We briefly describe the status of the Onsala\ua0twin telescopes and the experience gained since the official\ua0inauguration in May 2017

Casey, Simon

Elgered, Gunnar

Haas, R\ufcdiger

Hammargren, Roger

Helldner, Leif

Hobiger, Thomas

Johansson, Karl-\uc5ke

Lerner, Mikael

Pantaleev, Miroslav

Pettersson, Lars

Wennerb\ue4ck, Lars

English

Chalmers Research

Status of the Onsala Twin Telescopes – One Year After theInaugurationDownloaded from: https://research.chalmers.se, 2020-01-17 16:22 UTCCitation for the original published paper (version of record):Haas, R., Casey, S., Elgered, G. et al (2019)Status of the Onsala Twin Telescopes – One Year After the InaugurationIVS 2018 General Meeting Proceedings "Global Geodesy and the Role of VGOS – Fundamental toN.B. When citing this work, cite the original published paper.research.chalmers.se offers the possibility of retrieving research publications produced at Chalmers University of Technology.It covers all kind of research output: articles, dissertations, conference papers, reports etc. since 2004.research.chalmers.se is administrated and maintained by Chalmers Library(article starts on next page)Status of the Onsala Twin Telescopes – One Year After theInaugurationRu¨diger Haas, Simon Casey, Gunnar Elgered, Roger Hammargren, Leif Helldner, Thomas Hobiger,Karl-A˚ke Johansson, Mikael Lerner, Lars Pettersson, Miroslav Pantaleev, Lars Wennerba¨ckAbstract We briefly describe the status of the Onsalatwin telescopes and the experience gained since the of-ficial inauguration in May 2017.Keywords VGOS, OTT, broadband observations1 IntroductionThe Onsala twin telescopes [1] are two identicalVGOS-type telescopes which are named ONSA13NEand ONSA13SW in IVS terminology. They aredesigned by MT Mechatronics and are equippedwith 13.2-m diameter main reflectors and ring-focussubreflectors. The telescopes were built during 2015–2017 [2] and inaugurated in connection with the 23rdWorking Meeting of the European VLBI group forGeodesy and Astrometry (EVGA) in May 2017, seeFigure 1.The telescopes are located at a distance of 70 m.There are two slightly different receiver systemsinstalled on the telescopes. ONSA13NE hosts areceiver with a QRFH-feed covering 3–18 GHz, whileONSA13SW is equipped with an Eleven-feed covering2.2–14 GHz [3]. Both feeds are dual-linear polarized.The two receiver systems are cryogenically cooled[4] and are connected to one phase and cable delaymeasurement system (CDMS) each. The two CDMSwere purchased from the MIT Haystack Observatory.The H-maser for the time and frequency distributionis located in the maser room at about a 1 km cableChalmers University of Technology, Department of Space, Earthand Environment, Onsala Space ObservatoryFig. 1 Picture taken during the inauguration of the Onsala twintelescopes in May 2017, with ONSA13SW on the left andONSA13NE on the right side. (Photo Onsala Space Observatory)distance from the telescopes. Each system has a digitalbackend of type DBBC3 with eight Core3H boards,which are located in the backend room within abouta 15 m distance from the observatory maser room.The signal chain for both the CDMS systems and thereceived signals from the telescopes to the backendroom uses optical fibers that are insulated against