J/A+A/677/A144 RoboPol sample of optical polarimetric standards (Blinov+, 2023)
The RoboPol sample of optical polarimetric standards.
Blinov D., Maharana S., Bouzelou F., Casadio C., Gjerlow E.,
Jormanainen J., Kiehlmann S., Kypriotakis J.A., Liodakis I., Mandarakas N.,
Markopoulioti L., Panopoulou G.V., Pelgrims V., Pouliasi A.,
Romanopoulos S., Skalidis R., Anche R.M., Angelakis E., Antoniadis J.,
Medhi B.J., Hovatta T., Kus A., Kylafis N., Mahabal A., Myserlis I.,
Paleologou E., Papadakis I., Pavlidou V., Papamastorakis I., Pearson T.J.,
Potter S.B., Ramaprakash A.N., Readhead A.C.S., Reig P., Slowikowska A.,
Tassis K., Zensus J.A.
<Astron. Astrophys., 677, A144 (2023)>
=2023A&A...677A.144B 2023A&A...677A.144B (SIMBAD/NED BibCode)
ADC_Keywords: Stars, standard ; Polarization ; Optical
Keywords: polarization - techniques: polarimetric - standards
Abstract:
Optical polarimeters are typically calibrated using measurements of
stars with known and stable polarization parameters. However, there is
a lack of such stars available across the sky. Many of the currently
available standards are not suitable for medium and large telescopes
due to their high brightness. Moreover, as we find, some of the
polarimetric standards used are in fact variable or have polarization
parameters that differ from their cataloged values.
Our goal is to establish a sample of stable standards suitable for
calibrating linear optical polarimeters with an accuracy down to
10-3 in fractional polarization.
For 4yr, we have been running a monitoring campaign of a sample of
standard candidates comprised of 107 stars distributed across the
northern sky. We analyzed the variability of the linear polarization
of these stars, taking into account the non-Gaussian nature of
fractional polarization measurements. For a subsample of nine stars,
we also performed multiband polarization measurements.
We created a new catalog of 65 stars (see table 2) that are stable,
have small uncertainties of measured polarimetric parameters, and can
be used as calibrators of polarimeters at medium and large telescopes.
Description:
We obtained 1044 polarization measurements of 107 stars using two
different polarimeters. Most observations were performed in the
Cousins R-band and the SDSS r'-band with the RoboPol polarimeter
along a 4-yr time interval. After applying a variability analysis to
these monitoring data, we selected 65 stars that have five or more
measurements and do not demonstrate significant variability in linear
polarization in the red bands. These stars are listed in Table 2, and
they can be used as optical polarimetric standards for calibration of
instrumental polarization. For 24 stars, we did not have enough data
to conclude whether they are variable or stable, while the remaining
18 stars were found to exhibit significant variability in
polarization.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 94 65 Average polarization parameters of stable
(2σ S.L.) stars in the established
standards sample
tablea1.dat 110 107 Standards candidates sample information
tablea3.dat 89 53 Multiband single epoch measurements
with ALFOSC/NOT for 9 stars
tablea4.dat 86 107 Average polarization parameters of the
sample stars
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ID Star identifier
17- 18 I2 h RAh Right ascension (J2000)
20- 21 I2 min RAm Right ascension (J2000)
23- 27 F5.2 s RAs Right ascension (J2000)
29 A1 --- DE- Declination sign (J2000)
30- 31 I2 deg DEd Declination (J2000)
33- 34 I2 arcmin DEm Declination (J2000)
36- 39 F4.1 arcsec DEs Declination (J2000)
41- 49 F9.5 deg RAdeg Right ascension (J2000)
51- 58 F8.5 deg DEdeg Declination (J2000)
60- 66 F7.4 --- q Weighted average Q/I relative Stokes parameter
corrected for the instrumental polarization
and EVPA zero-point
68- 73 F6.4 --- e_q Error on weighted average Q/I relative Stokes
parameter
75- 81 F7.4 --- u Weighted average U/I relative Stokes parameter
corrected for the instrumental polarization
and EVPA zero-point
83- 88 F6.4 --- e_u Error on eighted average U/I relative Stokes
parameter
90- 94 F5.2 mag Gmag Gaia DR3 G magnitude
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ID Star identifier
18- 32 A15 --- OName Alternative identifier
34- 35 I2 h RAh Right ascension (J2000)
37- 38 I2 min RAm Right ascension (J2000)
40- 44 F5.2 s RAs Right ascension (J2000)
46 A1 --- DE- Declination sign (J2000)
47- 48 I2 deg DEd Declination (J2000)
50- 51 I2 arcmin DEm Declination (J2000)
53- 57 F5.2 arcsec DEs Declination (J2000)
59- 77 I19 --- GaiaEDR3 Gaia EDR3 id
79- 83 F5.2 mag rpmag ?=- Synthetic SDSS r' magnitude from
Gaia Collaboration et al. (2022)
85- 89 F5.2 mag Gmag Gaia EDR3 G-band magnitude
91-103 A13 --- SpType Spectral type
105 A1 --- Sample [BLHZ] Sample
107 I1 --- Nrband Number of observations in the SDSS-r band
109-110 I2 --- NRband Number of observations in the Cousins-R band
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 18 A18 --- ID Star identifier
20 A1 --- Band [UBVRgri] Observed band
22- 28 F7.5 --- q Relative Stokes parameter Q/I
30- 36 F7.5 --- e_q Relative Stokes parameter Q/I error
38- 46 F9.5 --- u Relative Stokes parameter U/I
48- 55 F8.5 --- e_u Relative Stokes parameter U/I error
57- 64 F8.5 % PD Fractional polarization
66- 72 F7.5 % e_PD Fractional polarization error
74- 81 F8.5 deg EVPA Electric vector position angle
83- 89 F7.5 deg e_EVPA Electric vector position angle error
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 15 A15 --- ID Star identifier
17- 18 I2 --- Nmeas Number of measurements
20- 24 F5.3 % PD Mean of the fractional polarization
26- 30 F5.3 % e_PD Mean of the fractional polarization error
32- 36 F5.1 deg EVPA Mean of the electric vector position angle
38- 41 F4.1 deg e_EVPA Mean of the electric vector position angle error
43- 50 F8.5 --- q Relative Stokes parameter Q/I
52- 58 F7.5 --- e_q Relative Stokes parameter Q/I error
60- 67 F8.5 --- u Relative Stokes parameter U/I
69- 75 F7.5 --- e_u Relative Stokes parameter U/I error
77- 78 A2 --- VarFlag Variability flag for 2σ S.L. (1)
80- 86 F7.5 --- pvalue ?=- p value
--------------------------------------------------------------------------------
Note (1): Variability flag as follows:
NV = stands for non-variable
V = variable
UN = uncertain
--------------------------------------------------------------------------------
History:
Copied at
https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/IV9TXX
(End) Patricia Vannier [CDS] 23-Nov-2023