Help Page for the HST/WFPC2 Image Catalog 1.1

The Image Catalog for the Hubble Space Telescope/Wide Field Planetary Camera 2 makes it possible to select WFPC2 images of the ringed planets based on a broad variety of constraints. For example, you may quickly identify all the images of Saturn taken through the F555W filter in 1995. 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.

Note that all WFPC2 images of Jupiter, Saturn, Uranus, Neptune or any of its moons or rings are included in this database, although only a limited set of these images are actually archived by the Rings Node. For other images, links to the data archive at the Space Telescope Science Institute are provided.

Change History

1.0 (March 13, 2000) Original catalog form on line.
1.1 (December 8, 2000) Any ring observation ID in an output listing now serves as a link to a page containing an image preview and more information about the data, plus links to the data files.

INDEX

Query Options

Glossary


INSTRUCTIONS

The Image Catalog for the Hubble Space Telescope/Wide Field Planetary Camera 2 makes it possible to select WFPC2 images of the ringed planets based on a broad variety of constraints. You can accomplish this by entering values into the fields you see on the query 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 WFPC2 images that match the constraints you have entered.

Note: Only a small subset of the HST/WFPC2 images of the ringed planets have been archived at the PDS Rings Node. Specifically, only Saturn ring images from 1994 and 1995 have been archived; they are available on CDROMs RPX_0001, RPX_0002, RPX_0003, RPX_0004, and RPX_0005. Additional images are found in this catalog and can be obtained directly from the data archive at Space Telescope Science Institute.

The numerous fields on this form permit you to enter many different kinds of constraints. Entering values in different fields results in an "and" operation. For example, if you select Planet=SATURN and Filter Name=F555W, you will see all the WFPC2 images of the Saturn system (including Titan) obtained using the F555W filter. 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.

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.

Obtaining Data

For images archived at the Rings Node, a detailed listing returns a list of file names, which are active links to copies of the CDROMs on line at the Rings Node. Alternatively, you may email a request for the CDROMs to Neil Heather.

For images not archived a the Rings Node, the detailed listing provides a link to the STScI archive where the data can be obtained.

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QUERY OPTIONS

Listing type

Three listing types are supported. A 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. A Detailed listing returns a detailed summary of every parameter for each matching image, in addition to the match count and summary listing.

Match Count

When the Match Count listing type is selected, you only see the number of unique images in the database that match the given constraints.

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, you see 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 you need more information, repeat the same query while requesting a Detailed listing. The parameters included in a Summary listing are the query record, HST file name, targeted CCD, target name, observation date, exposure time, filters, gain, and instrument mode.

In a summary listing, you can click on the HST file name to see a 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. You 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, you see 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 preview option turned on, a 200x200, pre-stretched image appears with each image that has been archived at the Rings Node. With the option turned off, you can click on "[PREVIEW]" following the Query record number to see the preview image. For images not archived at the Rings Node (which can be recognized by PDS Data Set ID = "none"), you can click on "[STScI PREVIEW]" to go to a form at the Space Telescope Science Institute where this image can be previewed.

Note that a Detailed listing query is limited to 10 matches if 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. You 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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Include previews

If this option is turned on ("Yes"), a 200x200, pre-stretched thumbnail preview of each image that has been archived at the Rings Node is included with each detailed listing. For those images not archived at the Rings Node (which can be recognized by PDS Data Set ID = "none"), you can click on "[STScI PREVIEW]" to go to a form at the Space Telescope Science Institute where the image can be previewed.

This option overrides a Summary listing, converting it to a Detailed listing. This option is ignored for Match count listing. With this option, the number of images returned from any query is limited to 10.

If this option is turned off ("No"), thumbnail preview images are still available via links from the summary and detailed listings.

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Skip the first _____ matches

The number of matches returned from a query is limited to 1000 for a summary listing, 100 for a detailed listing without preview images, and 10 for a detailed listing with preview images. You can view additional images via the Skip the first _____ matches option. Just repeat the query with a number entered into this field, and that number of images will be skipped. For example, a value of 100 will mean that matching images 101-200 will be shown on a detailed listing (or 101-1100 on a summary listing).

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GLOSSARY

Aperture Type

The Aperture Type value indicates the type of instrument pointing used for an observation. The most common values are PC1, WF2, WF3, WF4, WFALL, PC1-FIX, WF2-FIX, WF3-FIX, WF4-FIX, and WFALL-FIX. Additional values are associated with specific filters: FQUVN33, POLQN33, POLQN18, POLQP15P, POLQP15W, FQCH4NW2, FQCH4NW3, FQCH4NW4, FQCH4N33, FQCH4N15, FQCH4P15, and F160BN15. See the WFPC2 Instrument Handbook for further information about these apertures.

