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the current generation of ground - based interferometers , such as the palomar testbed interferometer ( pti ) @xcite , the naval prototype optical interferometer ( npoi)@xcite , the infrared optical telescope array ( iota3)@xcite , and the center for high angular resolution in astronomy ( chara ) array @xcite , is advancing stellar astronomy in a number of ways . @xcite , for example , reviewed the state of optical and infrared interferometry . one direction of progress is the increasing number of spectroscopic binaries that are being resolved as visual binaries . this allows the determination of their three - dimensional orbits and the derivation of accurate masses for the component stars and distances to the systems , distances that in many cases are more accurate than those from the _ hipparcos _ satellite .    in recognition of this development we have started a program to determine substantially improved spectroscopic orbits for bright , field spectroscopic binaries . the program has two benefits : the provision of new radial velocities and spectroscopic orbits of a quality that matches or exceeds the prospective interferometric observations and , for some binaries , the detection of the secondary spectrum and measurement of secondary radial velocities for the first time . we now briefly consider these two points in turn .    while some interferometric studies , such as that of 12  boo @xcite , include complementary new radial velocities , the usual practise is to take the radial velocities for the binary concerned from the literature . the precision of such velocities often falls short of that needed to match the interferometric observations . for example , in their recent determination of the three - dimensional orbit of the bright spectroscopic binary @xmath17  psc , @xcite had to complement their interferometric measurements with radial velocities observed in 1944 and 1945 @xcite . their resulting best - fit solution for the three - dimensional orbit has rms velocity residuals of 4.8 and 3.6 km  s@xmath13 for the primary and secondary , respectively . orbits with large velocity residuals are not exceptional because of the generally lower resolution and low signal - to - noise ratio of spectra obtained in the first roughly three - quarters of the twentieth century , for example , of the first 100 systems in the _ eighth catalogue of the orbital elements of spectroscopic binaries _ @xcite , 63 have orbits that were published in 1980 or earlier and 24 have orbits that were published in 1950 or earlier , long before the advent of radial velocity spectrometers and charge - coupled device detectors , which can produce spectra with very high signal - to - noise ratios . similar proportions must apply for all 1469 systems in the catalogue . while these proportions will have improved as a result of the substantial number of new spectroscopic binary orbits that have been published since 1989 @xcite , most such orbits are for newly discovered binaries . with respect to the detection of the secondary spectrum , we note that without secondary radial velocities and a determination of the secondary s spectroscopic orbit , the linear separation between the binary components is unknown and the determination of the three - dimensional orbit is incomplete . increasing the pool of double - lined spectroscopic binaries ( sb2s ) thus increases the number of spectroscopic binaries available for fruitful interferometric observation . in addition , binary systems with components of significantly different masses provide the greatest constraints on evolutionary models . considering that the majority of spectroscopic binaries are single - lined spectroscopic binaries ( sb1s ) , there is ample opportunity here . @xcite , for example , found that two - thirds of the spectroscopic binaries in their _ ninth catalogue _ ( there is no reason to think the catalogue s incompleteness affects this statistic much . ) our program uses new , high - resolution , red - wavelength spectra obtained with the 2.1 m telescope at mcdonald observatory of the university of texas and the coud feed telescope at kitt peak national observatory ( kpno ) . @xcite provided a preliminary description of our program and an initial list of observed stars , which has now been expanded to over 40 systems . these come primarily from a sample of 130 candidate systems obtained by searching the _ eighth catalogue _ for sb2 systems that could profit from renewed spectroscopic observation and sb1 systems with large enough mass functions to suggest that high signal - to - noise ratio spectra might transform them into sb2 systems ( e.g. , * ? ? ? the stars are north of @xmath1840  in declination and generally brighter than @xmath19 mag . others have also seen the need for improved radial velocities for spectroscopic binaries . for example , @xcite has successfully applied the iodine absorption - cell method for determining very precise radial velocities to the measurement of radial velocities of _ both _ components in sb2s . hitherto , this technique , which uses an iodine absorption cell to impose a reference spectrum on the stellar spectrum and is notable for its use in the discovery of extrasolar planets , has been restricted to the radial velocities of single stars or stars with companions of insignificant relative brightness . his pioneering investigation , which was carried out on the keck  i telescope with the hires spectrograph , was limited to five objects including a radial - velocity standard and two sb2s . among the latter was 64  psc ( hd  4676 ) , a well - known , bright spectroscopic binary ( f8v , @xmath20 days ) with a three - dimensional orbit determined by @xcite , using their own interferometric observations made with pti and radial velocities from @xcite . konacki s combined fit of his new radial velocities and the @xcite interferometric data leads to better - determined orbital and physical parameters for 64  psc . in particular , the rms velocity residual of 24 m  s@xmath13 , determined from his new fit , is a striking improvement compared to the rms residual of 810 m  s@xmath13 ( average @xmath21 m  s@xmath13 ) given by @xcite for their radial - velocity solution . our new velocities are not as precise as the iodine - cell velocities from the keck  i telescope  we will see that for 12  boo , which has a similar spectral type to 64  psc , the rms residual for our velocities is 110 m  s@xmath13  but their quality is still a good match with that of current interferometric observations . there is thus ample opportunity for radial velocities from small and medium - sized telescopes , measured by traditional methods , to make a worthwhile contribution .    