Re: data format

From: paul (astro@pgog.net)
Date: Fri Feb 14 2003 - 09:40:55 EST

  • Next message: sattrack@hal-pc.org: "Epoch Date Age Analysis"

    rob, here is some info complied by george lewis,
    see utility.txt \IOD 
    if you are not already reporting in the otwg format,
    then it is suggested you use IOD format.  Russell
    has a slightly different format that is also explained
    in utility.txt.  george's app will convert all to IOD.
    
          OTWG2IOD is used to convert observations reported using the Optical
    Tracking Working Group (OTWG) format to the IOD format. Current users of this
    format are David Brierley, Peter Wakelin and, with some departures from the
    format definition, Rainer Kracht. I used it myself when reporting my
    observations to the RGO during 1992-1997. After the OTWG ceased to exist
    in March 1997--thereby requiring the format to stand on its own merit--I
    concluded that the format was not worth continued support in view of its
    limitations.
    
          An example of visual satellite observations reported using the OTWG
    format is the following:
    
    
    8406503987697070622352907  01   12200054  +28239  01  4             +60+70     R
    8406503987697070622353151  01   12195728  +27210  01  4              6  7      R
    8406503987697070922261699  01   12194904  +10114  01  4             +60+80 0121R
    9506601987697070923295348  01   12022498  +38388  01  4             -20+30     I
    8204103987697071321341505  01   12215863  +39184  01  4             +60INV 0061F
    8204103987697071321344828  01   12225397  +49310  01  4             +60INV     F
    7806401987697071321521988  01   12155067  -24270  01  4             +40        S
    9605102987697071322024366  01   12020449  +64470  01  4             +40+70 0169R
    9607201987697071322272203  01   12125823  +18392  01  4             +40+70     I
    8406503987697071322433271  01   12231279  +73585  01  4             +7 INV     F
    8807801987697071323065989  01   12230253  +14515  02  4             +5 +7      F
    
    
          Two format descriptions are given below. The first was received from the
    Royal Greenwich Observatory in 1992. The second was posted by David Brierley to
    the Seesat-L Internet forum in 1998. The two definitions don't agree in regard
    to how the magnitude fields are defined. They also don't agree in regard to the
    use of letter designations in columns 6 and 7. They don't agree on the use of
    "INV" in columns 72-74, which the RGO description makes no mention of. The RGO
    version has an additional optical characteristics code (X). Finally, Brierley's
    version doesn't mention AZ/EL observations (format types 4-6).
    
          OTWG2IOD is based on a combination of these format descriptions. Letter
    designations in columns 6 and 7 are accommodated. "INV" in columns 72-74 is
    accommodated. The magnitude fields as given in Brierley's definition allow xMm
    or Mmm, where "x" denotes a sign (+ or -), "M" denotes 0-9, "m" denotes .0-.9,
    and "mm" denotes .00 to .99. As it makes no sense for visual observers to
    claim an accuracy of 1/100 of a magnitude, the "Mmm" usage is not recognized by
    OTWG2IOD. Columns 69 and 72 must be either "+", "-" or " " (blank). This
    prohibits reporting of magnitudes of 10.0 or greater. The two digits that
    follow are interpreted as magnitudes of X.Y, where X and Y are both in the
    range 0-9.
    
          Format numbers 1-6 for positional observations, as given in the RGO
    description, are accommodated.
    
          Since the OTWG format is based on strict column assignment of data, it
    is possible to perform a check of each column prior to conversion of each
    observation. If OTWG2IOD encounters an unexpected value in any column, it
    reports the column number containing the questionable value and the complete
    observation line in OTWGLIST.OUT and goes on to the next observation without
    attempting to convert the observation with the unexpected value. The slant
    range and slant range uncertainty fields are not included in the check of each
    observation.
    
          As the OTWG format does not include the object number, the object number
    is acquired from SSR.ID or DECAYED.ID as in RDE2IOD.
    
          The main difference between the OTWG format and Russell Eberst's format
    is that observations reported using the OTWG format are complete within each
    line. Any observation reported in the OTWG format may be taken out of context
    without losing anything in terms of the information needed for analysis, e.g.,
    date, coordinate frame, observation uncertainty, etc. This is an essential
    feature of a complete observation report format and it has been retained in the
    IOD format.
    
