طلب الدقة العالية في الأسترومترية يتطلب حلاً تصحيحياً رياضياً دقيقاً. في هذا العمل، نقدم تصحيحاً متوسطاً للكاميرا الزرقاء لمجموعة العدسات الكبيرة التي تتيح دقة استرومترية نسبية تقريباً بمقدار 15 ماس لمرشحي الباند الضوئي B_Bessel و V_Bessel. يتم استخدام نتيجة هذا الجهد في عمليتين مرشحتين: الأول هو قياس الحركة الصحيحة المطلقة لمجموعة النجوم المفتوحة M67 مقارنة بالأجرام الخلفية؛ والثاني هو تنظيف الرسم البياني اللون-المقياس لـ M67 من العناصر الحقلية، مما يتيح دراسة نهاية سلسلة تبريد الأشباح البيضاء. يمكن أن تجد كثير من التطبيقات الأخرى هذا التصحيح التشويشي مفيداً.
High precision astrometry requires an accurate geometric distortion solution. In this work, we present an average correction for the Blue Camera of the Large Binocular Telescope which enables a relative astrometric precision of ~15 mas for the B_Bessel and V_Bessel broad-band filters. The result of this effort is used in two companion papers: the first to measure the absolute proper motion of the open cluster M67 with respect to the background galaxies; the second to decontaminate the color-magnitude diagram of M67 from field objects, enabling the study of the end of its white dwarf cooling sequence. Many other applications might find this distortion correction useful.
We show the astrometric potential of the Wide Field Imager at the focus of the MPI-ESO 2.2m Telescope. Currently, we are able to measure the position of a well-exposed star with a precision of $sim$4 mas/frame in each coordinate (under 0.8 arcsec see
Wide-Field Corrector designs are presented for the Blanco and Mayall telescopes, the CFHT and the AAT. The designs are Terezibh-style, with 5 or 6 lenses, and modest negative optical power. They have 2.2-3 degree fields of view, with curved and telec
High-precision astrometry requires accurate point-spread function modeling and accurate geometric-distortion corrections. This paper demonstrates that it is possible to achieve both requirements with data collected at the high acuity wide-field K-ban
Omega Centauri is the most well studied Globular Cluster because of its numerous puzzling features. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions on the color-magnitude diagram promises to clarify some o
The solar-age open cluster M67 (C0847+120, NGC2682) is a touchstone in studies of the old Galactic disk. Despite its outstanding role, the census of cluster membership for M67 at fainter magnitudes and their properties are not well-established. Using