here we report new orbit determinations for three bright spectroscopic binaries , rr  lyn , 12  boo , and hr  6169 . analysis of our new velocities provides significant improvements in the orbital elements of the systems . indeed , in the case of hr  6169 some of the revisions are substantial . table  1 gives basic data for the systems ; all three are known sb2s , have orbital periods near 10 days , and eccentric orbits . we now briefly look at each system individually . rr  lyn has long been known as both an eclipsing and spectroscopic binary . its orbit has a period of 9.95  days and a modest eccentricity , @xmath22 . the star s peculiar abundances are indicated in its metallic - lined spectral classification , which reflects primarily the spectral type of the primary . @xcite classified it as a3/a8/a6 , based on its ca  ii k line , its hydrogen balmer lines , and its metallic lines , respectively , while @xcite called the hydrogen lines a7 and the metallic lines f0 . @xcite compared the two components with evolutionary tracks and also used their photoelectric photometry on the @xmath23 system @xcite to place the components of rr  lyn in a @xmath24 diagram . from those results they estimated individual spectral types of a6  iv for the primary and f0  v for the secondary . thus , the primary has already begun to leave the main sequence , while the secondary is still ensconced within it . the metallic - line status of the primary is not in doubt @xcite , while that of the secondary remains uncertain , although the abundances of @xcite indicate possible metallicism . @xcite published the first spectroscopic orbit . more recent , but now quite old orbits were published by @xcite and @xcite . kondo s orbit has the advantages that it sampled the primary and secondary radial velocity curves more fully than popper s and that it has a single systemic velocity , while popper determined different systemic velocities for the primary and secondary . photoelectric light curves of rr lyn have been reported by @xcite , @xcite , @xcite , @xcite , @xcite , and @xcite . the last of these studies used precise photometry in the @xmath25 and @xmath26 bandpasses @xcite , which are based on but somewhat different from the johnson @xmath27 and @xmath26 photometric bandpasses . @xcite showed that the primary and secondary eclipse depths in @xmath4 are @xmath28 and @xmath29 , respectively , the fractional luminosities , also in @xmath4 , are @xmath30 , @xmath31 , and the orbital inclination is @xmath32 . both @xcite and @xcite needed the addition of third light to solve the light curves , while @xcite , who also did a photometric analysis , found no requirement for third light . this last result is supported by @xcite , who demonstrated that their observations in all filters are fitted by the same geometry and that their model matches the observations without any need to invoke third light . in a later paper , however , @xcite presented new evidence for a third body , based _ not _ on an analysis of the light curve , but on the times of the eclipse minima . the presence of the third star , which @xcite suggested is a very low - mass , low - luminosity object that contributes an insignificant amount of light to the system , is inferred from quasi - periodic oscillations in the times of primary and secondary minima . they proposed an extemely eccentric orbit ( @xmath33 ) with a rather long orbital period of @xmath34 years for it . the 64-year timespan of the published photoelectric minima amounts to only one - and - a - half orbital periods , however , so the case for the third body can not yet be regarded as conclusive . the sb2 system 12  boo is the only one in our trio that already has a determination of its three - dimensional orbit @xcite . the two components have an orbital period of 9.60  days and are of very similar mass , having a secondary to primary mass ratio of 0.97 . the system s combined spectral type is f8  iv @xcite or f8  v @xcite . @xcite found that the primary is leaving the main sequence , and with @xmath35  k it is now marginally _ cooler _ than the secondary ( @xmath36  k ) . @xcite was the first to determine its spectroscopic orbit . newer orbital elements have been published by @xcite and @xcite . @xcite presented the newest set of radial velocities as well as interferometric observations . details for these more recent spectroscopic orbits , including the present investigation , are summarised in table  2 . prior to its publication , we were unaware of the new investigation of 12  boo by @xcite . thus , in spite of the element of ( unintentional ) redundancy here , our own study of 12  boo , based on radial velocities acquired from 2002 to 2005 , is still of interest because our velocities turn out to be significantly more precise , allowing us to determine improved spectroscopic orbital elements . compared to rr  lyn and 12  boo , the previous work on hr 6169 has been quite modest . this binary has a combined spectral type of a2  v @xcite or a1  iv @xcite . the first and , to date , only spectroscopic orbit is that of @xcite , which was based on radial velocities from blue photographic spectrograms obtained at the cassegrain focus of the 1.8 m telescope at the dominion astrophysical observatory ( dao ) . this sb2 system has an orbit with a period of 10.56 days and a moderate eccentricity , @xmath37 . our observations were collected from 2002 april through 2005 october at the mcdonald observatory and kpno , with the majority of spectra of all three program stars obtained at mcdonald . the mcdonald observations were acquired with the 2.1 m telescope , the sandiford cassegrain echelle spectrograph @xcite , and a reticon ccd with 27@xmath38m@xmath39 pixels arranged in a 1200@xmath40400 pixel format . the spectrograms cover the wavelength range 5700 to 7000     and have a resolving power of 60,000 . the collapsed one - dimensional stellar spectra have a representative signal - to - noise ratio of @xmath41300 . each stellar observation was followed by an observation of a thorium  argon comparison spectrum . the observations at kpno were obtained with the coud feed telescope , coud spectrograph , and a ti  ccd detector . all the spectrograms were centered at 6430   , cover a wavelength range of about 80   , and have a resolution of 0.21    or a resolving power of just over 30,000 . the spectrograms typicaly have signal - to - noise ratios of 200 - 250 . the data were processed and wavelength - calibrated in a conventional manner with the iraf package of programs . the spectra of the three systems are double - lined and , at most orbital phases , the secondary lines are well separated from their primary counterparts . in rr lyn there are numerous lines of both the primary and secondary with the secondary lines being distinctly weaker , while in 12  boo the primary and secondary lines are also numerous and are of roughly similar strength . in hr  6169 the primary is represented by only a few lines from ionised species , while the secondary has numerous lines , mostly from neutral species , which are also sharper than those of the primary . in this system , therefore , at the yellow and red wavelengths covered by our observations the secondary lines are much _ better _ for velocity measurement than those of the primary . we now outline the procedures used to measure the mcdonald and kpno radial velocities . for the mcdonald velocities we proceeded as follows : the wavelengths of well - defined primary and secondary lines were measured by fitting gaussian profiles with the splot routine of iraf , the wavelength differences between the measured wavelengths and rest wavelengths @xcite of the lines provided the topocentric radial velocities , telluric o@xmath42 lines near 6300    ( @xmath43 band ) and 6900    ( b band ) were measured in the same way so as to determine the offset between the stellar spectrum and its associated thorium argon comparison spectrum , the stellar topocentric velocities were then corrected by subtracting from them the telluric line offset in velocity form , and , finally , the heliocentric correction led to the heliocentric radial velocities . the mcdonald velocities are , thus , absolute velocities . the kpno radial velocities were determined with the iraf cross - correlation program fxcor @xcite . the iau radial velocity