J/AJ/169/226 Zorro/Gemini-South astrometric data of binary stars (Mendez+, 2025)
Southern binaries with the Zorro Speckle Camera @ Gemini South.
Mendez R.A., Tokovinin A., Costa E., Dirk M.
<Astron. J., 169, 226 (2025)>
=2025AJ....169..226M 2025AJ....169..226M
ADC_Keywords: Stars, double and multiple; Binaries, orbits; Interferometry;
Photometry, infrared; Optical; Positional data
Keywords: Visual binary stars ; Speckle interferometry ; Multiple stars ;
Companion stars ; Solar neighborhood ; Halo stars ;
Spectroscopic binary stars ; Low mass stars ;
High contrast techniques ; Stellar masses ;
Fundamental parameters of stars ; Stellar photometry
Abstract:
We present measurements in the context of a survey of southern
hemisphere binary and multiple stellar systems observed with the Zorro
Speckle dual diffraction-limited optical imaging camera on the 8.1m
Gemini South telescope carried out between 2019 and 2023. The overall
motivation of our survey and some initial results of these
observations are outlined to demonstrate the capabilities and
limitations of Zorro. We report on the astrometric characterization of
the instrument in terms of the precision and accuracy of our
measurements and provide details of our custom-made data reduction
pipeline. For targets with separations smaller than 0.4", an overall
precision of 1mas in the radial and tangential directions is obtained,
while the uncertainty in position angle is 0.2°. Relative
astrometry and contrast brightness in the two Zorro filters at 562 and
832nm are reported for 70 pairs on 64 distinct systems (six are
triples). Eleven new binaries are found, mostly of small separations
(down to 15mas) and large brightness contrast (up to Δm=6 in the
red channel). Our results indicate that the Zorro instrument, when
properly calibrated, delivers excellent-quality data for visual binary
studies of tight and/or faint companions.
Description:
Zorro is a fast, low-noise, dual-channel and dual-plate-scale imager,
which in speckle mode provides simultaneous two-color (blue and red)
diffraction-limited optical imaging (FWHM 20mas at 650nm) of objects
as faint as V∼17mag over a field of view (FOV) of 6.7". It is
mounted on the 8.1m optical/infrared Gemini South telescope in Chile.
In speckle mode, four narrowband filters are available, two of which
can be used simultaneously in the blue and red "arms" of the
instrument. For our survey we selected the Edmund Optics filter #562
on the blue side (562nm central wavelength, 54nm wide) and filter #832
(832nm central wavelength, 40nm wide) on the red side.
Between 2019 and 2023, we have been awarded more than 74hr of mostly
highest-priority (Band 1) time with Zorro@GeminiSouth through highly
rated proposals by the time allocation committee, but, due to the
COVID pandemic, a fraction of this time (∼30%) could not be
executed. We did 11 observing runs for a total of 64.2hr.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
targets.dat 17 210 List of targets (added by CDS)
table2.dat 194 384 Resolved systems astrometric data
table4.dat 119 589 Unresolved targets data
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See also:
B/wds : The Washington Visual Double Star Catalog (Mason+ 2001-2020)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/311 : Hipparcos, the New Reduction (van Leeuwen, 2007)
V/117A : Geneva-Copenhagen Survey of Solar neighbourhood (Holmberg+, 2007)
J/A+AS/124/75 : Multiple star catalogue (MSC) (Tokovinin 1997-1999)
J/AJ/124/1144 : Orbits of 171 single-lined spect. binaries (Latham, 2002)
J/AJ/139/743 : Speckle interferometry in 2008-09 (Tokovinin+, 2010)
J/AJ/140/1623 : PHASES diff. astrometry data archive. II. (Muterspaugh+, 2010)
J/other/A+ARV/18.67 : Accurate masses and radii of normal stars (Torres+, 2010)
J/ApJ/746/101 : Diameters and temperatures of AFG stars (Boyajian+, 2012)
J/ApJ/757/112 : Stellar diameters. II. K and M-stars (Boyajian+, 2012)
J/A+A/546/A69 : Orbits of visual binaries & dynamical masses (Malkov+, 2012)
J/MNRAS/437/2303 : Radial velocity curves of alpha Lib A (Fuhrmann+, 2014)
J/AJ/149/8 : RV of southern visual multiple stars (Tokovinin+, 2015)
J/AJ/150/50 : Speckle interferometry at SOAR in 2014 (Tokovinin+, 2015)
J/AJ/152/141 : Solar neighborhood. XXXVII. RVs for M dwarfs (Benedict+, 2016)
J/AJ/153/212 : Obs. of binary stars at the WIYN telescope (Horch+, 2017)
J/ApJ/838/54 : Accurate astrometry & RVs of 4 multiple syst. (Tokovinin+, 2017)
J/ApJS/235/6 : Updated Multiple Star Catalog (MSC): Dec 2023 (Tokovinin, 2018)
J/AJ/157/56 : DSSI obs. of binary & trinary star systems (Horch+, 2019)
J/ApJ/871/63 : How to constrain your M dwarf. II. Nearby binaries (Mann+, 2019)
J/AJ/158/48 : Speckle interferometry at SOAR in 2018 (Tokovinin+, 2019)
