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Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area)

Frequently-asked questions:


What does this data set describe?

Title:
Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area)

Abstract:
This is an index of the 3.75-minute quarter quadrangle areas that cover the State of Connecticut. There are four 3.75-minute quarter quadrangles per 7.5-minute quadrangle area. The index includes a polygon feature for each 3.75-minute quarter quadrangle area. Note that the boundaries of the polygon features in this layer DO NOT correspond exactly with the quadrangle boundaries published on the topographic quadrangle maps because the polygon feature boundaries are based on the Connecticut State Plane Coordinate System, North American Datum of 1983 (NAD83) and the boundaries on the quadrangle maps are base on the Connecticut State Plane Coordinate System, North American Datum of 1927 (NAD27). This index was generated by mathematically projecting the 3.75-minute latitude and longitude quarter quadrangle corner coordinates to Connecticut State Plane Coordinate System, NAD83.  It represents a true NAD83 index of 3.75-minute quadrangle areas. Polygon attribute information is comprised of codes to uniquely identify individual quarter quadrangle areas. This is static information that is not subject to change.

  1. How should this data set be cited?

    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher), 1995, Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area): State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Other citation details:
    The State of Connecticut, Department of Environmental Protection is the collector of the data (compiler), the creator and maintainer of the data layer (editor), and producer (publisher) of this information for use. The 2005 Edition includes that same spatial data originally published in 1995 with the addition of metadata.

  2. What geographic area does the data set cover?

    Bounding coordinates:
    West: -73.771430
    East: -71.600912
    North: 42.255441
    South: 40.869442

  3. What does it look like?

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/quarterquadindexnad83areafullview.gif (GIF)
    Full view of Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area)

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/quarterquadindexnad83areaquadview.gif (GIF)
    View of Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area) with the Spring Hill, Connecticut quadrangle (quad no 41)

    http://www.cteco.uconn.edu/metadata/dep/browsegraphic/quarterquadindexnad83areadetailview.gif (GIF)
    Detail view of Connecticut USGS 7.5 Minute Quarter Quadrangle Index (NAD83 Area) boundaries that do not register (e.g. line up) with the corner of a USGS topographic quadrangle map, which was published in NAD27. This index registers to the NAD 83 corner tics on the topographic quadrangle map. These NAD83 tics are offset from the corners of the topo map area that was published in NAD27.

  4. Does the data set describe conditions during a particular time period?

    Calendar date: unknown
    Currentness reference:
    publication date

  5. What is the general form of this data set?

    Geospatial data presentation form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      Indirect spatial reference:
      State of Connecticut, United States of America

      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • G-polygon (748)

    2. What coordinate system is used to represent geographic features?

      The map projection used is Lambert Conformal Conic.

      Projection parameters:
      Lambert Conformal Conic
      Standard parallel: 41.200000
      Standard parallel: 41.866667
      Longitude of central meridian: -72.750000
      Latitude of projection origin: 40.833333
      False easting: 999999.999996
      False northing: 499999.999998

      Planar coordinates are encoded using coordinate pair.
      Abscissae (x-coordinates) are specified to the nearest 0.000250.
      Ordinates (y-coordinates) are specified to the nearest 0.000250.
      Planar coordinates are specified in survey feet.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

      Vertical coordinate system definition:
      Altitude system definition:
      Altitude resolution: 1.000000
      Altitude encoding method: Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area)
    Quarter Quadrangle areas represented as polygon features. (Source: State of Connecticut, Department of Environmental Protection)

    OBJECTID
    Internal feature number. (Source: ESRI)
                      

    Sequential unique whole numbers that are automatically generated.

    QGNO
    Geographic Quadrangle Number - An ID number designated by the State of Connecticut, Department of Environmental Protection, Natural Resources Center in the 1980's to uniquely identify individual quadrangle maps that cover Connecticut and adjacent areas of Massachussets, New York and Rhode Island. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Numeric value. Quadrangle maps published by the USGS that cover the Connecticut mainland and coastal area are assigned numeric values ranging from 1-116. Other quadrangle areas that encompass the waters of Connecticut in Long Island Sound and in nearby portions of Massachussets, New York, and Rhode Island are assigned other unique numeric values.

