CHAPTER 4: A STARCAT Cookbook In This Chapter... Typical STARCAT Session / 16 Logging In / 16 Basic Commands / 18 Selecting Screens / 19 Defining Search Criteria / 26 Scanning the Data Base / 30 Proprietary Rights / 31 Retrieving Files From the Archive / 31 Converting File Formats / 38 Using FTP / 41 Now That You Have Your Data... / 43 Selecting Files and Data Retrieval Mode / 45 Getting Help Within STARCAT / 48 Sending Feedback to STScI / 50 This chapter explains how to use STARCAT to select and obtain observations of interest from the HST archives. After you are comfortable with the material in this chapter, you may find it particularly helpful to read about search strategies in Chapter 6, and the following topics in Chapter 7: o "Searching an Area Around a Centered Position" on page 89 o "Using Output Files" on page 94 o "Table-Row Format" on page 90 (the "List" command) Typical STARCAT Session Archive researchers are typically looking for observations that match some criteria, such as those taken in a particular area of the sky, of a particular object, or with a particular instrument. A user may want to simply obtain a listing of relevant observations, or may want to actually retrieve the dataset for an observation from the archive. The process of using STARCAT to locate and retrieve observations of interest consists of the following steps: 1. Login to STARCAT (see below) 2. Select appropriate screens (page 19) 3. Define your search criteria by qualifying screens and fields (page 26) 4. Scan the archive database (page 30) 5. Mark files of interest for later retrieval (page 31) 6. Retrieve files (page 31) Before delving into the archives too deeply, keep in mind that an online help facility is available within STARCAT. The online help is described on page 48. Logging In To use STARCAT, you need to first log in to the archive host computer, as described on page 7, using TELNET from a terminal or window emulating a VT100. Log in with your assigned username, if you have registered, or with the generic guest account (password archive). o Once you log in to STDATA or STDATU, you start STARCAT by typing: $ starcat o To get out of STARCAT at any point, press several times The Banner Screen The first screen you will see is the STARCAT banner screen (Figure 4.1). A message of the day may appear on the screen before the banner screen; the message of the day contains important information about the archive system. Press and the message will disappear. Note that the banner screen shows the current version of STARCAT and the appropriate version of the HST Archive Manual (and Primer). Compare this version number to the cover pages of your documents to see if your manuals are current. o If there is no menu bar at the bottom of the screen, press to bring up the menu (or type menu). o Press to access the HST catalog, you will then be placed in the top-level menu (described on page 20). Figure 4.1: STARCAT Banner Screen Basic Commands STARCAT is normally used as a menu-driven system. If the menu does not appear on the bottom of your screen, you can bring it up by pressing when you first log in, or by typing menu. (See "About Modes..." on page 85 for help using STARCAT in Prompt mode). The menu is a box at the bottom of the screen that lists available commands, all of which can be invoked by pressing the single character keystroke listed to the right of the command name. A sample command menu is shown in Figure 4.2. For example, pressing would exit the catalog. Figure 4.2: Sample Menu Commands in the menu bar change depending on the context of the current screen. A complete description of all of the menu bar commands can be found in Chapter 8 of the HST Archive Users Manual. Note that some of the commands may not be available at STScI. Choosing Menu Options When the command menu is displayed, one of the commands is always underlined. Pressing will invoke that command. You can move the underline to another command by using the cursor keys, or you can invoke a command directly by pressing the single-letter keystroke shown to the right of the command name. Refreshing the Screen Display Occasionally, your screen display may get distorted or overwritten. If this happens, you can press to refresh the screen. Selecting Screens Screen selection, sometimes called catalog navigation, is simply the process of moving through the STARCAT menus to find data screens that contain information of interest to you, or that have fields that you can use to define your search criteria. As you move through STARCAT, keep in mind that there are two types of screens: o Menu Screens present a list of options that must be selected. These menus typically take you to lower-level data screens. o Data Screens present information from the archive