standard stars @xmath44 vir , hr  5694 , and hr  7560 , which have late - f spectral classes , were used as cross - correlation reference stars . their velocities of 4.4 , 54.4 , and 0.0 km  s@xmath13 , respectively , were adopted from @xcite . in the kpno spectra , lines in the wavelength region redward of 6445    are not particularly suitable for measurement because most features are blends , and there are a number of modest strength water vapor lines . thus , the radial velocities were determined from lines in the region 6385    to 6445   . unfortunately , this 60    portion of the spectrum is so small that a mismatch , caused by the varying strength of line blends , between the spectral type of the program star and that of the cross - correlation standard can significantly affect the measured velocity . thus , instead of cross - correlating this entire 60    wavelength region , only the wavelength regions around the strongest and least - blended lines were cross - correlated . for our stars with components of late - a or f spectral type the list includes five lines , the fe  i lines at 6394 , 6412 , 6421 , and 6431    plus the ca  i line at 6439   . the weakness of those neutral lines in the spectra of early - a stars means that the only measurable lines in their kpno spectrograms are the two fe  ii lines at 6417 and 6433   , which can provide good velocities if the lines are narrow enough . each cross - corrrelation profile was fitted with a gaussian function .    because different techniques were used to measure the mcdonald and kpno radial velocities , the two velocity systems may have slightly different zero points . we will examine this possibility in  6 . table 3 gives the calendar dates , heliocentric julian dates and heliocentric radial velocities for the mcdonald and kpno observations . @xcite identified several luminosity - sensitive and temperature - sensitive line ratios in the 6430 - 6465    region . they employed those critical line ratios and the general appearance of the spectrum as spectral - type criteria . however , for stars that are hotter than early - g spectral class , the line ratios in that wavelength region have little sensitivity to luminosity . thus , for the a and f stars of our three systems , we have used the entire 80    spectral region of our kpno observations to estimate just the spectral classes of the individual components . in the 6430    region most of the strongest features are fe  i lines with the addition of three fe  ii and three ca  i lines . the luminosity class may be determined by computing the absolute visual magnitude with the _ hipparcos _ parallax and comparing that magnitude to evolutionary tracks or a table of canonical values for giants and dwarfs . spectra of our three binaries were compared with the spectra of a number of a and f type stars primarily from the lists of @xcite and @xcite . the reference - star spectra were obtained at kpno with the same telescope , spectrograph , and dectector as our binary - star spectra . to facilitate a comparison , the spectra of the reference stars were rotationally broadened and shifted in radial velocity with a computer program developed by @xcite and @xcite . this spectrum addition enables us to determine a continuum intensity ratio of the binary components at 6430   , a wavelength that is about 0.6 of the way between the central wavelengths of the johnson @xmath4 and @xmath26 bandpasses . if the two stars have very similar spectral types , this intensity ratio is also the luminosity ratio and , thus , can be converted directly into a magnitude difference . however , if the lines of the secondary are intrinsically stronger than those of the primary , as would be the case , for example , if the components were main sequence stars of rather different spectral types , then the continuum intensity ratio results in a minimum magnitude difference . we have determined projected rotational velocities from our red - wavelength kpno spectra with the procedure of @xcite . for each star the full width at half - maximum of several metal lines in the 6430    region was measured and the results averaged . an instrumental broadening of 0.21  was removed from the measured broadening by taking the square root of the difference between the squares of measurements of the stellar and comparison lines , resulting in the intrinsic broadening . the calibration polynomial of @xcite was used to convert this broadening in angstroms into a total line broadening in kilometers per second . for a - type stars this line broadening corresponds to the _ v _  sin  _ i _ value . for f - type stars , macroturbulent broadening has been taken into account . following @xcite , for early - f stars a macroturbulence of 5 km  s@xmath13 was adopted and removed , while for mid - f and late - f stars values of 4 and 3 km  s@xmath13 , respectively , were used . all three systems have eccentric orbits , so we obtained simultaneous solutions of the primary and secondary radial velocities by the lehmann  filhes method to determine the orbits . a preliminary to the orbit calculation was the assignment of suitable weights for the various velocities . typically the primary and secondary spectra are of different quality because the components can differ , sometimes markedly , as to strength of lines , line width , and number of available lines , resulting in primary and secondary velocities that are of different weight . also , the mcdonald velocities , because of the higher resolution by a factor of two and the substantially greater wavelength coverage of the mcdonald spectra , resulting in a larger number of available lines , are somewhat more precise than the kpno velocities and therefore have higher weight . for each system there are , thus , four different sets of velocity , each with its own weight . these weights , which are given in table  3 , were chosen so as to approximately equalize the products of the weights and the mean square velocity residuals for the different sets of velocity . once the weights were assigned , the velocities were then solved to determine the spectroscopic orbits . the velocity residuals ( table 3 ) for the orbital solutions , given to two decimal places to facilitate our examination , allow a straightforward check on the consistency of the radial velocities from the two observatories . any systematic difference between the mcdonald and kpno velocities will manifest itself as a corresponding difference between the average residuals , calculated with regard to sign , for the two types of velocity , while if they are consistent then their average residuals , apart from statistical fluctuations , will be identical and equal to zero . a comparison of the residuals for the mcdonald and kpno radial velocities is given in table  4 . although the differences are all smaller than or similar to their estimated errors , they all have the same sign , thus suggesting an offset of order 0.1  0.2 km  s@xmath13 between the mcdonald and kpno velocities . we attach the most importance , however , to the primaries of rr  lyn and 12  boo because of the six stars in our three systems these two have the most well - determined radial velocities , and in both cases there is no evidence of an offset . this simple check , therefore , indicates the possible presence of an offset of 0.1  0.2 km  s@xmath13 between the mcdonald and kpno velocities , but the results are inconclusive . in the absence of clear evidence of an offset , we decided not to adjust either set of velocities . we now look at the