Target Naming Conventions

    Target names are used to provide unique designations for the targets that will be used throughout the proposal. These names will generally also be used in Phase II, and ultimately to designate targets in the HST data archive. Prospective proposers and archival researchers will use these names to determine whether HST has observed a particular object. This facility will be most useful if consistent naming conventions are used.

    The following conventions must be followed in naming targets:

    Catalog Name

    The preferred order for catalogs to be used for the designation of various classes of objects is provided below. It is arranged in order of decreasing preference. If a target is not contained in these catalogs, other catalog designations may be used (e.g., 4U X-ray catalog designation, Villanova white-dwarf catalog number, etc.). The use of positional catalogs (SAO, Boss, GC, AGK3, FK4, etc.) is discouraged.

    For uncataloged targets, see the section below on Uncataloged Targets.


    1. Henry Draper Catalog number (e.g., HD140283)is preferred. HDE numbers are discouraged, except in the Magellanic Clouds.
    2. Durchmusterung number (BD, CD, or CPD). In the southern hemisphere, adopt the convention of using CD north of -52 degrees and CPD south of there (e.g., BD+30D3639 , CD-42D14462 , CPD-65D7691 ).
    3. General Catalog of Variable Stars designation, if one exists (e.g., RR-LYR , SS-CYG ).
    4. AFGL designation.
    5. IRC designation.
    6. IRAS designation.

       Star Clusters and Nebulae

    1. New General Catalog (NGC) number (e.g., NGC6397 , NGC7027 ).
    2. Index Catalog (IC) number (e.g., IC418 ).
    3. For planetary nebulae for which you do not have an NGC or IC designation, the Perek-Kohoutek designation (e.g., PK208+33D1 ) may be used.
    4. For H II regions for which you do not have an NGC or IC designation, the Sharpless catalog number (e.g., S106 ) may be used.
    5. For IR nebulae, AFGL designation.

       Galaxies and Clusters of Galaxies

    1. NGC number (e.g., NGC4536 ).
    2. IRAS designation.
    3. IC number (e.g., IC724 ).
    4. Uppsala Catalog number, only if an NGC or IC number is not available (e.g., UGC11810 ).
    5. For clusters of galaxies, the Abell catalog number, but only if an NGC or IC number is not available (e.g., ABELL2029 ).

       Quasars and Active Galaxies

    1. The name defined in the compilation by Veron-Cetty and Veron must be used (e.g., 3C273 ).

    Uncataloged Targets

    Objects that have not been cataloged or named must be assigned one of the following designations:

    1. Isolated objects must be designated by a code name (the allowed codes are STAR , NEB , GAL , STAR-CLUS , GAL-CLUS , QSO , SKY , FIELD , and OBJ ), followed by a hyphen and the object's J2000 equatorial coordinates, if possible, rounded to seconds of time and seconds of arc (e.g., for a star at J2000 coordinates RA = 1H 34M 28S, DEC = -15D 31' 38", the designation would be STAR-013428-153138 ).
    2. Uncataloged objects within star clusters, nebulae, or galaxies must be designated by the name of the parent body followed by a hyphen and the rounded J2000 coordinates, if possible, of the object (e.g., for a target within NGC 224 with J2000 coordinates RA = 0H 40M 12S, DEC = +40D 58' 48", the designation would be NGC224-004012+405848 ).
    3. Positions within nebulae or galaxies may also be designated by the name of the parent object followed by a hyphen and a qualifier. The qualifier should be brief, but informative (e.g., the jet in NGC 4486 could be designated NGC4486-JET ). Other examples are: NGC5139-ROA24 , LMC-R136A , ABELL30-CENTRAL-STAR , NGC205-NUC .

    Special Targets

    The names of certain types of targets must be designated by appending a code to the target name. For example, -CALIB should be appended to the name of a target that is being observed only as a calibration standard for other observations. These designations will assist in planning of the observing schedule. The three possible codes are listed in the following table.

    Designations of Special Targets

    Target Type



    External calibration target


    An astronomical target used for calibration (e.g., BD+28D4211-CALIB ).

    Astrometric reference star


    Stars used to determine astrometric positions of other targets (e.g., HD20731-01-REF would designate reference star 01 near HD 20731). Note that the "parallax star" (the target whose position is being measured) may not have a -REF suffix.

    Offset acquisition target


    A target that will be used for an offset acquisition; it is the object that will be acquired first, from which an offset will be applied to move to the target of interest (e.g., 3C273-OFFSET).

    Special Calibration Observations

    The Observation Summary of a Phase I proposal should include not only all relevant external calibration targets, but also any (non-default) internal calibration targets and calibrations using the Earth. Allowed target names for such observations include: ANTI-SUN, ANY, BIAS, CCDFLAT, DARK, EARTH-CALIB, INTFLAT, KSPOTS, NONE, ORBIT-POLE, UVFLAT, VISFLAT, WAVE. These names may not be used for other external pointings.

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    Last updated: June 9, 2000