Introduction and Wide Band Continuum Resources

by Gustaaf Van Moorsel last modified Mar 10, 2017 by Lorant Sjouwerman

It is possible that NRAO has already been able to retrieve your resources from what you specified in your proposal.  If this is the case you will find these in a resource catalog labeled with the project name in the column at the left.  However, you should follow the examples below to get a feel for what is in your resource catalog. You will want to check the entries in your resource catalog, especially if you require specific frequency settings, and the examples will help you check and/or modify the content.

When you are planning simple wide band observations at default VLA frequencies only, and thus all anticipated resources are already defined in the "NRAO Defaults" catalog, it is still strongly suggested that you make separate personal catalogs for your different PBs/SBs, e.g., in the catalog with the proposal ID generated automatically. Simply copy the resource of interest (including pointing resources if needed) from the "NRAO Defaults" catalog to your project catalog.  Not only will the reason become clear later on, it also creates an opportunity to get used to the tool and you will find that scheduling using small catalogs will be faster over the web interface.  If you plan a spectral line observation, it is instructive to read the wide band case first as this saves repeating information.  Resources for wide band and spectral line observations may be mixed in the same resource catalog and resource group.

Wide-band resources

The observer has the following choices, described in the next two sections:

    Please consult the Guide to Observing with the VLA about setup-scans and 3 bit resources.

    Using an NRAO default

    Suppose your SB consists of VLA default frequency full polarization wide band observations in C band and in Ka band, and that you want to populate your personal catalog in first instance with these default (polarization) wide band resources. For this particular example, this is what to do: Option 1 uses the Resource Wizard, Option 2 uses predefined NRAO resources..

    • Make sure you have navigated to the RCT, shown in the navigation strip as Instrument Configurations.
    • From the top menu strip, select FILE - CREATE NEW - CATALOG; you can skip this step (and the next step) if the catalog you want to use already exists and is writable (i.e., the catalog name is not in slanted red font), e.g., the catalog automatically generated with your project ID.
    • Your new catalog with the default name "[New Catalog]" appears in the main editing window. Change the name of the catalog to something useful (to remind you of its purpose) by navigating to the Properties tab.
    • Optionally add the names of coauthors that you want to share the catalog resources with and who may edit the resources in the catalog.
    • At this stage you can opt to group your resources. This is not necessary, but convenient if you are going to have many resources. If you want to group resources in this catalog, select FILE - CREATE NEW - GROUP, and name your group under the Properties tab.
    • Click to navigate back to the first tab: Resources.

    Option 1, using the Wizard:

    • Select from the top menu strip FILE - CREATE NEW - 8/3-BIT INSTRUMENT CONFIGURATION
    • For 3-bit configurations, a pop-up will request inputs for the band, array configuration and polarization products, for 8-bit configurations you are taken directly to the Basics tab to select the band and the correlator integration time.
    • Upon selecting, name the resource, (select band) and confirm the integration time (which is set to the default) in the Basics tab.
    • Optionally change the Baseband center frequencies in the third Basebands tab and validate in the Validation tab.

    Option 2, copying an NRAO template:

    • Select the NRAO defaults resource catalog and e.g., D/Any config group.
    • In the resource table to the right (main editing window), check C16f5 wide and the Ka band wide band option you want (i.e., Ka64f3 for 8 GHz full polarization, or perhaps Ka16f3 for 2 GHz bandwidth). If you don't know which Ka band resource to select, study the details of each before selecting one, or simply select all. If you selected a group first (and not the whole NRAO Defaults catalog), you may not be able to select both bands in one go; simply repeat these steps. If the resources are not on the same page when selecting the whole NRAO Defaults catalog, simply change the number of resources per page from 25 to 50 or 100.
    • From the top menu strip, select EDIT - COPY - INSTRUMENT CFGS..
    • Select your newly named resource catalog (or group within it).
    • From the top menu strip, select EDIT - PASTE - INSTRUMENT CFGS.. The resources now show up on the right hand side.
    • This can also be achieved by copy/paste of entire groups and/or entire catalogs using the top menu strip options or the menu icons at the top of the (left hand side) resource catalog column. Use the fly-over tool-tip help to identify the proper icon for each action.
    • Maybe you want to check the resource properties using the Show/Edit icon for each catalog entry, especially if you copied one of the Ka band resources as you would probably want to check the polarization or channel separation for each. You can also reorganize your resources by adding groups (FILE - CREATE NEW - GROUP) and move your resources around using the column icon menu, or using EDIT in the top menu strip. Unwanted resources can be deleted using EDIT - CUT - INSTRUMENT CFGS. and similarly unwanted groups or catalogs can be removed using EDIT - CUT - CATALOG/GROUP or by using the scissors in the icon menu.

    If you are unhappy with the name of the catalog or group you can always rename it by selecting it and then clicking on the Properties tab. If you want to change some parameters, choose the relevant items in the next list. Refer to Figure 3.4.

