u471cb.m77t - MGD77 data file for Geophysical data from field activity UGEOLEG_4 (U-4-71-CB) in Venezuela, Caribbean Sea from 08/18/1971 to 10/01/1971

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Frequently anticipated questions:

What does this data set describe?

Title:
u471cb.m77t - MGD77 data file for Geophysical data from field activity UGEOLEG_4 (U-4-71-CB) in Venezuela, Caribbean Sea from 08/18/1971 to 10/01/1971
Abstract:
Single-beam bathymetry,gravity, and magnetic data along with transit satellite navigation data was collected as part of field activity UGEOLEG_4 (U-4-71-CB) in Venezuela, Caribbean Sea from 08/18/1971 to 10/01/1971, http://walrus.wr.usgs.gov/infobank/u/u471cb/html/u-4-71-cb.meta.html
These data are reformatted from space-delimited ASCII text files located in the Coastal and Marine Geology Program (CMGP) InfoBank field activity catalog at http://walrus.wr.usgs.gov/infobank/u/u471cb/html/u-4-71-cb.bath.html http://walrus.wr.usgs.gov/infobank/u/u471cb/html/u-4-71-cb.grav.html and http://walrus.wr.usgs.gov/infobank/u/u471cb/html/u-4-71-cb.mag.html into MGD77T format provided by the NOAA's National Geophysical Data Center(NGDC). The MGD77T format includes a header (documentation) file (.h77t) and a data file (.m77t). More information regarding this format can be found in the publication listed in the Cross_reference section of this metadata file.
Supplemental_Information:
The navigation data are digitally collected using a Satellite Integrated Navigation (SINS) system. The system is a space-based satellite navigation maintained by the United States government and is accessible using a satellite receiver. This system provides navigational accuracy of approximately 200 m.The Data Acquistion, Processing, and Storage (DAPS) group performs a number of processing steps to the navigation data once it is collected which can vary by cruise. These steps are outlined within the header information in each individual digital navigation (.05x) space-delimited ASCII data file. The header information rows are indicated by lines beginning with the character "!". There is no information on how the single-beam bathymetry, gravity, and magnetic data were collected. For each data gathering cruise leg, the available data in the following categories are forwarded to NGDC: navigation, gravity, magnetics, bathymetry, and seismic shot points. The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC.
  1. How might this data set be cited?
    U.S. Geological Survey, and Coastal and Marine Geology Program, 2013, u471cb.m77t - MGD77 data file for Geophysical data from field activity UGEOLEG_4 (U-4-71-CB) in Venezuela, Caribbean Sea from 08/18/1971 to 10/01/1971: U.S. Geological Survey, Menlo Park, CA.

    Online Links:

    This is part of the following larger work.

    Steele, Wm. Clinton, Degnan, Carolyn H., Deeter, Gary B., and Riordan, Jean A., 1980, DESCRIPTION OF MARINE GEOPHYSICAL DATA COLLECTED BY THE U.S. GEOLOGICAL SURVEY AND HOW TO OBTAIN IT: U.S. Geological Survey Open File Report 167, U.S. Geological Survey, Menlo Park, CA.

    Online Links:

