Browse Version History

v9.0, May 28, 2021.

• Over the previous ~9 months with many interim updates, the Browse database transition was completed. Browse now uses the same database as Xamin, so the results from the two interfaces should be the same.
• Corrected and re-enabled the "Save to Hera" functionality.
• Many bugs fixed.

Minor change/fix, May 9, 2012.

• Added error messages to "Search based on" area on for invalid or unresolved targets when multiple targets are submitted. Also added error messages for batch interface.

Bug Fix, July 21, 2009.

• Updated Veron Catalog link on the main Browse Form

v8.4, October 9, 2007.

• Added a progress box on the tabbed results display page to show how many tables have been processed. When processing is complete the table and row totals are displayed.

v8.3, September 20, 2007.

• The Archive page has been updated. The organization of the interactive forms section has been improved, obsolete sections have been removed and the Suzaku mission has been added to the Quick Search form.
• A table query progress box has been added to the Tabbed Display to indicate how many tables have been queried as tables are processed. The final number of tables and rows is displayed when the query has completed.

v8.2, March 29, 2007.

• Coordinates and other values in results tables are now more accurately formatted.
• A couple bugs that affected the Related Links in results tables were fixed.
• Message displayed when requested data products are not available were improved

v8.1, October 30, 2006.

• Release of new Chandra Field of View Search. Search for targets within active field of view of Chandra observations and display FOV plots.
• A new link to the Chandra FOV search represented by the letter F has been added to the Services column of the Chandra Observations table
• Processing of Parameter constraints that include SQL has been improved.
• To improve the integrity of data product downloads the FTP link to tar files has been eliminated. The HTTP link remains and users are encouraged to also use the Create Download Script and Preview and Retrieve options

v8.0, June 26, 2006.

• Release of new Browse Tabbed Display
• A solid-colored non-hypertext arrow now indicates the current sort column for each results table
• The commands generated in the Create Download Script option have been changed to follow links in the FTP archive.

v7.5.2, May 23, 2006.

• When appropriate, links have been added to the GCN (Gamma ray bursts Coordinates Network) in the Services column in results tables.
• A GRB name resolver has been added to Browse to allow coordinate conversion for object names that are valid gamma ray burst names.

v7.5.1, January 25, 2006.

• The table summary on the Browse results page is now sorted correctly when a query is submitted from the Browse Keyword Search page.
• Class select lists on the Parameter Search page are now sorted alphabetically
• Minor style changes were made to the Browse Keyword Search page

v7.5, December 19, 2005.

• The Browse Keyword Search interface has been added. This new interface allows users to perform a query by entering parameters that relate to the data users wish to display, a process similar to querying an internet search engine. Access this interface via the HEASARC Archive page
• The "Search was based on" information has been added to the Text formatted results page
• The table name/row count summary on the results page has been changed to sort by table priority.

v7.4.1, November 22, 2005.

• The Text Table output format has been enhanced to include more of the advanced features included with the HTML output format while still maintaining a fast display time.

v7.4, November 1, 2005.

• Java plotting has been improved with bug fixes and additional features: additional y axis plotting, log axis for histogram plots, and the option to display and download plot values.
• If a data products tar file size is possibly too large to download without timing out an option to create a download script will be displayed.
• A new switch has been added to commands in the Create Download Script option so that commands can be used behind a firewall.

v7.3.1, September 7, 2005.

• Style change to the results summary table that appears on the query results page.
• Fixes to bugs that affected the Related Links section of tables on the query results page.

v7.3, July 6, 2005.

• The capability to analyze data products on the Hera system is now available. Clicking the 'X" in the Services column in the results table will copy data products to Hera system and start up a Hera session. Some setup may be required. Information can be found on the Hera page.
• Several significant improvements have been made to the batch interface.
• A file name filter has been added to the Data Products selection area. The asterisk is used a wildcard and multiple constraints (treated as boolean OR) can be entered separated by a semicolon. There is an example on the results page and a couple of examples in the data products section of Help. (Some XTE data products are treated differently and are not part of this change. The file name filter for all XTE files will come later)
• Duplicate files have been eliminated from the data products Create Download Script and Retrieve options.
• Related links in the result tables should now display even if the parameters used in the dependency and criterion fields are not in the default set
• The Parameter Query page now accepts "null" as a constraint for coordinates and dates.
• The number of new windows that appear when links are clicked on the query results page has been reduced. Windows are now reused for similar types of requests. Redisplay options (Text Format, Printer-Friendly Format) will all be displayed in the same window. Data Product listings will all go to one window. New windows will open for requeries.

v7.2, March 8, 2005.

