Using the Resource Catalog Tool (RCT)

The previous subsections on resources were dealing with resources defined to do the scientific astronomical observations you proposed for. However, to get the most out of your data, it sometimes is helpful to add some specialized scans to the SB in order to optimize the observations or to aid in the calibration of the instrument. Typical for high frequency (higher than ~ 15 GHz) are pointing scans and tipping scans. The observing mode for such scans (pointing or tipping) is selected at the scan level in the OPT. For pointing scans, typically one would use resources that are different from your scientific observation resources, e.g., a different bandwidth, correlator setting, or even a different observing band. We have added some of these resources to the NRAO defaults catalog, available to the OPT at the scan level or to copy/paste to your personal resource catalog.

Pointing scans are used to improve telescope pointing accuracy which increases the sensitivity of the observations. As the instantaneous telescope pointing is only accurate to several arcseconds, this error may become a considerable fraction of the primary beam at high frequencies. Solving for this error is done using primary pointing scans on a strong source at X band, after which a secondary pointing may be performed at the observing frequency if deemed useful. The actual pointing action is selected as Interferometric Pointing under scan mode in the scan details (see OPT), which may use the resources named Pointing presented in the Pointing setups resource group in the NRAO defaults resource catalog.

Tipping scans are used to obtain a measurement of the atmospheric opacity at high frequencies, which allows for an estimate of the loss of sensitivity due to absorption of emission from the source of interest by the atmosphere. The actual telescope tipping action is selected as Tipping under scan mode in the scan details (see OPT). Because you typically want to do tipping scans at your observing frequency you would either use resources from the NRAO defaults catalog or you would reuse your own resource at the frequency you want; no new resources are needed.

Resources at 4, P, and U band: Currently there are no receivers at 4, P and U band (75 MHz, 300 MHz and 15 GHz) on the array. For U band we recommend to use the lower part of the K band receivers (around 19 GHz) instead. This should have been proposed for at the proposal stage. No observations at 4 and P band are anticipated for some time.

Resources at S band: S band is currently deployed on the array. It is likely that if you proposed for observations at S band, not all antennas will be outfitted with S band receivers. At this moment it is not possible to use the other antennas in a different subarray. Commissioning of subarrays with WIDAR is not planned for some time.

Resources at X band: Until the end of the EVLA construction, around late 2012, the VLA type X band receivers will be kept on the array. This means that there is limited X band tuning, only from about 8.0 to 8.8 GHz. Consult the Observational Status Summary or the NRAO eNews web pages for the latest news on this receiver upgrade.

Resources at K band: There is an issue with specifying the frequency of output pair AC at Ka band. That is, tuning any part of the AC output pair band below 32.24 GHz will not result in valid data. Only the BD output pair can be tuned to frequencies below 32.24 GHz; use the BD output pair instead of AC output pair when you only need one output pair for your resource with a frequency tuning below 32.24 GHz. If the OPT web application validation detects that any part of the bandwidth of output pair AC is tuned below this 32.24 GHz it will try to swap the AC output pair with the BD output pair. If this is not possible, it will issue an error (in red font) in the interface feedback strip if this frequency is specified as a fixed sky frequency. It will issue a warning (blue font) for rest frequencies, as the particular tuning depends on the details of observing date, telescope pointing direction and source velocity definitions. Note that a rest frequency above 32.24 GHz may shift to below 32.24 GHz once it is assigned to a scan in the OPT. This should give you an error in the OPT; you should be aware of this possibility and pay attention to this. However, it is better to assign output pair BD to the resource if you anticipate this might happen, if you still have this freedom in your resource of course.

The very wide bandwidth of the Ka band receiver, from 26.5 to 40 GHz, would suggest that output pair separations of up to ~ 13 GHz are possible. Restrictions in the signal path, however, limit this separation to 10.5 GHz. The OPT web application validation will issue an error if the separation between output pairs AC and BD is more than 10.5 GHz in sky frequency (with output pair AC tuned the higher frequency one). A separation of more than 10.5 GHz in rest frequency will result in a warning as, e.g., highly red-shifted lines may end up with less separation when the actual sky frequencies are calculated.

Before creating or modifying anything it is a good idea to save what you have now; in the icon menu click the left-most icon ( Save projects/catalogs in this tree), or use FILE - SAVE ALL.

Suppose your SB consists of EVLA default frequency full polarization continuum observations in C band and in L band, and that you want to populate your personal catalog in first instance with these default (polarization) continuum resources. For this particular example, this is what to do:

• Make sure you have navigated to the RCT.
• 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).
• A white dialog window shows up on the top left; name your catalog and press [ok].
• Make sure your new catalog in the tree is highlighted (or select it). The tiny yellow dot on the open book icon indicates that there are unsaved changes in this 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, name your group and press [ok].
• Select the NRAO defaults resource catalog.
• In the resource table to the right (main editing window), check C band and the L band continuum options you want (L band, L band 16 cm, L band 22 cm, L band 23/16 cm). If you don't know which L band resource to select, study the details of each before selecting one, or simply select all.
• From the top menu strip, select EDIT - COPY - COPY INSTRUMENT CFGS..
• Select your newly named resource catalog (or group within it).
• From the top menu strip, select EDIT - PASTE - 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 L band resources as you would probably want to check the sky frequency 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 Cut.
• If you are unhappy with the name of the catalog or group you can always rename it by highlighting it and then using the top menu strip: EDIT - CATALOG PROPERTIES or EDIT - GROUP PROPERTIES.
• From the top menu strip, select FILE - SAVE ALL. This can also be done by clicking the left-most icon from the icon menu at the top of the resource catalog column. Notice that the interface feedback strip on the bottom shows Saved catalog ... in black font.
• Check that the little yellow dot on the open book icon has gone (otherwise your catalog was not saved).