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -70.32740
    East_Bounding_Coordinate: -61.72080
    North_Bounding_Coordinate: 18.59110
    South_Bounding_Coordinate: 10.46670
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 18-Aug-1971
    Ending_Date: 01-Oct-1971
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: tab-delimited ASCII text files
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference: Venezuela, Caribbean Sea
      This is a Point data set. It contains the following vector data types (SDTS terminology):
      • Point
    2. What coordinate system is used to represent geographic features?
      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.000001. Longitudes are given to the nearest 0.000001. Latitude and longitude values are specified in Decimal degrees. The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.25722210100002.
  7. How does the data set describe geographic features?
    u471cb.m77t
    MGD77T single-beam bathymetry, gravity, and magnetic data file for U471CB (Source: NOAA's National Geophysical Data Center, See Hittelman and others (2010) Cross_Reference section above for details about the MGD77T format and citation information.)
    SURVEY_ID
    Survey identifier supplied by the contributing organization (Source: NGDC) This identifier varies in format and is supplied by the contributing organization
    TIMEZONE
    Time-zone correction (Source: NGDC) In our datasets, no correction was applied. All values equal 0.
    DATE
    YYYYMMDD (Source: NGDC)
    Range of values
    Minimum:19710818
    Maximum:19711001
    Units:Year, month, day
    TIME
    Time (Source: NGDC)
    Range of values
    Minimum:0
    Maximum:2359
    Units:hours and decimal minutes
    LAT
    Latitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:10.46687
    Maximum:18.5911
    Units:decimal degrees
    LON
    Longitude (Source: World Geodetic System 1984 Geographic Coordinate System)
    Range of values
    Minimum:-70.3274
    Maximum:-61.7208
    Units:decimal degrees
    POS_TYPE
    Indicates how lat/lon was obtained (Source: NGDC)
    Range of values
    Minimum:1
    Maximum:3
    Units:1 = observed fix, 3 = interpolated fix, nil = unspecified
    BAT_TTIME
    Bathymetry, 2-way travel time (Source: U.S. Geological Survey)
    Range of values
    Minimum:0.04
    Maximum:7.23
    Units:seconds
    CORR_DEPTH
    Bathymetry, corrected depth (Source: U.S. Geological Survey)
    Range of values
    Minimum:31
    Maximum:5535
    Units:decimal meters
    BAT_CPCO
    Bathymetric Correction code - details the procedure used for determining the sound velocity correction to depth (Source: NGDC)
    Range of values
    Minimum:59
    Maximum:59
    Units:01-55 Matthews' Zones with zone , 59 Matthews' Zones, no zone specified, 60 S. Kuwahara Formula, 61 Wilson Formula, 62 Del Grosso Formula, 63 Carter's Tables, 88 Other (see Add. Doc.), 97 Computed using 1500 meters/sec, 98 Unknown if Corrected, 99 Unspecified
    BAT_TYPCO
    Bathymetry type code - indicates how the bathymetric value was obtained (Source: NGDC)
    Range of values
    Minimum:1
    Maximum:3
    Units:1 - Observed, 3 - Interpolated (Header Seq. 12), 9 - Unspecified
    MAG_TOT
    Magnetics total field - 1st sensor (Source: NGDC)
    Range of values
    Minimum:36860.1
    Maximum:47577.9
    Units:gammas
    MAG_RES
    Magnetics residual field field (Source: NGDC)
    Range of values
    Minimum:-595.4
    Maximum:4721.9
    Units:gammas
    GRA_OBS
    Observed gravity (Source: NGDC)
    Range of values
    Minimum:978454.6
    Maximum:978662.4
    Units:milligals
    EOTVOS
    EOTVOS correction - E = 7.5 V cos(phi) * sin(alpha) + 0.0042 V*V (Source: NGDC)
    Range of values
    Minimum:-67.5
    Maximum:-3.2
    Units:milligals
    FREEAIR
    Free-air Anomaly = G(observed) minus G(theoretical) (Source: NGDC)
    Range of values
    Minimum:-391.4
    Maximum:92.6
    Units:milligals
    Entity_and_Attribute_Overview:
    Bathymetry, gravity, magnetic and navigation data for U.S. Geological Survey bathymetry survey U471CB in MGD77T format.
    Entity_and_Attribute_Detail_Citation:
    Attributes are obtained from MGD77T data files created from the navigation and bathymetry best files. MGD77T is the standard, defined data format used for geophysical data in the National Geophysical Data Center. See Cross_Reference section above for citation details.

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
    • Coastal and Marine Geology Program
  2. Who also contributed to the data set?
    Eli Silver (Chief Scientist, USGS Western Region)
  3. To whom should users address questions about the data?
    Gregory K. Miller
    U.S. Geological Survey
    Physical Scientist
    600 4th Street South
    St. Petersburg, FL
    USA

    (727) 803-8747, ext. 3020 (voice)
    gmiller@usgs.gov

Why was the data set created?

These data and information are intended for science researchers,students, policy makers, and general public. These data are not to be used for navigation purposes. The data are reformatted into MGD77T standard format for inclusion into NOAA's NGDC geophysical database. From there the data will be made available to GeoMapApp ( http://www.geomapapp.org/ ) and Virtual Ocean ( http://www.virtualocean.org/ ) Earth-browsing software. Access to the data is also provided via the USGS Coastal and Marine Geoscience Data System ( http://cmgds.marine.usgs.gov/ ).