catalog on a one-screen-per-data-base-record basis. From the data screens you can define search criteria and browse the catalog. From the top level menu, the most important menu command for most users will be , which is used to select options from the list that appears in the top window. This command allows you to move down to lower-level submenus and eventually, to the data screens. Data screens are the heart of STARCAT because this is where search criteria are specified and information is displayed. As you move into the lower-level data screens, note that the menu commands change. Command menus vary depending on the context of the screen. STARCAT Structure STARCAT's view of the HST archive is hierarchical and is illustrated in Figure 4.3 below. You need to traverse the menu screens to get to the data screens, which is where you will actually begin doing an archive search. Figure 4.3: STARCAT Catalog Structure Chapter 6 contains advice on screen selection and useful strategies for conducting archival searches. Chapter 9 contains detailed descriptions of the contents of each screen. A good starting point for most searches is the GENERAL screen, available both through the top-level menu and from within the POST-OBS menu. Moving Through Screen Levels When you first get into the HST catalog, you are in the Top Level Menu. Figure 4.4 shows the top-level menu and Table 4.1 lists the commands available from the menu screens. The available menu screens are listed along with a brief description of their contents. You move through the menu levels by selecting choices from the menu. To select screens, you need to: 1. Press to choose the select option 2. Use the cursor keys to move to a screen name that you want to see 3. Press to go to the selected screen If you find yourself on the wrong screen, press to move up to the previous level. Figure 4.4: Top Level Menu Command Menu/Prompt Select Retrieve Create Scr Forward Backward Down Line Up Line First Scr Last Scr Help Modify Pswd Exit Scr Exit HST Keystroke P S R C F B + - 1 L H M E Z Function Toggle between Menu and Prompt modes Choose options from the list Write out a list of marked data files Create a user-defined screen for the archive that will appear under the Personal menu Display next screen of options (if multiple screens are required to display all options) Display previous screen, if options extend over more than one screen Display next option Display previous line option Display first screen of options Display last screen of options Display the online help for this screen Change your personal STARCAT password Go to the next higher level menu. Exits the HST catalog from the top-level menu Leave the HST catalog; returns to the STARCAT banner screen Table 4.1: Menu Commands Data Screens The archive catalog is searched and files are identified for retrieval from within data screens. Figure 4.5 shows a sample data screen and Table 4.2 gives a listing of commands that are available from within data screens. Figure 4.5: Sample Data Screen Command Menu/Prompt Help Doc Output_File Center Qualify UnQualify Restart List FindNext BackFind Scan Next_mark Mark ModQuery Mark All Exit Keystroke P H D O C Q A R L F B S + X M Y E Function Toggle between menu and prompt mode Display online help for this screen Display documentation for this data screen; includes explanations of fields, data types, and their origins Write contents of displayed fields to a file Search for values in the neighborhood of specified RA and DEC Specify search criteria Clear all previous search criteria Execute previous search from beginning Invoke table-row format Search for first (next) record matching speci- fied criteria Search for previous record matching criteria (the buffer will allow you to move back approximately 250 records) Find all records matching criteria Display next record marked for retrieval Mark currently-displayed record for retrieval Directly edit the SQL query generated by STARCAT Mark for retrieval all records in the archive that match the search criteria Return to the higher-level menu screen Table 4.2: Data Screen Commands Defining Search Criteria This and the following sections describe how to go about searching the archive catalog for datasets of interest from a data screen. Qualifying Fields Qualifying fields is simply the process of defining your search criteria. To qualify fields, you need to: 1. Press to place the cursor into the data screen. 2. Move through the fields using the cursor keys (or you can press the key to jump from field to field). 3. Specify the search criteria using the relational operators shown in Table 4.3. Note that functions operating on numeric fields are shown in the middle column, while those operating on character fields are shown in the right column. 