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HD 2893


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Observations of Binary Stars with the Differential Speckle Survey Instrument. I. Instrument Description and First Results
First results of a new speckle imaging system, the Differential SpeckleSurvey Instrument, are reported. The instrument is designed to takespeckle data in two filters simultaneously with two independent CCDimagers. This feature results in three advantages over other specklecameras: (1) twice as many frames can be obtained in the sameobservation time which can increase the signal-to-noise ratio forastrometric measurements, (2) component colors can be derived from asingle observation, and (3) the two colors give substantial leverageover atmospheric dispersion, allowing for subdiffraction-limitedseparations to be measured reliably. Fifty-four observations arereported from the first use of the instrument at theWisconsin-Indiana-Yale-NOAO 3.5 m Telescope9The WIYNObservatory is a joint facility of the University of Wisconsin-Madison,Indiana University, Yale University, and the National Optical AstronomyObservatories. in 2008 September, including seven components resolvedfor the first time. These observations are used to judge the basiccapabilities of the instrument.

Speckle interferometry of nearby multiple stars. IV. Measurements in 2004 and new orbits
The results of speckle interferometric observations of 104 binary and 6triple stars performed at the BTA 6 m telescope in 2004 October arepresented. Nearby low-mass stars are mostly observed for the program,among which 59 there are new binaries recently discovered by theHipparcos astrometric satellite. Concurrently with thediffraction-limited position measurements we obtained 154 brightnessratio measurements of binary and multiple star components in differentbands of the visible spectrum. New, first-resolved binaries are thesymbiotic star CH Cyg with a weak companion at 0.043″ separationand the pair of red dwarfs, GJ 913 = HIP 118212. In addition, we derivedthe orbital parameters for two interferometric systems: the CN-giantpair HD 210211 = HIP 109281 (P = 10.7 yr) and the G2V-K2V G2V-K2V binaryGJ 9830 = HIP 116259 (P = 15.7 yr).

Speckle Observations of Binary Stars with the WIYN Telescope. IV. Differential Photometry
Five hundred seventy-six magnitude difference measures are presented for260 binary stars. These measures are derived from CCD-based speckleobservations taken at the WIYN 3.5 m telescope at Kitt Peak NationalObservatory during the period 1997-2000. Separations of the systemsrange from over 1" down to near the diffraction limit of the telescope.A study of multiple measures of the same targets indicates that themeasures have a typical uncertainty of better than 0.13 mag per 2 minuteobservation, and that multiple observations can be averaged to arrive atsmaller uncertainties. Results presented here are also compared, insofaras it is possible, with measures in the Hipparcos Catalogue and toprevious studies using adaptive optics. No major systematic errors wereidentified.The WIYN Observatory is a joint facility of the University ofWisconsin-Madison, Indiana University, Yale University, and the NationalOptical Astronomy Observatory.

Speckle Observations of Binary Stars with the WIYN Telescope. II. Relative Astrometry Measures during 1998-2000
Five hundred twelve relative astrometry measures are presented for 253double stars, including 53 double stars discovered by Hipparcos. In 15cases, relative astrometry is reported for the first time for newlyconfirmed pairs. In addition, 20 high-quality nondetections ofcompanions are reported for stars suspected of being nonsingle byHipparcos. Observations were taken using a fast-readout CCD camerasystem at the WIYN 3.5 m telescope at Kitt Peak, Arizona. In comparingthese measures with ephemeris predictions for binary stars with verywell known orbits, we find that the measurement precision is better than3 mas in separation and 1° in position angle per individualobservation. Measurement precision and detection capabilities are fullydiscussed, and confirmed orbital motion is reported in four cases of theHipparcos double star discoveries. The WIYN Observatory is a jointfacility of the University of Wisconsin-Madison, Indiana University,Yale University, and the National Optical Astronomy Observatory.

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Osservazione e dati astrometrici

Costellazione:Balena
Ascensione retta:00h32m07.07s
Declinazione:-12°17'42.3"
Magnitudine apparente:8.295
Distanza:72.569 parsec
Moto proprio RA:47.8
Moto proprio Dec:-26.5
B-T magnitude:9.006
V-T magnitude:8.354

Cataloghi e designazioni:
Nomi esatti
HD 1989HD 2893
TYCHO-2 2000TYC 5271-803-1
USNO-A2.0USNO-A2 0750-00125978
HIPHIP 2532

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