COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                        NUMBER 472

                                  Konkoly Observatory
                                  Budapest
                                  1970 October 14


       PREOUTBURST OBSERVATIONS OF NOVA SCUTI 1970

        The nova that G. Alcock discovered on July 31, 1970
(1) was visible on 45 blue-light plates (103a-O, no filter)
taken on five consecutive nights by A. Sandage with the
48-inch Palomar Schmidt between JD 2,435,279 and 2,435,283.
These plates have been made available to M. Harwood for her
continuing study of the variables in the Scutum Star Cloud.
        From precise positions by H. Kosai (2) and T. Seki
(3) the nova was identified; it is marked by an open circle
on the finder chart (3'.5 by 2'.7). The brightest star is
8th magnitude SAO 142593. An independent identification of
the nova was made on Sky Survey prints at Tokyo Observatory
(2) and M. Huruhata (4) confirms that the same star was
selected there.
 
                       [FIGURE 1]

 A flyspanker was used for determining the magnitudes
of comparison stars A(m_pg= 19.0) and B(m_pg= 19.5), by extrapolation 
of sequence Krieger C, which has been photoelectrically 
placed on the international system (5)
        No convincing variation of Nova Scuti 1970 was found
from eye estimates, the star never being brighter than A
nor fainter than B. The average magnitude from all 45 estimates 
was 19.3.
        For magnitudes cited in the IAU Circulars and unpublished 
AVVSO observations (6), it appears that maximum
light occurred  on or shortly before the date of discovery
at m_vis 6,9. On that date B-V was probably + 0m8. Hence the
blue magnitude would have been  7.7, indicating an increase
of at least 11.6 magnitudes.
            
                                L.J.ROBINSON    M.HARWOOD
                                Cambridge,  Mass. U.S.A.


References

1. IAU Circular 2269
2. IAU Circular 2272
3. IAU Circular 2274
4. Private communication
5. M. Harwood, Leiden Annals, 21, 387 [BIBCODE 1960AnLei..21..387H ]
6. Courtesy M.W. Mayall