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SLR Observations at the "Quasar" Network Stations
I.Gayazov, V.Mitryaev, S.Smolentsev, I.Rahimov, A.Diyakov, V.Shpilevski, V.Pshenkin, Ya.Rets
Institute of Applied Astronomy, Saint Petersburg, Russia

WPLTN-2012 September 24 - 28, 2012 Saint Petersburg


SLR systems installation at the "Quasar" observatories
Observatory Zelenchukskaya Badary Stage
Dome building System installation Testing Dome building System installation Testing Dome building System installation Testing Observatory
Zelenchukskaya Badary S v e tl o e

Apr May Jun

2011 Jul Aug Sep Oct Nov

Svetloe

Date of the first observations
18.05.2011 28.07.2011 25.10.2011


"Sazhen-TM" SLR system
«Research-and-Production Corporation "Precision Systems and Instruments"»
Main technical characteristics Ranging distance: day 400-6000 km night 400-23000 km Aperture 25 cm Wavelength 532 nm Beam divergence 12" Laser pulse frequency 300 Hz Laser pulse width 300 ps Pulse energy 2.5 mJ Mass 170 kg Normal points precision 1 cm Angular precision 1-2"


"Sazhen-TM" at Zelenchukskaya observatory


Cut-off angles for SLR systems at the stations SVEL (1888) ZELL (1889) BADL(1890)


Observations
· The regular software of SLR system developed by the producer is used for preparing the observation sessions and their implementation · The observational data from all stations in the initial format are collected at the Institute (IAA RAS) · The special software has been developed for pre-analysis and reduction of observational data

BADL 07 04 2012 Lageos 1


Statistics of observations January 1 - August 15, 2012
All satellites
Station 1888 1889 1890 Total number of passes 254 384 512 Number of Number of Used for % of Number RMS, processed registered NPs rejected of NPs mm passes pulses 206 364 456 683073 616431 9.8 1.5 2.3 1513 2682 6471 30.2 26.6 39.1

1448739 1426928 3234719 3159425

Lageos 1 & Lageos 2 satellites
Station 1888 1889 1890 Total number of passes 87 78 86 Number of Number of Used for % of Number processed registered NPs rejected of NPs passes pulses 73 74 81 48716 72492 139112 46775 71681 138125 4.0 1.1 0.7 382 527 896 RMS, mm

30.8 26.7 39.9


Program package for reduction of observations
Main features: · Statistical analysis of raw data · Forming Normal Points according to ILRS recommendations · Output normal point data in CSTG and CRD formats · Full automation of data reduction · Using the ILRS CRD_check utility to verify the CRD files c o n s i s te n c y Results: ­ Formal errors of normal points are about 5 mm. ­ On the average 4 % of returned pulses are rejected when preprocessing the observational data ­ Uploading the normal points in CRD format to EDC has been started in April 2012 ­ Disturbing facts (errors in the first version of the program)


Orbital analysis of L1&L2 observations
· The analysis of the observations quality is made now i n t h e c o u rs e o f f i t t i n g t o p re c i s e o rb i t s o f L a g e o s s a t e l l i t e s which are derived from observations of global network stations · Preliminary coordinates of reference points of the SLR systems, defined from local geodetic surveying with respect to GNSS antenna markers, are used

BADL 56024 MJD Lageos 1


1888 (SVEL) L1&L2 observations

Mean= -0.12 cm

Mean RMS= 1.02 cm


1889 (ZELL) L1&L2 observations

Mean= 0.37 cm

Mean RMS= 0.86 cm


1890 (BADL) L1&L2 observations

Mean= -1.49 cm !

Mean RMS= 1.12 cm


System delay calibration data 1888 (SVEL)


System delay calibration data 1889 (ZELL)


System delay calibration data 1890 (BADL)


Summary
· Normal points of L1 & L2 satellites have an accuracy about 1 cm · Further work to be done:
­ Full use of the time keeping system (H-maser) of observatories ­ Investigation of stability of the system delay measurements ­ Improvement of station coordinates ­ Development of more sophisticated program for primary data analysis based on algorithm accounting the essentially irregular distribution of signal registration moments


Thank you for your attention!