• A new search option has been added. Users can now enter an object or pair of coordinates and click the submit button without selecting a mission. A Summary of Browse tables and the number of rows matching the criteria will be displayed. Specific missions or tables can then be queried from the summary .
• Bugs that prevented successful All Vizier Catalogs queries and cross-correlations of queries made using a time search were fixed.
• The main Browse Form page was updated to make mission categories clearer and to provide wavelength information for non high energy missions.

v7.1, December 29, 2004.

• A new Table Name/Row Count Summary appears on the Results page.
• The new link dependency field in the database has been incorporated
• A Create Download Script button has been added to the data products options located below results tables. This option will display or create a file of download commands for data products
• Links to the ADS page have been added to tables that contain bibcode values
• More information on data products page has been added to make it clear when data products are not available

v7.0, January 30, 2004.

• Added capability to download a Query to a file for later use. If a query is savable then a button will appear on the Results page. To upload the query select the Query File And Sessions Upload button on the Main search page.
• Added capability to upload a file of objects to use for searches. An Object file can be in Pure Text format or a list with objects and/or coordinate pairs delimited by semi-colons or new lines. A Save All Objects To File button that saves targets from all tables to a local file in the Pure Text format is located on the Results page.
• Fixed bug that displayed incorrect radius units on the Results page in the Your Search was Based On box
• Tables that are empty for a query are now included in requery searches.
• Added capability to display dataset ID information for tables that have this information in the database

v6.8, September 10, 2003

• The user is now able to reissue a query from the results page. At this point the only items that can be changed are the position, max rows returned, and the radius.
• When a user queries for more than one position, the original position specified is printed in the radius column to let the user know which rows correspond to each position.
• A random Browse Tip, a Tip Archive button and link, and a Printer-Friendly Version button have been added to the query results page
• Small SkyView optical and x-ray images now appear on the results page of single object queries. These images are links to larger images at the SkyView site.
• A link to an optical SkyView image has been added to the Services column (O)
• The default radius for Vizier queries is now 1 arc minute
• Users can now specify a parameter query as an expression. That expression can include other fields - for example, a user could search based on color by specifying in the mag2 field: '>=(mag1 + 1)'. The parentheses are required, that is the signal to Browse not to require the user input to pass the type check.
• Start/Reset/More Options buttons are now at top of form as well as at the bottom of main query page
• The table legend now appears only once on the results page. The style of the tables on the results page has been changed to fit more data in the visible scroll window.
• Data Products/Further Action selections have been moved to the scrolled area under each results table.
• Most page headers now have more meaningful text, some have colors
• Windows will be brought to front when processing is complete
• The character set that can be used for the Hera login password is now restricted and checked
• The capability to specify linked tables based on parameters or position has been added. Actual implementation of linked tables will be added at a later date.

v6.7, June 18, 2003.

• Changed parameter query interface, so that instead of min and max entry boxes, there is one box per parameter field where the user can compose a more flexible query term, using the operators: '=', '<','>','<=', '>=', '..' (range operator), and can negate any of these by prefixing it with '!', for example '!..'. Users can 'OR' query terms for the same parameter using ';', 'or', or '|' between terms. For example, '<=5 or 10; 20 .. 40'. Nulls are supported by typing 'null'.
• If a user enters a contraint in the parameter form for a field that is not returned by default, a javascript function checks its checkbox so that the field will be returned in the results.
• The cosmetic style of all tables has been changed.
• A pure text output format has been added. This format will display the results table(s) in pure text format, with no html headers, footers, links, etc.

v6.6, December 17, 2002.