tem-perature variations. The two DBBC3s are connectedto a FlexBuff recorder that currently has a capacity of360 TB and is connected with a 10 Gbps connection tothe Swedish fiber backbone. Both telescope towers, aswell as the elevation and azimuth cabins, are equippedwith numerous temperature and humidity sensors tomonitor environmental changes.1718 Haas et al.2 VGOS Test ObservationsWe began participating in VGOS test experiments withthe two telescopes in the autumn of 2017. These wereprimarily performed with the current “Haystack VGOSsetup”, i.e. eight frequency bands of 32 MHz band-width each for four RF-bands and two polarizations,e.g. 64 frequency bands in total. First fringes in someof the frequency bands were found with ONSA13NEfor session VT7268 on 25/26 September 2017. A cou-ple of days later, first fringes in some RF-bands forONSA13SW were found in session MC7278 on 5/6October 2017. Based on the experience gained, thesystems were improved, and for VT7317 on 13/14November 2017, fringes in all bands and all polariza-tions were found for ONSA13NE. A comparable per-formance was achieved for ONSA13SW in VT8039,observed 8/9 February 2018.The ambitious plan to participate also in theCONT17-VGOS sessions could unfortunately notbe realized because it had not been proven beforeMk4/DiFX fourfit 3.19 rev 2315 0059+581.0410KU, 134-1828A, GSGGAO12M - ONSA13NE, fgroup X, pol Ixy8169.429.7815.674141.70.0e+00-0.001264-0.0026220.000672 -3.9366000.00001.000vt813436502018:134182814.00182844.00182829.002018:135:2239472018:135:2324382018:135:06503901h02m45.7624s+58˚24’11.137"Fringe qualitySNRInt timeAmpPhasePFDDelays (us)SBDMBDFringe rate (Hz)Ion TEC Ref freq (MHz)AP (sec)Exp.Exper #Yr:dayStartStopFRTCorr/FF/buildRA & Dec (J2000)Amp. and Phase vs. time for each freq., 6 segs, 5 APs / seg (5.00 sec / seg.), time ticks 5 secUValidityLG S3032.40 Freq (MHz)127.5 Phase3.2 Ampl.256.3 Sbd box0/30 APs usedU/L461.5 PC X delays (ns)G463.6 PC Y delays (ns)G682.2 PC X delays (ns)S675.4 PC Y delays (ns)S36:51 PC phaseG:S31:3 Manl PCG:SPC ampG 90107S3064.40138.53.8256.90/30459.4461.4683.4677.7105:-7331:14951063096.40146.94.0256.60/30458.2459.9682.8674.1-165:16132:15881123224.40144.93.6257.00/30455.4457.2680.2673.1-71:17835:1294773320.40139.94.6257.60/30455.1456.6680.2685.7-45:-13531:-481813384.40146.74.2257.10/30455.5457.2677.8680.9-151:4132:293733448.40130.13.1256.90/30455.7458.0675.2682.398:-10832:-2592583480.40139.13.4257.10/30457.1458.5680.2681.4-145:632:-1779655272.40141.35.4256.00/30790.2792.3676.6692.97:-9831:-695525304.40151.35.9256.40/30788.5789.1677.5692.8-102:-15635:294515336.40145.36.1256.50/30786.2786.9677.0692.8179:14533:582485464.40161.26.2256.80/30783.0784.8676.4691.2-51:-5631:786455560.40157.07.5257.40/30783.2784.3683.3692.0178:-14232:370585624.40154.16.9257.20/30783.5785.0683.7691.091:-4232:-480665688.40149.66.3257.20/30783.7785.1684.9691.8-13:4032:-1681785720.40147.55.8256.90/30785.0786.2683.2692.7-69:7728:-1368596392.40140.36.1255.90/30791.2793.2673.3685.066:-16032:1682556424.40140.66.8256.20/30787.5789.2673.1685.8-52:-17733:783496456.40137.76.9256.60/30785.6787.5672.1684.7-137:17132:1079446584.40126.35.6256.90/30783.1785.1674.0683.6-14:15533:884436680.40129.27.4257.40/30783.0784.5680.3685.2-149:9332:573456744.40121