COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2187

                                 Konkoly Observatory
                                 Budapest
                                 1982 August 13

                                 HU ISSN 0374-0676





           A SINGLE NIGHT LIGHT CURVE OF 44i Boo *


    The W-Ursae Majoris type eclipsing binary 44 i Boo was observed on
the 7-8 April 1982. The observations were obtained with the 40 cm
reflector of the Rothney Astrophysical Observatory near Calgary, Canada,
using an uncooled RCA 1P21 and a V filter closely matching the standard
Johnson system.
    Sky conditions were non-photometric necessitating the use of
Calgary's Rapid Alternate Detection System, (Robb, et. al., 1982). This
system allows the measurement of the variable star, comparison star and the
appropriate sky values within a period of 1 second. Sixty of the 1-second
periods were added appropriately to give 1-minute integrations. Each
integration has been reduced to give differential magnitudes and comparison
star observed magnitudes. The largest variation of successive comparison
star measurements was 0.015 magnitudes per minute or 0.00025 magnitudes per
second. This is the first use of this system to observe a variable star
and an analysis of the errors of the system is in preparation.
    The comparison star used was SAO 45347, which has V = 8.1 mag and G5
spectral type. Since the difference in (B-V) of the comparison and
variable is 0.066 magnitude and the (B-V) color variation of 44 i Boo is
small (0.013), (H. W. Duerbeck, 1978), the differential magnitudes have
been transformed to the Johnson system with a constant additive term of -


* Rothney Astrophysical Observatory Publication, Series B, No. 9.


0.002 magnitudes. A constant nightly correction of +0.020 magnitudes was
added to the differential magnitudes to correct for the systematic
differing aspect of the instrument. Because the differential airmass never
exceeded 0.004, differential extinction is negligible.

                           [FIGURE 1]

          Figure 1. V light curve of 44i Boo on JD 2445067

The differential V magnitudes are shown plotted in Figure 1 against
heliocentric phase calculated with the ephemeris of Duerbeck, (1978).
Overlap of consecutive cycles lies between phases 0.23 and 0.25, increasing
the scatter of the data and emphasizing the need for single night light
curves. Phases of minimum light were found by a computer program based on
essentially the method of Kwee and Van Worden, (Chia, et. al., 1977), to be
0.0285 +- .0018 and 0.5232 +- .0014. A truncated four-term Fourier series
was fit to the intensity data including the brighter component between
phases 0.1 to 0.4 and 0.6 to 0.9. The coefficients normalized by A0 with
their usual meaning are A0 = 1.0 +- .0009, A1 = -0.0052 +- 0.0012,
A2 = -0.0395 +- .0014, B1 = -.0114 +- .0007, B2 = -0.0018 +- .0008. Assuming
the primary of the triple system is 1.45 times brighter than the variable
pair in V, as found by Bergeat, et. al. (1981), its effect can be removed
by dividing the non-A0 terms by 2.45. The A1 and A2 coefficients are then
not significantly different from those reported by Duerbeck, (1978) for the
years 1975, 1976 and 1977. The B1 term is very much larger, however, since
the difference in maxima is 0.035 magnitudes. Thus one can see from the
O-C's that the period has changed and from the light curve that 44 i Boo is
again in the active phase.





               R. M. ROBB
               Physics Department
               University of Victoria
               Victoria, B.C.
               Canada V8W 2Y2

               E. F. MILONE
               Rothney Astrophysical Obs.
               Physics Department
               University of Calgary
               Calgary, Alberta T2N 1N4
               Canada





References:

Bergeat J., van't Veer F., Tunel M., Garnier R., Sifille F. and Roux S.,
   1981, Astron. Astrophys., 94, pp. 350-358 [BIBCODE 1981A&A....94..350B ]
Chia T., Milone E., and Robb R., 1977, Ap. Space Sci., 48, pp. 3-19 [BIBCODE 1977Ap&SS..48....3C ]
Duerbeck H., 1978, Astron. Astrophys. Supp., 32, pp. 361-374 [BIBCODE 1978A&AS...32..361D ]
Robb R., Milone E., Babbot F., Hansen C., and Swadron D., 1982, BAAS
   Vol. 14, No. 1, p. 574 [BIBCODE 1982BAAS...14..574R ]


                       [DATAFILE 1]




                  CORRIGENDUM

   In I.B.V.S. No. 2166 the 2nd sentence "From uvby photometry
obtained in 1970 ..." should read "From uvby photometry obtain-
ed in 1978, 1979 and 1980 ...".

                             C. STERKEN