On the query form, you may select images that match a particular value of Aperture Type. Enter the text to match into the box and select the type of match from the menu. Five different types of matches are permitted.

The value of Aperture Type appears in the detailed listing but not in the summary listing.

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Browse Image

The Browse Image indicates the name of a small, pre-stretched version of the image, in GIF format. Browse images provide a quick, easy-to-display glimpse of the image if you are unsure whether to examine the full image. The browse image contains all four WFPC2 CCDs mosaicked together, with the PC image scaled appropriately relative to the others.

The browse image name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Click on the file name to see the GIF image; click on "[label]" following the name to view the PDS label.

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Calibrated Image

The Calibrated Image indicates the name of the full, calibrated image in FITS format. This is the file most easily used for scientific analysis.

The calibrated image name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Calibrated Image Mask

The Calibrated Image Mask indicates the name of a data quality mask image associated with the full, calibrated image. The file is in FITS format. See the label for a description of how to interpret the values in the file.

The calibrated image mask name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Data Archive Link

The Data Archive Link appears in detailed listings for images that are not currently archived at the Rings Node. It provides a URL connecting to the data archive at the Space Telescope Science Institute where you can obtain the data.

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Data Quality

The Data Quality provides a brief description of the quality of the image data. Possible values are OK, DATA-DROP, FILL_DATA, GSFAIL, GYROS, LOCKLOST, NOISY, NO-SOURCE, NO_TLM, POOR, RECENTER, SATURATED, TDF-DOWN, TM_GAP, UNDEREXP, and UNKNOWN.

You can select data of a particular quality by chosing the desired value from the list on the query form. The value of the field appears in the detailed listing but not in the summary listing.

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Data Set ID

The Data Set ID provides the name of PDS's identifier for the data set to which an image belongs, if any. Currently Saturn ring images from 1994 and 1995 have been archived by the Rings Node under ID HST-S-WFPC2-3-RPX-V1.0. Other images have not been archived by the PDS, and so have not been assigned an ID.

You can select images from a particular PDS data set by chosing its ID on the query form. The ID associated with a data set appears as a field in the detailed listing but not in the summary listing.

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Engineering Data

The Engineering Data indicates the name of a FITS-format file containing WFPC2 engineering data.

The engineering data field cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Engineering Data Mask

The Engineering Data Mask indicates the name of a FITS-format data file containing quality mask information associated with the engineering data file. See the label for a description of how to interpret the values in the file.

The engineering data mask name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Exposure Time

Exposure Time is the time interval between the opening and closing of the camera shutter, in seconds.

On the query form, you 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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Exposure Type

The Exposure Type of an HST image is either NORMAL or INTERRUPTED. This parameter cannot be constrained in a query. It's value only appears in a detailed listing.

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FGS Lock

The Fine Guidance Lock of an HST image describes how an image was pointed. Possible values are FINE, GYROS and UNKNOWN. This parameter cannot be constrained in a query. It's value only appears in a detailed listing.

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Filter Name

The Filter Name contains the name of the HST/WFPC2 filter(s) used in an image. Examples are F410M, F555W, and FQCH4N. For images that use two filters, the filter name is constructed by appending the two filter names with an underscore in between, e.g. F130LP_F160BN15. The filter with the shorter wavelength is always listed first.

You may select images that match a particular value of Filter Name by entering text into the box on the query form and selecting the type of match from the menu. Five different types of matches are permitted.

The filter name appears appears as a column in the summary listing and as an entry in the detailed listing.

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Gain Mode ID

The Gain Mode ID identifies the gain state of the WFPC2, Gain determines the factor that multiplies an instrument's output signal to increase or decrease the output level. For WFPC2 cameras, the valid values are A2D7 and A2D15.

If you select a value of gain mode ID on the query form, only images obtained with that mode will be returned. If you leave the field blank, then the gain mode is unconstrained.

The value of each image's gain mode ID appears as a column in the summary listing and as an entry in the detailed listing.

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HST File Name

The HST File Name is a unique identification for each HST image, as assigned by the Space Telescope Science Institute. Examples are U2TF0101T and U46A0106R.