Figure 2.4: Web browser screen shot of an editable resource (top portion).

If you want to change some parameters, choose the relevant items in the next list. Refer to Figure 2.4. This list is the list of items in order to create your own resource from scratch:

• Make sure you have navigated to the RCT.
• From the top menu strip, select FILE - CREATE NEW - CATALOG or select an existing personal catalog.
• A white dialog window shows up on the top left; name your catalog and press [ok].
• Make sure your new catalog in the tree is highlighted (or select it). The tiny yellow dot on the open book icon indicates that there are unsaved changes in this 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, name your group and press [ok]. Next, select your group.
• From the top menu strip, select FILE - CREATE NEW - INSTRUMENT CONFIGURATION. You will be presented with a blank-slate resource page. A filled in example is shown in Figure 2.4.
• In the first table on top, name your resource, select an observing band and enter some descriptive information in the comments field at the bottom of the page. The latter will be useful at some stage, really.
• For this full polarization continuum observation you typically would want to keep the correlator mode set to ".. two subbands ..". Low frequency observers who want to observe so called pseudo-continuum and do not need all polarization products may want to set up a narrow spectral line observation at a fixed sky frequency as described in the next subsection.
• For output pairs AC and BD, enter the frequency (and unit) you require at the center of the band you wish to observe at. Frequencies without units are assumed to be in Hz. Check your frequencies! Use Sky as the frequency type (currently a must).
• Choose a correlator integration time, in integer seconds with a minimum of 1 second, or use 5 seconds if you don't really care.
• For this continuum observation example you typically would want to keep the subband (observing) bandwidth set to 128 MHz, i.e., the maximum of 128 MHz bandwidth per output pair. Observations close to RFI, or observations that scientifically require narrower bandwidths would have the user set a different bandwidth for each of the output pair AC and BD. To select a bandwidth different from 128 MHz, simply click the blue circle of the desired option in the selected column. During OSRO, the AC and BD subband bandwidth must be the same.
• For this continuum observation example you typically would want to keep the frequency as a central sky frequency (tick mark in front of central sky frequency, not in front of rest frequency). The frequency range of this setting will be reported next to the field you just entered. There may be scientific arguments that would require to observe in a very narrow continuum band on a line. This line then needs to be Doppler tracked and therefore one would select rest frequency; a frequency range is dependent on the actual calculated sky frequency and thus not reported here. This option is currently disabled, see section A.3.
• 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 using the top menu strip: EDIT - CATALOG PROPERTIES or EDIT - GROUP PROPERTIES.
• From the top menu strip, select FILE - SAVE ALL. This can also be done by clicking the left-most icon from the icon menu at the top of the resource catalog column. Notice that the interface feedback strip on the bottom shows Saved catalog ... in black font.
• Check that the little yellow dot on the open book icon has gone (otherwise your catalog was not saved).

Incorrect or unfinished template resources - the ones which generate red errors in the interface feedback strip - may be saved for future use. 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 (re)source catalog entries, make sure they are correct before you continue with using them in the OPT. Unlike Jobserve, the OPT does not have the "User Defaults" capability; when you have modified a resource you have to use the OPT to reassign the new resource separately to every source that needs it. Also, global edit has not yet been fully implemented. Check your catalogs before making scans!

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 an editable legacy ID 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 continuum observations at default EVLA frequencies only, and thus all anticipated resources are already defined in the NRAO defaults catalog, it is strongly suggested that you make separate personal catalogs for your different PBs/SBs. Simply copy the resource of interest from the NRAO defaults catalog to your Personal 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 continuum case first as this saves repeating information. Resources for continuum OSRO1 and OSRO2 spectral line observations may be mixed in the same resource catalog and resource group.

After creating a (re)source catalog, the new information needs to be saved in the data base. Upon FILE - EXIT, if there are any unsaved changes, a dialog box will appear with the question whether to save the changes or not. Navigating between the tools will implicitly save changes in the tool you are moving away from. To be absolutely sure your changes are saved, use FILE - SAVE ALL before exiting or navigating to another tool (or at any other convenient occasion). If in the meantime your session has expired, you will find an Autosave: .. catalog (with the same name of the catalog that had unsaved data) that contains the unsaved changes at the moment your session expired; you have the option to continue with that catalog and delete the old catalog, or start with the old catalog and simply delete the Autosave: .. catalog. In the former case you may rename your Autosave: .. catalog using EDIT - CATALOG PROPERTIES.