4. Press when you have qualified all the fields of interest, i.e., specified all of your search criteria. Operator = == != > >= < <= .. , [] | & Wildcard Operators * ? Numeric Function Equal Equal Not equal Greater than Greater than or equal Less than Less than or equal Range, e.g., 1..5 Alternatives, e.g., 1,5 N/A Logical OR Logical AND N/A N/A Character Function Equality, wildcards allowed (i.e., * or ?) Exact equality Not equal Greater than Greater than or equal Less than Less than or equal N/A N/A Alternatives, e.g., =[OBA]* N/A N/A 0 or more characters Any single character Table 4.3: Relational Operators for Qualifying Fields When qualifying fields, there are certain keystroke commands that are available to you for clearing fields, toggling between insert and overstrike modes, and finishing your qualification. These commands are listed in Table 4.4. Keystroke Function Next field Toggle insert/replace mode Clear qualification from field Exit-Qualification complete Table 4.4: Qualification Keyboard Commands You can also completely clear all of the qualifications on a screen by bringing up the command menu (press if you're in the mid- dle of qualifying fields) and pressing . Sample Qualifying Step Suppose that you want to find out if there are any publicly available (i.e., non-proprietary) HST observations taken in the vicinity of an object at a known position. Figure 4.6 shows the GENERAL screen being used to perform the following steps: Define the Position 1. Press to begin qualifying. 2. Use cursor keys to move to the Target RA field. 3. Type in a range of values to bound the search area. First, specify the right ascension (Target RA). (Note that Target RA and Dec are in J2000 coordinates.) We use the values 02 42..02 43. Note the use of the range operator (..). 4. Use cursor keys to move to the DEC field. 5. Type in the declination range. We use -00 01..-00 00. When using the range operators, the values must be ordered such that the second value is greater than the first. If you're not sure about what format to use when specifying values, look at a few sample records before qualifying the fields. Acceptable formats for dates include 01-Feb-92 or Feb 01 92 Acceptable formats for RA and DEC include: 01 05 10.57 -10 50 10.65 01 05 -10 50 Spaces and dashes can be used interchangably. Specify Only Public Data 6. Use the cursor keys to move to the release_date field. 7. Limit the search to less than today's date, for example, if you were doing the search on January 1, 1993, you would type: <01-JAN-93 8. Press to end the qualification. 9. Scan the archive, as described in the next section. Figure 4.6: Qualifying Fields Scanning the Data Base After you tell STARCAT what you're looking for by qualifying fields, you begin the search using one of the three search commands: o Press to invoke the FindNext command which will find the first (or next) record that matches your criteria. o Press (the BackFind command) to search backward for the pre- vious matching record. o Press to quickly scan the archive, retrieving all records that match your search criteria. Scanning stores approximately 240-250 records in a display buffer, so if you specify a fairly general set of search criteria, you will overflow the buffer; if you wish to see each returned record by backstepping, you will need to restart your search by pressing and then using the FindNext and BackFind commands. Figure 4.7: Search Results Proprietary Rights Most HST observations are proprietary for a period of one year after the exposure is taken. Users should keep in mind that while the database information is not proprietary, the data may be. There will be many instances where an observation is described in the HST catalog, but the data are not yet available to the public. Only non-proprietary HST data can be retrieved through STARCAT by archival researchers. The keyword release_date, which is displayed on the GENERAL screen-and all of the INSTRUMENT data screens-gives the date when the dataset becomes non-proprietary and available for retrieval from the archives. Retrieving Files From the Archive To retrieve files from the HST archive, you need to: 1. Mark datasets (records) for retrieval. 2. Build a list of files that you wish to retrieve (page 32). 3. Choose a retrieval mode; either 9-track or Exabyte tape for shipment, or disk for later FTP (page 34). 4. Review the list of files and make any necessary changes (page 35). 