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 15-Dec-1995 (process 1 of 7)
    Navigation Data >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U471CB.N]U471CB.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > Person who carried out this activity:
    U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 2 of 7)
    Gravity Data >10/31/1998 /tiger/u/u471cb/grav/u-4-71-cb.161_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >04/22/86 CLINT DUA0:[DATA.U471CB]U471CB.160; >DRB0:[DRS.NGDC]UNREFNGDC.EXE; >This file came from an NGDC file called U471CB.999. >Start time is 231/1610 and ends at 274/1500. > >03/07/86 BARB DUA0:[DATA.U471CB]U471CB.160 >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >Input was... >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U471CB.N]U471CB.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 3 of 7)
    Magnetics Data >06/20/2012 carolyn u-4-71-cb.220_050 > >Reprocessed using subroutines from Susan Macmillan's >IGRF SYNTHESIS PROGRAM http://www.ngdc.noaa.gov/IAGA/vmod/igrf11.f >with IGRF-11 coeffiecients integrated into the source code. >/infobank/programs/mag/magred11/magred11.for >Using geodetic coordinate system (Earth shape approximated by spheriod) >with altitude 0.0 km (for sea level). > >Input was... >10/31/1998 /tiger/u/u471cb/mag/u-4-71-cb.200_050 >/bear/programs/edit/automerge/automerge > >Converted to time format with year at start. > >03/10/86 CAROLYN DRS$DATA:[U471CB.M]U471CB.200; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 >was U471CB.220 from 71BKUP > >03/22/85 CAROLYN USR$DISK:[DRS.DATA.U4.M]U471CB.220; >USR$DISK:[DRS.REFMT]REFORMAT.EXE;3 > >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U471CB.N]U471CB.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 31-Oct-1998 (process 4 of 7)
    Bathymetry Data >10/31/1998 /tiger/u/u471cb/bath/u-4-71-cb.325_050 >/bear/programs/edit/automerge/automerge > >Input was... >Converted to time format with year at start. > >03/07/86 BECKIE DUA0:[DATA.U471CB]U471CB.325; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >Input was... >Converted to time format with year at start. > >02/11/86 KAYE DUA0:[DATA.U471CB.N]U471CB.050; >DRB0:[DRS.REFMT]REFORMAT.EXE;5 > >time, lat, long, time(sec) to nearest nav fix, data values Person who carried out this activity:
    U.S. Geological Survey (USGS) , Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 20-Jun-2012 (process 5 of 7)
    MGD77 file creation - The available data for each cruise leg are re-formatted and combined into the Marine Geophysical Data Exchange Format (MGD77) and into the internal NGDC SEIS-NAV format by USGS using several USGS developed FORTRAN programs.The FORTRAN programs sample the navigation to every integer minute of the cruise. When necessary, the latitudes and longitudes are linearly interpolated. If the time between the actual navigation fixes exceeds five minutes, no data are included in the MGD77 file.To build the MGD77 file, gravity, magnetics, and bathymetry are added to this sampled navigation. When necessary, gravity, magnetics, and bathymetry data are linearly interpolated if the time between the actual data samples does not exceed five minutes. If a time gap exceeds this, the data are not reported.The navigation data are merged with the seismic shot point data in a SEIS- NAV format file. For this file, navigation data are interpolated for each shot point. Both types of files are written to magnetic tape and sent to NGDC. Person who carried out this activity:
    U.S. Geological Survey (USGS), Coastal and Marine Geology (CMG)
    Attn: Carolyn H. Degnan
    Geophysicist
    USGS Pacific Coastal & Marine Science Center, 400 Natural Bridges Drive
    Santa Cruz, CA
    USA

    (831) 460-7452 (voice)
    (831) 427-4748 (FAX)
    infobank@octopus.wr.usgs.gov
    Date: 01-Feb-2017 (process 6 of 7)
    Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog. Person who carried out this activity:
    U.S. Geological Survey
    Attn: Alan O. Allwardt
    Contractor -- Information Specialist
    2885 Mission Street
    Santa Cruz, CA

    831-460-7551 (voice)
    831-427-4748 (FAX)
    aallwardt@usgs.gov
    Date: 19-Oct-2020 (process 7 of 7)
    Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:
    U.S. Geological Survey
    Attn: VeeAnn A. Cross
    Marine Geologist
    384 Woods Hole Road
    Woods Hole, MA

    508-548-8700 x2251 (voice)
    508-457-2310 (FAX)
    vatnipp@usgs.gov
  3. What similar or related data should the user be aware of?
    Hittelman, Allen M., Groman, Robert C., Haworth, Richard T., Holcombe, Troy L., McHendrie, Graig, Smith, Stuart M., and Metzger, Dan R., 2010, The marine geophysical data exchange format - MGD77 / MGD77T: National Geophysical Data Center, National Oceanic and Atmospheric Administration, Boulder, CO.