• Bibliography links have been added to the services column in the tables of query results. These are links to abstracts at ADS which reference the observations selected. Try searching any of the public mission archives.
• Remote data products can now be included in tarfiles just like local data products. Try the Chandra products.
• Name resolver conflict reporting: If the positions returned by NED and SIMBAD differ by more than 10 arcsec (or 10% of the radius entered by the user, whichever is greater), the user is warned. The query is still performed with the default name resolver, but the user is given a link with which to query the secondary name resolver. (To try this out, try the object 'terzan 6'.)
• The default search radius for a cross correlation is the larger of the two tables' search radii. (Was set to the radius of the primary table.)
• A process limit has been added so that no more than 15 Browse queries can be running at once. (NOTE: We are now running on two machines; this limit applies to each machine.)
• Some changes to the display of results tables - alternating rows are color shaded and the horizontal ruling is gone. The search summary box is outlined but not divided with internal ruling. Comments?
• Bugfix: If a user searches on observation date in a table with both a start date and end date, the results should now be correct.
• Users won't be able to tell, but the underlying data products code has been rewritten as object-oriented modules so that other sites that install Browse as their archive interface can simply drop in a new module that provides methods to access their data products.
• Search summary is now printed on cross-correlation results page.
• Modifications made for compliance with section 508 accessibility requirements.

v6.5, October 21, 2002.

• Users now have the ability to retrieve pre-defined groups of data for RXTE observations. These are labeled as Intermediate, Standard, or Complete RXTE products, and have file types of TAR. Users can select them just like any individual product and they will be merged into a single TAR file.
• A new output type has been added which creates a spreadsheet containing the results of a query. This spreadsheet has a mime-type of application/vnd.ms-excel, and is a cross-platform binary file compatible with MS Excel as well as other spreadsheet software such as Gnumeric and OpenOffice.
• Changed the search radius input parameters so that the user can specify an arbitrary radius and choose the unit independently.
• Minor display changes and bug fixes.

v6.4, March 25, 2002.

• A new feature offers the ability to query information services outside Browse from the results page. These are in two locations: a new column in the results table holds single-letter quick links to a few services, including a quick link to the data products (labeled 'D') in Browse. Even more services are offered in the 'Further Actions:' section in a selection menu. Use the checkboxes on each row to select one or more rows to get services for, and select one or more services in the menu, then click 'GO'. A new window will appear with the links to the requested services.
• Added a scrollbox around each results table. Only browsers that understand CSS2 will show this correctly, the others should ignore it and display tables the same as before.
• Many minor display changes and bug fixes.

v6.3, January 14, 2002.

• An option to get results in Astrores XML format has been added.
• Users can now sort the results of cross-correlations.
• Users can now plot the results of cross-correlations.
• There are individual RESET buttons for each row on the parameter search form, so users can reset the min and max settings for a single parameter.
• The old main interface (still available from the new main interface) now has the ability to query by observation dates.
• If a user sends a batch query for a nonexistent table, a list of all available tables is returned.

v6.2, October 29, 2001.

• Based on suggestions from an independent review of Browse, we have modified the style of the forms in Browse, especially the main form, and the results page.
• Users can now query for observation dates just as easily as for position. The date field accepts single dates, multiple dates, and ranges of dates, in YYYY-MM-DD hh:mm:ss format, where hh:mm:ss is optional, or in MJD format.
• Added the ability to redisplay results tables in different formats.
• Added the ability to get all fields for both tables in a cross-correlation.
• On the parameter search form, the 'range' operator has been renamed to 'between', and a new operator, 'outside', has been added, which means 'not between x and y'.
• Added default sorting of results: for tables with data products and a field matching /exposure/, table is sorted by decreasing exposure time. For tables without data products or without an exposure column, if the user specified a position to search on, the results are sorted by offset from that position. Otherwise no sorting is done on the results.
• The Proposal table type is now selected by default on the main form.
• Added back in the links to Ftools on the data products listing (lost in V6.0)
• Coordinates are now reported with their correct accuracy.

v6.1, August 28, 2001.

• The query summary box has returned and has been improved. This is a section at the top of the query results which shows the query choices (including defaults) that were made for the query. This also shows any parameter query specifications, which the previous summary box didn't report.
• Users can now elect to receive query results in FITS tables, which can then be analyzed or plotted with standard FITS tools, such as HEAsoft.

v6.0, July 9, 2001.