    QUAD_NO
    Quadrangle Number - An ID number designated by the State of Connecticut, Department of Environmental Protection, Natural Resources Center in the 1980's to uniquely identify individual quadrangle maps. (Source: State of Connecticut, Department of Environmental Protection)
                      

    Numeric value. Quadrangle maps published by the USGS that cover the Connecticut mainland and coastal area are assigned numeric values ranging from 1-116. Other quadrangle areas that encompass the waters of Connecticut in Long Island Sound are assigned numeric values that range from 1213 to 1218, 1310 to 1313, and 1407 to 1408. Quadrangles in nearby portions of Massachussets, New York, and Rhode Island are assigned other numeric values.

    QUAD_SEC
    Quadrangle Section (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    NE
    Northeast quarter quadrangle
    NW
    Northwest quarter quadrangle
    SE
    Southeast quarter quadrangle
    SW
    Southwest quarter quadrangle

    QUADRANGLE
    Quadrangle Name - Name of the quadrangle map published by the USGS (Source: State of Connecticut, Department of Environmental Protection)
                      

    Text value

    CTQUAD_FLG
    Connecticut Quad Flag - Identifies quadrangles that cover the State of Connecticut (Source: State of Connecticut, Department of Environmental Protection)
                      

    ValueDefinition
    T
    True
    F
    False

    SHAPE
    Feature geometry. (Source: ESRI)
                      

    Coordinates defining the features.

    SHAPE.area
    SHAPE.len
    Entity and attribute overview:
    Use the QUAD_NO attribute to distinguish individual USGS topographic quadrangle areas. Use the QUAD_SEC attribute to distinguish between the four quadrants (NE, NW, SE, and SW) for each topograhic quadrangle area. Combine (concatinate) the QUAD_NO and QUAD_SEC attribute values to uniquely identify quarter quadrangle polygon features. For example, the four quarter quadrangle polygon features for the Clinton quadrangle (quadrangle number 98) are 98NE, 98NW, 98SE, and 98SW. Use the Connecticut Quadrangle Flag attribute (CTQUAD_FLG) to select quadrangles that cover the geographic area for the State of Connectictut with the following expression - CTQUAD_FLG = "T".
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Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)


  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    Howie Sternberg
    State of Connecticut, Department of Environmental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time
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Why was the data set created?

Use this layer as an index to the set of USGS Digital Orthophoto Quarter Quadrangles published by the U.S Geological Survey, in cooperation with U.S. Department of Agriculture and the Connecticut Department of Environmental Protection. The USGS Digital Orthophoto Quarter Quadrangle (DOQQ) photos for Connecticut were published at 1:12,000 scale and are available from the State of Connecticut, Department of Environmental Protection.

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How was the data set created?

  1. Where did the data come from?

    Source 1 - Indexqq (source 1 of 3)

    State of Connecticut, Department of Environmental Protection (data compiler, editor, and publisher), 1995, Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area): State of Connecticut, Hartford, Connecticut, USA.

    Online links:
    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    Indexqq is in ArcInfo coverage format with polygon and tic features.

    Source 2 - Quarter_Quad_Index_NAD83_Area.shp (source 2 of 3)

    State of Connecticut, Department of Environmental Protection (data compiler, editor, and publisher), 1995, Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area): State of Connecticut, Hartford, Connecticut, USA.

    Online links:
    Other citation details:
    The State of Connecticut, Department of Environmental Protection is the collector of the data (compiler), the creator and maintainer of the data layer (editor), and producer (publisher) of this information for use. The 2005 Edition includes that same spatial data originally published in 1995 with the addition of metadata.

    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    Quarter_Quad_Index_NAD83_Area.shp is in ESRI Shapefile format with polygon features.

