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Raw Data Field Descriptions

Table of Contents

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List of Fields

Description of Fields

 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.

star_num
  • OAO-3 object number
  • Valid range: 1 to 558
  • Type: 16-bit integer
  • 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.

obs_num
  • Observation number
  • Valid range: 1 to 35
  • Type: 16-bit integer
  • 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.

rec_num
  • Record number
  • Valid range: 1 to 23,355
  • Type: 16-bit integer
  • The sequential scan number for a particular object number. Since each row in the binary table represents one spectral scan, this parameter is also the row number in the binary table.

pgm_id
  • Observing program name
  • Type: character, size 4
  • 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.

yr_obs
  • Year of observation (GMT)
  • Valid range: 1972 to 1982
  • Type: 16-bit integer
  • 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.

day_obs
  • Day of observation (GMT)
  • Valid range: 1 to 366
  • Type: 16-bit integer
  • See note for yr_obs.

hr_obs
  • Hour of observation (GMT)
  • Valid range: 0 to 23
  • Type: 16-bit integer
  • See note for yr_obs.

min_obs
  • Minute of observation (GMT)
  • Valid range: 0 to 59
  • Type: 16-bit integer
  • See note for yr_obs.

sec_obs
  • Second of observation (GMT)
  • Valid range: 0 to 59
  • Type: 16-bit integer
  • See note for yr_obs.

frst_set
  • First SET time
  • Valid range: 1 < = entry < = ?
  • Type: 16-bit integer
  • Units: 0.25 mintute intervals
  • 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) since for 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 occurs.

last_set
  • Last set time
  • Valid range: ? to ?
  • Type: 16-bit integer
  • Units: 0.25 mintute intervals
  • The time of the last data point of the scan. See frst_time for more information.

lan_set
  • SET time of the most recent ascending node crossing
  • Valid range: ? to ?
  • Type: 16-bit integer
  • Units: 0.25 mintute intervals
  • ?????????

lan
  • Longitude of ascending node
  • Valid range: 0.0 to 360.0
  • Type: floating point
  • Units: degrees
  • Longitude of ascending node for the orbit when the scan started. (This number is useful for particle background estimates.)

dump_orb
  • Orbit number for data dump
  • Valid range: 0 to 45000
  • Type: 32-bit integer
  • Orbit number in which data was dumped to ground. This is not necessarily the same orbit in which the data was taken.

sat_parm
  • Satellite orbit parameters number
  • Valid range: 0 to 999
  • Type: 16-bit integer
  • 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 reference.

    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] 

                        31622400 (1973)
                    63158400 (1974)

eth_parm
  • Earth orbit parameters number
  • Valid range: 0 to 99
  • Type: 16-bit integer
  • Serial number for the earth orbit parameters used in deriving the earth's radial velocity. See "sat_parm" for more information.

tube_name
  • Detector tube name
  • Valid entries: U1, V1, U2, V2, V3, U3
  • Type: character, size 2
  • See tube_num for description.

tube_num
  • Detector tube number
  • Valid range: 1 through 6
  • Type: 16-bit integer
  • Describes the number of the detector used for the particular observation. The detector may be one of six detectors and is designated as follows: 
              Name    Exit Slit*   Wavelength    Step Size*
                 (Angstroms)  (Angstroms)   (Angstroms)
       1 - U1       0.05        710-1500**     0.025
       2 - V1       0.10       1640-3185       0.05
       3 - U2       0.20        750-1645       0.20
       4 - V2       0.40       1480-3275       0.40
       5 - V3        ?     stationary at 3430   -
       6 - U3        ?     stationary at 1320   -

*Note: Exit slit and step size vary slightly with wavelength.
**For brighter stars, the 1500-1560 angstrom range can be scanned 
with U1 in the first order.

nnn
  • Number of points in a scan
  • Valid range: 0 to 32767
  • Type: 16-bit integer

wve_frst
  • First wavelength of scan
  • Valid range: (see wve_last below)
  • Units: Angstroms
  • Type: floating point

wve_last
  • Last wavelength of scan
  • Valid range: 
      
           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)
  • Units: Angstroms
  • 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).

    max_cnts
  • Maximum counts per channel
  • Valid range: 1 to 32767
  • Type: 32-bit integer

min_cnts
  • Minimum counts per channel
  • Valid range: 1 to 32767
  • Type: 32-bit integer

avg_cnts
  • Average counts per channel
  • Valid range: 1 to 32767
  • Type: 32-bit integer
  • The average of the counts in the scan.

sigma
  • Sigma of counts
  • Valid range: 1 to 32767
  • Type: 32-bit integer
  • The rms dispersion (sigma) from the mean for the counts in the scan.

stand
  • Background status .AND.
  • Valid range: 0 to 1
  • Type: 8-bit byte
  • 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.

stor
  • Background status .OR.
  • Valid range: 0 to 1
  • Type: 8-bit byte
  • 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 backgrounds.

frst_com

scnd_com

thrd_com

frth_com

version
  • Processing version number
  • Valid range: ? to ?
  • Type: 16-bit integer

rvs_num
  • Revision number
  • Valid range: ? to ?
  • Type: 16-bit integer

redc_yr
  • Year of last data reduction
  • Valid range: 1972 to 1982
  • Type: 16-bit integer

redc_day
  • Day of last data reduction
  • Valid range: 1.000 to 366.999
  • Type: floating point

tlambda
  • Wavelength table
  • Valid range: 710 to 3275
  • Type: floating point vector
  • Units: Angstroms
  • Wavelengths in a heliocentric reference frame; they were originally provided by Princeton in the star's rest frame.

tcounts
  • Counts table
  • Valid range: ? to ?
  • Type: floating point vector
  • Units: counts per 14 seconds

tback
  • Background table
  • Valid range: ? to ?
  • Type: floating point vector
  • Units: counts per 14 seconds
  • 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 particle-induced count 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.

tlan
  • Time table
  • Valid range: ? to ?
  • Type: 32-bit integer vector
  • Units: 0.25 minute intervals (see frst_set for a more complete description).

tstatus
  • Background status table
  • Valid range: 0 to 2
  • Type: 16-bit integer vector

References.
Jenkins, E.B., "Instructions for Information Retrieval from the Copernicus Disk Data Set", revised 29 September 1975

Snow, T.P., "A Guide for Guest Investigators Using the Princeton Telescope on the Satellite COPERNICUS, Version 2", Princeton University Observatory, Princeton, N.J., April 1975

Barker, E. S., Lugger, P. M., Weiler, E. J., & York, D. G. 1984, ApJ, 280, 600.

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.

Data location.

 Anonymous ftp site on archive.stsci.edu in pub/copernicus.

Document URL.

 https://archive.stsci.edu/copernicus/rdf.html

Origin of documentation.

 This document was compiled by the Copernicus Archive Project. Project members included staff from the GSFC Laboratory for Astronomy and Solar Physics (LASP) and the GSFC Astrophysics Data Facility (ADF).