.07.7257.40/30783.1784.5680.5683.8126:-10232:280526808.40128.37.4257.00/30784.0784.9678.3682.636:9631:-177506840.40137.27.6257.00/30785.5786.1680.0684.4-18:-16828:-1684510232.40147.45.0255.60/30788.9789.8657.7667.7-12:3330:-10301110264.40150.35.2256.00/30785.8786.8659.0666.3-94:-16626:-18291410296.40144.35.0256.00/30784.4785.5659.5667.9-157:-1928:-13261510424.40148.05.5256.60/30781.7782.6659.6667.550:-15230:2251910520.40144.97.2257.60/30781.6782.5666.7675.7-9:-15532:4211910584.40146.57.1257.30/30782.3783.6666.6673.3-59:-2532:1272110648.40127.86.7257.10/30782.7783.6678.8674.4-122:7434:7262310680.40143.17.0257.20/30783.9784.3666.7675.2-155:-131:62220All141.75.7256.8Group delay (usec)(sbd)Sband delay (usec)Phase delay (usec)Delay rate (us/s)Total phase (deg)5.88653055959E+035.88653191795E+035.88653324757E+03-2.79719444486E-01174.7Apriori delay (usec)Apriori clock (usec)Apriori clockrate (us/s)Apriori rate (us/s)Apriori accel (us/s/s)5.88653318195E+035.2279350E+012.0399998E-07-2.79719556486E-01-5.15219039879E-05Resid mbdelay (usec)Resid sbdelay (usec)Resid phdelay (usec)Resid rate (us/s)Resid phase (deg)-2.62236E-03-1.26400E-036.56164E-051.12000E-07141.7+/-+/-+/-+/-+/-9.3E-071.0E-043.1E-071.8E-082.4RMS Theor. Amplitude 5.674 +/- 0.034 Pcal mode: MULTITONE,  MULTITONE PC period (AP’s) 1,  1 dTEC +/-  0.027ph/seg (deg) 0.6 0.8 Search (64X1024) 5.655 Pcal rate: 0.000E+00,  0.000E+00  (us/s) sb window (us)   -1.000    1.000amp/seg (%) 1.2 1.4 Interp. 0.000 Bits/sample: 2x2 SampCntNorm: disabled mb window (us)   -0.016    0.016ph/frq (deg) 9.7 1.9 Inc. seg. avg. 5.663 Sample rate(MSamp/s): 64 dr window (ns/s)   -0.005    0.005amp/frq (%) 24.7 3.3 Inc. frq. avg. 5.743 Data rate(Mb/s): 8192 nlags: 256 t_cohere infinite ion window (TEC)  -88.00    88.00G: az 317.8  el 49.5  pa 93.2 S: az 340.1  el 29.1  pa 20.6 u,v (fr/asec) 212.887  -528.785 simultaneous interpolatorControl file: cf_3641_meanval_GHEVYSI    Input file: /data-sc03/mike/vt8134/3650/134-1828/GS..0410KU    Output file: Suppressed by test modeSamplers: abcdefgh ijklmnop qrstuvwx yzABCDEF Fig. 2 Fringe plot of a scan observed during VT8134 on baselineGGAO12M-ONSA13NE. (Kindly provided by Mike Titus fromthe MIT Haystack Observatory.)CONT17 that the necessary system performance couldbe achieved.Figure 2 gives an example of a fringe plot for an ob-servation on the baseline GGAO12M to ONSA13NE.This fringe plot was kindly provided by Mike Titusfrom the MIT Haystack Observatory, who is corre-lating the VGOS test sessions. It becomes clear thatfringes were found in all frequency channels and bothpolarizations, but at that time the ONSA13NE systemhad some variations in the amplitude of the four IF-bands.Because the DBBC3 backends can be configuredflexibly in various different modes, we also started tocarry out test observations together with the Kashima34-m telescope using the “Kashima VGOS setup”, i.e.observing and recording complete 1-GHz windows.The first session, OK8051, was performed on 20February 2018 using one 1 GHz wide band in twopolarizations, and fringes were found.Table 1 gives an overview of all VGOS test sessionsthat one or both OTT participated in until June 2018.Table 1 Overview of the VGOS test sessions in whichONSA13NE (Oe) and ONSA13SW (Ow) participated