COMMISSIONS 27 AND 42 OF THE IAU 
              INFORMATION BULLETIN ON VARIABLE STARS 
                           Number 3789 
 
                                           Konkoly Observatory 
                                           Budapest 
                                           15 October 1992 
 
                                           HU ISSN 0374 - 0676 
 
        DO ALL THREE VARY: omicron UMa, 23 UMa AND HR 3245? 
 
 
 Jackisch (1963) had reported, on the basis of 16 observations between 
1954 and 1957, that omicron UMa (HR 3323, NSV 4093) was variable by 0.08V in 
a period of 358 days. He also indicated the possibility of a secondary 
period of 0.05 day with an amplitude of 0.02V. The recent NSV 
catalogue (Kholopov 1982) gives a range from 3.30 to 3.36V. However, 
these values come from the USNO catalogue of photelectric magnitudes 
(Blanco 1968) and do not not necessarily indicate the amplitude of the 
suspected variable, only the range of discordances among six observers 
using different equipment. In not one of the six determinations was 
any suspicion of variability mentioned. Jackisch fortunately indicated 
which two stars he had use to comparison, HR 3245 and 3757 (23 UMa, NSV 
4506). Both have subsequently been reported as variable. Henriksson 
(1977) found HR 3245 to be a possible eclipsing variable, 5.74V, amp. 
0.062V. HR 3757 had been announced by Lau (1914) as varying from 3.3 
to 3.8v in a short period. But a visual variation of only 0.5 mag is 
within the probable errors of naked-eye determination. The recent NSV 
gives 3.65-3.68V, but this again represents the discordance among five 
independent observers. 
 
 Clearly, all three of these stars (Table I) should be observed 
photoelectrically to ascertain which actually do vary, and determine 
types and periods for those that do. 
 
                               Table I 
HR     Name            NSV            (1950)            V    amp?    Per d 
3245    -               -     8h14m57s   + 62d39.8'   5.7   0.06 
3323   omicron UMa    4093    8 26  06   + 60 53.3    3.3   0.08?   358? 
3757   23 UMa         4506    9 27  37   + 63 16.9    3.7   0.03    short 


 
                                        DORRIT HOFFLEIT 
                                        Department of Astronomy 
                                        Yale University, Box 6666 
                                        New Heaven, CT, U.S.A. 
 
References: 
 
Blanco, V. M., et al., 1968, Publ. U. S. N. O., 21. 772pp  [BIBCODE 1968PUSNO..21....1B ]
 
Henriksson, G., 1977, Ast. and Astrophys., 54, 309  [BIBCODE 1977A&A....54..309H ]
 
Jackisch, G., 1963, Sonneberg Veroff., 5, 231 
 
Kholopov, P. N., 1982, New Catalogue of Suspected Variable Stars, 
  Moscow, 360pp  [BIBCODE 1982ncss.book.....K ]
 
Lau, H. E., 1914, A. N., 196, 425  [BIBCODE 1914AN....196R.425L ]