The Advanced Voyager Image Catalog makes it possible to select images from the PDS CDROMs based on a broad variety of constraints, including constraints on the geometric content of an image. For example, you may quickly identify all the Voyager 2 Uranian ring images for which the filter was CLEAR or BLUE, the exposure time was at least 15 seconds, and the phase angle was less than 40 degrees. You accomplish this by entering the appropriate values into the fields you see on the form and then clicking on the Submit Query button at the bottom of the page. After a short wait, you will see a listing of all the images that match the constraints you have entered.
The numerous fields on this form permit the user to enter many different kinds of constraints. In most cases, entering values in different fields results in an "and" operation. For example, if you select Planet=SATURN and Spacecraft=VOYAGER_1, you will see all the Saturn images from the Voyager 1 encounter. However, selecting values within the same group of parameters results in an "or" operation. For example, if you select Jupiter Targets=IO and then select Jupiter Targets=EUROPA in the next column, you will find all the images of either Io or Europa. If you leave a field blank, that particular parameter is unconstrained. Because the form has so many fields, it is very common for most of them to be blank.
The upper half of the query form lets you constrain parameters that also appear on the standard Voyager query form. The lower half contain additional parameters to constrain the viewing geometry, lighting geometry, timing, and wavelength range of the image.
Use the Listing type box near the bottom of the page to choose among three possible ways to display the results of a query. Match Count simply counts the number of matching images in the database but does not return a list. A Summary listing returns a table of the matching images in addition to the match count. This is the default. A summary listing can return up to 1000 images at a time. A Detailed listing returns a detailed summary of every parameter for each matching image, in addition to the match count and summary listing. A detailed listing can return up to 100 images at a time. If you exceed the image limit for either a summary or detailed listing, you can see the remaining images by entering a number of images to skip over into the Skip box.
Once you made your selections, click on the Search Catalog button at the bottom of the page to submit your query. If at any time you wish to erase all of your entries in the form and start over, click on the Reset Form button.
Ordering Data
A detailed listing returns a list
of file names, which are active links to copies of the CDROMs on line at
the Rings Node.
The Voyager image CDROM containing a particular Voyager image can be determined by examining the Compressed image field of a detailed listing. The full directory path is shown, beginning with the CDROM volume ID of the form VG_00xx.
Alternatively, you may simply email a request to Neil Heather. We can also fill requests for limited numbers of images by electronic transfer.
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Query listings always begin with a summary of the SQL query and the
options selected, followed by the number of matches. SQL is the
language used by the database; you do not need to understand it but, if
a query fails, please report this text to the Rings Node to help us to diagnose
the problem.
Summary listing
When the Summary listing type is selected, the user sees
the typical
Match Count listing followed by a table
of the matching images. This is the most common type of query and
serves as the default. Only the most often used parameters of each
image are listed; if the user needs more information, repeat the same
query while requesting a
Detailed listing.
The parameters included in a Summary listing are the
Query record,
FDS count,
planet,
spacecraft,
camera,
nominal target,
filter,
exposure time,
scan rate,
shutter mode
and ring information flag.
In a summary listing, you can click on the FDS count to see a 200x200 preview of the image.
Note that a Summary listing query is limited to 1000 matches.
If more matches are found, only the first 1000 will be shown. The
Match Count
section will list both the number of matches found and the (possibly
smaller) number listed in the table. The user can repeat the query with
a number entered into the
Skip the first _____ matches
field in order to see the additional images.
Detailed listing
When the Detailed listing type is selected, the user sees
the typical
Match Count listing and
Summary listing first.
Following is a list of every database parameter for each matching image.
In addition, the Summary listing section has active links to each
section of the Detailed listing; simply click on the record
number in the summary to jump to the detailed information.
In a detailed listing with the previews option turned on, a 200x200, pre-stretched image appears with each entry. With the option turned off, you can click on "[PREVIEW]" following the Query record number to see the preview image.