J/AJ/158/167 : Speckle obs. & orbits of multiple stars (Tokovinin+, 2019)
J/AJ/158/222 : Orbits of subsystems in multiple stars. VI. (Tokovinin, 2019)
J/AJ/159/233 : Observations of binary stars with the DSSI. IX. (Horch+, 2020)
J/AJ/160/7 : 2019 SOAR speckle interfero. of binary stars (Tokovinin+, 2020)
J/AJ/160/251 : RVs & orbital data, 5 triple stars (Tokovinin+, 2020)
J/AJ/161/144 : Inner & outer orbits in 13 multiple stars syst (Tokovinin, 2021)
J/AJ/162/41 : Speckle interferometry at SOAR in 2020 (Tokovinin+, 2021)
J/AJ/163/161 : Spectro. of Subsyst. in Multiple Stars. VIII. (Tokovinin, 2022)
J/AJ/164/58 : Speckle Interferometry at SOAR in 2021 (Tokovinin+, 2022)
J/MNRAS/517/2925 : ORB6 binaries in Gaia EDR3 (Chulkov+, 2022)
J/AJ/165/220 : Spectro. orbits of subsyst in multiple stars X (Tokovinin, 2023)
http://www.astro.gsu.edu/wds/orb6.html : Sixth Catalog of Orbits of Visual
Binary Stars (Hartkopf+, 2001)
Byte-by-byte Description of file:targets.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- WDS Washington Double Star Catalogue (B/wds)
designation
12- 17 I6 --- HIP [3640/115038]? Hipparcos number (I/239)
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Byte-by-byte Description of file:table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- WDS Washington Double Star Catalogue (B/wds)
designation
12- 24 A13 --- Disc WDS Discoverer designation and system
components (1)
26- 31 I6 --- HIP [4754/114962]? Hipparcos number (I/239)
33- 39 F7.4 yr Epoch [19.37/23.51] Epoch in fraction of Julian
year - 2000.0yr
41- 43 I3 --- Filt [562/832] Filter name
45 I1 --- Ncub [1/7] Number of cubes (of 1000 images each)
averaged to produce our measurement
47- 52 F6.2 deg PA Position Angle (θ)
54- 57 F4.1 mas errTan [0/10.3]? Tangential formal error
(Sep x σPA)
59- 64 F6.4 arcsec Sep [5e-3/1.63] Angular separation in the sky
(ρ)
66- 69 F4.1 mas e_Sep [0/10.5]? Uncertainty in Sep
71- 73 F3.1 mag dmag [0/7.5] Magnitude contrast in Filt
75- 76 A2 --- Code Data quality code (2)
78- 82 F5.1 deg (O-C)PA [-45/252]? Residual in PA between
measurement and predicted orbit
(Δθ)
84- 89 F6.3 arcsec (O-C)Sep [-0.37/0.25]? Residual in Sep between
measurement and predicted orbit
(Δρ)
91- 98 A8 --- Ref Orbit reference from Orb6 (3)
100- 194 A95 --- Comments Relevant comments
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Note (1): Objects with HD or HIP number in the DD means that they are
new binaries, and a DD name is pending from the WDS curators.
Note (2): Data quality code as follows:
q = firm quadrant detection on the "shift-and-add" (SAA) images;
: = uncertain measurement, data are noisy and dmag is likely
over-estimated, or tentative resolution.
Note (3): Orbit references from http://www.astro.gsu.edu/wds/orb6.html
as follows:
Cvn2011 = Chauvin+, 2011A&A...528A...8C 2011A&A...528A...8C
Doc2009g = Docobo+, 2009AJ....138.1159D 2009AJ....138.1159D
Doc2014d = Docobo+, 2014IAUDS.183....1D 2014IAUDS.183....1D
Hor2019 = Horch+2019, J/AJ/157/56
Hrt2014b = Hartkopf+, 2014IAUDS.184....1H 2014IAUDS.184....1H
Izm2019 = Izmailov, 2019AstL...45...30I 2019AstL...45...30I
Jte2018 = Josties+, 2018IAUDS.196....1J 2018IAUDS.196....1J
Mdz2017 = Mendez+, 2017AJ....154..187M 2017AJ....154..187M
Mut2010b = Muterspaugh+2010, J/AJ/140/1623
Tok2020e = Tokovinin+2020, J/AJ/160/7
SOAR2021 = Tokovinin+2021, J/AJ/162/41
Tok2015a = Tokovinin+2015, J/AJ/149/8
Tok2015c = Tokovinin+2015, J/AJ/150/50
Tok2017a = Tokovinin+2017, J/ApJ/838/54
Tok2018e = Tokovinin, 2018IAUDS.195....1T 2018IAUDS.195....1T
Tok2019c = Tokovinin+2019, J/AJ/158/48
Tok2019d = Tokovinin, 2018IAUDS.198....1C 2018IAUDS.198....1C
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Byte-by-byte Description of file:table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- WDS Washington Double Star Catalogue (B/wds)
designation
12- 24 A13 --- Disc WDS Discoverer designation and system
components (1)
26- 31 I6 --- HIP [3640/115038]? Hipparcos number (I/239)
33- 39 F7.4 yr Epoch [19.37/23.51] Epoch in fraction of Julian
year - 2000.0yr
41- 43 I3 --- Filt [466/832] Filter name
45- 46 I2 --- Ncub [1/11] Number of cubes (of 1000 images each)
averaged to produce our measurement
48- 52 F5.3 arcsec SepMin [0.01/0.06] Angular resolution or minimum
separation
54- 57 F4.2 mag Det0.15 [0/9.8] Detection limit, possible
companions, 5σ at 0.15"
59- 62 F4.2 mag Det1.00 [0/7.8] Detection limit, possible
companions, 5σ at 1.00"
64- 119 A56 --- Comments Relevant comments (2)
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Note (1): We adopt the HD or HIP number for those that are not
previously listed in the WDS (and hence do not have a DD name yet).
Note (2): In comments, a : means uncertain measurement.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Robin Leichtnam [CDS] 19-Jan-2026