You may select images that match a particular value of HST file name by entering text into the box on the query form and selecting the type of match from the menu. Five different types of matches are permitted.

The HST file name value appears as a column in the
summary listing and as an entry in the detailed listing.

The HST File Name is also known as the source ID in the database and the labels.

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HST Proposal ID

The HST Proposal ID is a unique four-digit number associated with each HST observing program. On the query form, you may specify a proposal ID and only images from this observing program will be returned. The value appears in the detailed listing along with the Principal Investigator's last name.

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HST Target Name

The HST Target Name specifies the name of the target as identified by the Principal Investigator. Examples are SATURN, TITAN, URANUS, IO-TORUS-WEST and SATURN-WEST-ERING.

You may select images that match a particular value of HST target name by entering text into the box on the query form and selecting the type of match from the menu. Five different types of matches are permitted.

The HST target name value appears as a column in the summary listing and as an entry in the detailed listing.

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Instrument Mode

The Instrument Mode for the Wide Field/Planetary Camera 2 has a value of either FULL or AREA. Full-mode images are 800x800 pixels. Area-mode images are 400x400, and are constructed by averaging 2x2 boxes of pixels into a single pixel.

You can select images of a particular Instrument Mode by selecting a value from the menu on the query form. The value of this parameter appears as a column in the summary listing and as an entry in the detailed listing.

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Note

The Note field contains a brief textual description of the image.

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 "SL-9" appears in the Note field for the images you are interested in, you can select only 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.

You may select images that match a particular value of the Note field by entering the text to match into the box on the query form and selecting the type of match from the menu. Matches are case-insensitive. Four different types of matches are permitted.

The value of the note appears only in detailed listings. It can contain up to three lines of text.

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Observation Header

The Observation Header indicates the name of a FITS-format data file containing parameters that describe the observation. See the label for a description of how to interpret the values in the file.

The observation header name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Observation Time

The Observation Time gives the UTC date and time at which the shutter opened for the given image. Times are given by default in PDS format, of the form "yyyy-mm-ddThh:mm:ss.sss".

In queries, you can specify a range of observation times, and the query will return any observations 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.

The UTC date but not time of an observation is included as a column in the summary listing; the entire date and time are included as a field in the detailed listing.

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PI Last Name

The PI Last Name specifies the last name of the principal investigator responsible for the observations. You may select images from a particular investigator by entering his/her last name into the box on the query form. The search is not case-sensitive. The PI's last name appears on the detailed listing following the Proposal ID.

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Planet

The Planet indicates the central body for a particular WFPC2 image. Possible values are JUPITER, SATURN, URANUS and NEPTUNE.

Using the Planet field on the query form, you 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 detailed listings.

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Query record

The Query record is a temporary identifier for each of the matching images found by the most recent query. Values range from 001 to the total number images found.

Note that the query record number counts all matching records, regardless of the particular query options selected. For example, if you have 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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Raw Image

The Raw Image indicates the name of the full, uncalibrated image in FITS format. Note that the calibrated image is easier to use for most scientific analysis.

The raw image name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Raw Image Mask

The Raw Image Mask indicates the name of a data quality mask image associated with the full, uncalibrated image. The file is in FITS format. See the label for a description of how to interpret the values in the file.

The raw image mask name cannot be constrained as a part of a query. Its value is shown only on a detailed listing, and then only for images archived by the Rings Node. If present, the field value gives the name of the file on the PDS CDROM, in a Unix-style format. Shift-click on the file name to download the data; click on "[label]" following the name to view the PDS label.

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Ring Observation ID

The Ring Observation ID is used by the Rings Node as a unique identifier for data in the catalog. For HST/WFPC2 images it has the form "p/IMG/HST/WFPC2/yyyy-mm-dd/nnnnnnnn/ccd" where Note that each of the four individual fields of a WFPC2 image is assigned a unique ring observation ID, even though all four are always grouped within data files.

The Ring observation ID cannot be constrained on the query form. All four values associated with a WFPC2 image are 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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Targeted CCD

The Targeted CCD indicates which of the four of CCDs of the WFPC2 was used for targeting, and is therefore most likely to contain the planet and rings. Possible values are PC1, WF2, WF3, and WF4. In your query, you can select images with a particular targeted CCD by chosing one of these four options on the menu. You may also choose "Any WF" to return images in which the targeted image is WF2, WF3 or WF4 but not PC1. The value of the targeted CCD appears as a column in the summary listing and as an entry in the detailed listing.

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Last update 8 December 2000

Mark Showalter