Some differential reference stars catalogues around extragalactic radio sources obtained from photographic and CCD-observations at different observatories are considered. Compiled catalogue of star positions in fields of 30 ×30  is intended for reduction of ERS optical observations using the telescopes equipped with CCD-cameras. Photographic observations of the fields around 74 ERS were made at the Pulkovo Observatory, around 115 ERS – at the AO KNU, around 188 ERS – at the AIRA in Bucharest. The 208 fields around ERS at NAO using the telescope equipped with a CCD-camera were obtained. The first results of the creation of uniform compiled catalogue are given. Astrometric positions for stars brighter than 16 magnitude in more than 20 fields around ERS are presented. A comparison of our results with those of other authors is made

Bocsa, G.

Dement'eva, A.

Kleschenok, V.

Maigurova, N.

Narizhnaya, N.

Pinigin, G.

Popescu, P.

Protsyuk, Yu.

Ryl'kov, V.

Kinematika i fizika nebesnyh tel (Online)

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REFERENCE STARS COMPILED CATALOGUEAROUND EXTRAGALACTIC RADIO SOURCES.REDUCTION TECHNIQUES AND THE FIRST RESULTSV. Ryl’kov1, A. Dement’eva1, N. Narizhnaya1, G. Pinigin2, N. Maigurova2,Yu. Protsyuk2, V. Kleschenok3, G. Bocsa4, P. Popescu41Main (Pulkovo) Astronomical Observatory, RAS (MAO RAS)65/1 Pulkovskoye Shosse, 196140 St.-Petersburg, Russiae-mail: vryl@gao.spb.ru2Research Institute “Nikolaev Astronomical Observatory”, MES of Ukraine (NAO)1 Observatorna Str., 54030 Mykolaiv, Ukrainee-mail: pinigin@mao.nikolaev.ua3Astronomical Observatory, National Taras Shevchenko University of Kyiv (AO KNU)3 Observatorna Str., 04053 Kyiv, Ukrainee-mail: klev@observ.univ.kiev.ua4Astronomical Institute of the Romanian Academy (AIRA)5 Cutitul de Argint Str., Bucharest, Romaniae-mail: petre@aira.astro.roSome diﬀerential reference stars catalogues around extragalactic radio sources obtained from pho-tographic and CCD-observations at diﬀerent observatories are considered. Compiled catalogueof star positions in ﬁelds of 30′× 30′ is intended for reduction of ERS optical observations usingthe telescopes equipped with CCD-cameras. Photographic observations of the ﬁelds around 74 ERSwere made at the Pulkovo Observatory, around 115 ERS – at the AO KNU, around 188 ERS –at the AIRA in Bucharest. The 208 ﬁelds around ERS at NAO using the telescope equipped witha CCD-camera were obtained. The ﬁrst results of the creation of uniform compiled catalogue aregiven. Astrometric positions for stars brighter than 16 magnitude in more than 20 ﬁelds aroundERS are presented. A comparison of our results with those of other authors is made.INTRODUCTIONTo connect optical and radio astrometrical coordinate systems it is very important to observe common objectsboth in optic and radio waves. As the most ERS are very faint it is possible to resolve this problem in opticalrange with ground-based telescopes using CCD-detectors. Currently, many programs are made to establishreference frame around astrometrical extragalactic radio sources (ERS) [1, 4, 5]. This frame is needed toobserve ERS in optical range with suﬃcient accuracy without multistage link from the faint determined objectsto the bright reference stars.We have four original star catalogues. These catalogues were obtained to observe faint ERS in future witha CCD-camera [1]. Three of these catalogues were photographically obtained using the astrographs, and one ofthem was obtained with the Axial Meridian Circle equipped with a CCD-matrix (see Table 1). Photographicobservations have been obtained with the Normal Astrograph (330/3464) at the Pulkovo Astronomical Ob-servatory (MAO RAS) in the 1990s – 74 ERS ﬁelds (35 are calculated). 115 ERS ﬁelds have been obtainedwith the Astronomical Observatory, National Taras Shevchenko University of Kyiv (AO KNU) Astrograph(200/4126). 188 ERS ﬁelds have been performed with the Double Astrograph (380/600) at the AstronomicalInstitute of the Romanian Academy (AIRA) in Bucharest. 