results for the individual systems . table 5 gives the spectroscopic orbital elements of rr  lyn obtained from the solution of our radial velocities . for comparison , the elements of @xcite and the photometrically - based elements of @xcite are also listed . figure  [ fig1 ] shows our radial velocities along with the calculated radial - velocity curves for our orbital elements . although the photometrically determined orbital period is more precise than our spectroscopically measured value , the difference between the two 10-day periods corresponds to less than 1 second . we have retained the spectroscopic period for the determination of our spectroscopic orbit , since adopting the photometric period does not change the orbital elements . examining the solutions in table  5 , one sees that to within the uncertainties all three investigations give the same eccentricity of 0.08 . this agreement is especially pleasing in the case of @xcite because their photometric determination of the eccentricity is completely independent of our spectroscopic one . we note that our determination of @xmath45 ( 1794 @xmath15 06 ) is the first accurate measurement of this element and that to within its uncertainty , it is @xmath46 , which means the major axis of the true orbit and the line of nodes coincide . also of interest , we find that our and kondo s determinations of @xmath47 and @xmath48 are the same to within the uncertainties . we will compare the two @xmath49-velocity determinations shortly . the minimum masses are also in agreement , with our uncertainties being about 10 times smaller than kondo s . as we have seen , rr  lyn is also a detached eclipsing binary so the photometric and spectroscopic orbital elements can be combined to provide the sizes and masses of the components as well as the linear separation between the primary and secondary . this is done in table  6 . the new mass determinations of @xmath50  m@xmath7 and @xmath51  m@xmath7 are extremely precise , having uncertainties of only 0.4% and 0.3% , respectively . although our new determinations of the masses and radii of the primary and secondary are more precise than those of @xcite , our values differ only slightly from theirs . the new primary and secondary masses are just 0.037m@xmath7 and 0.017m@xmath7 larger , respectively , than theirs , while the new primary and secondary radii differ from theirs by 0.00  r@xmath7 and 0.01  r@xmath7 , respectively . we will not rediscuss , therefore , the evolutionary state of rr  lyn because our new results would have little impact on the conclusions of @xcite in this regard . instead , we note that insofar as our new masses and radii confirm theirs , so we support their determinations of other derived quantities . in particular we confirm their photometric estimate of the system s distance , 73.5 @xmath15 2.8  pc , and its age , @xmath52 billion years . we now look at the question of the third body in the system . as already mentioned , @xcite proposed the presence of a third star in an extremely eccentric orbit ( @xmath53 ) with a period of 39.7 years as an explanation of variations in the times of minima of the primary and secondary eclipses . the proposed star is of low mass , estimated to be 0.10m@xmath7 if its orbit is coplanar with that of the eclipsing pair . thus , it would make a negligible contribution to the spectrum , but its presence would cause a regular variation of the systemic velocity of the eclipsing pair as the center - of - mass of the eclipsing pair orbits the center - of - mass of the entire system . in view of the long interval between the observations of @xcite and ours , it is natural to compare kondo s systemic velocity with ours to see if there is a variation . the difference between our and kondo s @xmath49-velocities is insignificant . from table  5 we see that it is @xmath54 with the estimated uncertainty being set by the uncertainty in kondo s result . the observations thus set an upper limit of @xmath55 km  s@xmath13 on any difference between the two @xmath49-velocities . what is the predicted difference that would be caused by the proposed third star ? to answer this question we note that we do _ not _ need to know the ( unknown ) systemic velocity of the entire system ; calculation of the _ orbital motion _ alone , of the center of mass of the eclipsing pair , is sufficient to provide the predicted @xmath49-velocity _ difference _ that we want . @xcite have provided estimates of all the orbital elements needed to calculate the predicted variation of the @xmath49-velocity of the eclipsing pair , with the exception of @xmath56 , and , from the information they give , one can infer @xmath57 km  s@xmath13 . we can thus calculate the predicted variation of the @xmath49-velocity of the eclipsing pair due to its motion in the proposed 39.7-year orbit , and this is shown in figure  [ fig2 ] . it is apparent from that figure that the predicted difference of @xmath49-velocities is tiny , only @xmath58 km  s@xmath13 . the smallness of the difference results from the extreme eccentricity of the proposed orbit , so the velocity variation outside of periastron passage is slight , and because , by chance , kondo s observations and ours are separated by almost exactly one orbit and thus are at the same phase .    our null result , therefore , is consistent with the predicted minute change in the @xmath49-velocity of the eclipsing pair of stars caused by the presence of the proposed low - mass third star . of course , the result is also consistent with the absence of such a body , and so we are unable to either confirm or deny its existence . as can be seen in figure  [ fig2 ] , the extreme eccentricity of the 39.7-year orbit means that usually the @xmath49-velocity of the eclipsing pair changes very gradually . so , during most of the orbit , radial velocities are almost impervious to the presence or absence of the third body . near periastron it is a different story , however , as the third star swoops toward the eclipsing pair , and their @xmath49-velocity suffers an abrupt change with a total amplitude of 2.5 km  s@xmath13 . at the next periastron passage in 2028 one or two precise radial velocities will readily confirm or refute the existence of the third star .      in their recent investigation of the 12  boo system @xcite combined their interferometric observations of the visual orbit and complementary , new radial velocities to make an accurate determination of the system s three - dimensional orbit and the masses and radii of its components . they then use these basic parameters to discuss the system s evolutionary status . although our own work duplicates theirs to some extent , our radial velocities are more precise , so our results provide a useful check on the spectroscopic component of their investigation .    