    	  ==========================================================
    
    OTWG Format Description From RGO (1992):
    ---------------------------------------
    
    01  y    Satellite number as yynnncc
    02  y
    03  n    Unidentified sats are labelled 9900000
    04  n
    05  n
    06  c    cc =1 for A  2 for B etc
    07  c
    
    08  s    Site number
    09  s
    10  s
    11  s
    
    12  y   time of obs
    13  y
    14  m
    15  m
    16  d
    17  d
    18  h
    19  h
    20  m
    21  m
    22  S
    23  S
    24  s  decimal point is implied between 23 and 24
    25  s
    26  s  24-27 should be left blank unless zero is significant
    27  s
    
    28  A
    29  a  implied decimal point between 28 and 29
    30  a  Timing accuracy in seconds
    31  a
    32  a
    
    33  t  timing standard  1 = UTC  2 = speaking clock  3 = BBC pips
    
    34  c  code for position type
    35  p
    36  p            c=1-3    positions are in HMS and DMS
    37  p   c = 1  pppppppp = HHMMSSss   qqqqqqq = DDMMSSs
    38  p
    39  p   c = 2             HHMMmmmm             DDMMmmm
    40  p
    41  p   c = 3             HHMMmmmm             DDddddd
    42  p
    43  s (sign + or 1 or blank)
    44  q           c=4-6   positions are in azimuth and elevation
    45  q   c = 4             DDDMMSSs             DDMMSSs
    46  q
    47  q   c = 5             DDDMMmmm             DDMMmmm
    48  q
    49  q   c = 6             DDDddddd             DDddddd
    50  q
    
    51  a
    52  a   c = 1,4          aaaa is seconds of arc  SSSs
    53  a   c = 2,5                  minutes     "   MMmm
    54  a   c = 3,6                  degrees     "   Dddd
    
    55  e   Epoch 0=date of obs  1=1855  2=1875 3=1900 4=1950 5=2000
    
    56  R
    57  R
    58  R   Slant range in Kilometres
    59  R
    60  R
    61  r
    62  r
    63  r
    
    64  A
    66  A
    66  a  Slant range accuracy in kilometers
    67  a
    68  a
    
    69  M  (+ or -)
    70  M  Maximum magnitude
    71  M
    
    72  m  (+ or -)
    73  m  minimum magnitude
    74  m
    
    75  S
    76  S
    77  S  Flash period in seconds
    78  s
    79  s
    
    80  F S=steady  I=irregular R=regular variations F=constant flash period
          X= Irregular flash period  E unusually faint because of eclipse
    
    	   =========================================================
    
    
    OTWG Format Description From David Brierley (1998):
    --------------------------------------------------
    
    CODING FOR "RGO" POSITIONAL REPORTS
    
    Decimal points are omitted.
    x=sign (+ is optional).
    
    Bytes:
    1-7     COSPAR International Designator in numerical form,
    	e.g. 6710402. Use letters for fragments >99.
    8-11    COSPAR Site number
    12-17   Date (YYMMDD)
    18-27   Time UT (HHMMSSssss)
    28-32   Time accuracy (Sssss)
    33      Time standard used: 1=radio, 2=phone
    34      Coordinate system used in bytes 35-54
    If byte 34=1
    35-42   RA (HHMMSSss)
    43-50   Dec (xDDMMSSs)
    51-54   Angular accuracy (SSSs)
    If byte 34=2
    35-42   RA (HHMMmmmm)
    43-50   Dec (xDDMMmmm)
    51-54   Angular accuracy (MMmm)
    If byte 34=3
    35-42   RA (HHMMmmmm)
    43-50   Dec (xDDddddd)
    51-54   Angular accuracy (Dddd)
    55      Epoch: 4=1950.0, 5=2000.0
    56-63   Range (for radar observations)
    64-68   Range accuracy (ditto)
    69-71   Max brightness (xMm or Mmm) during a period of
    about a minute centred on the observation
    72-74   Min brightness (xMm, Mmm or "INV" if invisible)
    75-79   Flash period or period of regular variation (SSSss)
    80      Appearance: S=steady, I=irregular, R=Regular variation
    	F=Flashing, E=in Eclipse
    
    Extracted from "The Reporting of Satellite Observations"
    (1973), Radio and Space Research Station, Slough, England.
    
    David Brierley
    
    -----------------------------------------------------------------
    Unsubscribe from SeeSat-L by sending a message with 'unsubscribe'
    in the SUBJECT to SeeSat-L-request@satobs.org
    http://www.satobs.org/seesat/seesatindex.html
    



    This archive was generated by hypermail 2b29 : Fri Feb 14 2003 - 10:03:08 EST