• Almost complete rewrite of underlying code, using object-oriented methods to increase code extensibility.
• CDS VizieR Integration: Users can now perform searches on tables provided by VizieR, including cone, parameter, and cross-correlations with tables provided by the HEASARC. The results are flagged with the color pink, and wherever possible, there is a link provided to switch the user to the corresponding step in doing a query using the VizieR interface. Users can also plot the results of VizieR queries.
• We have improved the response time on printing results by streamlining the HTML code.
• Data products are listed in sets, instead of simply listing all the files.
• Tarring of data products is now displayed as it goes: the estimated size of the final tarfile is printed, then each filename is printed as it is added to the tarfile, so that users can see the tarfile's progress.
• Cross-correlations look slightly different - the results are printed side-by-side, with the columns labeled with letters: ie 'a' and 'b', to indicate which table they belong to. Each row has a single checkbox which refers to data from both tables. E.g., if you ask to view the associated data products you will get them from both tables. If you click on the right arrow you will get data from both tables.
• Parameter units are displayed in the column headers for results where units are available. They are also shown on the parameter search form and on the 'display all paramters' page.
• For tables which contain long fields, ie abstracts, users can now search for strings within the fields. The long fields are displayed on a separate line from the other columns. This should eliminate the need for the Argus tool.
• The ISO mission has been added.
• The Object table type is now checked by default.
• The parameter query form now accepts values in scientific notation.
• Javascript checkboxes on the data products page allow users to select all products at once, or select all products associated with a table row at once.
• Data products' file sizes are all reported in kB, for easy comparison. The final tarfile estimated and actual file sizes are reported in whatever the appropriate units may be - kB, MB, or GB.
• Abstracts (or other long fields) are now displayed properly in the single row display. Units and parameter descriptions are also shown.
• Plotting: the ability to sample the data is now done within the plotting software, instead of requerying the database, and so it should be much faster.

v5.3.1, April 10, 2001.

• In order to reduce the number of tables searched automatically by the Basic search, a priority filter has been added. For each combination of table type and mission, only the highest priority (a subjective judgement made by HEASARC staff) tables will be automatically searched.
• The missions on the main interface have been rearranged a bit, with the active xray missions grouped.
• On the main interface, there are 'check all' checkboxes beside the title for each section. Clicking the checkbox checks all the checkboxes in that section.
• Expanded the error message given when no tables are found.
• On the results listings, the box containing the list of data sets and the box containing the action buttons are always side-by-side now.
• On the results listings, the row of buttons containing the plot, cross-correlation and display buttons is now below the box containing the data sets and action buttons.
• Fixed an inconsistency where the up and down arrows on the table listings page had the reverse meaning than the arrows on the query results listing page.
• Changed the date given at the top of the query results page from i.e. 11/13/01 to November 13 2001.
• Added key to sort arrows in left menu of table listing page, and added alt text to the arrows in the column headings.
• On the results page, the 'Show file sizes' and 'Show GIF previews' checkboxes are now checked by default.
• Long parameter names are broken up in column headers on results pages.
• Minor cosmetic changes.

v5.3, March 12, 2001. internal release

• Combined Basic and Advanced interfaces into one interface:
  • Only the 'Archive and Observations' table type is selected by default - this gives roughly the same selections as the Basic interface. If more table types are desired, user can select more.
  • Entering an object or coordinates and clicking 'Basic Search' will do an immediate search just like the old Basic interface.
  • Clicking on 'Advanced Search' will go to a table selection page just like the old Advanced Interface.
  • There is a link from w3basic.pl to w3browse.pl.
  • On the combined interface, the missions have been rearranged, and some frequently-used tables have been added. There are 'check all' boxed beside each category name to check or clear all the boxes in a category.

v5.2.1, January 24, 2001.

• Added navigation trail to the 'list all tables' (index) page, and to the cross-correlation page.
• On the advanced interface, hid the table type of 'physics'. Moved 'physics data' to 'atomic data', in its own box.
• Rearranged the order of the form sections on the cross-correlation page (tables first, then options) and added links to other Browse interfaces.
• Added a provision to w3query.pl for not having a navtrail as input.
• Moved the plot, cross-correlation, and 'display all params' buttons to right under each table.

v5.2, January 2, 2001.