    Source 3 - Quarter_Quad_Index_NAD83_Area (source 3 of 3)

    State of Connecticut, Department of Environmental Protection (data compiler, editor, and publisher), 1995, Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area): State of Connecticut, Department of Environmental Protection, Hartford, Connecticut, USA.

    Online links:
    Other citation details:
    The State of Connecticut, Department of Environmental Protection is the collector of the data (compiler), the creator and maintainer of the data layer (editor), and producer (publisher) of this information for use. The 2005 Edition includes that same spatial data originally published in 1995 with the addition of metadata.

    Type of source media: disc
    Source scale denominator: 24000
    Source contribution:
    Quarter_Quad_Index_NAD83_Area is in GeoDatabase Feature Class format

  2. What changes have been made?

    Date: 1995 (change 1 of 3)
    The polygon boundaries for this layer were not manually digitized but rather mathematically generated by projecting the latitude and longitude coordinate values that define the corners of the 3.75-minute quarter quadrangle areas to the Connecticut State Plane Coordinate System, North American Datum of 1983 (NAD83). The latitude and longitude coordinates of the four corners for each quarter quadrangle formed the end points of four line features that bound each polygon feature. These lines of latitude and longitude spaced at 3.75-minute intervals were generated for the purpose of creating quarter quadrangle polygon features.

    Person responsible for change:
    Deborah Dumin
    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher)

    Data sources produced in this process:
    • Source 1 - Indexqq

    Date: 2005 (change 2 of 3)
    Export to Shapefile Format - Converted polygon feature data from ArcInfo Coverage named INDEXQQ to a Shapefile named Quarter_Quad_Index_NAD83_Area.shp. Excluded the AREA, PERIMETER, INDEXQQ#, and INDEXQQ-ID attributes from the Shapefile because their values are only maintained by ArcInfo software with data that is in ArcInfo Coverage format.

    Person responsible for change:
    Howie Sternberg
    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher)

    Data sources used in this process:
    • Source 1 - Indexqq

    Data sources produced in this process:
    • Source 2 - Quarter_Quad_Index_NAD83_Area.shp

    Date: 20060101 (change 3 of 3)
    Convert to GeoDatabase Feature Class format - Defined new Feature Class named Quarter_Quad_Index_NAD83_Area; and imported the attribute definitions, loaded features and imported metadata from  Quarter_Quad_Index_NAD83_Area.shp shapefile. 
    
    Spatial Reference Properties for Feature Class:
    
    Coordinate System: NAD_1983_StatePlane_Connecticut_FIPS_0600_Feet
    XY Domain MinX: 100000; MaxX: 2247483.645
    XY Domain MinY: 200000; MaxY: 2347483.645
    Precision: 1000

    Person responsible for change:
    Howie Sternberg
    State of Connecticut, Department of Environmental Protection (data compiler, editor and publisher)
    79 Elm Street
    Hartford, Connecticut 06106
    USA

    860-424-3540 (voice)

    Data sources used in this process:
    • Source 2 - Quarter_Quad_Index_NAD83_Area.shp

    Data sources produced in this process:
    • Source 3 - Quarter_Quad_Index_NAD83_Area

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

  1. How well have the observations been checked?

    The USGS 3.75 Minute Quarter Quadrangle Index layer depicts the quarter quadrangle areas for the 7.5 minute USGS topographic quadrangle maps as polygon features with boundaries originally based on a NAD83 horizontal datum rather than NAD27 used by the USGS to publish the topographic quadrangle maps. All attributes have valid values. Values are within defined domains. The accuracy test for the QGNO, QUAD_NO, QUAD_SEC, and CTQUAD_FLG attribute values were conducted by manually entering and visually inspecting and verifying values. The QUADRANGLE attribute is the English language equivalent of (decodes) the QUAD_NO field values and was populated by joining the feature attribute data table to a lookup data table with QUAD_NO used as the relate key field. This lookup data table contain records with information that account for the unique occurrences of QUAD_NO.

