The photoelectric photometry presented in this paper was carried out in October 5-12, November 6-8 and December 2-4 1999 (Table 1) with the 91-cm Cassegrain telescope at the "M. G. Fracastoro'' station of Catania Astrophysical Observatory on Mt. Etna (Italy).

The telescope feeds a single channel photon-counting photometer equipped with a cooled EMI 9893Q/350A photomultiplier and standard UBV filters. The program stars were observed differentially with respect to two close comparison stars:
HD 23654 (c1) (V=7.72, B-V=+1.23, U-B=+1.12)
HD 23712 (c2) (V=6.46, B-V=+1.70, U-B=+2.07)
for the Pleiades members, and
HD 22156 (c3) (V=7.32, B-V=+1.11, U-B=+0.84)
HD 20296 (c4) (V=7.53, B-V=+0.06, U-B=-0.01)
for the Alpha Persei members. The integration time in U, B and V filters for the program stars was set to 48, 24 and 24 s, respectively, and the observing sequence c-v-v-c was employed, where (v) is the program star. The sky was measured close to each star. After sky background subtraction, the observations were corrected for atmospheric extinction and converted into the Johnson UBV system by means of standard stars which were observed each night. Due to the short duration of an observing sequence, the two v-c values were finally averaged to obtain one single data point. No significant light variations were detected from the differential measures of the comparison stars, indicating that the light of the comparison stars was constant, within 0.015, 0.017, 0.020 mag in the V band and B-V and U-B colours, respectively.

The observations of each program star have been analysed using a Scargle-Press period search routine to derive the period of the photometric modulation (Scargle 1982; Horne & Baliunas 1986). In Table 2 the author reports the Hertzprung (HII) and AP catalogue number, variable name, brightest V-band magnitude, mean B-V and U-B colours, V-band light curve amplitude, photometric period (P) obtained by the periodogram analysis and its uncertainty ( $\Delta P$ ), false-alarm-probability (FAP) of the peak frequency and number of observations ( $N_{\rm obs}$ ).

Table 2: Photometric properties inferred in the present monitoring: V-band brightest magnitude and mean colours, light curve amplitude, rotation period along with its uncertainty and false-alarm-probability and number of data points
Pleiades cluster program stars

HII Other $V_{\rm max}$ $\langle B-V\rangle$ $\langle U-B\rangle$ $\Delta V$ Period $\pm \Delta P$ FAP $N_{\rm obs}$

number name (mag) (mag) (mag) (mag) (d)

HII 250
10.69 0.67 0.15 0.04 $0.591\pm0.002$ 0.19 13

HII 324 V632 Tau 12.90 1.11 0.75 0.29 $0.411\pm0.001$ 0.05 13

HII 335 MX Tau 13.65 1.31 0.60 0.10 $0.4073\pm0.001$ 0.08 15

HII 345 11.40 0.83 0.33 0.07 $0.723\pm0.003$ 0.26 12

HII 625 V811 Tau 12.61 1.20 0.69 0.11 $0.421\pm0.001$ 0.08 15

HII 686 OU Tau 13.40 1.00 0.32 0.15 $0.391\pm0.001$ 0.07 15

HII 738 V1041 Tau 12.28 1.17 0.67 0.13 $0.854\pm0.004$ 0.03 17

HII 739 V696 Tau 9.44 0.61 0.05 0.03 $0.917\pm0.003$ 0.17 14

HII 882 12.55 1.06 0.70 0.15 $0.581\pm0.001$ 0.02 16

HII 1039 13.04 1.20 0.84 0.08 $0.784\pm0.002$ 0.06 16

HII 1532 13.92 1.30 0.91 0.08 $0.918\pm0.002$ 0.04 16

HII 1653 V338 Tau 13.34 1.19 1.01 0.16 $0.759\pm0.003$ 0.16 11

HII 2244 V664 Tau 12.57 1.03 0.66 0.13 $0.562\pm0.001$ 0.18 12

HII 3063 V677 Tau 13.46 1.24 1.03 0.12 $0.884\pm0.001$ 0.04 13

Alpha Persei cluster program stars

AP Other $V_{\rm max}$ $\langle B-V\rangle$ $\langle U-B\rangle$ $\Delta V$ Period $\pm \Delta P$ FAP $N_{\rm obs}$

number name (mag) (mag) (mag) (mag) (d)

