Research Paper J. Astron. Space Sci. 29(2), 151-161 (2012) http://dx.doi.org/10.5140/JASS.2012.29.2.151 Stars,Technical Companions, Paper and their Interactions: A Memorial to Robert H. Koch J. Astron. Space Sci. 28(4), 345-354 (2011) V700http://dx.doi.org/10.5140/JASS.2011.28.4.345 Cygni: A Dynamically Active W UMa-type Binary Star II † Chun-HweyImplementation Kim1,2 and and Jang Validation Hae Jeong1,2 of Earth Acquisition Algorithm for 1Department of Astronomy and Space Science, Chungbuk National University, Cheongju 361-763, Korea 2Communication,Chungbuk National University Ocean Observatory, and Chungbuk Meteorological National University, Satellite Cheongju 361-763, Korea Sang-wook Park1, Young-ran Lee1, Byoung-Sun Lee2, Yoola Hwang2, and Un-seob Lee1† An1Ground intensive Systems analysis Division, of 148 Satrec timings Initiative, of V700 Daejeon Cyg 305-811,was performed, Korea including our new timings and 59 timings calculated from2Satellite the System super Researchwide angle Team, search Electronics for planets and Telecommunications (SWASP) observations, Research and Institute, the dynamical Daejeon evidence305-700, Korea of the W UMa W subtype binary was examined. It was found that the orbital period of the system has varied over approximately 66y in two complicated cyclical components superposed on a weak upward parabolic path. The orbital period secularly increasedEarth acquisition at a rate is to ofsolve +8.7 when (±3.4) earth × can10-9 be day/year, visible from which satellite is one after order Sun acquisition of magnitude during lower launch than and earlythose opera obtained- by previoustion period investigators. or on-station The satellite small anomaly. secular Inperiod this paper, increase the isalgorithm interpreted and testas a result combination of the Communication, of both angular Ocean momentum lossand Meteorological(due to magnetic Satellite braking) (COMS) and Earth mass-transfer acquisition from are presented the less massivein case of component on-station satellite to the moreanomaly massive status. component. The Onealgorithms cyclical for componentthe calculation had of a Earth-pointing 20.y3 period withattitude an controlamplitude parameters of 0.d0037, including and thethose other attitude had directiona 62.y8 period vector, with an amplituderotation matrix, of 0. andd0258. maneuver The components time and duration had an are approximate based on COMS 1:3 relation configuration between (Eurostar their periods3000 bus). and The a coordinate1:7 ratio between theirsystem amplitudes. uses the reference Two plausible initial frame. mechanisms The constraint (i.e., calculatingthe light-time available effects time-slot [LTEs] tocaused perform by thethe earth presence acquisition of additional bodiesconsiders and eclipse, the Applegate angular separation, model) solarwere local considered time, and as infra-red possible earth explanations sensor blinding for conditions.the cyclical The components. results of Elec Based- on tronics and Telecommunications Research Institute (ETRI) are compared with that of the Astrium software to validate the the LTE interpretation, the minimum masses of 0.29 M⊙ for the shorter period and 0.50 M⊙ for the longer one were calculated.implemented The ETRI total software. light contributions were within 5%, which was in agreement with the 3% third-light obtained from the light curve synthesis performed by Yang & Dai (2009). The Applegate model parameters show that the root meanKeywords: square Earth luminosity acquisition, variations attitude control (relative parameter, to the luminosities time-slot, communication, of the eclipsing ocean components) and meteorological are 3 times satellite smaller than the nominal value (∆L/Lp,s ≈ 0.1), indicating that the variations are hardly detectable from the light curves. Presently, the LTE interpretation (due to the third and fourth stars) is preferred as the possible cause of the two cycling period changes.1. INTRODUCTION A possible evolutionary implication for the V700 Cygsun acquisitionsystem is discussed. is completed, the position of the earth is kept in the vision of the satellite by adjusting the three- KeCommunication,ywords: W UMa-type Ocean star, and V700 Meteorological Cyg, period change, Satellite light-time axis effects,attitude ofmagnetic the satellite activities with reference to the relative (COMS, Chollian) was launched on July 26, 2010 and is position of the sun and the satellite. When the initial at- now in operation successfully (Lee et al. 2011). COMS titude of the satellite is stabilized, the normal attitude is Satellite Ground Control System (SGCS) is developed by kept by obtaining the field of view (FOV) toward the earth 1. INTRODUCTION star is 374K cooler than the less massive 0.60 M⊙ star with a Electronics and Telecommunications Research Institute by means of the earth observation sensor. temperature of 5770 K. The fill-out factor is approximately (ETRI), and the algorithm of parameters and events for This paper describes mainly the earth acquisition pro- The eclipsing nature