table  7 lists the spectroscopic orbital elements from the combined interferometric and radial velocity solution of @xcite with our new radial - velocity solution . the two sets of orbital elements are in excellent agreement , and the uncertainties of our elements are usually smaller than those of @xcite . with the exception of the period , for which our observational timespan is quite short , all our elements are improved determinations and for four of them ( @xmath59 , @xmath47 , @xmath48 , and @xmath49 ) the improvement is a factor of two . there is also good agreement between the two @xmath49 velocities , where we find @xmath60 km  s@xmath13 , while they find @xmath61 km  s@xmath13 , which argues that our and their radial velocities have the same zero point . to make the most of the radial velocities , we also obtained a combined solution of our radial velocities and theirs , making no adjustment to either set of velocities . ( the weights for our velocities in this solution are given in table  3 , while the weights for theirs were 0.1 and 0.05 for the primary and secondary , respectively . )    the elements from this combined spectroscopic solution are also listed in table  7 . they represent an all - round improvement , with the period determination , in particular , being sharpened thanks to the longer timespan , 1987 to 2005 , of the combined observations . figure  [ fig3 ] shows our radial velocities and those of @xcite along with the calculated radial velocity curves for the combined solution of the two sets .    with the help of the inclination , @xmath62 , from the orbit of @xcite we determine new values of the stellar masses and the semi - major axis of the relative orbit . we find @xmath63m@xmath7 , @xmath64m@xmath7 , and @xmath65 gm . these results certainly confirm those of @xcite , which are @xmath66m@xmath7 , @xmath67m@xmath7 , but are more precise . finally we look at the orbital parallax , @xmath68 , and distance of the system . the orbital parallax is simply @xmath69 ( arcsec)/@xmath69 ( au ) where @xmath69 denotes both the angular and linear sizes , respectively , of the true orbit . the angular size of the orbit , @xmath70  mas , of course , comes from the visual - orbit determination @xcite . we note , however , that the uncertainty in the angular size of the orbit , which is 0.5% and is much bigger than the uncertainties in the determinations of the linear size of the orbit ( 0.1% for theirs and 0.06% for ours ) , dominates the uncertainty in the orbital parallax . thus , although we have improved the determination of the linear size of the orbit , there are no corresponding improvements in the orbital parallax or distance of 12  boo , so we content ourselves with restating the results of @xcite  @xmath71mas and a distance to the system of @xmath72pc . table  8 lists the orbital elements of hr  6169 , derived from the solution of our radial velocities , as well as the elements obtained by @xcite . in figure  [ fig4 ] our radial velocities and those of @xcite are compared with the radial velocity curves calculated from our elements alone . for hr  6169 , in the yellow and red region of the spectrum where we measured our radial velocities , the only useful lines representing the primary are the two siii lines at 6347 and 6371    and a smattering of very weak feii lines , while the secondary is represented by lines of neutral and ionised species that are both more numerous and sharper . for this reason the _ secondary _ velocities are more precise than those of the primary . it follows that the secondary velocities have much higher weight than those of the primary ( see table  3 ) , the secondary radial - velocity curve is better defined than that of the primary , and @xmath48 is better determined than @xmath47 . comparison of our results with young s reveals some very significant discrepancies , especially for the @xmath49 velocity . at first sight the large difference of @xmath73 km  s@xmath13 between our @xmath49 velocity ( @xmath74 km  s@xmath13 ) and young s ( @xmath75 km  s@xmath13 ) suggests the presence of an unseen third star , which must have changed the @xmath49 velocity of the spectroscopic - binary pair in the 84 years between the two measurements . a glance at figure  [ fig4 ] , however , shows there is no need to invoke a third star . instead , a simpler explanation of the difference can be found because of a systematic error in young s @xmath49 velocity , caused by blending of the primary and secondary lines in his spectra . @xcite remarked that in his spectra with smaller primary - secondary velocity separations the primary lines and their secondary counterparts were blended , so that he was only able to measure a single blend velocity , which he adopted as the primary velocity . inspection of figure  [ fig4 ] shows that these blended primary velocities cluster around the smaller velocity extremum associated with the nodal passage near apastron . they mostly fall below the @xmath49 velocity and , being dragged upwards and towards it , are too positive and , not being balanced by the few velocities that are dragged downwards , their presence in young s orbit solution made his @xmath49 velocity too positive . similar considerations account for his semi - amplitude of the primary being too small , @xmath76 km  s@xmath13 compared with our value of @xmath77 km  s@xmath13 . unlike our other two systems , rr  lyn , which is an eclipsing system , and 12 boo , for which interferometric observations have been used to determine a visual orbit , hr  6169 has no direct determination of its orbital inclination . thus , at present we can only compute the minimum masses of its two components , which are 2.20 @xmath15 0.01 and 1.64 @xmath15 0.02 m@xmath16 for the primary and secondary , respectively . @xcite classified the combined spectrum of rr  lyn as a3/a8/a6 , based on its ca ii k , hydrogen balmer , and metal lines , respectively , providing a general starting point for our determination . the rapid rotation of most a - type stars plus a variety of abundance peculiarities make it difficult to identify a significant number of slowly rotating reference stars for that spectral class . despite the limited choices , identified primarily from the work of @xcite , we obtained a reasonable fit to the spectrum of rr  lyn with hr  3354 ( spectral classes of a3/a5/a7 = calcium / hydrogen / metals @xcite ) for the primary plus hr  1613 ( spectral type of a9  v @xcite and [ fe / h ] @xmath78 0.0 @xcite ) for the secondary . while the iron lines of the primary are fitted relatively well by hr  3354 , the calcium lines of this reference star are too weak . our results for the stellar components , however , are similar to those of @xcite , who determined spectral types of a6  iv plus f0  v from their @xmath23 photometry and a comparison with evolutionary tracks . the continuum intensity ratio of our fit is 0.236 , which corresponds to a magnitude difference of 1.6 . this is in rough agreement with the results of @xcite , who used the @xmath79 photometric system @xcite and found a @xmath4-band luminosity ratio of 0.276 , which corresponds to a magnitude difference of 1.40 . our magnitude difference is consistent with the luminosity classes assigned by @xcite . thus , we adopt their estimated spectral types .      guided by previous spectral classifications , we used hr  7560 ( f8  v @xcite and mean [ fe / h ] = 0.06 @xcite ) as a proxy for both components , but found the lines of the resulting composite spectrum fit to be too strong . however , with hr  5694 ( f8  iv - v @xcite and mean [ fe / h ] = @xmath180.10 @xcite ) used for both components we found an excellent fit to the spectrum of 12 boo . the continuum intensity ratio of this fit is 0.637 . because the spectral classes of the two stars are essentially identical , this value is also the luminosity ratio at 6430   , a wavelength that is about 0.6 of the way between the center of the johnson @xmath4 and @xmath26 bandpasses . the intensity ratio produces a magnitude difference of 0.5 with an estimated uncertainty of 0.1 . such a difference is in accord with the more precise @xmath80@xmath4 magnitude of 0.48 determined by @xcite . the slightly subsolar iron abundance is also in agreement with the results of @xcite and @xcite , who found [ fe / h ] = @xmath180.03 @xmath15 0.09 and @xmath180.1 @xmath15 0.1 , respectively .      