COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2275

                                     Konkoly Observatory
                                     Budapest
                                     1983 February 1

                                     HU ISSN 0374-0676



               THE NEW PERIOD OF AD Boo


  The eclipsing system AD Boo (BD +25deg2800) was observed photoelectrically
with the 60 cm telescope at Peking Astronomical Observatory from April to
June in 1981.
  A total of 1518 photoelectric B,V observations were made on 14 nights. The
star used as a comparison was BD +25deg2803 and BD +25deg2801 was used as a check
star.
  Four times of primary minimum were determined. The secondary minimum was
also observed four times.
  The times of minima have been calculated by Kwee and van Woerden`s method.
Table I lists the times of minimum light.



                    Table I

        Minima of the light curve of AD Boo in yellow band

 JD Hel.   m.e.     rem.
2444000+

701.0941   0.0003   II
704.1985   0.0005   I
730.0570   0.0005   II
731.0935   0.0005   I
736.2642   0.0004   II
766.2627   0.0003   I



  All the observations for AD Boo were corrected for differential 
extinctions. Figure 1 gives the V light curve of the binary.

  The observations show that

  (1) the system is Algol type,
  (2) its period given by earlier observers is wrong, the period is about
      2.0688112 days, twice of that given by them,
  (3) the primary and secondary minima are 0.64 mag and 0.40 mag in yellow,



0.68 mag and 0.37 mag in blue, respectively, in these light curves.


                           [FIGURE 1]

              Figure 1   V light curve of AD Boo


  From Van Buren's (1974) and our epochs the new ephemeris was found:

       JD Hel. Min I = 2444704.1985  + 2.0688112d E
                          +/-0.0004 +/-0.0000002

  An analysis of these light curves is in progress.



       ZHAI DI SHENG, ZHANG RONG XIAN and ZHANG JI TONG
               Peking Astronomical Observatory
                          CHINA




 Reference:
 Van Buren, D., 1974, J. Amer. Assoc. Var. Star Observ., 3, No. 1, 6-10 [BIBCODE 1974JAVSO...3....6V ]



             [Corrigenda from IBVS 2651]

		Corrigenda

---------------------------------------------------
IBVS No.   Page   Line	 incorrect     correct
---------------------------------------------------
2274	   2	  3	 2444985.908   2444985.1908
2275	   1	  7	 four times    three times
2275	   1	  8	 four times    three times
---------------------------------------------------




		  ZHAI DI-SHENG, ZHANG RONG-XIAN,
		  ZHANG JI-TONG,
		  Beijing Astronomical Observatory, China