COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     NUMBER 351

                                  Konkoly Observatory
                                  Budapest
                                  1969 May 30


              THE PERIOD OF EV Sct

      Only 12 cepheids in galactic clusters are available
for the calibration of the period-luminosity-colour relation
(1). It is therefore surprising that the data for one of
them, EV Sct, are uncomplete. First, the reality of the
cluster NGC 6664, of which it is supposed to be a member,
is still questionable as pointed out by Bakos (2) and
J. Stock (cited by Becker, 3). Secondly, the light curve and
the period of EV Sct as derived by Arp (4) is based on only
11 photoelectric observations.
     It is the aim of this note to improve at least the
latter situation. Williams (5) has observed EV Sct by
narrow-band photometry in five nights and has derived
V magnitudes of the UBV-system. There is no indication that
systematic errors are introduced by this magnitude 
transformation. Using these additional observations the period
can be improved to 3.0910d +/- 0.0002d. This is sufficiently
accurate that the much earlier observations by Bakos and
Oosterhoff (cited by Bakos, 2) can be unambiguously combined
with the later observations. One finds then the elements:

      J.D.(Max) = 2 436 120.998 + 3.09097d  E
                         +/-15       +/-6

As seen in the figure this period brings the observations

           		[FIGURE 1]

by Arp (4) and Williams (5) to very good agreement. There
is therefore no need to adjust the other photometric
elements published by Arp.

Astronomisches Institut der Universitat Basel
May 18th, 1969


                           G. A. TAMMANN





References

  1. Sandage, A. and Tammann, G. A. 1969, Ap.J. 157 (in press) [BIBCODE 1969ApJ...157..683S ]
  2. Bakos, G. A. 1950, Leiden Ann. 20, 177 [BIBCODE 1950AnLei..20..177B ]
  3. Becker, W. 1963, Zeitschr. f. Astroph. 64, 77 [BIBCODE 1966ZA.....64...77B ]
  4. Arp, H. C. 1958, Ap.J. 128, 166 [BIBCODE 1958ApJ...128..166A ]
  5. Williams, J.A. 1966, A.J. 71, 615 [BIBCODE 1966AJ.....71..615W ]