5. Submit the retrieve request (page 35). Once your retrieval request has been submitted, you can check on its status from within STARCAT (page 37). Marking Records When STARCAT displays screens describing datasets that you want, you can mark the file-or dataset. When STARCAT marks a file, it stores the record so that you can later build a list of all marked records, save the list to a file, and then retrieve the data from the archives-saving and retrieving are discussed in the next two sections. There are two ways to mark a record: o Press to mark only the record that is currently displayed o Press to mark all records found during a scan (i.e., all datasets that satisfy the query constraints) When you are done marking records for retrieval, press to Exit the data screen. Figure 4.8: Marking Record for Retrieval Building a List of Files for Retrieval After you are done searching the archives and marking datasets of interest, you need to build a list of files that will actually be retrieved. Each dataset can be composed of many files (see Chapter 10 for an explanation of archive classes and a complete description of file names, types and extensions). In general, you will only want to retrieve a subset of the files for each dataset. (See "Selecting Files and Data Retrieval Mode" on page 45 for help in choosing the appropriate files and retrieval method.) To build the list of files for retrieval: 1. Press from within a menu screen to begin the filtering process (This command is not available from within the data screens-press if you need to exit to a menu screen). This will bring up the Archive Retrieval File Type Selection Screen, with its default values. 2. If the defaults are appropriate, press to continue. This will bring up the Dearchiving Screen, which is described in the next section. 3. If the defaults are inappropriate, press to qualify. Specify archive classes, file extensions, and version numbers for the files you want. Unless otherwise specified, the highest version number of each requested file will be retrieved-this is almost always what you will want. 4. When you are done specifying the archive classes and file extensions, press and then press to bring up the next screen-the Dearchiving Screen (Figure 4.10). Figure 4.9: Archive Filtering Screen Choosing a Retrieval Mode 1. Press to specify your dearchiving media choices and enter your STARCAT username and password. 2. Press when you are done entering values, then press to continue. Figure 4.10: Dearchiving Screen If you are retrieving files via the LAN, you cannot retrieve FITS files. If you want FITS files, you must convert GEIS to FITS after retrieving the files, as described on page 38. You must fill in all requested information before the system allows you to proceed through this screen and submit the actual retrieve request. If you are only retrieving a few files, you can retrieve the GEIS files and transfer them back to your home institution via FTP. If you wish to do this, specify LAN, otherwise, specify Exabyte or 9-track tape (see the next section, below). An example of how to retrieve files and transfer them using FTP begins on page 51. Editing the File Retrieval List Before submitting your retrieve request, you can review it and edit it. Type to edit the request. This step uses your default editor. If you did not previously specify a default editor by using the change_editor command, the default editor-EDT on STDATA or vi on STDATU-will be used. In the editor, you can make any changes you want to the retrieval request, such as deleting or adding file names. . Figure 4.11: Editing the Retrieval List Submitting the Request To submit your request: 1. Press 2. Write down the request number when it is displayed 3. Press to exit the screen and continue working in STARCAT After you press , a message will appear telling you that the request was submitted; the message displays a request identification string (which is your user name followed by a four-digit number). Note the request identification string-it is the means for identifying and tracking your file request. The retrieval file list is written to the directory from which you are running STARCAT. It will be named with the file request identification string as the file name, followed by an extension of .req, for example, oort0129.req. Figure 4.12: Request Submission Screen Checking the Status of Your Request You can check on the status of your retrieval request by using the Req status command from the UTILITIES menu under the STARCAT banner screen. (Exit the HST catalog, press to bring up the UTILITIES menu, then press to invoke the Req status command). When your retrieve request is completely processed and your files retrieved from the archive, you will be notified via e-mail. This message will be sent to your e-mail address at your home institution. The message will identify the request by number and will provide status details, on a file by file basis, of the completed request. If you requested the data via LAN, you can proceed to convert the data format (if desired) and