Observations of tlie gravitationally lensed quasar Q?737+0305 were made with the 1.5-meter AZT-22 telescope a t Maidanak (Uzbekistan) on 17-19 September 1995. All four components of the quasar are clearly resolved. T h e results of photometric measurements of the components are presented. It is confirmed that the component A again became the brightest one in the system. A noticeable change of t,he mutual colours of the components A and B in comparison with previous observations is detected and discussed. We cannot decide, on the basis of existing observational data, whether varying extinction or "chromatic" microlensing is the cause. Stronger, correlated colour changes i n the system are probably caused by quasar variability. T h e dominant time scale of the microlensing-governed brightness variations since the discovery is of the order of 10 years. A correlation between radio brightness and optical coloiir is found but cannot be explained.Key words; gravitational lensing -quasars: Q7237+0305 -techniques: photometric A A A subject classification: 160; 161 IiitrotliictionThe object Q2237+0305 discovered in 1985 by FIuchra et al.( 1 9 8~4 , is a quasar (to = 1.695), gravitationally lensed by a nearby galaxy (zg = 0.039). Because of the small tlist.ance to tlie lensing galaxy, the object. is very promising for investigations of gravitat.ioiial lens phenomena. A t the same time, the geometry of the object (four star-like quasar components in a circle of approximately 1.8" in diameter around the centre of the lensing galaxy), makes it rather difficult for observations. Nevertheless, a large amount of observational data on the object is accumulated by now, as well as a variety of theoretical investigations.Coordinates of the four quasar components, measiiretl from ground-based observations (Yee 1988;Racine 1991), are in excellent agreement with Ifubble Space Telescope dat.a (Crane et al. 1991;Rix et al. 1992). A number of successful models of the system (Kent & Falco, 3988; Schtieider et al. 1988, Wambsganss and Paczynski 1994) allowed to obtain estimates of the rnass distribution in the lensiiig galaxy and to predict quite well the observed locations and, to a lesser degree, the mutual briglit,iiesses of the quasar cotnponents. Yee (1988), in his pioiieering work, discovered colour difTcrences of the components and explained them by different amounts of extinction in the lensing galaxy. Observations in IR (Nadeau et al. 1991)

Photographic UBV photometry of NGC 2976, a low-luminosity member of the central M81 group of galaxies, is presented. Young stars in the central disk determine the optical view and the classification of this Sc(pec) galaxy. It is surrounded by a halo of an old pspulation which contains nearly all the mass and half the luminosity of the system. This halo has some properties typical of spheroidal dwarf galaxies: an exponential brightness profile, an ellipticity trend of the isophotes typical of low-mass systems, and mass and luminosity near the upper limit of typical dwarfs. In the central population I disk, star formation proceeds in dense associations scattered irregularly in a broad ringlike region of 1.2 kpc radius just inside the turnover of the rotation curve. This star formation episode may last since some 108a; it is possibly triggered by gas infall from the interstellar cloud generated during encounters between other group members in the central M81 group. A direct triggering by recent encounters is excluded since NGC 2976 is undisturbed in its outer parts. K e y words: galaxies: NGC 2976 --stellar populations -dust A A A subject classification: 157 IntroductionThe population content of galaxies and its development with time has since long attracted considerable attention. T h e distribution (and kinematics) of stars of different age and of different metal content bears valuable information about the history of galaxy evolution. Observed intensity profiles of the old population, trends in the ellipticity of the isophotes, systematic variations of metallicity and colours can be compared with predictions from evolutionary models t o get insight into the past history of the systems (for instance Larson 1975, Larson and Tinsley 1978, Arimoto and Yoshii 1986, 1987, Katz and Gunn 1991. The occurence and the distribution of young stars and their relation to the interstellar gas and dust are indicative of the processes which trigger star formation. Irregularities in the distribution of stars and interstellar matter may be signatures of recent interactions with neighbouring systems. Since every galaxy has its special history determined by environmental and initial conditions, discussion of individual galaxies is of its own value and is supplementary to the observation of selected parameters of a great number of objects for statistical discussion. Our interest in NGC 2976 is twofold. First, this Sc(pec) galaxy (de Vaucouleurs et al. 1976) is a member of the M81/M82 group of galaxies. It contains a large number of young concentrated star forming regions in its inner disk; many of them are conspicuous Ha-regions (Hodge and Kennicut 1983). T w o other members of this group, NGC 3077 and M82, suffered close encounters with M81 during the last 109a (for instance Cottrell 1977, Kilian 1980, Brouillet et al. 1991a. A huge cloud of interstellar matter, now enshrouding these galaxies, was probably generated by these events. A faint extension of the cloud links NGC 2976 t o the central group (Appleton et al. 1981(Appleton e...

We re-investigate the lenticular galaxy NGC 3384, a member of the Leo I galaxy group, using HST and multi-colour Calar Alto observations. Various approaches are used to visualize the two known peculiar components, the so-called inner component (IC) and the elongated component (EC), on the HST images. The methods were checked in detail using synthetical images from simulated galaxies. For the first time, we make the IC as well as the inner part of the EC visible on direct images. The results confirm both the bar-like appearance of the inner EC and the quasi-elliptical shape of the IC. The IC resembles an inclined disk where the surface brightness becomes successively shallower towards the centre compared to an exponential profile. The orientation of the inner part of the EC is perpendicular to the major axis of the IC. The broad-band colour indices are shown to be in agreement with model predictions for a 5 to 7 Gyr old stellar population of quasi-solar metallicity. No significant large-scale variations of the colour indices over the main body of the galaxy are found. We discuss the previously reported colour gradients close to the nucleus and argue that the most plausible explanation is reddening by small amounts of dust though unsharp masked HST images do not provide significant hints for clumpy dust. According to the episodic dust settling scenario suggested by Lauer et al. (2005), the very low dust fraction indicates that NGC 3384 is in a post-activity phase and at the beginning of a new dust-settling cycle.

Lichtelektrische und photographische Messungen der Nova Herculis werden mitgeteilt. Die Lichtkurve und der Verlauf der Farbenindizes werden diskutiert, zum Teil unter Einbeziehung fremder MeOreihen. Der durch interstellare Extinktion hervorgerufene Farbexzess der Nova wird zu E B -v = + o"45 f OTIO abgeschatzt.

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