  2. How accurate are the geographic locations?

    The horizontal positional accuracy of this data complies with the United States National Map Accuracy Standards for 1:24,000 scale maps. According to this standard, not more than 10 percent of the locations tested are to be in error by more than 1/50 inch (40 feet) measured on the publication scale of a USGS 7.5 minute topographic quadrangle map.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    The degree of completeness is based on the extent to which the data covers the geographic area of the State of Connecticut. The layer is complete because it includes four 3.75 minute quarter quadrangle polygon features for all of Connecticut 7.5 minute quadrangle areas, including areas defined by 7.5 minutes of latitude and longitude where the USGS published 1:24,000-scale topographic quadrangle maps and areas of 7.5 minutes of latitude and longitude entirely covered by water (in Long Island Sound) where the USGS did not publish 7.5 minute topographic quadrangle maps.

  5. How consistent are the relationships among the observations, including topology?

    Polygon features conform to the following topological rules. Polygons are single part. There are no duplicate polygons. Polygons do not self overlap. Polygons do not overlap other polygons. The tests of logical consistency were performed by the State of Connecticut using ESRI ArcInfo software to maintain feature topology in ArcInfo coverage format. The data is topologically clean. The ArcInfo Clean function was repeatedly used following edits to verify topology and enforce a minimum distance between vertices of 4 feet (fuzzy tolerance) and a minimum allowed overshoot length of 0 (zero) feet (dangle length).

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How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access constraints: None. The data is in the public domain and may be redistributed.
Use constraints:
No restrictions or legal prerequisites for using the data. Although this data set  has been used by the State of Connecticut, Department of Environmental Protection, no warranty, expressed or implied, is made by the State of Connecticut, Department of Environmental Protection as to the accuracy of the data and or related materials.  The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the State of Connecticut, Department of Environmental Protection in the use of these data or related materials. The user assumes the entire risk related to the use of these data. Once the data is distributed to the user, modifications made to the data by the user should be noted in the metadata. When printing this data on a map or using it in a software application, analysis, or report, please acknowledge the State of Connecticut, Department of Environmental Protection as the source for this information. For example, include the following data source description when printing this layer on a map: Quarter Quadrangle Boundary - From the USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area) layer, published by the CT DEP. Source map scale is 1:24,000.

Distributor 1 of 1

  1. Who distributes the data set?

    State of Connecticut, Department of Enviromental Protection
    79 Elm Street
    Hartford, Connecticut 06106-5127
    USA

    860-424-3540 (voice)
    860-424-4058 (FAX)
    dep.gisdata@ct.gov
    Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

  2. What's the catalog number I need to order this data set?

    Connecticut USGS 3.75 Minute Quarter Quadrangle Index (NAD83 Area)

  3. What legal disclaimers am I supposed to read?

  4. How can I download or order the data?

    • Availability in digital form:


    • Data format:
      in format Shapefile, Feature Class (version ArcGIS)
      Network links:http://www.ct.gov/deep

    • Cost to order the data: An online copy of the data may be accessed without charge.


  5. Is there some other way to get the data?

    The data distributor does not provide custom GIS analysis or mapping services. Data is available in a standard format and may be converted to other formats, projections, coordinate systems, or selected for specific geographic regions by the party receiving the data.

  6. What hardware or software do I need in order to use the data set?

    Geographic information sytem (GIS), computer-aided drawing or other mapping software is necessary to display, view and access the information.

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Who wrote the metadata?

Dates:
Last modified: 20111208

Metadata author:
Howie Sternberg
State of Connecticut, Department of Environmental Protection
79 Elm Street
Hartford, Connecticut 06106-5127
USA

860-424-3540 (voice)
860-424-4058 (FAX)
dep.gisdata@ct.gov
Hours of Service: Monday to Friday, 08:30 to 16:30 Eastern Standard Time

Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata(FGDC-STD-001-1998)

Metadata extensions used:
  • http://www.esri.com/metadata/esriprof80.html

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