The descriptions of these parameter fields were obtained primarily from
Appendix A of Jenkins (1975). The field names below are identical to
the value of the TTYPEn
FITS keywords contained in the Binary table extensions of the raw data sets,
and are listed in the order in which they are stored in the table.
The Copernicus master star number assigned by Princeton during the
mission based on the order in which the targets were first obeserved.
Some object numbers were assigned for testing purposes.
Consequently, there are only 551 objects with astronomical data. See the
Copernicus target list
for more information.
The first observation of a specific object is 1, the second is 2, etc.
Each observation may have multiple scans. Also,
sometimes the same observation number was used for scans taken
at different times.
Identification of the particular observing program. The first two
characters were usually the initials of the Principal Investigator followed
by two digits (e.g. LS15, DY02). The
program name also identified the command sequences which generated the
carriage motion(s) for the observing session.
The yr_obs, day_obs, hr_obs, min_obs,and sec_obs actually refer to the
GMT time when the satellite crosses the ascending node of the orbit. The
atual time of observation for a given scan is obtained by adding the FRST_SET
value times the length of 1 SET (i.e., 15.72887) to this GMT time.
Note U3 data wasn't routinely stored until September, 1973. Data taken before
then won't contain U3 scans unless it was re-reduced later.
The time of the first data point in the scan.
The times given for first_time and last_time are expressed in terms
of 1/4 minutes (i.e. delta SET = 1), and the origin time = 0 for each
orbit corresponds to the first SET change after the ascending node was
crossed. This time
system was chosen in preference to SET (i.e., Spacecraft Equivalent Time)
the latter one must anticipate the possibility that an overflow may
occur (4096 to 0000), which would complicate any program making use of
times. The time relative to the node crossing has two additional
advantages: (1) It can be represented by small numbers (<2^10) which
can be squeezed into the wavelength word, thus saving space on the
disk, and (2) This is the time reference used by the program which
estimates the particle background count rates.
The data field lan_set gives the actual SET when TIME = 0 for the
times in the scan. Note that the GMT will
not be exactly equal to when the node crossing occurred; it can be off
by as much as 16 sec. [actually 1 SET = 15.72887 seconds], since the
time base chooses the first SET incrementation after a crossing
Serial number for the list of orbital elements used in the derivation
of the orbital component of the satellite's radial velocity. These
numbers are also necessary for the evaluation of LAN and the time
Calculations of the earth and satellite orbital velocity make use of a
time reference (in seconds) whose origin is at the beginning of the
year in question (instead of 1972). To find this time for years other
than 1972 one need only to subtract the following values from ISECS
[the number of seconds from the beginning of 1972] or DSECS [the real*8
representation of ISECS]
U1 valid range: 710 through 1500 A
V1 valid range: 1640 through 3185 A
U2 valid range: 750 through 1645 A
V2 valid range: 1480 through 3275 A
V3 valid range: 3430 A (fixed)
U3 valid range: 1320 A (fixed)
Type: floating point
The first and last wavelength points of a scan (fields wve_frst and
wve_last); the wavelengths are
heliocentric. These are the minimum and maximum wavelengths for the scan.
However, the minimum may be either the first or last wavelength point (vice
versa for the maximum) depending on the scan direction. These values are
identical for U3 and V3 which did not scan. During the mission all
wavelengths were assigned in the star's rest frame; these were converted
to heliocentric. Air wavelengths are
given for lambda >2000 Angstroms; for lambda <2000 Angstroms vacuum
wavelengths are specified.
Note the U1 and U2 tubes were generally restricted to wavelengths greater
than the Lyman-limit (912 Å), although (as listed in the avbove tables)
the carriages allowed observations to wavelengths as short as 710 (Å).
Three logical variables which represent cumulative .AND. operations on
the three respective logical conditions for the status of all values in a
scan's BKGND array. If one of the letters is T (corresponding to a
logical .TRUE.) all points in the scan have the particuular background
correction, while F means some (or all) of the points have the background
omitted in the sum.
Cumulative .OR. representation of the background status (see
"stand"). T (for .TURE.) means some (or all) of the points have
backgrounds computed, while F (for .FALSE.) means all of the points no
This table contains the estimated zero-level counts at every point
along the scan, as determined during processing of the data at Princeton
during the mission. Under ideal circumstances the background numbers
should represent the sum of three sources which elevate the true spectrum
zero-level to finite count levels. These sources are (1) charged
rate, (2) scattered light (principally from the grating, and (3) stray
light (entering the U1 and U2 vent holes). In practice, corrections for
(2) and (3) were not applied to the data as part of the production
processing. In most cases, however, the particle background is provided.
Corbally, C.J., and Garrison, R.F. 1983,
"Which Map of Absolute Magnitudes: Keenan or Schmidt-Kaler?", in
The MK Process and Stellar Classification, ed. R.F. Garrison
(David Dunlap Observatory, Toronto).
Kitchin, C. R. 1984, "Astrophysical Techniques"
published by Adam Hilger, Ltd. Bristol England
Rogerson, J. B., Spitzer, L. Drake, J. F.,
Dressler, K., Jenkins, E. B., Morton, D.C., & York, D. G.
1973, ApJL, 181, 97.
Yale Bright Star (YBS) Catlogue Version 5.
Compiled/edited by D.A. Klinglesmith III, J.T. Lauroesch, P.J. Lawton,
and R.W. Thompson.
This document was compiled by the
Archive Project. Project members included staff from the GSFC Laboratory
for Astronomy and Solar Physics (LASP) and the GSFC
Astrophysics Data Facility (ADF).