncertainty
93-100 F8.3 mas/yr pmDE [-203/14] Proper motion in DEC (1)
102-106 F5.3 mas/yr e_pmDE [0.1/1]? pmDE uncertainty
108-113 A6 --- SpT White dwarf spectral type (1)
115-120 F6.1 pc Dist [51.9/1833]? Distance (1)
122-127 F6.1 pc e_Dist [0.2/1248]? Dist uncertainty
129-133 I5 K Teff [9261/75000]? Effective temperature (2)
135-138 F4.2 [cm/s2] logg [6.8/8.4]? Log of surface gravity (2)
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Note (1): Coordinates, proper motions, spectral type, and distance measurements
are from GAIA DR2.
Note (2): Effective temperature and surface gravity measurements are from
the SDSS or the Villanova catalogs.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- Name Star name
28- 29 I2 h RAh Hour of right ascension (J2000)
31- 32 I2 min RAm Minute of right ascension (J2000)
34- 39 F6.3 s RAs Second of right ascension (J2000)
41 A1 --- DE- Sign of declination (J2000)
42- 43 I2 deg DEd Degree of declination (J2000)
45- 46 I2 arcmin DEm Arcminute of declination (J2000)
48- 53 F6.3 arcsec DEs Arcsecond of declination (J2000)
55- 60 F6.3 mag gmag [12.8/19.9]? PS1 g-band (AB) magnitude
62- 66 F5.3 mag e_gmag [0.002/0.04]? gmag uncertainty
68- 73 F6.3 mag rmag [13.2/20.4]? PS1 r-band (AB) magnitude
75- 79 F5.3 mag e_rmag [0.001/0.06]? rmag uncertainty
81- 86 F6.3 mag imag [13.6/20.7]? PS1 i-band (AB) magnitude
88- 92 F5.3 mag e_imag [0.002/0.1]? imag uncertainty
94- 99 F6.3 mag zmag [13.9/20.9]? PS1 z-band (AB) magnitude
101-105 F5.3 mag e_zmag [0.002/0.2]? zmag uncertainty
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- Name Star name
28- 29 I2 h RAh Hour of right ascension (J2000)
31- 32 I2 min RAm Minute of right ascension (J2000)
34- 39 F6.3 s RAs Second of right ascension (J2000)
41 A1 --- DE- Sign of declination (J2000)
42- 43 I2 deg DEd Degree of declination (J2000)
45- 46 I2 arcmin DEm Arcminute of declination (J2000)
48- 53 F6.3 arcsec DEs Arcsecond of declination (J2000)
55- 60 F6.3 mag Gmag [11.7/20.1] Gaia G-band magnitude
62- 66 F5.3 mag e_Gmag [0/0.01] Gmag uncertainty
68- 73 F6.3 mag RPmag [12/20.3] Gaia Rp-band magnitude
75- 79 F5.3 mag e_RPmag [0.001/0.2] RPmag uncertainty
81- 86 F6.3 mag BPmag [11.4/19.9] Gaia Rp-band magnitude
88- 92 F5.3 mag e_BPmag [0.005/0.2] BPmag uncertainty
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Cycle [20/22] HST Cycle number
4- 29 A26 --- Name Stellar identifier
31- 35 I5 --- PID [12967/13711] Program identifier (1)
37- 45 A9 --- Image Image name
47- 48 I2 h RAh Hour of Right Ascension (J2000)
50- 51 I2 min RAm Minute of Right Ascension (J2000)
53- 56 F4.1 s RAs Second of Right Ascension (J2000)
58 A1 --- DE- Sign of the Declination (J2000)
59- 60 I2 deg DEd Degree of Declination (J2000)
62- 63 I2 arcmin DEm Arcminute of Declination (J2000)
65- 68 F4.1 arcsec DEs Arcsecond of Declination (J2000)
70- 74 A5 --- Filter Filter
76- 78 I3 s Texp [15/680] Exposure time
80- 89 A10 "Y/M/D" obs.date Observation date
91- 98 A8 "h:m:s" obs.time Observation time
100-114 A15 --- Aper WFC3 aperture
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Note (1): Proposal IDs 12967 and 13711, PI: A. Saha.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 26 A26 --- Name Star name
