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J/A+AS/112/99                Calar Alto Obs. sky brightness (Leinert+, 1995)
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Measurements of sky brightness at the Calar Alto Observatory
     Leinert C., Vaisaenen P., Mattila K., Lehtinen K.
    <Astron. Astrophys. Suppl. Ser. 112, 99 (1995)>
    =1995A&AS..112...99L      (SIMBAD/NED BibCode)
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Keywords: atmospheric effects - site testing

Description:
    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.

File Summary:
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  FileName      Lrecl  Records   Explanations
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ReadMe              80        .   This file
table3a             58     2748   Narrow intermediate band surface photometry
table3b             58      769   UBVRI broad band surface photometric data
table3c             34       18   End and beginning of astronomical twilight
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See also:
  J/A+AS/119/153 : La Silla Observatory sky brightness 1978-1988 (Mattila+ 1996)

Byte-by-byte Description of file: table3a
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   Bytes Format    Units       Label    Explanations
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   3-  8  I6       "DD/MM/YY"  Date     Date
  10- 11  I2       ---         Filter   [1/8] Filter number (1)
  15- 21  F7.4     h           LST      Local sideral time
  26- 33  F8.2     ct/s        2.2mTel  []? 2.2m telescope measurement
  37- 45  F9.2     ct/s        1.23mTel 1.23m telescope measurement
  53- 58  F6.2 10-11W/m2/sr/nm SuBr     Surface brightness
                                         (10-9 ergs/s/cm2/sr/Angstroem) (2)
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Note (1): For the narrow band data the FILTERS 01 ... 08 correspond to
          u (Stroemgren), 392nm, 403nm, b, 525nm, 580nm, 710nm, and 820nm,
          respectively.
Note (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.
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Byte-by-byte Description of file: table3b
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   Bytes Format  Units   Label    Explanations
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   3-  8  I6     "DD/MM/YY" Date     Date
  10- 11  I2     ---        Filter   [1/5] Filter number (1)
  15- 21  F7.4   h          LST      Local sideral time
  25- 33  F9.2   ct/s       2.2mTel  2.2m telescope measurement
  37- 45  F9.2   ct/s       1.23mTel 1.23m telescope measurement
  52- 58  F7.2   "S_10"     SuBr     Surface brightness (2)
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Note (1): For the broad band data the FILTERS 01 -- 05 correspond to Johnson
          bands U, B, V, R, and I, respectively.
Note (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.
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Byte-by-byte Description of file: table3c
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   Bytes Format  Units     Label    Explanations
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   3-  8  I6    "DD/MM/YY" Date     Date
  12- 18  F7.4   h         End      End of Twilight (LST)
  21- 27  F7.4   h         Beg      Beginning of Twilight (LST)
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(End)                                             Simona Mei [CDS]   13-Mar-1995