Table 1: Journal of the observations. Note that the data coming from Sierra Nevada and San Pedro Martir (SPM) have been transformed in the Johnson system as discussed in Sect. 2.2.

HJD-2450000	HJD-2450000	Duration	Filter
start (days)	end (days)	(hours)
	Loiano CCD (Italy)
2545.585	2545.659	1.8	B
2547.599	2547.681	2.0	B
2548.547	2548.611	1.5	B
2549.503	2549.623	2.9	B
2628.347	2628.627	6.7	B
2629.286	2629.453	4.0	B
2630.454	2630.513	1.4	B
2654.252	2654.332	1.9	B
	Fairborn-APT (USA)
2976.875	2976.892	0.4	BV
2977.851	2977.936	2.0	BV
2978.721	2978.933	5.1	BV
2983.573	2983.920	8.3	B
2984.711	2984.917	4.9	BV
2987.765	2987.902	3.3	BV
	SOAO (Korea)
2977.170	2977.333	3.9	BV
2980.910	2981.063	3.7	V
2983.007	2983.191	4.4	BV
	OSN (Spain)
2988.267	2988.500	5.6	uvby
3047.364	3047.472	2.6	uvby
3048.299	3048.459	3.8	uvby
	Loiano TTCP (Italy)
2946.330	2946.703	9.0	BV
2947.287	2947.441	3.7	BV
2973.393	2973.636	5.8	BV
	SARA (USA)
2970.631	2970.756	3.0	B
	SPM (Mexico)
2970.494	2970.818	7.8	uvby
2972.495	2972.841	8.3	uvby
2973.493	2973.775	6.8	uvby
2974.487	2974.585	2.4	uvby
2977.485	2977.847	8.7	uvby
	BAO (China)
2972.974	2973.383	9.8	V
2974.032	2974.146	2.7	V
2974.939	2975.382	10.6	V
2976.940	2977.078	3.3	V
2984.196	2984.292	2.3	V
	Teide-OGS (Spain)
2977.506	2977.603	2.3	V
	Serra la Nave (Italy)
2966.462	2966.62	3.9	BV
2967.337	2967.61	6.7	BV
2973.348	2973.61	6.4	BV