208 ERS ﬁelds have been derived with the AxialMeridian Circle (180/2480) using a CCD-matrix at the Nikolaev Astronomical Observatory.These four catalogues have been reduced to about the same epoch. In order to increase the star positiondensity and accuracy around ERS it was decided to compile these four catalogues. Since they were obtainedwith diﬀerent telescopes and image registration techniques it was needed to link their position to common epochand to analyze the systematic coordinates diﬀerences of the same stars.c© V. Ryl’kov, A. Dement’eva, N. Narizhnaya, G. Pinigin, N. Maigurova, Yu. Protsyuk, V. Kleschenok, G. Bocsa, P. Popescu, 2004328Table 1. Catalogues included to the reference stars compiled cataloguePlace Name Type Size Number Number Observation Numberof observations of catalogue of observations of ﬁelds, min of ﬁelds of stars epochMykolaiv AMC1B CCD 60×24 208 14403 1996–1998 12–14Bucharest PIRS-B Photo 60×60 188 4700 1991–2000 12–15Pulkovo Pul ERS Photo 35×35 35 4500 1991–1995 10–16Kyiv PIRS-K Photo 60×60 115 2875 1989–1993 12–15THE COMPARISON OF CATALOGUESThe proper motions for considerable part of stars were taken from the Catalogue positions and proper motions(UCAC) which consists of 48 millions of stars. It is clearly that the four considering catalogues are diﬀerone from another, i.e., they will be included in compiled catalogue with diﬀerent weights. The catalogue ofthe Nikolaev Observatory consist of the most measurements of alone star: up to 6. The catalogue of the PulkovoObservatory is situated at the second place: from 3 to 5 plates for ﬁeld. All the others have one measurementof each star of the ﬁeld. All catalogues have the weights for compiled catalogue which are equals the number ofstars measurements.Therefore, in order to detect the systematic diﬀerences some ﬁelds from the AMC1B and Pul ERS catalogueshave been compared, because the most coincided stars are included into them. The Mykolaiv catalogues andthe Pulkovo catalogues have been reduced to equinox J2000.0 and the diﬀerences of positions for coincided starshave been calculated. The mean diﬀerences and their errors are given in Table 2.Table 2. The comparison of coincided stars of the AMC1B (Mykolaiv) and Pul ERS (Pulkovo) cataloguesN Name Number of stars in ﬁeld Mean (O–C)of ﬁeld Mykolaiv Pulkovo Coincided RA Err DEC Err1 0026+346 106 148 57 −0.006 0.047 −0.41 0.432 0133+476 206 159 76 0.024 0.047 −0.27 0.353 0355+508 82 117 45 0.010 0.034 −0.21 0.314 0420+417 76 112 28 0.017 0.045 −0.34 0.445 0552+398 235 148 57 0.009 0.033 −0.13 0.366 0923+392 21 56 11 −0.060 0.026 −0.50 0.767 2200+420 278 92 53 0.007 0.041 −0.19 0.388 2337+264 98 92 44 0.018 0.036 −0.23 0.559 2351+456 78 110 25 −0.040 0.047 0.03 0.38Figure 1. The residuals in RA and DEC for 76 coincided stars in ERS 0133+476 ﬁeldWe can practically see obvious negative component in declination for all nine ﬁelds. The lesser positivecomponent take place in right ascension. If stars of this ﬁeld from AMC1B to compare with coincided starsfrom Tycho-2, then mean diﬀerence is −0.006s± 0.055s in RA and systematic AMC1B coordinate overstatingis keeping: −0.22′′± 0.29′′. This fact needs in additional investigations for all stars ﬁelds.329Figure 2. The residuals in RA and DEC for 28 coincided stars in ERS 0133+476 ﬁeldTHE COMPILED CATALOGUE2503 stars of the main catalogue have been included in the former version of compiled catalogue for 25 referencestars ﬁelds around ERS by means of mutual identiﬁcations coincided stars. These stars have proper motions inUCAC. Their positions have been obtained from other compiled catalogues not coincided with main catalogue.Coordinates of all stars are referred to J2000.0. Initial data for each included catalogue and the ﬁrst results offormer version compiled catalogue for 25 ﬁelds are given in Table 3.Table 3. The number of stars of reference stars compiled catalogue for ERSN Name Main Number Starsof ﬁeld Pulkovo Mykolaiv Bucharest Kyiv catalogue of stars all∗1 0026+346 164 116 55 25 P 148 2012 0133+476 174 228 66 24 M 206 2863 0355+508 165 146 63 25 P 117 1874 0420+417 159 87 51 25 P 112 1605 0552+398 165 260 66 25 M 235 3256 0923+392 61 23 63 26 P 56 647 1641+399 145 133 55 24 P 131 1568 1652+398 120 133 54 25 M 101 1499 2200+420 107 309 68 25 M 278 32710 2319+272 72 112 72 25 M 65 11511 2337+264 104 112 47 25 M 98 14612 2351+456 119 91 62 25 P 110 16313 0234+285 – 93 74 25 M 90 13614 0400+258 – 80 65 25 M 73 10715 0420–014 – 123 71 22 M 55 6116 0440–003 – 44 59 25 M 39 4217 0457+024 – 81 66 (25) M 71 11118 0458–020 – 86 25 24 M 34 6219 0500+019 – 81 66 (25) B 53 7420 0528+134 – 11 68 25 K 23 3321 0711+356 – 106 54 24 M 95 13022 0735+178 – 89 55 25 M 80 10723 0738+313 – 96 54 24 M 88 11124 0748+126 – 97 45 25 M 91 10925 0906+015 – 62 64 22 M 54 91The table consists of the number of stars in working catalogues, the initial catalogue (P – Pulkovo, M –Mykolaiv, B – Bucharest, K – Kyiv), and the number of stars in compiled catalogue – common at workingcatalogues and with the addition of stars from separate catalogues.The equatorial coordinates of more than 3400 stars have been calculated for 25 ﬁelds around extragalacticradio sources. They were reduced to epoch J2000.0 in the ICRS frame. Practically, all the ﬁelds included morethan 100 stars around ERS by diameter 35–40 arcminutes.330THE FARTHER WORKAll the processes of compiled