2. Observations and reductions

All observations reported in this paper were obtained with the 0.65-m Cassegrain reflector of the Ondejov Observatory installed at the Hvar Observatory of the Faculty of Geodesy, University of Zagreb, Croatia. A single-channel photoelectric photometer with an unrefrigerated EMI 6256S photomultiplier has been used (for more details on the instrumentation and reduction, see Harmanec et al. 1977a, Harmanec et al. 1994a and references therein).

Since 1972 until summer 1978 the data were recorded with a strip-chart recorder and a D.C. amplifier with 16 (later 15) gains in about 06 steps. Then, the recorder was replaced by a voltage-frequency digital converter with four decimal digits and thirty 05 gains defined by very stable resistors. The converter was designed at the Vienna University Observatory, and manufactured by Anton Paar, KG, in Graz, Austria. Careful calibrations of the gains of the original system were carried out, and properly used, in each observing season. The gains of the voltage-frequency converter turned out to be so stable that a mean calibration, based on several seasons of measurements, was invariably used in the final reductions.

The data reduction was carried out with the help of the reduction program HEC22 Rel. 12 (Harmanec et al.\ 1994a) which ensures a stable and accurate transformation into the standard Johnson UBV system. A careful determination of accurate UBV magnitudes of all comparison, check and standard stars by the same authors allowed to utilize virtually every measurement of standard and comparison stars on good nights to the definition of the nightly transformation coefficients (extinction, zero point and its derivative in each passband), thus ensuring the best possible reduction of the available data. The seasonal transformation coefficients were derived in such a way as to take into account all inevitable changes of the detection system, mirror alumunizations, etc.

A typical observing sequence consisted of 3 to 5 individual differential observations per star each night. Depending on the scatter of individual observations, we classified all observing nights into three categories, "excellent", "normal", and "poor" and assigned them weights 2, 1, and 0.5, respectively. Corresponding typical rms errors per one observation for all-sky observations are listed in Table 3 of Harmanec et al.\ (1994a).

The rms values for differential observations are generally lower. Judging by the results for the check stars, we estimate that the constant stars have the rms per one observation lower than 0015 in V and B and 0017 in U. There are, of course, other effects, affecting the accuracy. The accuracy is generally higher for later observations with the voltage-frequency converter and decreases for fainter stars and for stars with lower declination. In spite of the extent of our material, we are not able to properly evaluate all these effects on a statistical basis. Yet, we believe that some conclusions about variability or constancy are possible.

Table 1 (click here) gives the basic information about all objects ever observed in the course of the Be program at Hvar, including information about the comparison and check stars used. Mean UBV magnitudes of all program stars and the associated rms errors per one observation of unit weight are also given. It is seen that low-amplitude microvariables have rms errors only slightly larger than those of supposedly constant stars. Perhaps the best example is the well-known periodic variable LQ And, with a full amplitude of 004 in all three passbands, which has the rms errors of 0014, 0014, and 0018 in V, B and U, respectively. The rms errors should be treated with caution for stars with a small number of observations for which accidental larger errors can affect them substantially. It seems, however, that all stars with a sufficient number of observations (say over 30) and rms errors higher than 0015 in V and B and 0020 in U should be suspected of variability.

   