from dao photographic plates , @xcite determined magnitude differences for 82 spectroscopic binaries , including hr  6169 . he described the spectrum of this system as consisting of two narrow - lined early - a stars and concluded that both components were dwarfs . his low - weight magnitude difference in the blue region of the spectrum is 0.7 @xmath15 0.4 .    unlike our results for 12 boo and rr  lyn we have had difficulty finding a good combination of reference stars to represent the spectrum hr  6169 . given the a spectral class of the components , the lines of both stars are quite weak in the 6430    region with all but one of the lines being less than 5% deep in the combined spectrum . the primary component has the stronger fe  ii lines and weaker fe  i lines and so is earlier in spectral class . from the metal lines our best estimates of those spectral classes are a1 for the primary and a7 for the secondary with a continuum intensity ratio in the 6430    region that corresponds to a minimum magnitude difference of @xmath411 . alternatively , the spectral types may be estimated from the colors of the components . guided by the above results , we found that the @xmath81 colors for stars of spectral types a1  v and a5  v , taken from table  ii of @xcite , plus an adopted @xmath4 magnitude difference of 0.9 result in the observed @xmath81 = 0.06 from the _ hipparcos _ satellite @xcite . we have adopted those spectral types and colors in our additional analyses . the two main theories of orbital circularization and rotational synchronization ( e.g. ; @xcite ) disagree significantly on absolute time scales but do agree that synchronization should occur first . from surveys of b and a stars @xcite concluded that synchronization occurs faster than circularization , confirming for early - type stars the theoretical results . the three systems discussed here have orbital periods between 9.6 and 10.6 days and eccentric rather than circular orbits . since two of the three systems contain a - type stars , the observed eccentricities of their orbits are not surprising . @xcite examined 62 spectroscopic binaries with a - type primaries and periods less than 100 days . they concluded that all systems with orbital periods @xmath82  3 days have circular or nearly circular orbits . they also found that many binaries with periods in the range of 3 to 10 days have circular orbits , while all those with periods greater than 10 days have eccentric orbits . thus , the eccentric orbits of rr  lyn and hr  6169 appear to be typical of a - type systems with periods near 10 days . @xcite has shown that in an eccentric orbit a star s rotational angular velocity will tend to sychronize with that of the orbital motion at periastron , a condition called pseudosynchronous rotation . with equation ( 42 ) of @xcite we calculated pseudosynchronous periods for the three systems . for rr  lyn our _ v _  sin  _ i _ values are 14.6 @xmath15 1 and 11.3 @xmath15 2 km  s@xmath13 for its primary and secondary , respectively . the uncertainties are estimated , with that for the secondary being larger because of the weakness of its lines . we assume that the orbital and rotational axes are parallel , so the rotational inclination is 874 . since it is so close to 90 , we adopt our _ v _  sin  _ i _ values as the equatorial rotational velocities of the components . from table  6 the radii are 2.57 and 1.59 r@xmath16 for the primary and secondary , respectively . those values , combined with the pseudosynchronous period of 9.59 days , lead to rotational velocities of 13.6 and 8.4 km  s@xmath13 . thus , the rotation of the primary is consistent with its pseudosynchronous value , while the secondary appears to be rotating slightly faster than pseudosynchronous . our projected rotational velocities for 12  boo , 13.0 @xmath15 1 and 10.3 @xmath15 1 km  s@xmath13 for its primary and secondary , respectively , are in good agreement with those determined by @xcite and @xcite . again we assume that the orbital and rotational axes are parallel , so the rotational inclination is 108 . thus , the observed equatorial rotational velocities become 13.7 and 10.8 km  s@xmath13 . the radii of the two components @xcite and the pseudosynchronous period of 7.84 days , lead to predicted rotational velocities of 15.9 and 12.0 km  s@xmath13 . thus , the primary is rotating slightly slower than its predicted velocity , while the secondary may well be rotating pseudosynchronously .      to determine if the components of hr  6169 are pseudosynchronously rotating we must first estimate their radii . from the _ hipparcos _ catalog @xcite the @xmath4 magnitude and @xmath81 color of the hr  6169 system are 6.42 and 0.062 , respectively . the _ hipparcos _ parallax of 6.17 @xmath15 0.087 ( mas ) @xcite corresponds to a distance of 162 @xmath15 24 pc . although at such a distance there may be a modest amount of interstellar reddening , the color of the system is consistent with the spectral type of the primary , and so we have assumed no interstellar reddening . as a result , the parallax , the @xmath4 magnitude , and the adopted @xmath4 magnitude difference of 0.9 (  7.3 ) were combined to obtain absolute magnitudes @xmath83 = 0.8 @xmath15 0.3 mag and @xmath83 = 1.7 @xmath15 0.3 mag for primary and secondary , respectively . a @xmath81 color of 0.03 for the primary and a @xmath81 of 0.14 for the secondary @xcite were adopted and then used in conjunction with table  3 of @xcite , to obtain the bolometric corrections and effective temperatures of the two components . the resulting luminosities of the primary and secondary are @xmath84 = 43 @xmath15 12 @xmath85 and @xmath86 = 17 @xmath15 5 @xmath85 , respectively , while the radii are @xmath87 = 2.6 @xmath15  0.4  @xmath88 and @xmath89 = 2.1 @xmath15 0.3 @xmath88 , respectively . the uncertainties in the computed quantities are dominated by the parallax and magnitude difference uncertainties plus , to a lesser extent , the effective temperature uncertainty , which is estimated to be @xmath15200  k.    because the orbit of hr 6169 has a moderately large eccentricity of 0.414 , the pseudosynchronous period of 4.95 days is less than half of the orbital period . with that period and the above radii , we obtain pseudosynchronous rotational velocities of 26.6 and 21.5 km  s@xmath13 for the primary and secondary , respectively . we have determined _ v _  sin  _ i _ values of 32 @xmath15 5 and 18 @xmath15 2 km  s@xmath13 for the primary and secondary , where the uncertainties are estimated . the minimum masses of the components are rather large , suggesting a relatively high orbital inclination . a comparison with canonical values of absolute magnitudes and masses for dwarfs of the appropriate spectral types @xcite suggests an inclination of about 70 . adopting this value , assuming , as has been done for the other two systems , that the rotational inclination has the same value , produces equatorial velocities of 34 and 19 km  s@xmath13 . thus , the primary appears to be rotating slightly faster than its pseudosynchronous velocity , while the secondary may be rotating pseudosynchronously . we have determined new spectroscopic orbits for the bright sb2 systems rr  lyn , 12  boo , and hr  6169 . the accuracies of the minimum masses ( @xmath2 and @xmath3 ) range from 0.13% for the secondary of 12  boo to 0.9% for the secondary of hr  6169 , while the accuracies of the linear sizes of the relative orbit ( @xmath90 ) range from 0.05% for 12  boo to 0.25% for hr  6169 . these results show our radial velocities provide well - determined spectroscopic orbits . which do justice to interferometric measurements of 12  boo @xcite and , we expect , will also do justice to prospective interferometric measurements of rr  lyn , hr  6169 , and other systems in our program .    