COMMISSION 27 OF THE I.A.U.
               INFORMATION BULLETIN ON VARIABLE STARS
                            Number 1499

                                                      Konkoly Observatory
                                                      Budapest
                                                      1978 November 3


       FAR-ULTRAVIOLET PHOTOMETRY OF RY SAGITTARII

During the flight of the Netherlands Astronomical Satellite ANS
far-ultraviolet photometry of the R Coronae Borealis-type star
RY Sagittarii was carried out. The observations were done on 5
April 1976 beginning at 20h13m20s. Alternately an integration of
64 seconds on the star and of 32 seconds on a field 5' away from
the star was performed. The following filters were used: 1549
(149 A), 1799 A (149 A), 2200 A (200 A), 2493 A (150 A), 3294 A
(101 A). Between brackets the width of each band is indicated;
the bands are to a good approximation rectangular. The total
number of useful integrations at each band is 8. To convert the
results to absolute flux, ANS observations of B3 V stars were
used together with a blanketed model atmosphere of Kurucz (see
Wesselius and Koester, 1978). The flux values for RY Sgr are
given in the Table:

 lambda, A                                        2200   2500   3300

 F_lambda; in units 10E-14 erg sE-1 cmE-2 AE-1    9.45   17.47  283.8
                                                +-0.31  +-0.91  +-5.7

   At 1550 A and 1800 A no signal has been detected (within the 
accuracy of measurements).

                            [FIGURE 1]

   Figure 1 shows the resulting fluxes for RY Sgr as well as the
magnitudes U,B,V for maximum brightness of this star taken from
Alexander et al.(1972) and converted to absolute fluxes. For
comparison we give also the calculated energy distribution for
a black body and for a grey body with a temperature of T=5500K
(normalized to lambda 4500 A)
   We have estimated the possible intensity of a graphite band  at
lambda 2200 A and arrive at the conclusion that this band is absent in
the spectrum of RY Sgr: It would be very interesting to perform
observations of this star at active phase (light minimum) when
the graphite band may appear due to strengthening of the 
circumstellar envelope.


                     B.E. ZHILYAEV, M.Ya. ORLOV,
                         P.R. WESSELIUS

                    Main Astronomical Observatory
                    Ukrainian Academy of Sciences
                    252127, Kiev, Goloseevo, U.S.S.R.



References:

Alexander, J.B. et al., 1972, Mon. Not. R. Astr. Soc., 158, 305 [BIBCODE 1972MNRAS.158..305A ]
Wesselius, P.R., Koester, D., 1978, Astron. Astrophys. (Submitted) [BIBCODE 1978A&A....70..745W ]