J/A+AS/112/99 J/A+AS/112/99 Calar Alto Obs. sky brightness C Leinert P Vaisaenen K Mattila K Lehtinen Astron. Astrophys. Suppl. Ser. 112 99 1995 1995A&AS..112...99L J/A+AS/119/153 : La Silla Observatory sky brightness 1978-1988 (Mattila+ 1996) atmospheric effects site testing We report measurements of the sky brightness at the Calar Alto Observatory during 18 moonless nights in the years 1989, 1990, 1991, and 1993. Most of the measurements were performed in eight intermediate band filters between 350nm and 820nm. A set of measurements was obtained in the broad band UBVRI filters during three nights in 1990. Typically 10 to 20 readings were obtained each night for one or two fixed positions (fixed in {alpha}, {delta}), selected to be free of stars down to a limiting magnitude of about B=20. The sky brightnesses were calibrated using standard stars.

Date Date "DD/MM/YY" Filter Filter number number=1 For the narrow band data the FILTERS 01 ... 08 correspond to u (Stroemgren), 392nm, 403nm, b, 525nm, 580nm, 710nm, and 820nm, respectively. --- LST Local sideral time h 2.2mTel 2.2m telescope measurement ct/s 1.23mTel 1.23m telescope measurement ct/s SuBr Surface brightness (10-9 ergs/s/cm2/sr/Angstroem) number=2 See section 2.1. of the article for description of the derivation of intensities. Summary: the ratio of 1.23m/2.2m counts (and interpolation where needed) has been used. An abrupt change in the intensities during a night indicates a CHANGE OF TARGET; these are readily seen from Fig. 3. of the article. 10-11W/m2/sr/nm Date Date "DD/MM/YY" Filter Filter number number=1 For the broad band data the FILTERS 01 -- 05 correspond to Johnson bands U, B, V, R, and I, respectively. --- LST Local sideral time h 2.2mTel 2.2m telescope measurement ct/s 1.23mTel 1.23m telescope measurement ct/s SuBr Surface brightness number=2 See section 2.1. of the article for description of the derivation of intensities. Summary: the 2.2 m telescope was used as monitoring telescope, and its values are used directly. An abrupt change in the intensities during a night indicates a CHANGE OF TARGET; these are readily seen from Fig. 3. of the article. => The unit "S_10" (tenth magnitude stars per square degree) corresponds to the surface brightness which produces per square degree the flux of a 10th-magnitude star in the observed wavelength range. "S_10" Date Date "DD/MM/YY" End End of Twilight (LST) h Beg Beginning of Twilight (LST) h Simona Mei CDS 1995Mar13 J_A+AS_112_99.xml