COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1829

                                  Konkoly Observatory
                                  Budapest
                                  1980 August 14

                                  HU ISSN 0374-0676



            THE VARIABILITY OF HR7442



    HR 7442 (GC27045,HD184786) was selected for photoelectric
monitoring from a list of potentially variable stars (Hoffleit,
1979). This bright star (V=6.2mag.) has a spectral type of M4.5 III
(Buscombe, 1977) and is well placed for Northern hemisphere observers 
(1950: R.A. 19h32m19s, Dec. 49d9.2').
    This star was observed during the second half of 1979 from
two observatories. The observations consist of 119 delta magnitudes
in the V band, taken on 28 nights scattered over this time interval. 
The nightly averages are plotted in Figure 1, and they show
an irregular variability on time scales of tens of days, with an
amplitude of about two tenths of a magnitude. Between JD2444192
and JD2444223 the comparison star (GC27078) was measured differentially 
with respect to GC26990 on five nights, and was found
constant to 0.01 magnitude.
    Since this was a search for variability, the data have not
been reduced to the standard UBV system. One observer (DRS) used
a 1P21 photomultiplier and standard V filter, and this instrumental 
system is quite close to the UBV standard. The other observer 
(TGM) used a silicon photodiode detector and filter, and
this instrumental system had a sufficiently different response
so that 0m13 had to be subtracted from its delta magnitudes to
bring them into agreement with the 1P21 data.
    The variations in HR 7442 seem to have cycle length that
range from 29 to 45 days, and this would lead to a tentative
classification of SRb (Hoffleit, 1980). The SRb class is defined
as having semiregular periods of 20 to 50 days, amplitudes under
0m5, and spectral classes M3.5 III to M5 III. An Lb star, such
as Gamma Ret, also bears a strong resemblance to HR 7442, so
the SRb classification remains tentative.

   One of us (TGM) has observed this star again in May and June
of 1980, and finds that HR 7442 continues to vary, with characteristics 
similar to those noted last year.

                      [FIGURE 1]

FIGURE 1: Observations of HR 7442 plotted as nightly averages of
          instrumental delta V magnitudes vs. Julian day (+2440000). Filled
          circles are measurements taken by DRS and open circles are 
          measurements taken by TGM.



                         DAVID R. SKILLMAN*
                         9514 48th Ave.
                         College Park, Maryland
                         20740, U.S.A.

                         THOMAS G. McFAUL*

                         East Hook Cross Road
                         Hopewell Jct.,New York
                         12533, U.S.A.


References:
Buscombe, W. 1977, MK Spectral Classifications, Third General Catalog, 
           Northwestern University, Evanston, Illinois [BIBCODE 1977msct.book.....B ]

Hoffleit, D. 1979, J.A.A.V.S.O., 8, 17 [BIBCODE 1979JAVSO...8...17H ]

Hoffleit, D. 1980, private communication




 *of the A.A.V.S.O.