transfer it via FTP to your home institution (remember that files have a lifetime of 5 days on the archive host computer). If you requested the data via Exabyte or 9-track tape, you can expect the data to be shipped within 1-2 weeks. Data Retrieved Via LAN When you retrieve data via LAN, your data will be written to a subdirectory of the data directory on the archive computer's disk. Subdirectories are named by the file request number displayed during the retrieval process. Go to that directory and type dir to see the list of files retrieved. For example, if your file request identification string was oort0129, you would type: $ data $ cd oort0129 $ dir Converting File Formats Files retrieved from the DMF archive by STARCAT are VMS-format GEIS files. GEIS files can be read using the STSDAS tool strfits (see the STSDAS User's Guide). If you plan to use STSDAS on a VMS system to analyse the data, you can directly transfer the retrieved files (using FTP) back to your home computer. If you plan to use STSDAS on a Unix system, you will first need to convert the GEIS files to Unix format using the STSDAS tool vax2sun (see below) because GEIS format is operating system dependent. If you do not plan to use the STSDAS software to analyse your data, you will want to convert your data to FITS format using the stwfits tool (see below) before using FTP to move files to your home computer. Users on STDATU must first convert their files to Unix-format GEIS files before converting them to FITS (i.e., first run vax2sun, and then run stwfits). Note that FITS files are operating system independent. GEIS files come in pairs: a header file with an extension ending in "h" (e.g., X00C0101T.C0H) and a data file with an extension ending in "d" (e.g., X00C0101T.C0D). FITS combines these two files into a single data file. VAX2SUN To convert your VMS format GEIS files to Unix format GEIS files you run the task vax2sun. This STSDAS tool has been provided as a standalone program on the archive computers. The program prompts you for input, asking first for the names of the header files to be converted and second for the names of the output file headers. Wild cards are not allowed but a short, comma-separated list is acceptable. To convert all the files in your directory, you can write the names of the header files to a text file using the files task and then input the list of files as in the example below. In the following example, we write all of the files out to a subdirectory on stdatu. % data % cd oort0129 % dir X00C0102T.C0H;1 X00C0102T.C0D;1 X00C0102T.C1H;1 X00C0102T.C1D;1 X00C0102T.D0H;1 X00C0102T.D0D;1 X00C0102T.SHH;1 X00C0102T.SHD;1 % files template: *.*h outfile: myfiles.lst % more myfile.lst X00C0102T.C0H X00C0102T.C1H X00C0102T.D0H X00C0102T.SHH % mkdir converted % vax2sun input: @myfile.lst output: converted % cd converted % dir X00C0102T.C0H X00C0102T.c0D X00C0102T.C1H X00C0102T.C1D X00C0102T.D0H X00C0102T.D1D X00C0102T.SHH X00C0102T.SHD The corresponding tool to convert from Unix to VMS format is sun2vax. This program also operates as a standalone program on the archive computers. Writing FITS Files FITS files are created using the stwfits task from STSDAS. It operates as a standalone program on the archive computers. To invoke it type stwfits. When you run stwfits you will be prompted for the name of the IRAF files you wish to convert and the name of the output FITS files. As with vax2sun (see above) you can give the program a list file containing the names of the header files you wish to convert. The output file name can be a single name, with no extension (e.g, fitsfile). Stwfits then creates a series of FITS files with that name and a sequentially increasing 3 digit number appended (e.g., fitsfile001, fitsfile002). For example: Using FTP You will use FTP to move your files across the network from the STDATA or STDATU host machine to your local host. To do this, you will need to: 1. Start FTP from your host computer and connect to the archive host stdata.stsci.edu or stdatu.stsci.edu 2. Move to the subdirectory of the dmf_stage directory where your data reside. 3. Set the transfer mode to binary. 4. Get the file(s). If you are retrieving a single file, you would use the get command instead of the mget command from within FTP. If you wish to retrieve any ASCII text file, including the PostScript documents, you can use the ASCII transfer mode (set the mode by typing ascii at the ftp> prompt); binary files, including GEIS and FITS data files, must be transferred in binary mode (type binary at the ftp> prompt). If you have questions about how to use FTP, see your local system support gurus, or contact the archive hotseat. Table 4.5 shows the commands you would use to retrieve HST data, ASCII files from the documents directory, and ASCII files from your home directory from each of the archive computers, if you logged in from a registered account. Function Retrieve HST data Retrieve PostScript version of manual Retrieve your starcat.log file from your home directory FTP Commands (VMS) ftp stdata.stsci.edu cd disk$stage:[DMF_STAGE] cd [.oort0129] binary mget X*.