COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2273

                                     Konkoly Observatory
                                     Budapest
                                     1983 January 25

                                     HU ISSN 0374-0676




       UBV AND SPECTROSCOPIC OBSERVATIONS OF PU VULPECULAE


  We present observations which were obtained during the very remarkable
brightening phase (especially in U) of PU Vul in October and November 1982
described by Purgathofer and Schnell (1983, hereinafter 'PS'). Table I lists
the UBV-results which were obtained by one of us (H.M.M.) as Visiting Astronomer 
at the 1m Yale University telescope of the Observatorio Interamericano
de Cerro Tololo (CTIO)+). A single channel photometer with a dry ice cooled
S4 type photomultiplier was available in pulse counting mode with data output
on a thermal printer.


                    Table I


          UBV-observations of PU Vul minus BD 21deg4165.

JD(244000+)      DeltaV'   e   DeltaB'   e   DeltaU'   e   n

       5271.52 -0.759      1 -0.748      5 -0.400      4   2
       5272.51    772      2    760      4    428      1   2
       5273.51    795      5    780      3    456      7   2
       5276.50    825      2    814      8    500      4   5
       5277.51    828      2    827      3    540      6   4
       5278.51    837      6    842      2    558      4   3
       5279.51    828      3    842      5    538      5   3
       5280.51    830      1    849      3    574      2   3
       5281.51 -0.834      4 -0.860      6 -0.590      6   3

     Notes: The columns headed by 'e' contain the values of the
         mean errors (in units of 0.001 mag) of the preceding
         values. 'n' is the number of integrations of 15 sec.



+)operated by the Association of Universities for Research in Astronomy
  (AURA), Inc. under contract with the National Science Foundation.



  Due to the early right ascension the measurements were taken in dawn.
Therefore, the sky readings were used to obtain a smooth curve from which
the respective sky values during the star measurements were taken. The air
masses of the photometric observations were always in the vicinity of 2.
  The differences in Table I are given in the observer`s system. Comparing
our results with those of PS we notice good agreement in the zero-points of
B and V. As our measurements exhibit a rather small scatter around a smooth
curve, we conclude that the comparison star BD 21deg4165 (which we have in
common with PS) is constant (at least over the time interval spanned by our
observations). Hence, the slight systematic variability of BD 21deg4165 
mentioned by PS must refer to longer time scales.
  Significant difference appears in U: Our U-curve is somewhat steeper than that
of PS, and our U of PU Vul is 0.1 mag fainter. This is consistent with a
smaller effective wavelength of our U-filter.
  Like PS we also lack an accurate transformation to the UBV-system. However,
we may use spectral classification in order to estimate how close we match
the UBV-system. Therefore, one of us (JH) has obtained spectrograms of PU Vul
parallel to the photometric run (and one in June 1982), at the 1.5 m telescope.
of the Leopold Figl - Observatory of the Vienna University using a dispersion
of 125 angstrom/mm at the Boller & Chivens spectrograph and unbaked IIa-O 
plates. The results are listed in Table II.

                   Table II


          Spectroscopic observations of PU Vul.

JD(2440000+)      height   n   spectral type

        5157.55   500      1   F8-9 I
        5273.34   350      1   F5 Ia
        5274.25   500      2   F6 I
        5275.26   500      3   F6 Ia


     Notes: The spectrum height is given in microns, 'n' is the
         number of spectrograms.


  During the brightening phase the H-beta line appears in weak, but definite
emission with a P Cyg type blue-shifted absorption. This was not found on
the first date of Table II.
  Taking into account the usual calibrations of supergiants in the UBV
system and the UBV results of PS we arrive at the following conclusions:



 The reddening should be 0.10<E(B-V)<0.15. Therefore the U-B values of
PS during the time of the spectroscopic observations would point to luminosity 
class III. However, this is not compatible with our spectral types.

 A consistent result would be reached by U-B values which are about 0.15
mag redder than those of PS. Our U-measurements which are 0.1 mag fainter
than those of PS comply with this condition considering the errors and
uncertainties involved.

  Nevertheless, the atmospheric conditions of PU Vul are likely to be
peculiar (which is indicated by the fact that the H and K lines of Ca yield
a somewhat later spectral type than the other lines - in agreement with
Yamashita et al. (1982)) and therefore our conclusions drawn from the comparison 
of spectroscopic and photometric observations are somehow straightforward
and preliminary.





                   J. HRON

                   H.M. MAITZEN

                Institut fur Astronomie
                der Universitat Wien
                Turkenschanzstrasse 17
                A-1180 Wien/Austria





 References:
 Purgathofer A., Schnell A.: 1983 Inf. Bull. Var. Stars No. 2264
 Yamashita Y., Maehara H., Norimoto Y.: 1982, Publ. Astron. Soc. Japan 34, 269 [BIBCODE 1982PASJ...34..269Y ]