for rr  lyn , an eclipsing binary with a well - determined orbital inclination , we have determined accurate new masses and radii for its components . the semi - major axis of the relative orbit , @xmath91r@xmath92 , plus the distance to the system , @xmath93  pc @xcite , lead to a predicted angular size @xmath94  mas for the true orbit and , because @xmath45 ( @xmath95 ) is @xmath96 to within its measurement error so the semi - major axis lies across the line - of - sight , this will also be the @xmath69 of the apparent orbit . we find that the expected effect of the unseen third star proposed by @xcite on our and kondo s ( 1976 ) radial velocities is so slight as to be well below the threshold of our measurement errors .    we have determined a new spectroscopic orbit for 12  boo , which confirms , and is more precise than , that determined by @xcite as part of their measurement of the three - dimensional orbit of this system . our investigation of hr  6169 corrects systematic errors in young s ( 1920 ) orbit and leads to significant revisions of the minimum masses and @xmath97 . at the distance of hr  6169 , @xmath98pc ( perryman et al . 1997 ) , the @xmath90 of 22.05 @xmath15 0.05  gm corresponds to an angular separation of 0.91mas .    in conclusion we find that radial velocities observed with small and medium - sized telescopes and measured by traditional methods provide a suitable spectroscopic contribution to the combination of measurements required for determination of three - dimensional orbits . we thank eshwar reddy and chris sneden for some helpful tips and david doss for his patient guidance , which was essential for the successful operation of the 2.1-m telescope at mcdonald and its instrumentation . we also thank richard green , former director of kpno , for continuing to make the coud feed telescope available . we appreciate daryl willmarth s invaluable assistance with the kpno coud feed telescope and our observations . this research at tennessee state university was supported in part by nasa grant ncc5 - 511 and nsf grant hrd-9706268 . matthews , l. d. , & mathieu , r. d. 1992 , in asp conf . 32 , complimentary approaches to double and multiple star research , iau colloquium 135 , ed . h. a. mcalister & w. i. hartkopf ( san francisco : asp ) , 244                                          lcrccccrc rr lyn & 2291 & 44691 & a3/a8/a6 & 5.53 & 0.238 & 12.01 & 9.95 & 0.08 + 12 boo & 5304 & 123999 & f8iv & 4.82 & 0.541 & 27.27 & 9.60 & 0.19 + ... & 6169 & 149632 & a2v & 6.42 & 0.062 & 06.17 & 10.56 & 0.41 +    lccc abt & levy 1976 & 1966  1971 & 20 & 1.3 + de medeiros & udry 1999 & 1987  1992 & 12 & 0.90 + boden et al . 2005 & 1987  2001 & 49 & 0.39 + this paper ( mcdonald and kpno ) & 2002  2005 & 24 & 0.14 +    lrrrrrrrrr + 2003 apr 22 & mcd & 52,751.635 & 0.3781 & 33.9 & @xmath99 & 1.000 & 0.100 & @xmath100 & 0.16 + 2004 feb 07 & mcd & 53,042.843 & 0.6598 & 25.3 & @xmath101 & 1.000 & 0.100 & 0.03 & @xmath102 + 2004 feb 08 & mcd & 53,043.803 & 0.7563 & @xmath103 & & 0.000 & & @xmath104 & + 2004 feb 09 & mcd & 53,044.812 & 0.8577 & @xmath105 & 36.5 & 1.000 & 0.100 & 0.11 & @xmath106 + 2004 mar 10 & mcd & 53,074.760 & 0.8691 & @xmath107 & 43.0 & 1.000 & 0.100 & 0.03 & 0.06 + 2004 mar 11 & mcd & 53,075.734 & 0.9670 & @xmath108 & 75.4 & 1.000 & 0.100 & @xmath109 & @xmath110 + 2004 apr 13 & mcd & 53,108.648 & 0.2766 & 2.9 & @xmath111 & 1.000 & 0.100 & 0.12 & @xmath112 + 2004 apr 15 & mcd & 53,110.647 & 0.4776 & 47.8 & @xmath113 & 1.000 & 0.100 & @xmath114 & @xmath106 + 2004 apr 24 & kp & 53,119.647 & 0.3826 & 35.5 & @xmath115 & 0.500 & 0.050 & 0.44 & @xmath116 + 2004 sep 25 & kp & 53,274.019 & 0.9050 & @xmath117 & 58.8 & 0.500 & 0.050 & @xmath118 & 0.21 + 2004 sep 28 & kp & 53,276.991 & 0.2039 & @xmath119 & 6.3 & 0.500 & 0.050 & @xmath120 & @xmath121 + 2004 nov 25 & mcd & 53,334.893 & 0.0260 & @xmath122 & 76.6 & 1.000 & 0.100 & 0.10 & @xmath123 + 2004 dec 03 & mcd & 53,342.913 & 0.8325 & @xmath124 & 24.6 & 1.000 & 0.100 & @xmath125 & 0.15 + 2005 jan 29 & mcd & 53,399.846 & 0.5572 & 45.6 & @xmath126 & 1.000 & 0.100 & 0.07 & 0.40 + 2005 apr 28 & mcd & 53,488.717 & 0.4934 & 48.3 & @xmath127 & 1.000 & 0.100 & @xmath128 & 0.01 + 2005 apr 29 & mcd & 53,489.670 & 0.5892 & 41.1 & @xmath129 & 1.000 & 0.100 & @xmath118 & 0.31 + 2005 apr 30 & kp & 53,490.636 & 0.6863 & 17.7 & @xmath130 & 0.500 & 0.050 & 0.58 & 0.59 + 2005 sep 21 & kp & 53,634.874 & 0.1898 & @xmath131 & 13.6 & 0.500 & 0.050 & @xmath132 & @xmath133 + 2005 oct 18 & mcd & 53,662.011 & 0.9185 & @xmath134 & 64.1 & 1.000 & 0.100 & 0.13 & 0.58 + 2005 oct 20 & mcd & 53,663.896 & 0.1080 & @xmath135 & 54.9 & 1.000 & 0.100 & 0.10 & 0.38 + 2005 oct 20 & mcd & 53,663.990 & 0.1175 & @xmath136 & 51.1 & 1.000 & 0.100 & 0.04 & 0.61 +   + 2002 apr 28 & mcd & 52,392.711 & 0.1964 & 76.7 & @xmath137 & 1.000 & 0.500 & @xmath138 & @xmath118 + 2002 apr 29 & mcd & 52,393.750 & 0.3046 & 51.3 & @xmath139 & 1.000 & 0.500 & @xmath125 & @xmath140 + 2003 mar 21 & mcd & 52,719.792 & 0.2512 & 65.6 & @xmath141 & 1.000 & 0.500 & @xmath142 & @xmath143 + 2003 apr 20 & mcd & 52,749.700 & 0.3651 & 33.7 & @xmath144 & 1.000 & 0.500 & 0.06 & 0.10 + 2003 apr 20 & mcd & 52,749.892 & 0.3851 & 27.6 & @xmath145 & 1.000 & 0.500 & 0.00 & 0.18 + 2003 apr 21 & mcd & 52,750.903 & 0.4904 & @xmath146 & 23.3 & 1.000 & 0.500 & @xmath147 & 0.27 + 2003 sep 06 & mcd & 52,888.618 & 0.8289 & @xmath148 & 69.2 & 1.000 & 0.500 & @xmath147 & 0.12 + 2003 sep 07 & mcd & 52,889.586 & 0.9297 & @xmath149 & 29.8 & 1.000 & 0.500 & 0.10 & @xmath150 + 2003 sep 08 & mcd & 52,890.584 & 0.0336 & 52.0 & @xmath151 & 1.000 & 0.500 & 0.09 & @xmath100 + 2004 feb 08 & mcd & 53,043.967 & 0.0034 & 35.0 & @xmath152 & 1.000 & 0.500 & 0.07 & 0.14 + 2004 feb 09 & mcd & 53,044.932 & 0.1039 & 76.7 & @xmath153 & 1.000 & 0.500 & @xmath154 & 0.16 + 2004 apr 13 & mcd & 53,108.880 & 0.7620 & @xmath155 & 75.0 & 1.000 & 0.500 & @xmath142 & 0.00 + 2004 apr 14 & mcd & 53,109.858 & 0.8638 & @xmath156 & 59.9 & 1.000 & 0.500 & 0.15 & @xmath116 + 2004 apr 26 & kp & 53,121.792 & 0.1063 & 77.4 & @xmath101 & 0.500 & 0.250 & 0.16 & 0.21 + 2004 jun 12 & kp & 53,168.659 & 0.9860 & 24.0 & @xmath157 & 0.500 & 0.250 & @xmath120 & 0.69 + 2004 jun 13 & kp & 53,169.752 & 0.0998 & 76.0 & @xmath158 & 0.500 & 0.250 & @xmath138 & 0.34 + 2004 sep 12 & mcd & 53,260.584 & 0.5570 & @xmath159 & 41.6 & 1.000 & 0.500 & 0.01 & 0.11 + 2004 sep 13 & mcd & 53,261.583 & 0.6610 & @xmath160 & 64.7 & 1.000 & 0.500 & 0.11 & @xmath116 + 2005 apr 27 & mcd & 53,487.876 & 0.2220 & 72.3 & @xmath161 & 1.000 & 0.500 & 0.07 & 0.16 + 2005 apr 28 & mcd & 53,488.844 & 0.3228 & 46.3 & @xmath162 & 1.000 & 0.500 & 0.03 & 0.11 + 2005 apr 29 & mcd & 53,489.708 & 0.4128 & 20.0 & 0.3 & 0.000 & 0.000 & 0.74 & 0.69 + 2005 may 01 & kp & 53,491.692 & 0.6193 & @xmath163 & 56.3 & 0.500 & 0.250 & 0.09 & @xmath143 + 2005 may 02 & kp & 53,492.672 & 0.7214 & @xmath164 & 72.9 & 0.500 & 0.250 & @xmath120 & @xmath154 + 2005 jun 11 & kp & 53,532.796 & 0.8990 & @xmath165 & 46.3 & 0.500 & 0.250 & 0.13 & 0.36 +   + 2002 apr 28 & mcd & 52,392.790 & 0.2518 & @xmath166 & 20.1 & 0.100 & 1.000 & 0.67 & @xmath167 + 2002 apr 29 & mcd & 52,393.881 & 0.3551 & @xmath168 & 35.1 & 0.100 & 1.000 & @xmath169 & @xmath170 + 2003 mar 21 & mcd & 52,719.891 & 0.2289 & @xmath171 & 14.3 & 0.100 & 1.000 & @xmath172 & 0.13 + 2003 apr 20 & mcd & 52,749.868 & 0.0678 & 35.7 & @xmath173 & 0.100 & 1.000 & @xmath174 & 0.10 + 2003 apr 21 & mcd & 52,750.881 & 0.1637 & & @xmath175 & & 0.000 & & @xmath176 + 2003 sep 06 & mcd & 52,888.661 & 0.2118 & & 8.8 & & 1.000 & & 0.11 + 2003 sep 07 & mcd & 52,889.664 & 0.3068 & & 30.1 & & 1.000 & & @xmath140 + 2004 feb 09 & mcd & 53,044.975 & 0.0150 & 75.0 & @xmath177 & 0.100 & 1.000 & @xmath178 & @xmath179 + 2004 mar 10 & mcd & 53,074.983 & 0.8569 & 14.3 & @xmath101 & 0.100 & 1.000 & 1.96 & @xmath180 + 2004 apr 10 & mcd & 53,105.944 & 0.7889 & & @xmath181 & & 0.000 & & 0.76 + 2004 apr 24 & kp & 53,119.942 & 0.1146 & 0.6 & @xmath182 & 0.025 & 0.500 & @xmath183 & @xmath174 + 2004 apr 26 & kp & 53,121.925 & 0.3024 & @xmath184 & 29.6 & 0.025 & 0.500 & 0.47 & @xmath167 + 2004 jun 14 & kp & 53,170.838 & 0.9345 & 62.4 & @xmath185 & 0.025 & 0.500 & 2.09 & 0.66 + 2004 jun 15 & kp & 53,171.771 & 0.0229 & 74.0 & @xmath186 & 0.025 & 0.500 & 2.95 & @xmath187 + 2004 sep 11 & mcd & 53,259.654 & 0.3456 & @xmath188 & 34.2 & 0.100 & 1.000 & @xmath114 & @xmath110 + 2004 sep 12 & mcd & 53,260.625 & 0.4375 & @xmath168 & 38.2 & 0.100 & 1.000 & 1.26 & @xmath189 + 2004 sep 13 & mcd & 53,261.620 & 0.5318 & @xmath190 & 34.8 & 0.100 & 1.000 & 1.23 & 0.16 + 2004 sep 13 & mcd & 53,261.685 & 0.5379 & @xmath191 & 34.3 & 0.100 & 1.000 & 2.07 & 0.14 + 2005 jan 29 & mcd & 53,400.003 & 0.6369 & @xmath141 & 21.6 & 0.100 & 1.000 & @xmath192 & @xmath178 + 2005 apr 27 & mcd & 53,487.910 & 0.9619 & 75.7 & @xmath193 & 0.100 & 1.000 & 0.00 & @xmath114 + 2005 apr 28 & mcd & 53,488.899 & 0.0556 & 48.0 & @xmath194 & 0.100 & 1.000 & 1.56 & 0.20 + 2005 jun 10 & kp & 53,531.732 & 0.1119 & 6.2 & @xmath195 & 0.025 & 0.500 & 2.55 & 0.25 + 2005 jun 13 & kp & 53,534.900 & 0.4119 & @xmath190 & 38.4 & 0.025 & 0.500 & 3.79 & 0.34 + 2005 jun 14 & kp & 53,535.789 & 0.4961 & @xmath188 & 37.6 & 0.025 & 0.500 & 1.56 & 0.77 + 2005 jun 15 & kp & 53,536.754 & 0.5875 & @xmath184 & 29.6 & 0.025 & 0.500 & 0.04 & 0.43 +    rlrrc rr lyn & primary & @xmath196 ( 15 ) & @xmath197 ( 5 ) & @xmath198 + & secondary & @xmath199 ( 15 ) & @xmath200 ( 5 ) & @xmath201 + 12 boo & primary & @xmath202 ( 17 ) & @xmath203 ( 6 ) & @xmath204 + & secondary & @xmath205 ( 17 ) & @xmath206 ( 6 ) & @xmath207 + hr 6169 & primary & @xmath208 ( 13 ) & @xmath209 ( 8) & @xmath210 + & secondary & @xmath211 ( 15 ) & @xmath212 ( 8) & @xmath213 +    lrrr @xmath214 ( days ) & 9.945080 & 9.9450740 & 9.945080 + & fixed & @xmath215 & @xmath216 + @xmath217 ( hjd ) & 2,438,048.97 & 2,444,988.49594 & 2,453,334.634 + & @xmath218 & @xmath219 & @xmath220 + @xmath59 & 0.081 & 0.0782 & 0.0793 + & @xmath221 & @xmath222 & @xmath222 + @xmath45 ( deg ) & 176.1 & 185 & 179.4 + & @xmath223 & @xmath224 & @xmath225 + @xmath47 ( km  s@xmath13 ) & 65.87 & & 65.65 + & @xmath226 & & @xmath227 + @xmath48 ( km  s@xmath13 ) & 83.1 & & 83.92 + & @xmath228 & & @xmath229 + @xmath49 ( km  s@xmath13 ) & @xmath230 & & @xmath231 + & @xmath232 & & @xmath233 + @xmath2 ( m@xmath7 ) & 1.88 & & 1.921 + & @xmath234 & & @xmath235 + @xmath3 ( m@xmath7 ) & 1.49 & & 1.503 + & @xmath236 & & @xmath237 + @xmath0 ( @xmath238 km ) & & & 8.950 + & & & @xmath235 + @xmath1 ( @xmath238 km ) & & & 11.441 + & & & @xmath239 + rms residual ( km  s@xmath13 ) & & & 0.11 + ( unit weight ) +    lr @xmath240 ( deg ) & @xmath241 + @xmath242 & @xmath243 + @xmath244 & @xmath245 + @xmath69 ( @xmath246 ) ( r@xmath7 ) & @xmath247 + @xmath248 ( m@xmath7 ) & @xmath10 + @xmath249 ( m@xmath7 ) & @xmath11 + @xmath250 ( r@xmath7 ) & @xmath8 + @xmath251 ( r@xmath7 ) & @xmath9 +    lrrr @xmath214 ( days ) & 9.6045492 & 9.604596 & 9.6045529 + & @xmath252 & @xmath253 & @xmath254 + @xmath217 ( hjd ) & 2,451,238.2729 & 2,452,400.4266 & 2,452,400.4292 + & @xmath255 & @xmath256 & @xmath257 + @xmath59 & 0.19233 & 0.19243 & 0.19268 + & @xmath258 & @xmath259 & @xmath260 + @xmath45 ( @xmath261 ) & 286.67 & 286.88 & 286.87 + & @xmath262 & @xmath263 & @xmath264 + @xmath47 ( km  s@xmath13 ) & 67.302 & 67.283 & 67.286 + & @xmath265 & @xmath266 & @xmath267 + @xmath48 ( km  s@xmath13 ) & 69.36 & 69.29 & 69.30 + & @xmath268 & @xmath227 & @xmath236 + @xmath49 ( km  s@xmath13 ) & 9.551 & 9.588 & 9.578 + & @xmath269 & @xmath239 & @xmath270 + @xmath2 ( m@xmath7 ) & & 1.218 & 1.218 + & & @xmath271 & @xmath271 + @xmath3 ( m@xmath7 ) & & 1.183 & 1.183 + & & @xmath271 & @xmath272 + @xmath0 ( @xmath238 km ) & & 8.720 & 8.720 + & & @xmath221 & @xmath273 + @xmath1 ( @xmath238 km ) & & 8.981 & 8.981 + & & @xmath235 & @xmath274 + rms residual ( km  s@xmath13 ) & 0.49 & 0.18 & 0.18 + rms residual ( km  s@xmath13 ) & & 0.10 & 0.11 +    lrr @xmath214 ( days ) & 10.56 & 10.559435 + & @xmath273 & @xmath275 + @xmath217 ( hjd ) & 2,422,422.236 & 2,453,171.529 + & @xmath276 & @xmath237 + @xmath59 & 0.430 & 0.4140 + & @xmath277 & @xmath278 + @xmath45 ( deg ) & 4.12 & 10.69 + & @xmath279 & @xmath280 + @xmath47 ( km  s@xmath13 ) & 62.41 & 71.35 + & @xmath281 & @xmath282 + @xmath48 ( km  s@xmath13 ) & 101.36 & 95.46 + & @xmath283 & @xmath284 + @xmath49 ( km  s@xmath13 ) & @xmath285 & @xmath286 + & @xmath287 & @xmath288 + @xmath2 ( m@xmath7 ) & 2.19 & 2.197 + & & @xmath277 + @xmath3 ( m@xmath7 ) & 1.35 & 1.642 + & & @xmath289 + @xmath0 ( @xmath238 km ) & 8.18 & 9.431 + & & @xmath269 + @xmath1 ( @xmath238 km ) & 13.28 & 12.618 + & & @xmath290 + rms residual ( km  s@xmath13 ) & 4.3 & 0.26 + ( unit weight ) +
radial velocities from the 2.1 m telescope at mcdonald observatory supplemented with radial velocities from the coud feed telescope at kpno provide new precise orbits for the double - lined spectroscopic binaries rr  lyn ( a3/a8/a6 ) , 12  boo ( f8iv ) , and hr  6169 ( a2v ) . 
 we derive orbital dimensions ( @xmath0 and @xmath1 ) and minimum masses ( @xmath2 and @xmath3 ) with accuracies of 0.06 to 0.9% . 
 the three systems , which have @xmath4 magnitudes of 5.54 , 4.83 , and 6.42 , respectively , are all sufficiently bright that they are easily within the grasp of modern optical interferometers and so afford the prospect , when our spectroscopic observations are complemented by interferometric observations , of fully - determined orbits , precise masses , and distances . in the case of rr  lyn , which is also a detached eclipsing binary with a well - determined orbital inclination ( @xmath5 ; khaliullin et al . 
 2001 ) , we are able to determine the semimajor axis of the relative orbit , @xmath6r@xmath7 , primary and secondary radii of @xmath8r@xmath7 and @xmath9r@xmath7 , respectively ; and primary and secondary masses of @xmath10m@xmath7 and @xmath11m@xmath7 , respectively . 
 comparison of our new systemic velocity determination , @xmath12 km  s@xmath13 , with the earlier one of @xcite , @xmath14 km  s@xmath13 , shows no evidence of any change in the systemic velocity in the 40 years separating the two measurements , a null result that neither confirms nor contradicts the presence of the low - mass third component proposed by @xcite . 
 our spectroscopic orbit of 12 boo is more precise that that of @xcite but confirms their results about this system . 
 our analysis of hr  6169 has produced a major improvement in its orbital elements . 
 the minimum masses of the primary and secondary are 2.20 @xmath15 0.01 and 1.64 @xmath15 0.02 m@xmath16 , respectively . 
 although all three systems have eccentric orbits , the six components of the systems are either pseudosynchronously rotating or very nearly so .