Note that a Detailed listing query is limited to 10 matches if the previews option turned on, or 100 if it is turned off. If more matches are found, only the first 10 or 100 will be shown. The Match Count section will list both the number of matches found and the (possibly smaller) number listed. The user can repeat the query with a number entered into the Skip the first _____ matches field in order to see the additional images.
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If this option is turned off ("No"), links to the thumbnail preview images are still available via links from the summary and detailed listings.
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The user may select images with a particular value of Anomaly using the field of this name on the query form. The value is only shown in a detailed listing. Anomaly is also known as "data_anomaly_type" in the database and on the CD-ROMs.
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The Browse image name cannot be constrained as a part of a query. Its value is only shown only on a detailed listing. Note that some images are duplicated on the CDROM set, so this field occasionally takes on multiple values. The value is constructed from the "browse_volume_id" and "browse_file_name" columns of the database, and is converted to a Unix format for display. This field is blank for images not yet available on CDROM.
If the image is available on a CDROM, then the value of Browse image serves as a link to the data file.
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The Compressed image name cannot be constrained as a part of a query. Its value is only shown only on a detailed listing. Note that some images are duplicated on the CDROM set, so this field occasionally takes on multiple values. The value is constructed from the "image_volume_id" and "image_file_name" columns of the database, and is converted to a Unix format for display. This field is blank for images not yet available on CDROM.
If the image is available on a CDROM, then the value of Compressed image serves as a link to the data file.
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A single edit mode can be selected in the Edit mode field on the query form; if the field is left blank, images of all edit modes are returned. The value of the Edit mode is only shown on detailed listings. This parameter is also known as the "edit_mode_id" in the database and on the CDROMs.
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The Earth received time cannot be constrained as a part of a query. Its value is only shown only on a detailed listing. It is also known as "received_time" in the database and on the CDROMs.
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In queries, you may specify a numeric range for the emission angle. Only images for which the angle is greater than or equal to the first value and less than or equal to the second will be returned.
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The Event time cannot be constrained as a part of a query. Its value is only shown only on a detailed listing. It is also known as "image_time" in the database and on the CDROMs.
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On the query form, the user may enter values for a minimum and a maximum exposure time, and only those images with exposure times between the two values (inclusive) are returned. If the first field is left blank, a minimum of zero is assumed; if the second is left blank, the maximum exposure time is effectively infinite.
On a summary listing, the exposure time is listed under the Texp heading. The value is also included on the detailed listing. Exposure time is also known as "exposure_duration" in the database and on the CDROMs.
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On the query form, the user may enter values for a minimum and a maximum FDS count, and only those images with identifiers between the two limits (inclusive) are returned. If the first field is left blank, a minimum of 00000.00 is assumed; if the second is left blank, the maximum of 65535.59 is assumed. FDS count is also known as "image_number" in the database and on the CDROMs.
The FDS count is included in the summary and detailed listings. In a summary listing, the FDS count is a link to a 200x200, pre-stretched thumbnail preview of the image.
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On the query form, the user may select up to three different color filters, and only images taken through one of these filters are returned, as if an "or" operation were being performed. The filter name and also its number (0-7) are listed on both the summary and detailed listings. Within the database and on the CDROMs, the filter is also known by "filter_name" and "filter_number".
Note that you can also select images by wavelength range.
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The Gain mode cannot be constrained on the query form. Its values is shown on a detailed listing only. Gain mode is also known as "gain_mode_id" in the database and on the CDROMs.
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The Image ID cannot be constrained on the query form. Its value is only shown in a detailed listing.
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In queries, you may specify a numeric range for the incidence angle. Only images for which the angle is greater than or equal to the first value and less than or equal to the second will be returned.
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The Instrument field on the query form enables the user to select images from only one of the two cameras. If the field is left blank, images taken by both cameras are returned. In a summary query, the instrument is listed under the Camera column with a value abbreviated to either WIDE or NARROW. The full Instrument name is shown in a detailed listing.
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In queries, use the ring data only? field to specify whether the query should include ring data only or any image that satisfies the specified constraints. Note that the ring radius and radial resolution parameters are undefined for images in which this field has the value NO.