N HD HD

10 .013 .012 .011

2905 B1Iae 45307 46692 2 4.162 4.299 3.516 2626 2011

10 .012 .011 .016

4180 o Cas B0IVe 45212 47915 6 4.430 4.400 3.813 4142 6114

343 .038 .035 .033

5394 B5IIIe 45307 46692 2 2.208 2.095 1.082 2626 2011

10 .017 .019 .026

6811 B7Ve 45212 47915 6 4.248 4.185 3.831 4142 6114

148 .009 .010 .012

10516 B2Vep 44935 48278 8 4.017 3.935 3.027 12303 11291

180 .024 .031 .034

13854 HR 654 B1Iabe 44985 46691 2 6.468 6.743 6.101 12303 11291

13 .018 .009 .012

14818 10 Per B2Iae 44935 48277 6 6.244 6.545 5.951 12303 11291

104 .021 .023 .030

18552 HR 894 B8Vne 44860 46441 5 6.137 6.073 5.675 18411 19736

111 .010 .010 .011

- RX Cas (B5)+K1III 42603 45309 4 9.033 10.229 10.4 95 18962 19193

209 0.170 0.186 0.349

21551 HR 1051 B8Ve 45307 46689 4 5.842 5.803 5.486 21278 21362

29 .010 .007 .007

22192 B5Ve 45307 46689 4 4.205 4.118 3.532 21278 21362

29 .011 .008 .010

22780 HR 1113 B7Vne 44988 45359 2 5.579 5.511 5.093 21856 23193

34 .009 .008 .009

23016 13 Tau B9Vne 44863 44863 1 5.710 5.689 5.402 23324 23432, 23288

3 .006 .008 .002

23180 o Per B1IIIe 44988 45359 2 3.841 3.889 3.165 21856 23193

33 .014 .014 .014

23302 17 Tau B6IIIe 44863 44863 1 3.742 3.614 3.210 23324 23432, 23288

3 .001 .004 .000

23480 V971 Tau B6IVe 44863 44863 1 4.221 4.147 3.754 23324 23432, 23288

3 .001 .006 .005

23552 HR 1160 B8Vne 45307 46689 3 6.187 6.245 5.927 21278 21362

17 .008 .005 .007

23630 B7IIIe 44863 44863 1 2.896 2.777 2.426 23324 23432, 23288

3 .005 .005 .012

23862 BU Tau B8Vpe 43140 44863 2 5.291 5.242 5.046 23324 23432, 23288

Pleione 22 .017 .018 .062

25940 MX Per B3Ve 43136 46689 5 4.014 3.986 3.432 21278 21362

48 Per 32 .019 .014 .012

29866 HR 1500 B8IVne 44921 45689 3 6.087 6.152 5.849 33641 29722

27 .009 .009 .014

32343 BV Cam B2.5Ve 45308 45697 2 5.168 5.094 4.356 39283 34233

11 Cam 9 .019 .007 .008

36576 V960 Tau B2IV-Ve 44902 46694 5 5.659 5.674 4.909 36589 36819, 37711

120 Tau 95 .033 .026 .035

37202 B1IIIpe 43135 47614 9 2.921 2.718 1.949 36589 36819, 37711

699 .068 .082 .101

37967 V731 Tau B2.5Ve 43136 46694 6 6.246 6.172 5.543 36589 36819, 37711

107 .013 .010 .020

 

N HD HD

62 .017 .019 .022

43285 HR 2231 B6Ve 44993 45661 3 6.064 5.946 5.439 44783 43526

25 .010 .010 .015

47054 HR 2418 B8Ve 44902 45661 3 5.516 5.429 5.057 42690 41692

42 .010 .012 .014

50658 B8IIIe 45014 45661 3 5.878 5.801 5.367 49949 52860, 50973

27 .015 .013 .014

58050 OT Gem B2Ve 44977 46159 4 6.449 6.268 5.420 58187 59059

125 .020 .017 .038

58715 B8Ve 44977 46159 4 2.889 2.784 2.517 58187 59059

155 .011 .015 .017

109387 B6IIIpe 42237 46110 6 3.809 3.697 3.144 107193 112429

217 .025 .028 .030

138749 B6Vnne 44801 48116 5 4.161 4.031 3.504 144206 142373

113 .014 .019 .023

45916 45918 173664 172883

142926 V839 Her B7Ve 41528 48114 14 5.746 5.643 5.282 144206 145389

4 Her 296 .016 .018 .025

162732 V744 Her B6Ve 41535 48127 16 6.759 6.639 6.181 162132 162579, 158414

88 Her 385 .070 .077 .125

164284 V2048 Oph B2Ve 45105 45153 1 4.667 4.638 3.785 164432 163641

66 Oph 57 .015 .015 .017

164447 HR 6720 B8Vne 45065 48123 4 6.515 6.447 6.070 166182 164852

179 .020 .020 .024

166014 o Her B9.5V 45065 48123 4 3.847 3.811 3.780 166182 164852

179 .014 .022 .024

168797 NW Ser B3Ve 44433 48133 6 6.135 6.118 5.498 170200 169578

MWC 601 328 .022 .022 .029

174237 CX Dra B2.5Ve 42977 48128 12 5.909 5.831 5.108 173664 172883

1064 .057 .041 .070

180968 ES Vul B0.5IVe 46235 47374 4 5.435 5.474 4.698 180889 181751

2 Vul 219 .015 .016 .020

183656 V923 Aql B6e 44073 48128 10 6.070 6.070 5.757 183324 183227, 184663

408 .031 .035 .047

183914 B8Ve 46679 46695 1 5.149 5.059 4.743 188260 180889, 181751

14 .006 .006 .004

184279 V1294 Aql B0.5IVe 44073 48128 10 7.050 7.111 6.405 183324 183227, 184663

405 .115 .108 .158

185859 HR 7482 B0.5Iae 46679 46695 1 6.498 6.887 6.277 188260 180889, 181751

14 .008 .007 .008

187399 V1507 Cyg B8IIIe 43014 43760 3 7.016 7.176 6.767 188170 186357

199 0.041 0.036 0.047

187811 12 Vul B2.5Ve 46679 46695 1 4.929 4.770 4.093 188260 180889, 181751

15 .006 .007 .013

189687 V1746 Cyg B3IVe 46245 47386 4 5.157 5.023 4.296 188892 193369

25 Cyg 132 .022 .014 .016

191610 V1624 Cyg B2.5Ve 42237 43019 7 4.950 4.803 4.030 many many

28 Cyg 360 .030 .030 .036

46262 47791 188892 193369

192044 20 Vul B7Ve 44794 48128 6 5.915 5.803 5.351 190993 191747

120 .011 .012 .015

 

