COMMISSION 27 OF THE I. A. U.
	   INFORMATION BULLETIN ON VARIABLE STARS
			Number 3496


                                              Konkoly Observatory
                                              Budapest
                                              23 July 1990
	
                                              HU ISSN 0374 - 0676

                 HN Cyg: A MISCLASSIFIED U Gem

  HN Cyg is listed in the 1985 edition of the GCVS as UG: (doubtful
classification among U Gem stars). It appears in the atlas and catalogue
of northern dwarf novae by Bruch et al. (1987, Astron.Astrophys.Suppl.
70, 481) who reported outbursts on April 17,1980 and Sept. 27,1981. On
these bases we included HN Cyg in our spectroscopic monitoring of dwarf
novae with the Asiago 1.8 m telescope equipped with a Boller & Chivens
spectrograph and CCD.
  On July 8, 1990 we detected HN Cyg very bright with respect to its
appearance on the Buch et al. finding chart. We took low resolution spectra
(7.7 Ang/pixel, range 3200-7600 Ang) that showed a late type spectrum
with strong TiO bands. Reobserving HN Cyg the following night with the
same equipment we found it still very bright and again it showed a late
type spectrum. From the depth of the TiO bands at 6200 and 7100 Ang
(see figure) a spectral type of M 6.5 can be derived using the calibration of
Kenyon & Fernandez-Castro (1987, Astron.J. 93, 938). For the luminosity
class the determination is somewhat more uncertain, also if we favour a III
class.
  Thus, HN Cyg does not seem to be a U Gem star. What is more probable, 
considering the large amplitude of variation and the optical spectrum
at maximum, is a classification of HN Cyg among the Mira variables.


                            [FIGURE 1]


Figure 1. Absolute spectrophotometry of HN Cyg on July 8 and 9, 1990. The
  flux is in unit of 10^-14 erg * cm^-2 * sec^-1 * A^-1.



			U. MUNARI ^1, R. CLAUDI ^2 and A. BIANCHINI ^2

1: Asiago Astrophysical Observatory, I-36012 Asiago (VI), Italy
2: Astronomical Observatory of Padova, I-35100:, Padova, Italy