• Added table types (observation, object, proposal, physics) to the columns reported for tables, also to the mission selection page. They currently work as filters on the missions but eventally will be separate query choices.
• A navigation line has been added which shows users where they are in the process of obtaining data.
• Clicking on FITS file links in the data products listing will send the file to the user's browser with a MIME type of x-fits. If the user has a FITS viewer defined, the file will be displayed.
• The 'Max GIF Size" option on the query page is now gone. It has been replaced with a checkbox to choose that the user wants to see GIF previews. The checkbox appears on the results page.
• If the user elects to view GIF previews, small GIFs are shown in the products listing. Clicking on them brings up the full size image in a new window.
• The hyperlinked mission names on the missions page are now links to help about the tables for that mission, instead of being a shortcut link to the next query step. This is more consistent with the rest of the browse query pages.
• Categories of data products are now listed as checkboxes on the query results page.
• Minor appearance changes.

v5.1.3, October 17, 2000.

• Tables can now be listed under more than one mission.
• Moved CGRO from Active Missions to Past Missions on the Basic interface.
• Moved the GRB tables to a new Mission: "Gamma-Ray Bursts" on the Advanced interface.

v5.1.2, August 15, 2000.

• Modified the plotting application so that the server-side application does not require an X server to plot/create the GIF. Instead, it uses a PJA package which can do the graphics without an X server.
• Fixed a bug in the Parameter interface where the query was not formed correctly if it contained a parameter with > 255 characters. Also, parameter searches are now case insensitive unless the parameter is > 255 characters.

v5.1.1, May 26, 2000.

• Modified server-side plotting so that the query retrieves only the parameters to be plotted. This speeds up the server- side plotting and allows plotting of many more rows of results.

v5.1, April 25, 2000.

• Made changes to Browse which allow users to view external URL data products.
• Added links to FTOOLS from the data products page. If there is a mission FTOOLS page, a link for it is also displayed.
• Added a JavaScript 1.2 routine that displays an 'All' checkbox on the Results Page. If a user selects it, all result rows for that table are selected, if a user unselects it, all result rows are marked as unselected for that table. This feature works if JavaScript is enabled.
• Added another JavaScript routine that sets the 'Data Products Options' to 'List data products for selected categories for selected observations', if a user selects any data product category on the Results page. This feature works only if JavaScript is enabled.
• Fixed a bug where cross-correlations on results of multiple objects was not working correctly.
• Fixed a bug where help files on olegacy system were not pointing there.
• Modified the plotting so that errors are reported from the Java application. Also, added silk.gsfc.nasa.gov as an available host.

v5.0.6, March 9, 2000.

• Created a new homepage and renamed W3Browse to Browse.
• Updated the Basic Interface with the latest changes.
• Made several other cosmetic changes. Cross-correlation on results was highlighted in more places. New icons were added to the results page. Added the new menubars to pages.

v5.0.5, December 15, 1999.

• Added REAL_REMOTE_HOST fix so that the corrected REMOTE_HOST will be recorded in the logs and in W3Browse error messages.
• Added capabilty which allows user to get all catalog rows. From the parameter search page if a user does not specify any query information, the whole catalog is returned (less than the max number of rows).
• The default max number of rows returned is now set to 250.
• Added changes to parameter interface so that 'not between' range or 'sef' searches are allowed by ngbrowse.
• Also, made changes to parameter interface so that ngbrowse does not have to make unnecessary calls to get metabase information.
• Fixed bug where spaces in a like query were not getting reocognized correctly.

v5.0.1, October 7, 1999.

• W3Browse Plotting was modified so that Aitoff projections are plotted using Galactic coordinates.
• Made several modifications to SQL queries so that they are compatible with both Sybase and Oracle. This is to make W3Browse distributable to ISAS, and ISDC.
• Updated SLA.pm changes [Ed]
• Updated Astro.pm and merged the Astro package into one big file. This W3Browse version does not use HDBrect but uses Astro's routines. Also, the Astro package does not use coco but SLA routines for coordinate conversion.
• Optimized the class id to class name conversion by eliminating calls to the database. The data is stored in a perl hash variable instead. Also, speeded up multiple table 'Search by Parameter' page by removing the use of 'union' to get table class ids.
• Fixed a rare bug in parameter search where min/max were not displayed correctly if they had spaces.
• Fixed another bug which occurred if the key information had a '=' character in it.
• Fixed a minor bug in 'minimize data' option of cross correlations results display.

v5.0, September 8, 1999.

