The measurement lasted for approximately 15 minutes for each star observed. The principle of the measurements is called point run which is normally used as an angular adjusting procedure for the telescope. For such a point run a certain area of the camera is covered with a prechosen virtual point grid. On each coordinate of this grid the star is subsequently focused and the anode current of each photomultiplier is read out and recorded. At the beginning and at the end of such runs, the central pixel is pointed to the star. In this pilot study stars were only projected onto approximately 15 photomultiplier tubes of the central region of the camera. The grid had a dimension of 15 $\times$ 15 points. Covering the whole camera surface by the calibration procedure is a trivial problem of more measuring time. The selected stars (see Sect. 2) which have been used and some characteristic data are listed in Table 1.

Table 1: Stars the photon flux of which is measured for the calibration. Given are their HR number, locii (right ascension, declination), spectral type (taken out of the Astronomical Almanac, Hagen & Boksenberg [1995], and only for 68 Her and 12 Vul from Friedrichsen [1993]) and their effective temperature (estimated with Lang [1992]). 10 Lac was measured twice. We are aware that the spectral types and absolute magnitudes of the chosen stars are slightly variable. This can in principle be considered by forthcoming applications of the method but was not in the scope of the present study
Flamsteed/Bayer HR No. Right Declination Spectral Effective

Designation Ascension Type Temperature

4
$\theta$ CrB 5778 15^h 32^m 44.9^s $+~31^{\circ}~22'~27''$ B6 Vnn $\sim$ 14000 K

22 $\tau$ Her 6092 16^h 19^m 36.3^s $+~46^{\circ}~19'~26''$ B5 IV $\sim$ 15000 K

68 Her 6431 17^h 17^m 19.4^s $+~33^{\circ}~06'~00''$ B3 III $\sim$ 17000 K

85 $\iota$ Her 6588 17^h 39^m 20.3^s $+~46^{\circ}~00'~31''$ B3 IV $\sim$ 19000 K

67 Oph 6714 18^h 00^m 25.2^s $+~02^{\circ}~55'~53''$ B5 Ib $\sim$ 13500 K

102 Her 6787 18^h 08^m 34.0^s $+~20^{\circ}~48'~49''$ B2 IV $\sim$ 21000 K

10 $\beta$ Lyr 7106 18^h 49^m 54.8^s $+~33^{\circ}~21'~26''$ B7 Vpe (shell) $\sim$ 13000 K

20 $\eta$ Lyr 7298 19^h 13^m 36.3^s $+~39^{\circ}~08'~17''$ B2.5 IV $\sim$ 19000 K

8 Cyg 7426 19^h 31^m 36.3^s $+~34^{\circ}~26'~36''$ B3 IV $\sim$ 18000 K

12 Vul 7565 19^h 51^m 04.0^s $+~22^{\circ}~36'~36''$ B2.5 Ve $\sim$ 19000 K

59 v832 Cyg 8047 20^h 59^m 40.4^s $+~47^{\circ}~30'~12''$ B1.5 Vnne $\sim$ 23000 K

66 Cyg 8146 21^h 17^m 44.0^s $+~34^{\circ}~52'~40''$ B2 Ve $\sim$ 22000 K

10 Lac 8622 22^h 39^m 03.5^s $+~39^{\circ}~01'~36''$ O9 V $\sim$ 33000 K

81 $\pi^2$ Cyg 8335 21^h 46^m 37.6^s $+~49^{\circ}~17'~19''$ B2.5 III $\sim$ 18000 K

Flamsteed/Bayer			HR No.	Right	Declination	Spectral	Effective
Designation				Ascension		Type	Temperature
4	$\theta$	CrB	5778	15^h 32^m 44.9^s	$+~31^{\circ}~22'~27''$	B6 Vnn	$\sim$ 14000 K
22	$\tau$	Her	6092	16^h 19^m 36.3^s	$+~46^{\circ}~19'~26''$	B5 IV	$\sim$ 15000 K
68		Her	6431	17^h 17^m 19.4^s	$+~33^{\circ}~06'~00''$	B3 III	$\sim$ 17000 K
85	$\iota$	Her	6588	17^h 39^m 20.3^s	$+~46^{\circ}~00'~31''$	B3 IV	$\sim$ 19000 K
67		Oph	6714	18^h 00^m 25.2^s	$+~02^{\circ}~55'~53''$	B5 Ib	$\sim$ 13500 K
102		Her	6787	18^h 08^m 34.0^s	$+~20^{\circ}~48'~49''$	B2 IV	$\sim$ 21000 K
10	$\beta$	Lyr	7106	18^h 49^m 54.8^s	$+~33^{\circ}~21'~26''$	B7 Vpe (shell)	$\sim$ 13000 K
20	$\eta$	Lyr	7298	19^h 13^m 36.3^s	$+~39^{\circ}~08'~17''$	B2.5 IV	$\sim$ 19000 K
8		Cyg	7426	19^h 31^m 36.3^s	$+~34^{\circ}~26'~36''$	B3 IV	$\sim$ 18000 K
12		Vul	7565	19^h 51^m 04.0^s	$+~22^{\circ}~36'~36''$	B2.5 Ve	$\sim$ 19000 K
59	v832	Cyg	8047	20^h 59^m 40.4^s	$+~47^{\circ}~30'~12''$	B1.5 Vnne	$\sim$ 23000 K
66		Cyg	8146	21^h 17^m 44.0^s	$+~34^{\circ}~52'~40''$	B2 Ve	$\sim$ 22000 K
10		Lac	8622	22^h 39^m 03.5^s	$+~39^{\circ}~01'~36''$	O9 V	$\sim$ 33000 K
81	$\pi^2$	Cyg	8335	21^h 46^m 37.6^s	$+~49^{\circ}~17'~19''$	B2.5 III	$\sim$ 18000 K

3 Measurements