* ftp stdata.stsci.edu cd disk$stdata0:[documents] cd [.manuals] ascii get archive_manual.ps ftp stdata.stsci.edu ascii get starcat.log FTP Commands (Unix) ftp stdatu.stsci.edu cd /stdatu/dmf_stage cd oort0129 binary mget X* ftp stdatu.stsci.edu cd /stdatu/u1/documents cd manuals ascii get archive_manual.ps ftp stdatu.stsci.edu ascii get starcat.log Table 4.5: FTP Commands for STDATA and STDATU for Registered Users Table 4.6 shows the commands you would use to retrieve files if you logged in as an archive guest user. Function Retrieve PostScript version of manual Retrieve your starcat.log file from your home directory (if your directory is called mydirectory) FTP Commands (VMS) ftp stdata.stsci.edu cd disk$stdata0:[documents] cd [.manuals] ascii get archive_manual.ps ftp stdata.stsci.edu cd mydirectory ascii get starcat.log FTP Commands (Unix) ftp stdatu.stsci.edu cd documents/manual ascii get archive_manual.ps ftp stdatu.stsci.edu cd data/mydirectory ascii get starcat.log Table 4.6: FTP Commands for Guest Users Now That You Have Your Data... Documentation on the Telescope and Instruments The User Support Branch (USB) at STScI serves as a central contact point between the scientific community and the Institute. A wide range of technical documentation on the telescope and its instruments can be obtained from the User Support Branch. The USB can be contacted at: User Support Branch Space Telescope Science Institute 3700 San Martin Drive Baltimore, Maryland 21218 USA Phone: (800) 544-8125 (in USA), or (410) 338-4413 E-mail: usb@stsci.edu Some of the documentation available from USB includes the following. (These documents are also distributed to astronomical libraries). o WF/PC Instrument Handbook, version 3.0 o FOC Instrument Handbook, version 3.0, April 1992 o FOS Instrument Handbook, version 2.0, April 1992 o GHRS Instrument Handbook, version 3.0, January 1992 o HSP Instrument Handbook, version 3.0, April 1992 o FGS Instrument Handbook, version 3.0 o OTA Handbook, version 2.0 o Target Acquisition Handbook, version 2.0 o Cycle 2 Calibration Plan, version 1.0, May 1992 o The GO and GTO Observing Programs, version 3.0, May 1992 o HST Archive Manual, version 3.0, January 1993 o HST Archive Primer, version 3.0, January 1993 o STEIS Guide Getting STSDAS HST datasets can be analyzed or recalibrated using the Space Telescope Science Data Analysis System (STSDAS) software available from STScI. There are two ways to get the software: o Anonymous ftp: The STSDAS software is available through the net- work on the host stsci.edu (130.167.1.2) in the directory: soft- ware/stsdas/v1.2 The best file for VMS users to get is stsdas1.2.tar, the best file for Unix users is stsdas1p2.tar.Z Figure 4.13: Getting STSDAS via Anonymous FTP o Magnetic tape: Copies of STSDAS can be provided on various tape for- mats for VMS and Unix systems. To request that the software be sent to you on magnetic tapes, complete the "STSDAS Software Request Form" available from the User Support Branch, or send e-mail to: sdas@stsci.edu. Learning and Using STSDAS A comprehensive discussion of STSDAS features or a tutorial on how to use the software is well beyond the scope of this manual. To learn how to use the system for doing data analysis, you can request copies of the documentation by sending e-mail to: hotseat@stsci.edu Selecting Files and Data Retrieval Mode You choose which files to retrieve for a given dataset using the Archive Filtering Screen and the mechanism of retrieval (FTP or Exabyte or 9-track tape) using the Dearchiving Screen (as was described in the previous section). Because there is a limit on the amount of data (<50 megabytes, see Chapter 2) that you can retrieve via FTP (and that you will want to retrieve via FTP given the physical limitations of the bandwidth communication to your home site), there is clearly an interplay between the files you choose to retrieve and the mechanism you choose for the retrieval. The quality of the data in the HST archive varies greatly (see Chapter 6). You may therefore wish to employ a strategy where you initially retrieve only that subset of files needed to begin analyzing the calibrated data. You may later decide that you wish to recalibrate the data or see the results of earlier calibration steps; you can then go back and retrieve either the full cal class dataset (i.e., the raw data and all the intermediate calibration steps) or a larger