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EXOLOG - EXOSAT Observation Log



This database table contains the EXOSAT observation log. This is a complete list of all EXOSAT observations, observing modes, and principal investigators. The log can be used to find out which targets were observed by EXOSAT, who observed them, and the current state of the data analysis.


Taylor B.G. et al., 1981 Sp. Sci. Rev., Vol. 30, p. 479.

White N.E. and Peacock A.P. 1988, X-ray Astronomy with EXOSAT,
    [eds. N.E. White and R. Pallivicini], Memoria S. A. It., p. 59.


The HEASARC revised this database table in August, 2005, in an effort to modernize its parameter names and add Galactic coordinates.


The `name` parameter gives the target name. This name usually corresponds to the target name as specified by the original observer. If a source has been observed by different observers it may be entered under two or more names. It is recommended that any search by `name` always be followed by a search on the found coordinates.

The Right Ascension of the EXOSAT pointing.

The Declination of the EXOSAT pointing.

The Galactic Longitude of the EXOSAT pointing.

The Galactic Latitude of the EXOSAT pointing.

The `time` of the observation refers to the start time. Times are accurate to the nearest second.

The end time of the observation. The units and use of this parameter are the same as those for `time`.

The number of the observation, in chronological order from the beginning of the mission.

target number

The principal investigator for the observation.

observer code

proposal code

A code was assigned to each EXOSAT proposal that approximately defined the class of object to be observed. The codes are as follows:

                 AGN - active galactic nuclei
                 EXG - other kinds of galaxies
                 CLU - clusters of galaxies
                 HLX - high luminosity galactic sources
                 LLX - low luminosity galactic sources
                 SNR - supernova remnants
                 OPS - operational activities
                 CAL - calibration
                 DEE - deep field
                 MIS - miscellaneous
                 PV  - performance verification
                 TOO - target of opportunity

For each observation there is one entry per instrument. The `instrument` parameter gives the name of the instrument. It can be `LE1`, `LE2`, `ME` or `GSPC`. The two LE telescopes are treated as separate instruments because the filters and other instrument modes can be different.

The OBC modes define on-board computer programs that were running during the observation. Each program has a short name, e.g., HTR3. More details about these programs can be found in the EXOSAT FOT handbook, available from the EXOSAT Observatory. The programs depend on the instrument as follows:

   LE:             O = old DIRECT
                   N = new DIRECT without spatial filter
                   D = new DIRECT with diamond filter
                   R = new DIRECT with rectangular filter

   ME:            T3 = HTR3 in full sub-mode
                  P1 = PULS (old version)
                  P2 = PULS2 (new version, with background spectrum)
                  E5 = HER5
                  EH = HER3 or HER4 (data per half array)
                  EQ = HER3 or HER4 (data per quadrant)
                  ED = HER3 or HER4 (data per detector)
                  E2 = HER2
                  D2 = MDIR2 (new direct)
                  I7 = HER7
                  T4 = HTR4
                  I6 = HER6
                  T3 = HTR3 OPT
                  T5 = HTR5

   GSPC:           0 = old DIRECT
                   N = new DIRECT
                   H = HEBL2 or HEBL4

This is a code that gives information concerning the instrument modes for each observation. The code depends on the instrument as follows:

    LE Filters:                        LE detector:
              P = PPL                             C = CMA with filter
              4 = 4000 Lexan                      G = CMA with grating
              A = Al/Pa                           P = PSD
              3 = 3000 Lexan
              B = Boron

   The orientation of the ME array halves:
                                 1 = half 1 offset for part of the period
                                 2 = half 2 offset for part of the period
                                 C = coaligned for part of the period.

   The number, as a hexadecimal digit, of ME high voltages on. If all 16
   detectors are turned on then no character is given. (The argon and
   xenon layers are treated here as separate detectors).

   The GSPC gain used:
                    1 = gain 1.0
                    2 = gain 2.0
                    + = non standard gain, probably 0.5.

The number of channels combined by the OBC; e.g., 1 means full resolution, and 4 means the summing of every 4 adjacent channels.

The ME PHA channel selection and compression:

               spectra                           intensity channels
               -------                           ------------------
            0 = all channels                      A = one argon, no xenon
            1 = argon 4-67 or 5-68, no xenon      B = two argon, no xenon
            2 = argon 4-67 and xenon 138-201      C = one argon, one xenon
            3 = argon 4-67 and xenon 132-195      D = four argon (HER7)
            4 = argon 4-35 and no xenon           E = 4 ranges, with one or
            5 = argon 0-63 and no xenon                more xenon
            6 = argon 0-127 and no xenon          X = one or two xenon, no
            ? = a non standard selection               argon

The accumulation time in seconds of the spectral data for the ME argon data.

The accumulation time in seconds of the spectral data for the ME xenon data.

intensity sample interval, sec

for archive request submission

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Contact Person

Questions regarding the EXOLOG database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 24-Aug-2005 14:32:59 EDT