betweenSeptember 2017 and June 2018. Both VGOS flavors, i.e.the “Haystack VGOS setup” (VT- and MC-sessions) and the“Kashima VGOS setup” (OK-sessions) were observed.Session date duration systemsVT7268 2017-Sep-25 24 h Oe –MC7277 2017-Oct-04 24 h Oe OwMC7278 2017-Oct-05 24 h Oe OwVT7303 2017-Oct-30 24 h Oe OwVT7317 2017-Nov-13 24 h Oe OwVT7331 2017-Nov-27 24 h – OwVT8039 2018-Feb-08 24 h – OwVT8060 2018-Mar-01 24 h Oe –VT8067 2018-Mar-08 24 h Oe –VT8078 2018-Mar-19 24 h Oe –VT8095 2018-Apr-05 24 h Oe –VT8109 2018-Apr-19 24 h Oe –VT8123 2018-May-03 24 h Oe –VT8134 2018-May-14 24 h Oe –VT8149 2018-May-29 24 h Oe –OK051 2018-02-20 1 h Oe –OK065 2018-03-06 1 h Oe –OK074 2018-03-15 1 h Oe –OK086 2018-03-27 20 h Oe –OK136 2018-05-16 1 h Oe –OK141 2018-05-21 20 h Oe –IVS 2018 General Meeting ProceedingsStatus of the Onsala Twin Telescopes 193 Conclusions and OutlookSince September 2017 we have participated in VGOStest sessions with one or both of the Onsala twin tele-scopes. We experienced a steep learning curve con-cerning, for example, the input RF-levels, the level ofphase calibration signals (PCAL), interaction betweenthe VLBI Field System (FS) and the DBBC3 back-ends, and operations as such. In general we achieved asteady improvement of the performance. Nevertheless,there are still aspects to improve, such as improved FS-DBBC3 communication, routine and simple determi-nation and monitoring of system temperature (Tsys)and system equivalent flux density (SEFD), and fine-tuning of the CDMS system.During the coming months we will thus continuethe fine-tuning of the VGOS systems in order to im-prove the performance. We aim at participating in allpossible VGOS sessions using all possible VGOS con-figurations. Our goal for 2018 is to gradually improvethe system performance, as well as reliability, in or-der to become fully operational in 2019 with bothONSA13NE and ONSA13SW.AcknowledgementsWe acknowledge the support provided by the Knut andAlice Wallenberg foundation and Chalmers Universityof Technology.References1. Haas R (2013) The Onsala Twin Telescope Project. In:N. Zubko and M. Poutanen (eds.) Proc. 21st EVGAWorkingMeeting, 61–65.2. Elgered G., Haas R, Conway J, Hammargren R, Helldner L,Hobiger T, Pantaleev M, Wennerba¨ck L (2017) The OnsalaTwin Telescopes: the Status at the Time for the Inaugura-tion. In: R. Haas and G. Elgered (eds.), Proc. 23rd EVGAWorking Meeting, 136–139.3. Flygare J, Pantaleev M, Billade B, Dahlgren M, Helldner L,Haas R (2017) Sensitivity and antenna noise temperatureanalysis of the feed system for the Onsala twin telescopes.In: R. Haas and G. Elgered (eds.), Proc. 23rd EVGA Work-ing Meeting, 10–14.4. Pantaleev M, Helldner L, Haas R, Johansson K-A˚, Petter-son L, Dahlstro¨m J, Dahlgren M, Kylenfall U, Billade B,Flygare J (2017) Design, implementation and tests of thesignal chain for the twin telescopes at Onsala Space Obser-vatory. In: R. Haas and G. Elgered (eds.), Proc. 23rd EVGAWorking Meeting, 15–19.IVS 2018 General Meeting Proceedings

Status of the Onsala Twin Telescopes – One Year After the Inauguration

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Status of the Onsala Twin Telescopes – One Year After the Inauguration

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