COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2444

                                      Konkoly Observatory
                                      Budapest
                                      13 December 1983

                                      HU ISSN 0374 -0676


                   EPSILON AURIGAE

The eclipsing variable epsilon Aurigae (period 27.06 years) began
fading from its normal magnitude (V=2.99) in August 1982, reached
its minimum in December 1982 (V ~~ 3.8) and it will reach its former
brightness from mid-December 1983 through June 1984.
This supergiant star (A8 Ia), at maximum, has its H_alpha-line
contaminated by two strong emissions. However, the outcome
equivalent width is only -0.04 A (Mendoza and Johnson, 1979). Yet,
this faint equivalent width is very easily detected with the
H_alpha -index, measured in the alpha(16)Lambda(9) photometric system (cf. 
Mendoza et al., 1983).
We have secured data for epsilon Aur in the alpha(16)Lambda(9) photometric
system with the Tonantzintla 1.0-m telescope (1977), and with the
San Pedro Martir 2.1 m telescope (1982 and 1983). The results are
given in Table I,

                     TABLE I

NARROW BAND PHOTOMETRY OF epsilon AUR
           (in magnitudes)
 alpha(16)  Lambda(9)    Date (U.T.)
--------------------------------------
    0.911     0.542  Jan 3,5,7,29; 1977*
    0.964     0.546  Sep 13 (11:47); 1982
    0.952     0.546  Sep 14 (12:10); 1982
    0.964     0.545  Sep 15 (11:15); 1982
    1.058     0.562  Nov 6  (11:54); 1983
    1.059     0.560  Nov 14 (09:53); 1983
--------------------------------------
* sigma(alpha,Lambda)=+-0.002 mag.


    The alpha(16)-index clearly indicates that the H_alpha -line of
epsilon Aur at minimum is less contaminated by emission. In 
particular, this index yielded an equivalent width, W(H_alpha)~~ 0
in September 1982, and W(H_alpha) >= 2A in November 1983 (see Table
I and loc. cit.). The Lambda(9)-index shows that epsilon Aur remains
with its extended atmosphere at maximum and at minimum light
(as indicated by the strength of its OI-7774 A line). Most
likely, its luminosity was slightly higher in November 1983
(see Table I).





               EUGENIO.E. MENDOZA V.
              Instituto de Astronomia
        Universidad Nacional Autonoma de Mexico
                    MEXICO





References:

Mendoza, E.E., Gomez, T., Ortega, R., and Quintero, A., 1983,
       Pub. A.S.P., 95, 48. [BIBCODE 1983PASP...95...48M ]
Mendoza, E.E., and Johnson, H. L., 1979, Pub. A.S.P., 91, 465. [BIBCODE 1979PASP...91..465M ]