of V700 Cyg (OV 26, 2MASS 27% in moderate contact with one another. The O-C COMS satellite configuration is developed according cess after the sun acquisition in case that the status of J20310525 + 3847006, CCDM J20311 + 3847A, WDS J20311 diagram with the light elements (C = HJD 2445163.4896 + to the document provided from Astrium to ETRI (Laine COMS changes from on-station to abnormal. Based on + 3847A) was discovered by Whitney (1952) who classified 0.d340045602 E) by Niarchos et al. (1997) showed a short- 2006). the orbit information for the COMS earth acquisition, the d it asIn athe W launchUMa-type and binaryearly operation star with period a period (LEOP) of 0. or340048. in articleterm describes period instability.the method A closeto search physical the propercompanion time that was m Thethe situation first photoelectric where the attitudeBV light ofcurves a satellite with isan not O ’Connellnor- periodsapproximately considering 1.4 the fainter constraints in the forV bandpass calculating than the V700 Cyg effectmal, the (Max satellite II fainter attitude than is notMax known I) were and secured thus it byshould Niarchos appropriatewas noted time by when Eggen the (1967). earth acquisitionV700 Cyg was can later be per catalogued- etbe al.fixed (1997) to a specific who studied direction global in order photometric to acquire properties the nor- of formedas CCDMfollowing J20311+3847A the sun acquisition. (Dommanget In case of & perform Nys 2002)- and themal systemattitude. through The position light curve of the synthesis sun is used as wellas the as ref period- ing theWDS earth J20311+3847A acquisition for(Mason COMS et at al. the 2001). selected The one earlier of history study.erences According to fix the satellite to those attitude authors, in aV700 specific Cyg direction. is a W UMa the calculatedwas well summarized time period, by the Niarchos algorithm et andal. (1997). simulation W-subtypeThe sun acquisition binary star refers with to thethe process spectral to type fix the of satelG5V- and result forIn attituderecent years, maneuver V700 process, Cyg was maneuver revisited time by Qian and (2003), lite attitude with reference to the solar position. Once the duration is verified. The actually realized earth acquisi- an orbital inclination of 79.9°. The more massive 0.92 M⊙ Molik & Wolf (2004), Xiang et al. (2009) and Yang & Dai This isis anan Open open Access Access article article distributed distributed under under the termsthe terms of the of the ReceivedReceived Nov 15, May 2011 20, Revised 2012 Revised Nov 23, May 2011 26, Accepted 2012 Accepted Nov 25, 2011May 28, 2012 Creative Commons Commons Attribution Attribution Non-Commercial Non-Commercial License License (http://cre (http://- †Corresponding†Corresponding Author Author creativecommons.org/licenses/by-nc/3.0/)ativecommons.org/licenses/by-nc/3.0/) which which permits premits unrestricted unrestricted non-commercial use, use, distribution, distribution, and and reproduction reproduction in any in medium,any medium, E-mail:E-mail: [email protected] [email protected] provided thethe originaloriginal work work is is properly properly cited. cited. Tel: +82-42-365-7919Tel: +82-43-261-3139 Fax: +82-42-365-7500 Fax: +82-43-274-2312 Copyright © The Korean Space Science Society 345 http://janss.kr pISSN: 2093-5587 eISSN: 2093-1409 Copyright © The Korean Space Science Society 151 http://janss.kr plSSN: 2093-5587 elSSN: 2093-1409 J. Astron. Space Sci. 29(2), 151-161 (2012) (2009). Qian (2003) obtained new light elements (C = HJD is a discussion of the implications of existing working 2449999.3003 + 0.d29063148 E) and noted that the short- hypotheses. term period instability detected by Niarchos et al. (1997) is not real but is caused by the use of an incorrect longer period. They also suggested that the orbital period varied 2. OBSERVATIONS AND TIMES OF MINIMA in a cyclical manner with a period of 40y and an amplitude of 0.d0095, which was superposed on a secular period The CCD photometric observations of V700 Cyg for the increasing at a rate of +8.41 × 10-8 d/yr. Molik & Wolf (2004) purpose of timing determination were made on the nights independently analyzed the times of minima that were of November 4 and 12 in 2008 with the 35 cm campus available to them and found only a cyclic period change station reflector at the Chungbuk National University of 46y without any secular change. Yang & Dai (2009) Observatory in Korea. The telescope was equipped with confirmed the result of Qian’s (2003) period study and an SBIG ST-8 CCD imaging system and electrically cooled obtained a cyclic period of 54y, with an amplitude of 0.d0212 with a 19' × 12'field of view. No filters were used in our longer than those identified by Qian (2003) and Molik observations. GSC 3152-527 and GSC 3153-193 were & Wolf (2004). Yang & Dai (2009) derived the rate of the chosen as the comparison and check stars, respectively. secular period increase as +2.89 × 10-8 d/yr, 3 times smaller The instrumentation used and reduction method for the than that of Qian (2003).