Get a list of Observation objects.

### Available end points:

- `/observations/` - Will list all Results in the database
- `/observations.json` - Will return all Results in json format. This can
also be achieved by using the accept header. `application/json`
- `/observations/<object_id>/` - Returns Results object with that id

### Available Methods:

- `GET`
- `HEAD`

### Available filters:

- `title`
- `uuid`
- `keywords`
- `status`
- `result_field`
- `discoveryKeywords`
- `updateFrequency`
- `nonGeographicFlag`
- `publicationState`
- `permissions`

### How to use filters:

These filters can be used like django query filters using __ for related model relationships.

- `/observations/?uuid=d594d53df2612bbd89c2e0e770b5c1a0`
- `/observations/?status=completed`
- `/observations/?results_field__dataPath__startswith=/neodc/esacci`
- `/observations/?discoveryKeywords__name=ESACCI`
- `/observations/?nonGeographicFlag=True`

Filters can be stacked to build an 'AND' relationship. E.g.

- `/observations/?publicationState__in=published,citable&nonGeographicFlag=True`
- `/observations/?publicationState__in=published,citable&discoveryKeyword__name=NDGO0003`

GET /api/v2/observations/7920/?format=api
HTTP 200 OK
Allow: GET, HEAD, OPTIONS
Content-Type: application/json
Vary: Accept

{
    "ob_id": 7920,
    "uuid": "e157d540c4c8805cd3ca9786ff611959",
    "title": "NCAVEO: Leaf Area Index measurements for the fields Brockley, Big Croft and Rickyard, near Chilbolton, recorded using INRA's LAI-2000 plant canopy analyser",
    "abstract": "Leaf Area Index (LAI) measurements were made in three fields near Chilbolton, as part of the Network for Calibration and Validation of Earth Observation data (NCAVEO) 2006 Field Campaign. Measurements were carried out over 14-15 June 2006 in fields Brockley (spring barley), Big Croft (oil seed rape) and Rickyard (winter wheat), each of which were planted with different crop types. LAI measurements were  made with the LAI2000 instrument loaned from INRA, France (Inst. Ref: N4431), including shadow cap (180 degrees) and measurement configuration: one top of canopy reading (reading A in files) followed by one bottom of canopy (reading B in files).\r\n\r\nWithin the main sensor the LAI2000 instrument has five separate silicon detectors arranged in concentric rings. When radiation is projected onto the detector each ring sees a different range of zenith angles, up to a maximum 74º field of view. There is no response at zenith angles between 74º and 90º. The sensor is filtered to respond only to radiation below 490nm to minimise the impact of leaf reflectance and transmittance on measured values. The outputs of the five detectors were measured   simultaneously for each above or below canopy measurement.  Five sample points were located within tramlines in each field and five 10 metre long transects were then set-up, centred on each of these points. 10 measurements were made at each flag. For further details regarding the data's collection and structure, please see the associated metadata document in linked documentation. ",
    "keywords": "",
    "publicationState": "published",
    "dataPublishedTime": "2007-10-17T14:54:18",
    "doiPublishedTime": null,
    "updateFrequency": "notPlanned",
    "status": "completed",
    "result_field": {
        "ob_id": "https://api.catalogue.ceda.ac.uk/api/v2/observations/7921/?format=api",
        "dataPath": "/neodc/ncaveo_field/data/LAI_LAI2000",
        "oldDataPath": [],
        "storageLocation": "internal",
        "storageStatus": "online",
        "volume": 100322,
        "numberOfFiles": 18,
        "fileFormat": "The data is in ASCII format, each file containing the data collected at one flag, as indicated by the four character code in the file name (e.g. ryrw). The first two letters indicate the field name, followed by the flag colour and crop type."
    },
    "timePeriod": "https://api.catalogue.ceda.ac.uk/api/v2/times/2266/?format=api",
    "geographicExtent": "https://api.catalogue.ceda.ac.uk/api/v2/bboxes/172/?format=api",
    "nonGeographicFlag": false,
    "phenomena": [
        "https://api.catalogue.ceda.ac.uk/api/v2/phenomona/84387/?format=api"
    ],
    "dataLineage": "These data were provided to NEODC by university of Southampton, who carried out work to convert formats to NASA-Ames, and write metadata documents. The metadata documents describing the processing are archived alongside the data as PDF files.",
    "removedDataTime": null,
    "removedDataReason": "",
    "language": "English",
    "identifier_set": [
        "https://api.catalogue.ceda.ac.uk/api/v2/identifiers/5149/?format=api"
    ],
    "projects": [
        "https://api.catalogue.ceda.ac.uk/api/v2/projects/7827/?format=api"
    ],
    "observationcollection_set": [
        "https://api.catalogue.ceda.ac.uk/api/v2/observationcollections/7824/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/observationcollections/30128/?format=api"
    ],
    "responsiblepartyinfo_set": [
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32530/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32535/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32529/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32532/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32533/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32534/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32536/?format=api",
        "https://api.catalogue.ceda.ac.uk/api/v2/rpis/32531/?format=api"
    ],
    "procedureAcquisition": "https://api.catalogue.ceda.ac.uk/api/v2/acquisitions/7922/?format=api",
    "procedureCompositeProcess": null,
    "procedureComputation": null,
    "permissions": [
        {
            "ob_id": "https://api.catalogue.ceda.ac.uk/api/v2/observations/2522/?format=api",
            "useLimitation": null,
            "accessConstraints": null,
            "accessCategory": "registered",
            "accessRoles": null,
            "label": "registered: None group",
            "licenceURL": "http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
            "licenceClassifications": "any"
        }
    ],
    "discoveryKeywords": [
        {
            "ob_id": 1138,
            "name": "NDGO0003"
        }
    ]
}