AP 15 14.15 1.34 1.42 0.10 $0.622\pm0.012$ 0.11 11

AP 19 V531 Per 11.59 0.77 0.40 0.08 $0.77\pm0.03$ 0.10 11

AP 32 HE684 10.65 0.58 0.20 0.06 $0.700\pm0.013$ 0.05 13

AP 43 12.75 0.96 0.65 0.13 $0.582\pm0.011$ 0.05 12

AP 93 11.84 0.94 0.59 0.04 $0.63\pm0.04$ 0.32 10

AP 193 11.99 0.81 0.35 0.11 $0.645\pm0.02$ 0.12 14

AP 244 12.78 0.93 0.56 0.10 $0.463\pm0.01$ 0.40 10

Pleiades cluster program stars
HII	Other	$V_{\rm max}$	$\langle B-V\rangle$	$\langle U-B\rangle$	$\Delta V$	Period $\pm \Delta P$	FAP	$N_{\rm obs}$
number	name	(mag)	(mag)	(mag)	(mag)	(d)
HII 250		10.69	0.67	0.15	0.04	$0.591\pm0.002$	0.19	13
HII 324	V632 Tau	12.90	1.11	0.75	0.29	$0.411\pm0.001$	0.05	13
HII 335	MX Tau	13.65	1.31	0.60	0.10	$0.4073\pm0.001$	0.08	15
HII 345		11.40	0.83	0.33	0.07	$0.723\pm0.003$	0.26	12
HII 625	V811 Tau	12.61	1.20	0.69	0.11	$0.421\pm0.001$	0.08	15
HII 686	OU Tau	13.40	1.00	0.32	0.15	$0.391\pm0.001$	0.07	15
HII 738	V1041 Tau	12.28	1.17	0.67	0.13	$0.854\pm0.004$	0.03	17
HII 739	V696 Tau	9.44	0.61	0.05	0.03	$0.917\pm0.003$	0.17	14
HII 882		12.55	1.06	0.70	0.15	$0.581\pm0.001$	0.02	16
HII 1039		13.04	1.20	0.84	0.08	$0.784\pm0.002$	0.06	16
HII 1532		13.92	1.30	0.91	0.08	$0.918\pm0.002$	0.04	16
HII 1653	V338 Tau	13.34	1.19	1.01	0.16	$0.759\pm0.003$	0.16	11
HII 2244	V664 Tau	12.57	1.03	0.66	0.13	$0.562\pm0.001$	0.18	12
HII 3063	V677 Tau	13.46	1.24	1.03	0.12	$0.884\pm0.001$	0.04	13

Alpha Persei cluster program stars
AP	Other	$V_{\rm max}$	$\langle B-V\rangle$	$\langle U-B\rangle$	$\Delta V$	Period $\pm \Delta P$	FAP	$N_{\rm obs}$
number	name	(mag)	(mag)	(mag)	(mag)	(d)
AP 15		14.15	1.34	1.42	0.10	$0.622\pm0.012$	0.11	11
AP 19	V531 Per	11.59	0.77	0.40	0.08	$0.77\pm0.03$	0.10	11
AP 32	HE684	10.65	0.58	0.20	0.06	$0.700\pm0.013$	0.05	13
AP 43		12.75	0.96	0.65	0.13	$0.582\pm0.011$	0.05	12
AP 93		11.84	0.94	0.59	0.04	$0.63\pm0.04$	0.32	10
AP 193		11.99	0.81	0.35	0.11	$0.645\pm0.02$	0.12	14
AP 244		12.78	0.93	0.56	0.10	$0.463\pm0.01$	0.40	10

2 Observations