COMMISSION 27 OF THE I.A.U.
                 INFORMATION BULLETIN ON VARIABLE STARS
                             Number 3231

                                                         Konkoly Observatory
                                                         Budapest
                                                         26 August 1988

                                                         HU ISSN 0374 - 0676


                       Cn 1-2 (=PK 326 -10d1)

The emission line object Cn 1-2 is listed in the Catalogue of Galactic
Planetary Nebulae by Perek and Kohoutek (1967) under the designation (326
-10d1) but is actually a symbiotic star. It is misidentified on the finder
chart in Perek and Kohoutek, but a correct identification is given in Allen's
(1984) Catalogue of Symbiotic Stars. Cn 1-2 is also known as Henize 1242
and He 2-177. Relatively few observations of Cn 1-2 have been made since
its first description by Annie J. Cannon (1921). Webster (1966; 1973) and
Allen (1984) established its identity as a symbiotic star which is also
confirmed by recent IUE observations (Feibelman 1988). The IUE spectrum is
practically identical to that of V1016 Cyg and very similar to HM Sge both
of which had dramatic increases in brightness by about 5 magnitudes in 1%596
and 1975, respectively. Webster (1973) gives an approximate V magnitude
of 12.5 for Cn 1-2, with minor fluctuations in emission line strengths.
   If Cn 1-2 experienced a brightening similar to that of V1016 Cyg and
HM Sge prior to 1921, it would represent a southern counterpart to such
objects and may form an important link to these unusual symbiotics.
However, the apparent constancy in brightness of Cn 1-2 (though greatly
under-observed during the past half century) may also signal a very long
wait for major changes to occur in V1016 Cyg and HM Sge. Because of the
importance of these objects to the understanding of stellar evolution and their
spectral similarity to Cn 1-2, observations of Cn 1-2 over a wide range of
wavelengths appears to be desirable in the hope of predicting the future
development of symbiotics of this type.


                         WALTER A. FEIBELMAN

                             Code 684.1
                     Laboratory for Astronomy and
                           Solar Physics
                   NASA Goddard Space Flight Center
                      Greenbelt, MD, 20771, USA



References:

Allen, D.A., 1984, Proc. Astr. Soc. Australia, 5, 369. [BIBCODE 1984PASAu...5..369A ]
Cannon, A.J., 1921, Harvard Circ, No. 224. [BIBCODE 1921HarCi.224....1W ]
Feibelman, W.A., 1988, Publ. Astr. Soc. Pacific, 100, (in press, Sept. issue). [BIBCODE 1988PASP..100.1101F ]
Webster, L., 1966, Publ. Astr. Soc. Pacific, 78, 136. [BIBCODE 1966PASP...78..136W ]
Webster, L., 1973, Mon. Not. Roy. Astr. Soc., 164, 381. [BIBCODE 1973MNRAS.164..381W ]