COMMISSIONS 27 AND 42 OF THE IAU 
        INFORMATION BULLETIN ON VARIABLE STARS 
                     Number 3716
 
                                          Konkoly Observatory 
                                          Budapest 
                                          24 April 1992 
 
                                          HU ISSN 0374 - 0676 
 
 
 
 
 
V 2101 Oph AND V598 Sco: TWO MISCLASSIFIED U Gem IN THE SOUTHERN 
 
                        HEMISPHERE 
 
 
Both V2101 Oph and V598 Sco are classified as U Gem stars in the 1985 
edition of the GCVS. 
Vogt et al. (1982 Astron. Astrophys., Suppl. 48, 383) confirm V2101 Oph as a 
UG in their atlas of southern dwarf novae on the basis of an enhancement of 
its brightness detected on two subsequent plates of the Palomar Observatory 
Sky Survey. The same outburst was also detected on a ESO plate (see also 
Terzan et al. 1988 Astron. Astrophys. Suppl. 76, 205). 
V598 Sco was discovered by H.H. Swope (1943 Harv. Ann. 109) and later 
reported by Petit (1960 J. Obs., 43, 17) in his catalogue of dwarf novae 
where five outbursts of the star are recorded. 
These stars have been included in a program for systematic monitoring of 
northern and southern DNe. 
During a six-days run in La Silla (Chile) with the 1.52 m ESO telescope 
equipped with a Boller & Chivens spectrograph, both stars have been 
observed. 
On March 30th 1992, V2101 Oph appeared much brighter than at quiescence 
(m_V=16). Compared with some standard stars in the field of view, the star 
seemed as bright as m_V = 13. This value is very close to the maximum 
brightness reported by GCVS (m_V_(Max) approx.= 12.5). 
Three grating spectra taken in the same night (range 4010 - 5998 A; 2 A 
resolution) showed a late - type spectrum with strong TiO bands. 
The spectrum observed the following night did not change and might fit an 
M5 II - III type. 
On March 30th 1992, V598 Sco was in its quiescent state with an apparent 
magnitude of approximately m_V = 17. 
The following night it appeared brighter, very close to the maximum value 
of m_V = 14, and we obtained two consecutive spectra. 
Also in this case we found a late type spectrum that can be classified as K5 
II. 
Thus both V2101 Oph and V598 Sco are not U Gem stars but more likely, 
semi-regular late type giants (SR - type). 


                              [FIGURE 1]

 Fig 1: The spectra of V2101 Oph and V598 Sco suggest M5 II - II and K5 II
                       types, respectively.
 

The two spectra are shown in Fig 1. 
 
 
 
             R.U. CLAUDI ^1 and A. BIANCHINI ^2 
 
 
   1 Osservatorio Astronomico di Padova, I - 35122, Padova, Italy 
   2 Dipartimento di Astronomia dell' Universita di Padova, 
                I - 35122, Padova, Italy