COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1506

                                 Konkoly Observatory
                                 Budapest
                                 1978 November 17




     PHOTOMETRIC HISTORY OF 24.1939 Aur = CSV 458


Independently Gyulbudagyan and Magakyan (Astron.Zhurn.Pis'ma 3,
p. 113) and Cohen (Monthly Not. RAS 184, p. 695) detected the faint
arc of nebulosity situated immediately south of the variable
star 24.1939 during systematic surveys of the POSS photographs
for unknown cometary nebula. The star's variability had been
discovered by Morgenroth (Astr.Nachr. 268, p. 273) long ago on
Sonneberg plates. By comparing the two adjacent POSS prints 846
and 1309 which overlap at the position of the object, Cohen 
confirmed the variability.
I checked the star's region on roughly 150 blue sensitive plates
of the Sonneberg collection, taken with the 14 cm camera  (f:5).
The object is mostly invisible, that means fainter than 15.3m to
15.8m. At four occasions however it can be observed well   above
the plate limit; these maxima are:

1931 Nov.  15 13.5m (confirmed by 2 plates of Nov. 5 and 13)
1934 Nov.   3 13.1
1945 March 15 14.4
1967 Dec.   2 14.7

Of course the nebulous arc is invisible throughout.
If there were not the spectroscopic findings of Cohen (especially 
his determination of the luminosity class) one would indeed
think the object to be a long period variable (as Morgenroth did),
because those four maxima and the one which is indicated by the
POSS print 0846 of 1953 Oct. 7/8 can easily be represented by
a period of 346d.
Another point of confusion is obvious: If the star is of spectral
type M2 and suffers an interstellar extinction of at least A_v=
2.2 mag, then from the red magnitude of 15.4m (POSS E 846) (all
these data according to Cohen l.c.) would follow a blue magnitude
of about 18.5m (supposed R = 3) whereas at POSS 0 846 the star
appears not fainter than 16m. Similar conclusions are valid for
the pair POSS 1309 with 16.3m as starting red magnitude. The strong
H_alpha emission, if present at that time, even strengthens this
contradiction.
The most important statement of the present paper probably 
concerns the existence of several maxima in the course of the time
interval checked, instead of one single fading possibly assumed
previously. Some further particulars of our photographic 
observations will appear in Mitt. Verand. Sterne Sonneberg 8, No. 5.





                            W. WENZEL
                         Sternwarte Sonneberg
                      Zentralinstitut fur Astrophysik
                     Akademie der Wissenschaften der DDR