• Rewrote the Plotting completely. A user may begin plotting after clicking on the plot icon on the Results page. Several new plotting capabilities were added in this release. These include:
  • plots can run on server-side to create GIF files or on the client-side as applets
  • users can do scatter plots, histograms, cumulative histograms, aitoff projections, sampling data
  • the java classes are provided with javadoc documentation
  • fully object-oriented design techniques were used to implement the software
• Replaced the use of HDBmc client-server software with the use if DBI/ModPerl based technology. This new method requires fewer network connections to the database. Users can set the limit on the number of rows it can query at the database level.
• Added Anti-cross-correlations and rewrote the cross-correlations interface. More display options were added to allow split line queries, and minimal column selection.
• Added capabilities that permit the Hera state saver to save the w3query pages.
• Fixed a bug in the Parameter Search interface where min=0 was not recognized.
• Added more links to the W3Browse help file from query pages.
• Added the Astro-e mission to the Advanced and Basic Interface.

v4.6.5, March 18, 1999.

• Added logging of W3Browse queries. The logs are kept in two different files. One file keeps track of the type of query requests and the second file tracks the tar requests.
• Modified code so that there is no limit on the number of results that get displayed after a cross-correlation request. If a query returns more than 2000 rows, the results are displayed in text format only.
• Modified the SQL to make it compatible with Oracle. In particular modified the select clause so that 'as' is used instead of '=' to rename columns.

v4.6, February 16, 1999.

• Redsigned and rewrote the W3Browse search interfaces.
• Redid the Missions Page. Added a help menubar on the left.
• Rewrote the tables display page so that tables are displayed in order by priority in an HTML table layout. Added a options menubar on the left. Tables can also be sorted by: Catalog, Short Form, Archived, Default Search Radius, and Mission name.
• Completely redid the parameter search query page. The parameters are listed in a table layout and the user is allowed to set parameters in one go instead of doing 'Build Query' each time.
• Added multiple table search by parameter capability. Only the common parameters get displayed.
• Modified the parameter search interface so that the 'class' parameter actually displays class names instead of numbers.
• Added capability which allows user to set result limit.
• Overall changed W3Browse Header() appearance.
• Moved pageCheck() Javascript routine to the top of the pages incase user decides to click on 'Stop' browser from loading a big page.
• Removed filter query option.

v4.5, June 15, 1998.

• Users now have an option to display search results and cross correlation results in text format.
• Added JavaScript form input checking to make sure that user has entered required information before submitting.
• Added code that displays help file documentation for valid tables when a user clicks on a mission name. These mission name links are found on pages that help set search criteria.
• Made necessary changes to make the MenuBar a client-side image map so that it works correctly with frames. Only the launch page shows up with the HEASARC frame. The rest of the pages do not have the frame.
• Added link to Astrobrowse from the launch page.

v4.4, May 08, 1998.

• A new interface was added to W3Browse which allows full table cross-correlations.
• Re-wrote routines that perform cross-correlations completely. The cross-correlation query is much neater since it is done as one big join instead of two separate queries. This is a major revision and cuts down the code size. The results from the database come together for both tables.
• Added cross-correlation by time feature.
• Rewrote routines that display cross-correlation results. The results are displayed in an HTML table layout. Right arrow images allow expansion of table rows.
• Made changes necessary so that the sort arrows are not displayed if only 1 result row is found.
• Added a new link for 'Multiwavelength Catalogs' on the Missions Page

v4.3, March 12, 1997.

• Redesigned the results page completely, added image buttons that allow sorting by parameter column, also added image buttons that allow users to display all parameters in a table row. Results for each table are grouped together.
• Optimized alot of the code by reducing calls to the database. Also, decreased the results page size by a large fraction by reducing the amount of hidden information stored for each result row. Unique key information is used to identify each result row.
• Redesigned the structures used for data products retrieval and parsing engines. The metabase unique_key value is used to retrieve data product information on a result row. The old method for finding data products was completely removed.
• Overall added more user error checks and tried to return informative messages to the user about possible W3Browse/user problems.
• Added code on the W3Browse side that makes sure that the correct version of the batch interface is being used. An error message is sent back to the user if the version is obsolete.
• Made changes so that if the query is a batch request, only query results or error messages will be returned. This reduces possible error in parsing exact HTML output.
• Modified the batch interface script, browse_extract.pl, so that it reports possible user/W3Browse errors.
• Modified missions page to shrink spaces between mission names, also added the OSO 8 mission.
• Added a $::writeHeader variable used to indicate if the content type directive has been printed. This variable is used wherever calls are made to the Error() function.

v4.2, December 4, 1997.