catalogue creation will be carried out by three stages.Stage 1. Obtaining compiled catalogue of reference stars to epoch J2000.0 by using the data from four above-mentioned catalogues. Other catalogues (UCAC, CaMC, PPM) are used for proper motions. The problem hasbeen solved to take into account the catalogues weights equaled to number of measurements. The ﬁrst resultsof this stage for 25 catalogues are given in Table 3. For this stage it is supposed to obtain 35 ﬁelds for Pul ERScalculated catalogues.Stage 2. Stars without proper motions will be added to 35 catalogues. It is the stars that are absent infamous catalogues. Positions for epochs of star observations will be appeared in the compiled catalogue. So, ifepoch diﬀerences for faint stars are not more than three years, the mean coordinates may be obtain.Stage 3. The same investigations will be made for another three catalogues. In order to take into accountthe AMC1B catalogue based on CCD-observations, as a main catalogue, it is necessary to analyze accurately itssystematic deviations. The analysis might be made using the stars with proper motions from other catalogues.Coordinates of these stars will be compared with these ones from the Tycho-2, CaMC, UCAC [6] or USNO-B [3].Taking into account that more than billion stars are included in the USNO-B catalogue, the importance of ourcatalogues to be increased, the accuracy of reference star positions is invaluable.Figure 3. The map of the stars ﬁeld around ERS 1418+546. Size of the interior ﬁeld is 30′× 30′. The star number iscorresponded to star number in catalogueFORMAT OF THE FORMER VERSION OF THE CATALOGUEPreliminary compiled catalogue are given in the next format – 110 positions are given for each star. The co-ordinates are in radians and in integer format without blank. All star positions recalculated to epoch J2000.0using the proper motions from UCAC.Positions1 – 4 the star number by given catalogue;5 – 11 the magnitude (from UCAC or obtained by observer);12 – 28 RA in radian at observation epoch to ICRS system for J2000.0 equinox;29 – 34 the error of mean RA, 0.001s;35 – 37 the number of RA observations;38 – 53 DEC in radian at observation epoch to ICRS system for J2000.0 equinox;54 – 59 the error of mean DEC, 0.001′′;33160 – 62 the number of measurements that are used to obtained declination;63 – 65 the inclusion index (0 or 1) of the AMC1B catalogue;66 – 67 the inclusion index (0 or 1) of the PIRS-B catalogue;68 – 69 the inclusion index (0 or 1) of the PIRS-K catalogue;70 – 71 the inclusion index (0 or 1) of the Pul ERS catalogue;72 – 83 RA of star in integer format HHMMSSDDD;84 – 94 DEC of star in integer format ±GGMMSSDD;95 – 102 the proper motion RA, mas/yr (without cos δ );103 – 110 the proper motion DEC, mas/yr.THE MAP OF THE STARS FIELD AROUND ERSIn order to comfort detected stars ﬁeld, when observations are made with a CCD-detector, every stars ﬁeld hasa map in pcx-format. In Fig. 3 the example of such map is given.The positions of detected stars will be assumed to compare with selective stars from the ERL398 [5] andUCAC catalogues. All versions of the catalogues for ERS are kept in magnetic tapes at the Laboratory ofAstrometry and Star Astronomy of the MAO RAS. These ﬁelds will be good standards to following observationsof the faint stars.[1] Babenko Yu., Daniltsev A., Vertypolokh A., et al. // Rom. Astron. J.–2003.–13, N 1.–P. 77–81.[2] Dement’eva A., Ryl’kov V. The Fields of Reference Stars for Optical Positional Observations of AstrometricExtragalactic Radio Sources // Astron. and Astrophys. Transactions.–1995.–9.–P. 127–138.[3] Monet D. G., Levine S. E., Canzian B., et al. The USNO-B Catalog // Astron. J.–2003.–125.–P. 984–993.[4] Ryl’kov V., Dement’eva A., Narizhaja N. Catalogues of stars for CCD-observations of galactic and extragalacticradio sources // Extension and Connection of reference frames using ground based CCD technique / Ed. G. Pinigin.–2001.–P. 35–42.[5] De Vegt C., Hindsley R., Zacharias N., Winter L. A Catalog of Faint Reference Stars in 398 Fields of ExtragalacticRadio Reference Frame Sources // Astron. J.–2001.–121.–P. 2815–2818.[6] Zacharias N., Raﬀerty T. J., Zacharias M. I. The UCAC Astrometric Survey // Astronomical Data AnalysisSoftware and Systems IX: ASP Conf. Ser / Eds N. Manset, C. Veillet, D. Crabtree.–San Francisco: ASP, 2000.–216.–P. 427.332

Reference stars compiled catalogue around extragalactic radio sources. Reduction techniques and the first results

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Reference stars compiled catalogue around extragalactic radio sources. Reduction techniques and the first results

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