Proposed Naming Convention for Unknown Objects

From: Ted Molczan (
Date: Sun Apr 09 2000 - 14:24:32 PDT

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    We frequently encounter the practical problem of how to name the unidentified
    objects that we find and track, especially those that are likely to be tracked
    for a long time. There are quite a few objects in geo-synchronous and Molniya
    orbits, and a few in LEO, in that category.
    Though there has never been a general agreement on a naming convention in the
    past, the recent spate of unknowns has inspired me to devise one, which I
    hereby propose for consideration.
    1. Design Constraints
    Here are the Musts and Wishes that constrained my design.
    1.1 Musts
    1.1.1. Be compatible in format with "standard" International Designators, and
    NORAD/US Space Command's catalogue numbers, but never in conflict with
    designations or catalogue numbers of officially reported objects.
    1.1.2. Be distinguishable from normal designations and catalogue numbers at a
    1.1.3. Be unlikely to "break" existing software.
    1.1.4. Be compatible with reporting formats in common use by observers.
    1.2 Wishes
    1.2.1. Rules easy to remember.
    1.2.2. As descriptive as possible.
    1.2.3. Easy to administer.
    2. Proposed Use of International Designator Fields
    I propose that for unknowns, we adopt the following format:
    YY = final 2 digits of the year
    DDD = day of year of first reported observation + 200. i.e. day 0 = 200; day
    365 = 565
    We add 200 to avoid conflict with normal International Designators, which use
    this field for the serial number of the launch. As I recall, the peak number of
    launches in a year has never exceeded 129, and in recent years has been well
    below 100, so adding 200 seems adequate. Of course, for an extra margin of
    safety, we could agree to add as much 600, in which case day 0 = 600 and day
    365 = 965.
    PPP = letter designating specific unknowns found that day.
    Russell Eberst's unknown of 4 April 2000 would look like this in element sets:
    00295A. He and others who use an all-numeric, 7 position, designator to report
    observations, could use write it as 0029501, much as they write standard
    International Designators.
    I see no reason why observers cannot continue to use temporary designations,
    like 9900000, until their unknowns are either identified, or recovered and
    tracked. In the latter case, the special permanent designation would be
    2.1 Design Considerations
    I was able to think of several more expressive uses of the 8 positions of the
    International Designator field; however, all would have been likely to violate
    at least one of the MUST design constraints.
    For example, I would like to have included letters of the alphabet in at least
    one of the first 5 positions; however, several leading observers use reporting
    formats in which those fields are all numeric. Also, I suspect that there are
    programs in use that require these field positions to be numbers.
    Also, I would like to have made more complete use of all 8 field positions.
    Rarely will we ever designate more than one or two unknowns on a given day, yet
    I have devoted three field positions to this, but please bear in mind that
    several leading observers use a reporting format which limits the international
    designator to only 7 positions, all of then numeric, i.e. YYLLLNN. In this
    format, the maximum of three letters in the "standard" International Designator
    (PPP) that identify the piece from a launch are coded as two digit numerics
    (NN), i.e. A = 01, L = 11.
    I believe that my proposal should cause few, if any, problems, and is
    reasonably easy to understand and remember. Just remember: "day of year plus
    3. Proposed Use of NORAD / U.S. Spacecommand Catalogue Field
    I propose that this field be used in much the same way that NORAD uses it: a
    simple serial catalogue number. To avoid conflict with official catalogue
    numbers, I recommend that ours begin with 90001.
    To avoid confusion with search elements, I propose that they be numbered
    between 70000-79999.
    Also, I recommend avoiding 80000-89999, since those are used by NORAD analyst
    elements, and have been released on occasion.
    I suspect that most observers prefer to use the NORAD number over the
    International Designator, and so would wish that it be used in a more
    descriptive manner; however, I have found that it is simply too short to be
    completely descriptive.
    Descriptive numbers might be easier to remember, but bear in mind that there is
    nothing descriptive about 16609, yet many of us remember it well, because the
    object itself is memorable.
    4. Name field on Line 0.
    I propose that the use of this field for un-identified objects, be left to
    everyone's discretion.
    5. Conflict Avoidance and Resolution
    I see little potential for conflict over the International Designator, since by
    definition it would be a function of the date of first observation. The format
    allows for multiple unknowns on the same day. In case more than one is found,
    perhaps their letter designations could be assigned according to the UTC time
    of the observation.
    The catalogue numbers may pose more of a problem, because they would be simple
    serial numbers. To minimize and resolve conflicts among observers over their
    assignment, I recommend that someone volunteer to maintain a registry of
    un-identified objects, which would be posted on the web. An observer or analyst
    needing a new number would simply select the next available number in the
    sequence by posting her intention to SeeSat-L. The maintainer would then update
    the record.
    6. Conclusion
    I hope that after some discussion, we can adopt a naming convention for unknown
    objects. If not this one, then a reasonable compromise.
    Ted Molczan
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