     

    Create your own resource from scratch

    • Make sure you have navigated to the RCT, shown in the navigation strip as Instrument Configurations.
    • From the top menu strip, select FILE - CREATE NEW - CATALOG or select an existing personal catalog.
    • Your new catalog with the default name "[New Catalog]" appears in the main editing window. Change the name of the catalog to something useful (to remind you of its purpose).
    • Optionally add the names of coauthorss that you want to share the catalog resources with and who may edit the resources in the catalog.
    • At this stage you can opt to also group your resources. This is not necessary, but convenient if you are going to have many resources. If you want to group your resources in this catalog, select FILE - CREATE NEW - GROUP,  and name your group under the Properties tab.
    • Click to navigate back to the first tab: Resources.
    • From the top menu strip, select FILE - CREATE NEW - 8/3-BIT INSTRUMENT CONFIGURATION. You will be presented with, e.g, the 3-bit resource page for which an example is shown in Figure 3.7:

    Figure 3.7 - 3-bit resource page. Note how the four 2GHz basebands cover 8GHz in K-band

    • In the first (Basics) tab, name your resource, select an observing band and enter some descriptive information in the comments field at the bottom of the page (not shown here).
    • Choose a correlator visibility integration time, in integer seconds with a minimum of 1 second, or use 5 seconds if you don't really care; the latter will reduce the size of the data set at the cost of time-averaging smearing away from the phase center. The correlator integration time may have to be adjusted later to remain within the maximum data rate for the specific setup you are creating.
    • Move to the Basebands tab (i.e., skip the Lines tab).
    • For the high frequency bands (K, Ka, and Q) the default is to use 3-bit samplers covering 8 GHz bandwidth using four 2 GHz basebands, but you may select the 8-bit system to use two 1 GHz basebands. For the low frequency bands the default is to use the 8-bit setup.
    • For each baseband select the baseband center frequency if the defaults won't work for you. If you plan on doing this remember the restrictions: for 3-bit the baseband centers for A1C1 and A2C2 must be within about 2.5 GHz (same for B1D1 and B2D2), and in cases where AC and BD are spread over a large range usually AC needs to have the upper center frequencies. Ka band has extra restrictions (see below or the OSS). Ignore the Doppler table below the baseband center frequency table.
    • Continue to the Subbands tab (i.e., skip the Line Placement tab).
    • Under every baseband tab (i.e. repeat this four or two times) click Fill Subbands. Each defined subband will fade a fraction of the color of the baseband in the graph on top.
    • If you are unhappy with any of the subbands you can delete individual subbands with the delete icon (delete) at the right hand side of the subband table. Mulitiple subbands can be selected and deleted with the Delete Selected Subbands button.
    • Subbands can be changed individually, or be selected and bulk-edited using Bulk Edit Selected Subbands. Note that editing is limited to the current baseband tab only; if you, e.g., want to change the polarization of the whole observation you have to repeat the editing in each of the baseband tabs. You can only enter the center frequency for subbands of 16 MHz and narrower, provided that they do not cross a 128 MHz boundary; wider subbands can only be selected from a fixed drop-down list.
    • You may sacrifice subbands in favor of more correlator products (channels or polarizations) in another subband. More of this will be described in the Spectral Line Resources section below.
    • If you want to start anew (using the already specified baseband centers), click Clear All Subbands to remove all subbands in all basebands, or delete the resource (or Group, Catalog) completely using the menu strip or icon menu.
    • Finally use the Validate tab to inspect your setup in terms of frequencies and correlator resources (i.e., baseline board pair allocations). Check your resource, from top to bottom. If you create more than one resource, check each of the resource properties using the Show/Edit icon for each catalog entry. You can also reorganize your resources by adding groups (FILE - CREATE NEW - GROUP) and by moving your resources around using the column icon menu, or using EDIT in the top menu strip. Unwanted resources can be deleted using Cut.
    • If you are unhappy with the name of the catalog or group you can always rename it by highlighting it and then clicking on the Properties tab.

    Incorrect or unfinished template resources — the ones which generate red errors in the interface feedback strip — will be saved for future use, when you exit and log in again. They will however not be usable when assigned to a scan in the OPT. The resource first must be fixed in the RCT after which it can be assigned to a scan in the OPT. Resources with warnings can be assigned to a scan, but the warning should be understood before continuing with OPT scheduling. This behavior also applies to sources in the SCT.

    Regardless of how you create (or how NRAO fills) your resource catalog entries, make sure they are correct before you continue with using them in the OPT. The OPT does not use global resource properties; when you have modified a resource you have to use the OPT to reassign the new resource separately to every scan that needs it.  For this a global edit has been implemented in the OPT. Check your catalogs before making scans!

    Options from the menu strip and icon menu

    In the previous recipes some usage of the options in the menu strip were given (e.g., FILE - CREATE NEW - CATALOG). The names of the actions are quite self-explanatory, similar to the menu strip options in the SCT:

    FILE CREATE NEW CATALOG EDIT [ADD TO GROUP]   -> [[group name]] HELP ABOUT THE RCT
    GROUP [REMOVE FROM CURRENT GROUP] ABOUT ME
    8-BIT INSTRUMENT CONFIGURATION CUT CATALOG NEW FEATURES
    3-BIT INSTRUMENT CONFIGURATION GROUP DOCUMENTATION
    EXPORT ...
    INSTRUMENT CFGS. CONTACT SUPPORT
    IMPORT COPY CATALOG
    EXIT GROUP
    INSTRUMENT CFGS.
    PASTE CATALOGS
    GROUPS
    INSTRUMENT CFGS.

    Menu strip options may act on both items in the left hand side column as well as items in the main editing window, and are grayed and striked out if the item is not active/highlighted (e.g., the catalog instead of the group). The icon menu was introduced in the previous chapter. Here the menu icons behave exactly the same as in the SCT.  The fly-over tool-tip help will remind you of their actions.