N HD HD

HR 7739 144 .053 .040 .055

193237 P Cyg B2pe 46287 47376 3 4.770 5.181 4.616 188892 193369

113 .030 .031 .033

193911 25 Vul B8IIIne 44817 48128 6 5.533 5.440 5.008 190993 191747

115 .010 .012 .017

194335 HR 7807 B2Ven 46238 47022 3 5.859 5.695 4.752 188892 193369

142 .028 .026 .038

195554 MWC 637 B9Vne 44431 47443 7 5.908 5.847 5.637 197770 194668, 194883

126 .012 .015 .017

198478 V1661 Cyg B3Iae 41528 47791 5 4.821 5.219 4.778 199311 199479

55 Cyg 113 .024 .024 .028

198625 HR 7983 B4Ve 46696 46696 1 6.395 6.339 5.786 199311 199479

3 .007 .005 .017

199478 HR 8020 B8Iae 46696 46696 1 5.694 6.147 5.816 201836

3 .008 .005 .003

200120 V832 Cyg B1ne 46258 47791 4 4.784 4.708 3.773 199311 199479

59 Cyg 127 .043 .030 .029

200310 V1931 Cyg B1Ve 46281 47791 4 5.397 5.202 4.274 199311 199479

60 Cyg 127 .028 .024 .035

201733 HR 8103 B4IVpe 46696 46715 1 6.623 6.483 5.817 199311 199479

9 .011 .009 .007

202904 B2Vne 44817 44818 1 4.352 4.263 3.428 204403 202349

6 .004 .006 .006

203467 6 Cep B3IVe 45536 48123 2 5.198 5.157 4.590 208218 202214

43 .014 .015 .021

205551 HR 8259 B9IIIe 45155 45194 1 6.176 6.164 5.906 207330 206259, 207793

18 .014 .017 .020

208392 EM Cep B1IVe 41954 48123 3 7.037 7.292 6.725 208218 202214

9 .049 .065 .065

214168 8 Lac B2Ve 43013 47791 8 5.727 5.572 4.684 214680 217101

125 .018 .020 .021

46673 46703 217101 214680

216057 MWC 393 B5Vne 44432 48115 9 6.147 6.067 5.573 218470 218407, 219080

204 .012 .012 .014

216200 V360 Lac B3IV:e 44473 47791 9 5.927 6.010 5.499 214680 217101

14 Lac 197 .021 .023 .026

46664 47458 217101 214680

217050 EW Lac B4IIIep 41534 41537 17 5.262 5.159 4.554 212593 218407, 219080

1112 .067 .075 .117

42240 48128 218470 219080

217543 MWC 395 B3Vpe 42261 47791 11 6.527 6.414 5.722 214680 217101

249 .026 .030 .039

217675 o And B6IIIpe 42614 42716 14 3.622 3.518 2.996 217782 214680

954 .035 .042 .052

42981 46340 214680 217101, 222439

46649 46715 217101 214680

46690 47061 214680 217101

47353 47458 217101 214680

218393 KX And B0:e 42261 48128 16 7.020 7.354 6.963 218470 218407

1197 .060 .070 .138

 

N HD HD

953 .029 .030 .043

224559 LQ And B4Ven 44433 44959 7 6.555 6.462 5.867 222439 224166

326 .014 .014 .018

45239 45269 222439 224166

45293 45344 223229 222439, 224166

45591 45646 223229 224166

46287 47457 223229 222439

225094 V639 Cas B3Iae 45307 46692 2 6.242 6.572 6.042 2626 2011

10 .022 .018 .020

Notes: Columns "From'' and "To'' contain JD-2400000 of the first and last observation of each star. "S'' is the number of seasons in which the given star was observed, and "N'' is the number of individual observations, respectively. The errors () quoted along with the mean UBV magnitudes are the rms errors of one observation of unit weight. They represent an objective measure of the level of variability of each observed star. Whenever available, the spectral types were taken from Slettebak (1982).

The standard UBV magnitudes of all comparison stars, adopted from Harmanec et al. (1994a), are given for convenience in Table 2. Table 3 gives the mean UBV magnitudes of all check stars used by us and their associated rms errors. For more frequntly observed stars these rms errors give an idea about the accuracy of observations and constancy of the comparison stars.

Some changes in the choice of comparison and check stars turned out inevitable because of a slight variability of the originally selected ones. This is documented individually in Table 1 (click here). Thanks to the new reduction, there are no or only negligibly small differences between the observations of the same variable relative to two or more different comparisons.

Complete differential and all-sky archives of all UBV observations secured in the course of the Be program at Hvar, along with the data retrieval program VYPAR, written by Dr. J. Horn (see Harmanec & Horn 1995) will be made available in a digital form in a separate publication (Harmanec et al. 1997).