COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 3246

                                                         Konkoly Observatory
                                                         Budapest
                                                         3 October 1988

                                                         HU ISSN 0374 - 0676


      RADIAL VELOCITIES OF THE BINARY STAR HD 37020 (Theta-1 Ori A)

HD 37020 was discovered as an eclipsing binary by Lohsen (1975). Baldwin
(1976) and Franz (1977) estimated its period P=65.4325 days. A tentative
spectroscopic orbit was determined by Lohsen (1976) using the radial velocity
data available in the literature and Baldwin's period.
   Systematic observations of HD 37020 were made at the Brera-Merate Observatory, 
using the 137 cm Ruths telescope and the B&C spectrograph mod. 31523.
   The average of 13 photographic spectra taken in the range 3700-4700 A
allowed a re-classification of HD 37020 as a B3 III-IV star. Spectra were
also taken in the sub-range 4050-4450 A using a Reticon device (Bonanno et al.,
1984); in both cases the reciprocal dispersion was 35A/mm. Nebular lines were
adopted as a reference for radial velocities; at last, photographic and Reticon
results are perfectly compatible.
   Orbital elements (Table I) and a velocity curve (Figure 1) were obtained,
assuming the light minimum as phase zero and a period of 65.4325 days.
Radial velocities are listed in Table II.


                            [FIGURE 1]


                    Table I

              a1 sin i = 0. 184 A.U.
                  e = 0. 476
                  m = 201.7d
                  V0 = 3.9 km/sec + Vn (*)
                  T0 = J.D. 2444201.623
        (*)Vn is the radial velocity of the Orion Nebula


                              Table II

Julian Date   Velocity   Error       Julian Date   Velocity    Error

2446819.41      -26     +/- 12       2447184.33        5      +/- 8
    822.39        1          7           192.28        5          3
    824.28       12         12           194.27      -17         12
    827.28        2         11           197.36       -5         17
    829.29        1          7           203.26      -46         11
    834.29        5          9           204.27      -72         11
    849.32        1          4           205.27      -61         17
    850.31       -7          7           206.30      -59          4
    857.31        4         10           207.30      -38         17
    867.33       -4          8           208.28      -32          3
    872.29       -7          6           209.30      -48         17
    875.30      -30          8           211.31      -29         17
    877.32      -65         11           212.29       -1          8



                 M. BOSSI, M. SCARDIA, M. TADINI

                Osservatorio Astronomico di Brera
                       via E. Bianchi 46
                         22055 Merate
                           Italy



References:

Baldwin, M., 1976, I.A.U. Circular, No. 3004. [BIBCODE 1976IAUC.3004....1M ]
Bonanno, G., Falomo, R., Ascione, A. and Bergamini, U., 1984, Brera Technical
   Report No. 2.
Franz, O.G., 1977, I.B.V.S., No. 1274.
Lohsen, E., 1975, I.B.V.S., No. 988.
Lohsen, E., 1976, I.B.V.S., No. 1211.



                          [FROM IBVS 3267]


                               AMENDMENT

In the No. 3246 issue of the IBVS both Figure 1 and Table I contain
erroneous data. The correct version of the Figure and Table on
HD 37020 is given below


                   Table I

a_1 sin i = 0.171 AU
e         = 0.709
omega     = 182 deg
V_0       = -5.8 km/sec + V_n (*)
T_0       = J.D. 2444194.651

(*) V is the radial velocity of the Orion Nebula


                          [FIGURE 1b]


              M. BOSSI, M. SCARDIA, M. TADINI

             Osservatorio Astronomico di Brera
                   via E. Bianchi 46
                     22055 Merate
                        Italy