    Online Links:

    Other_Citation_Details: 25 p.

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The validity or accuracy of bathymetry and navigation data is highly qualitative and depends on equipment and operating condition variables. Data quality is unknown, MGD77T files were formatted from InfoBank files identified as best available version.
  2. How accurate are the geographic locations?
    Unspecified
  3. How accurate are the heights or depths?
    Unspecified
  4. Where are the gaps in the data? What is missing?
    Start and end date/times of data >Navigation Data (u-4-71-cb.050 [SINS]) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197108182340000 197108211520000 >197109051840000 197109100000180 >197109100100000 197109100225000 >197109100241300 197109120930360 >197109120940480 197109131151060 >197109170400000 197109242030000 >197109252300000 197110011620000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Gravity Data (u-4-71-cb.161_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197108190000000 197108192140000 >197108192200000 197108211520000 >197109051840000 197109060110000 >197109060125000 197109061550000 >197109061605000 197109061755000 >197109061830000 197109071205000 >197109071225000 197109071500000 >197109071515000 197109072110000 >197109072140000 197109081200000 >197109081220000 197109082250000 >197109082305000 197109091140000 >197109091200000 197109091200000 >197109091215000 197109091215000 >197109091235000 197109091235000 >197109091250000 197109091250000 >197109091315000 197109092215000 >197109092250000 197109092355000 >197109100105000 197109100225000 >197109100245000 197109100305000 >197109100325000 197109101225000 >197109101245000 197109101710000 >197109101730000 197109110100000 >197109110120000 197109120840000 >197109170400000 197109190250000 >197109190310000 197109210630000 >197109210650000 197109211920000 >197109211940000 197109212010000 >197109212030000 197109240210000 >197109240230000 197109242030000 >197109252300000 197109282100000 >197109282115000 197109300755000 >197109300815000 197110011500000 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Magnetics Data (u-4-71-cb.220_050) >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >197108190450120 197108190450120 >197108190521000 197108190700120 >197108190721000 197108190950180 >197108191011060 197108191130480 >197108191151480 197108191151480 >197108191330420 197108200920480 >197108200941180 197108211320240 >197109051951360 197109052050060 >197109052110360 197109081809550 >197109081834460 197109081847110 >197109081914060 197109092154420 >197109092233520 197109092358160 >197109100102450 197109100354400 >197109100415050 197109120748400 >197109120815160 197109131149070 >197109170356550 197109212131120 >197109212151300 197109221441180 >197109221540180 197109241720420 >197109260250480 197109261640480 >197109261701180 197109262241120 >197109262320360 197109271510480 >197109271531240 197109271721060 >197109271741420 197110011540420 >YYYYMMDDHHMMSST YYYYMMDDHHMMSST >Bathymetry Data (u-4-71-cb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
  5. How consistent are the relationships among the observations, including topology?
    This data set is from one field activity with unknown instrument calibrations. Processed bathymetric depths were spot checked based on latitude and longitude against the Global Multi-Resolution Topography (GMRT) grid within GeoMapApp to ensure reasonable values.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: None. These data are held in the public domain.
Use_Constraints:
This information is not intended for navigational purposes. Read and fully comprehend the metadata prior to data use. Uses of these data should not violate the spatial resolution of the data. Where these data are used in combination with other data of different resolution, the resolution of the combined output will be limited by the lowest resolution of all the data. Acknowledge the U.S. Geological Survey in products derived from these data. Share data products developed using these data with the U.S. Geological Survey.This database has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use.Although this Federal Geographic Data Committee-compliant metadata file is intended to document these data in nonproprietary form, as well as in ArcInfo format, this metadata file may include some ArcInfo-specific terminology.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    345 Middlefield Road MS 999
    Menlo Park, CA
    USA

    (650) 329-5078 (voice)
    (650) 329-5190 (FAX)
  2. What's the catalog number I need to order this data set? Downloadable Data
  3. What legal disclaimers am I supposed to read?
    Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty, express or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, nor represent that its use would not infringe on privately owned rights. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of these data or related materials. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 19-Oct-2020
Metadata author:
Gregory K. Miller
U.S. Geological Survey
Physical Scientist
U.S. Geological Survey, 600 Fourth Street South
St. Petersburg, FL
USA

(727) 803-8747, ext. 3020 (voice)
gmiller@usgs.gov
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/SeriesReports/OFR/OFR_89-167/795.faq.html>
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