28- 40 A13 "Y/M/D" Date UT date of observation
42 A1 --- f_Date [e] Flag on Date (1)
44- 51 A8 --- Tel Telescope name (2)
53- 56 I4 0.1nm laml [3400/3520] Lower range of wavelength in Å
57 A1 --- --- [-]
58- 61 I4 0.1nm lamu [6360/8400] Upper range of wavelength in Å
63- 64 I2 0.1nm Res [7/12] Resolution in Å (3)
66- 71 F6.1 deg PA [-153/1000] Position angle (4)
73- 75 F3.1 --- Airmass [1/2.1] Airmass
77- 93 A17 --- Std Flux standard (5)
95- 98 F4.2 arcsec Slit [1/1.5] Slit
100-108 A9 s Exp Exposure time
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Note (1): Flag as follows:
e = Spectra from Gemini were obtained in queue mode and thus could be
observed over multiple nights. The UT date reported for these stars
represents an average of the actual dates.
Note that observations for SDSSJ081508 were separated by 10 months.
Note (2): Telescope used to obtain given spectrum as follows:
GEMINI-N = GMOS at the northern site for the Gemini Observatory;
GEMINI-S = GMOS at the southern site for the Gemini Observatory;
MMTO = Blue Channel spectrograph at the MMT Observatory.
Note (3): Resolution of the spectrum as determined from the full-width at half
maximum of sky lines present in the two-dimensional spectrum. This is,
in general, an upper limit as the resolution for the stellar spectrum
is determined by the seeing and the slit width. In many cases,
especially with the wider slits used with GMOS, the resolution of the
spectrum is better than this reported value.
Note (4): The position angle of the observations. Spectra from the MMT were
typically observed at the parallactic angle, while the Gemini data
were not.
Note (5): Flux standards used to calibrate the data:
Feige34, BD+284211, Feige110 = Stone 1977ApJ...218..767S 1977ApJ...218..767S ;
Massey+ 1988, III/116 ;
Massey & Gronwall 1990ApJ...358..344M 1990ApJ...358..344M
GD71 = Bohlin+ 1995AJ....110.1316B 1995AJ....110.1316B
G191B2B = Oke 1974ApJS...27...21O 1974ApJS...27...21O & Massey+ 1988, III/116
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Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Version Photometry software package
12- 37 A26 --- Name Stellar identifier (1)
39- 44 F6.3 mag F275W [10.4/20.4]? HST/WFC3 F275W band AB magnitude
46- 50 F5.3 mag e_F275W [0.001/0.04]? Uncertainty in F275W
52- 57 F6.3 mag F336W [-0.04/20.1] HST/WFC3 F336W band AB magnitude
59- 63 F5.3 mag e_F336W [0.001/0.04] Uncertainty in F336W
65- 70 F6.3 mag F475W [-0.009/19.9] HST/WFC3 F475W band AB magnitude
72- 76 F5.3 mag e_F475W [0.001/0.007] Uncertainty in F475W
78- 83 F6.3 mag F625W [-0.02/20.2] HST/WFC3 F625W band AB magnitude
85- 89 F5.3 mag e_F625W [0.001/0.02] Uncertainty in F625W
91- 96 F6.3 mag F775W [0.009/20.6] HST/WFC3 F775W band AB magnitude
98-102 F5.3 mag e_F775W [0.001/0.01] Uncertainty in F775W
104-109 F6.3 mag F160W [-0.02/22] HST/WFC3 F160W band AB magnitude
111-115 F5.3 mag e_F160W [0.001/0.03] Uncertainty in F160W
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Note (1): Offsets is the applied magnitude offsets between HST Cycle 20
and Cycle 22, derived from Fig. 9.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Aug-2020