• Modified software so that it is compatible with Sybase. The changes mainly affect the parameter search interface. Parameters of type character and length greater than 255 characters can not be searched using <, >, = operators.
• Added a separate W3Browse link to the launch page for browsers that do not support HTML tables.
• Batch query error messages are reported to Tom McGlynn.
• Added AXAF mission to Advanced Interface.
• Fixed bug in cross-correlation where extra columns were being displayed on the results page. [Ed]
• Fixed the Catalog Index interface, so that views and non-HEASARC tables do not link to TDAT files anymore.

v4.1, September 8, 1997.

• Added distributed database access capabilities. W3Browse no longer depends on the 'heasarc_' prefix for table names.
• Added catalog index page which lists all catalogs with links to HEASARC resources.
• Improved the launch page.
• Completely redesigned the missions page, links from mission names now go to cone search. If a mission does not support cone search, the link goes to parameter search.
• Made other cosmetic changes such as: added a new W3Browse panel on top of each page, moved the HEASARC menubar to the bottom of each page, moved several submit buttons to the top of the pages.
• Added capabilities that would allow SIMBAD to access W3Browse.
• Fixed a bug on the Cross Correlation page in which the cross correlation radius was not being encoded correctly.
• Fixed a bug in which data products were not showing up for certain specific cases.

v4.0.2, July 23, 1997.

• Fixed bug in Batch interface which resulted in incorrect header line being displayed.

v4.0.1, July 2, 1997.

• Added new catalog names to the missions page and added the <pre> tag to improve the layout of mission links in the HTML table.
• Fixed a bug in error display of no tables found to perform object/ coordinate search for a particular mission. Improved this error message to display a more meaningful message.
• Fixed a bug related to creating mission hyperlinks on the mission page.
• Fixed a bug which was giving an incorrect Search Offset value.
• Fixed a minor bug related to display of "Entries" in the batch interface.

v4.0, May 2, 1997.

• Added cross-correlation of query results of one table with another table of the user's choice.
• Added option to query results form to display all the database parameters of selected rows.
• Added option to override default parameter display and sorting to the table selection form of a Parameter Search. Also, made some other esthetic changes to this page.
• New mission(s)-selection form on the Advanced Interface's main page (only for browsers savvy enough to display HTML tables)
• Unified the code to retrieve the list of tables and construct the HTML form for selecting tables into one nify interface, greatly simplifying the code in several places and resulting in a consistent user interface for selecting tables that is also easier to understand for the user.
• Completely rewrote the code responsible for the Advanced Interface's Object Name/Coordinates Search page. This concludes the complete revamping of the W3Browse code base begun over 10 months ago. New code is more efficient, cleaner, is more modular, and no longer uses global variables unnecessarily. It consists of 20% fewer lines of code.
• Now uses object-oriented programming approach to astronomical object names and coordinates and name resolvers.
• Fixed a bug related to query results sorting and data products retrieval.
• Fixed a rare bug in the Parameter Query's implementation of the All option of the Fields menu that would cause an SQL syntax error when the default parameters for some table consisted of all the parameters for that table.

v3.8, January 10, 1997.

• Added support for the "List Individual Data Products (Selected Sets)" option to the Search Results form. This option is similar in effect to the "List Individual Data Products (All Sets)" option, but it only lists the data products in the data products sets that the user selects.
• Added arbitrary levels of filtering of query results via the "Filter Query Results" option on the Search Results form.
• Complete rewrite of Parameter Query interface to support successive filtering of queries, combining cone searches with parameter searches, and overriding parameter display and sort control. Modified Julian date values are now displayed (and can be entered) in ISO-standard format. Right ascension and declination fields have their equinox clearly labelled in the parameter list. Replaced Action select menu with multiple submit buttons if user has a modern Web browser.
• Basic interface now uses the same default search radii as the Advance Interface in all cases.
• Added SEARCH_OFFSET pseudo-column to the Search Results output of cone searches. This column of calculated values displays the distance from the center of the cone search to the coordinates of each object in the search results in units of arcminutes.
• Added histogram, log/log, and semilog plotting to the Java plotting applet. [Saima]
• Code is more modular and is now partially object-oriented.
• More efficient querying of the database. Some unnecessary database queries were removed after intelligently encoding the data for subsequent CGI usage. This should yield faster response times for the user and less overhead on the database.
• Added support for a batch interface to Object Name/Coordinates Search using Perl scripts that users can download.

v3.7, October 31, 1996.

