Abstract. The search for chemically peculiar (CP) stars in open clusters using photoelectric photometry sampling the presence of the characteristic flux depression feature at 5200Å via the ∆a-system (Maitzen 1976) has so far delivered data for objects usually no more distant than 1000 pc from the Sun. A series of fourteen papers (first: Maitzen & Hensberge 1981; for the time being last: Maitzen 1993) were devoted to 1240 stars in 38 open cluster fields.If one intends to study the presence of CP stars at larger distances from the Sun, classical photometry has to be replaced by CCD photometry. We have therefore initialized in 1995 a new survey in open clusters and the Large Magellanic Cloud using the CCD technology.As a first step, we have presented new ∆a-photometry of 22 CP2 stars in the galactic field to prove the capability of CCD photometry for our aim (Maitzen et al. 1997).In the first paper of a new series devoted to CCD photometry, we present data on NGC 2169 (13 stars investigated), Melotte 105 (114 stars), and NGC 6250 (48 stars). NGC 2169 was used to test our results with those of classical photometry which yields excellent agreement.For NGC 6250 we find two new definite CP2 (according to the definition by Preston 1974) stars (∆a = 0.065 and 0.026 mag) and two λ Bootis candidates. Twelve objects with only marginally peculiar ∆a-values for Melotte 105 were detected. Additional spectroscopic and photometric evidence is needed to substantiate their peculiarity.

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The Delta Scuti Network (DSN) is a collaboration of astronomers all around the globe who study and observe short-period variables. The field of scientific research includes high-precision photometric and spectroscopic global campaigns, mode identification techniques, and asteroseismological pulsation modeling. We present results for three stars that are receiving the most attention at the moment: 4 CVn, BI CMi, and 44 Tau. Our results demonstrate that a large number of simultaneously excited nonradial oscillations in stars on and above the main sequence can be detected by conventional means.

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