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Mask cannot be constrained on the query form. Its value is only shown on a detailed listing. It is also known as "sample_bit_mask" in the database and on the CDROMs.
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The Mission phase does not appear on the query form but the equivalent functionality is provided by the Planet field. The value of this field is included on the summary listing under the header Planet, with values of JUPITER, SATURN, URANUS or NEPTUNE. The Mission phase appears on the detailed listing. It is known as the "mission_phase_name" in the database and on the CDROMs.
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On the query form, you may enter a variety of different constraints on the Note field. The common theme is that you use these constraints to match text in the field. For example, if you have reason to believe that "F RING" appears in the Note field for the images you are interested in, you can select the images whose notes contain this text. Simply enter the text you wish to match in the field, without quotes. Note that the search is not case-sensitive.
Four different types of matches are permitted.
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In queries, you can specify a range of observation times, and the query will return any images that were being carried out during the interval given. Times can be entered in a broad range of formats; click here for the gory details.
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In queries, you may specify a numeric range for the phase angle. Only images for which the phase angle is greater than or equal to the first value and less than or equal to the second will be returned.
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Using the Planet field on the query form, the user can specify which of the four planets is of interest. This is probably the common field on the form to constrain. If it is left blank, images from all four planets will be listed. The value of this field is included on both the summary and detailed listings. In the detailed listing, it is actually indicated by the Mission phase, with values of JUPITER_ENCOUNTER, SATURN_ENCOUNTER, URANUS_ENCOUNTER and NEPTUNE_ENCOUNTER. It is also known as the "mission_phase_name" in the database and on the CDROMs
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Note that the query record number counts all matching records, regardless of the particular query options selected. For example, if the user has chosen to skip the first 100 matches, then query record values on the listing will begin with 101.
Query record values appear as the first column in a summary listing, under the heading #. When a detailed listing is requested, each # in the summary table serves as a hypertext link to the detailed information for the same image.
When the previews option is off, "[PREVIEW]" appears following the Query Record in the detailed listings, and this serves as a link to a 200x200, pre-stretched thumbnail preview of the image.
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The radial resolution is the typically equal to the intrinsic point spread function of the image, as projected into the ring plane.
In queries, you can specify a range of radial resolution values, and the query will return any image whose range of radial resolutions intersects the range requested.
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In queries, select YES if you only want images flagged as ring observations to be returned. Select NO if this flag should be ignored in the query.
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In queries, you can specify a range of ring event times, and the query will return any images corresponding to the interval given. Times can be entered in a broad range of formats; click here for the gory details.
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The Ring information parameter does not appear on the query form. The value of this field is included on the summary listing under the header Ring?, and also in the detailed listing.
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The Ring observation ID cannot be constrained on the query form and its value is only shown on a detailed listing.
Any Ring observation ID in an output listing serves as a link to a page containing an image preview and more information about the data, plus links to the data files.
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In queries, you can specify a range of ring radius values, and the query will return any images whose range of radii intersect the range requested.
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On the query form, the user may specify a single value for the scan mode, and only images with that value are returned. If the field is left blank, images with any scan rate are returned. The value for scan rate appears in a summary listing under the Scan heading, as well as in the detailed listing. Scan mode is also known as "scan_mode_id" in the database and on the CDROMs.
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The Spacecraft field on the query form enables the user to select images from only one of the two Voyagers. If the field is left blank, images taken by both Voyagers are returned. In a summary listing, the spacecraft appears under the Vgr heading with a value abbreviated to 1 or 2. The full spacecraft name is shown in a detailed listing. Spacecraft is also known as "spacecraft_name" in the database and on the CDROMs.
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Because of the large number of possible targets, the query form divides the target selections into groups under Jupiter, Saturn, Uranus, Neptune, and Other.
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The wavelength gives the range of wavelengths observed, in microns. A triplet of values specifying the mean, minimum and maximum are associated with each ring image.
In queries, you can specify a range of wavelength values, and the query will return any images whose range of wavelengths intersect the range requested. Note that you can also select images by filter name.
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Last update 8 December 2000