• Added Java applet for plotting arbitrary numerical columns in the results of searches. [Saima]
• Can now do cone searches on multiple object names and/or coordinate pairs by separating the entries with semicolons.
• Added facility for retaining arbitrary directory structures in the TAR files created by W3Browse for users to download.
• A cone search can now use a column in the table being queried as the default search radius.
• Removed Action select menu from Name/Coordinates page and replaced it with two radio buttons for Submit Query and Override Parameters Display. Added checkbox for plotting query results with Java.
• Modified the coordinate pair parsing routines to accept decimal absolute values less than 1.0 without a preceding zero. (I.e., one can now enter ".5", whereas before one was forced to enter "0.5" to avoid a parsing error.)
• Fixed a coordinate conversion bug in the parameter query routines related to the entry of coordinates in sexigesimal format.
• Fixed a bug in the Override Parameters Display option that was due to an undocumented difference between Perl 4 and Perl 5.
• Search Radius options with units of degrees should no longer be a problem for Web browsers using foreign-language encodings or strange Web browsers that don't support the full HTML character set standard. Also, added an option for a 3 degree search radius.
• Added link to a table's HTML help file for documenting data products sets.
• Tightened security again on external process invocations.
• The source code is now considerably more modular.

v3.6, September 20, 1996.

• Added W3Browse Basic Interface for novice users.
• CGRO, ROSAT, and XTE data products registered with the new Data Products Layer and defined suitable data products sets.

v3.5, August 26, 1996.

• Added support for more versatile, URL-based data products using the new HEASARC Data Products Layer.
• Can now retrieve data products sets from the Search Results page and avoid the listing of individual data products.
• Added the ability to do wild card searches in parameter queries using the like and not like operators.
• Added link to HEASARC acknowledgment from the main page.
• Source code now requires Perl 5 and is more modular.
• Improved efficiency of parameter query by removing two unneeded database queries.
• Fixed bug relating to GIF image display limit that prevented any GIF data product from being displayed on the Data Products Results page.
• Minor cosmetic changes. Better error messsages. Improved user direction.
• Updated the help-file documention.

v3.3.1, June 26, 1996.

• Fixed parameter query bug relating to table descriptions with parentheses in them.
• Added link to W3Browse usage statistics from the main page.
• All source code is now Perl 5-compatible.
• Now using special version of tar that is compatible with the SunOS 4.x version of tar.
• Updated the help-file documentation.

v3.3, May 7, 1996.

• W3Browse now displays modified Julian dates in ISO-standard year-month-day format.
• Created version history file and added a link to it from each W3Browse page.
• Centralized all source code that interacts with HDBmc. Made the source code more modular with more reusability.
• Better security on all HDBmc calls.
• Reduced the number of HDBmc calls in order to do an object name/coordinate search, resulting in better efficiency and faster response.
• Users can now select multiple missions on the main page and still be able to do a parameter query.
• Now uses table_document_url ZZGEN parameter for constructing all help links in the parameter query forms.
• The Fields and GIF Image Display Limit pop-up menus on the parameter query form now retain state between query builds.

v3.2.5, April 23, 1996.

• Searching for an object name and requesting that the output be displayed in galactic coordinates should now work.
• Coordinate precession problems encountered when the equinox of the table differed from the equinox that the user requested were fixed.
• Fixed bugs in display of coordinates returned by name resolvers. Message indicated that coordinates were J2000, but they were actually in the coordinate system specified by the user.

v3.2.4, March 13, 1996.

• A bug related to user-specification of the search radius was fixed. The degree ('°') and seconds ('"') symbols were not being recognized and converted to the appropriate integer values in arc minutes. This bug was an unforseen result of the major changes that were made to W3Browse a couple of versions ago to accommodate Mosaic's odd problems with forms.
• The data products' directory structure is now retained inside the TAR files created for the user to download.
• Minor tweaks were made to the HTML forms (mostly converting tab characters to spaces) to support the Microsoft Internet Explorer browser.

v3.2.3, March 6, 1996.

• Fixed bugs in usage of the 'sequence_id' virtual parameter in querying for data products.
• Minor esthetic tweaks to the HTML page that list the data products.