subset of those files (see Chapter 10 for a full description of the content of each type of science file per instrument). Table 4.7 lists, per instrument, the files that you will want to retrieve if you are interested only in the endpoints of the calibration process. These would be the files to retrieve either if you are interested in simply browsing the data to assess its quality or potential, or if you wish to directly analyze the final calibration products. The default mode in the filtering screen is to retrieve the last two products of the calibration process (the *.c0[h,d] and the *.c1[h,d] files), the raw data file (the *.d0[h,d]), and the standard header packet (the *.shh file). The raw data file enables you to fully recalibrate the data, and you may want to retrieve it in addition to the final calibration products in the instances where the file sizes are small. Instrument FOC FOS HRS HSP WF/PC Final Calibrated Files *.c1[hd] *.c0[hd], *.c1[hd] *.c0[hd], *.c1[hd] *.c0[hd], *.c1[hd], *.c2[hd], *.c3[hd] *.c0[hd] Table 4.7: Files Resulting from Calibration for Each HST Instrument Looking at Table 4.7, we see that the defaults are appropriate for typical HRS and FOS observations. However, for the WF/PC, only the *.c0[h,d] and the *.sh[h,d] files are needed, and for the FOC only the *.c1[h,d] and *.sh[h,d] are needed. Because the FOC and particularly, the WF/PC file sizes tend to be very large (see Table 4.8), you may wish to edit the final retrieval list so that you retrieve only the final calibration product for the imaging instruments. The situation is more complex for the HSP. For HSP observations, you will need to retrieve the *.c0[h,d], *.c1[h,d], *.c2[h,d], and *.c3[h,d] files if you want just the calibrated data and also the corresponding *.d[0,1,2,3][h,d] files if you wish to recalibrate the data. Instrument FOC FOS HRS HSP WF/PC Mode normal 512 x 512 zoom 1024 x 512 normal rapid readout normal rapid readout normal occasional normal (full mode) area mode Single File Size 1 MB 2 MB 2-8 KB > 4 MB 2-8 KB > 4 MB ~ 4 KB > 125 MB 10 MB 2.5 MB CAL Class Size ~4 MB 8-10 MB < 500 KB > 10 MB < 500 KB > 10 MB ~ 500 KB > 1 GB 26 MB 7 MB Table 4.8: Average Instrument Data File Size To give you an idea of the size of the files for each instrument, we list in Table 4.8 the typical sizes (and a range of possible sizes) of individual calibrated files for each instrument. Note that the *.*h files are ASCII header files and are typically about 20 kilobytes in size. File sizes vary within a given instrument depending on the observation mode. In particular, although the FOS and HRS instruments usually produce small datasets, when they are used in rapid read mode the datasets can be quite large (look for opmode = rapid on the GENERAL or INSTRUMENT screens). Likewise, the HSP can produce enormously large datasets. You can use table 4.8 as a guideline to help you determine whether to retrieve a file (or set of files) to magnetic disk for FTP back to your home computer (LAN) or whether to request that the data be sent to you via 9-track or Exabyte tape. The actual size of any given file can be determined using the FILES screen under the DATAFILES menu. Getting Help Within STARCAT There are several ways to get help in accessing the HST archives from within STARCAT. o Press for a list of other available keystroke commands o Press to look at the online help o Press from within a data screen to look at the documentation for that data screen Pop-Up Keyboard Help Pressing will bring up a short, online pop-up help screen. Figure 4.14: Pop-Up Help Display On-Line Help In addition, pressing will bring up a help screen. Within the help screen, you can: o Press for a list of relevant topics o Press for a list of topics and subtopics Figure 4.15: Context-Sensitive Help Facility Data Screen Documentation Data screens have an online documentation facility that describes what information is contained in each field on the screen, and where that information is located in the DMF database. Pressing from within a data screen will bring up the online documentation for that screen, for example, Figure 4.16 shows documentation for the prop_abstract screen. Figure 4.16: Data Screen Online Documentation Sending Feedback to STScI If you have any questions or comments about the HST archive or the STARCAT system, contact the HST archive support staff by sending e-mail to: archive@stsci.edu E-mail can be sent to this address directly from within STARCAT by invoking the Report () command from the Utilities menu (accessed from the banner screen: you can get to the banner page by exiting the HST catalog-press several times.). From the Utilities menu: 1. Press to bring up the mail editor 2. Type your message 3. Press to send the message 15