Frequency bands may not exactly be what is selectable in the resource summary Band in the table at the top of the page. It is known that some receivers are usable beyond the nominal range given in the band selection. Some of this information is provided in the table at the top after selecting an observing band, showing the 1dB and/or 3dB ranges. But this information may have been updated with new insight and not made it percolate through in the web application. When in doubt about using these extended tuning ranges ask the friendly NRAO staff. Always check the EVLA web page (https://science.nrao.edu/facilities/evla) for the latest news, e.g., on the number of available EVLA receivers on the array.

In the previous recipes some usage of the options in the menu strip were given (e.g., FILE - CREATE NEW - CATALOG). The menu strip options under FILE and EDIT are grayed out or missing if that particular option is not valid for the current selection (highlighted item in the catalog tree in the left hand side column). If the action you want to perform shows up as an invalid option (e.g., EDIT - GROUP PROPERTIES to change the name of your group of resources) this usually means that you are not at the right place in the tree (e.g., not in the group, but in the upper level catalog). The names of the actions are quite self-explanatory, so we only list them for reference in the table.

A similar list of menu strip options is available in the SCT and OPT, but with options specific to the tools - we will present those lists in the SCT and OPT chapters. Menu strip options may act on both items in the left hand side column as well as items in the main editing window.

The icon menu is the line of little icons at the top of the resource catalogs in the left hand side column. They have the same functionality as the options from the menu strip, although not every menu strip option is represented as they are not used as often. Only valid actions will have an icon in the menu, i.e., pasting an item may only be performed after copying or cutting the item first - until then the paste-icon will not appear. Hovering over an item with your mouse will display a fly-over help tool-tip to remind you of the action attached to the icon, but we also show them for reference below:

	Save projects/catalogs in this tree
	Cut (or delete) selected tree item
	Copy selected tree item
	Paste selected tree item

The same icon menu can be found in the SCT; for the OPT we will present extra icons for more options related to ordering scans in the OPT chapter. Remember that these icons only act on left hand side column items.

Of course you would want to avoid having to recreate all resources (and sources and projects, etc.) if you decide to delegate scheduling by, or accept scheduling for another co-investigator. For this purpose there is the option to export and import the catalogs (and projects) through locally saved files. When saved locally you have all freedom to communicate and share with your co-investigators. You would want to check your catalogs for correctness if you aren't absolutely sure you have already done so before saving. Exporting unused catalogs and projects (which later can be imported if needed) also keeps the information contained in the OPT web application limited which will speed up the operation over the web. From the top menu strip select FILE - EXPORT or FILE - IMPORT to interact with a dialog window. All dialog boxes in any of the tools can be moved around by dragging the dialog box header to a new part of the browser window. The default OPT web application file transfer export or import format is XML. The upload field or pressing the download button will interact with your local computer environment according to your browser upload and download rules.

Creating a spectral line resource is very similar to creating continuum resources as outlined above, except for the possibly difference in correlator mode, subband bandwidth and exact frequency tuning. There are some hints to spectral line features in the recipes in the previous section. In the grand scheme of end-to-end operations, resources with the requested correlator settings may be pre-filled from information submitted to the PST during the observing time allocation procedure. However, at this stage not much of this has been implemented, and in particular Doppler calculations are disabled (see section A.3).

The NRAO defaults resource catalog contains full polarization dual output pair spectra-polarimetry resources (the continuum resources). If they appeal to you, you can copy/paste them in a personal catalog just as for the continuum resources above and edit them as needed. Check the spectral line resource properties very carefully as the spectral line resources in the NRAO defaults have a fixed sky frequency whereas you probably want to use a rest frequency in combination with Doppler tracking^2.3. Most likely, however, you will opt to create your own resource from scratch, just like creating a continuum resource previously. Some items that may need extra attention are described below.

The correlator mode and other details such as the observing band and frequency should have been specified during the proposal submission stage. You may have received alternate suggestions by the PSC. In short, the correlator options are OSRO1 and OSRO2.

OSRO1 is mandatory for polarization or simultaneous dual frequency observations (within the same observing band). It delivers 64 frequency channels in full polarization for two independently tunable output pairs with identical subband bandwidths. The subband bandwidth, which is the total observing bandwidth per RCP and LCP output pair, can be chosen form 31.25 kHz to 128 MHz in powers of two. This yields a frequency channel separation of the subband bandwidth divided by 64 (488 Hz to 2 MHz).

OSRO2 can be chosen if no polarization information or if no simultaneous dual line observations are required, yielding a factor four better spectral resolution when using the same subband bandwidth compared to OSRO1.

Frequency tuning and frequency type (sky or rest) need to be set in the next table. Also supply the unit with your frequency (Hz, kHz, MHz, GHz), otherwise it assumes Hz by default. Choose either output pair AC or BD and note the restriction for Ka band in section 2.2.3. Select and enter the Rest Frequency if you anticipate Doppler tracking on a spectral line (currently disabled!), or Central Frequency if you know your exact sky frequency and do not want to apply Doppler tracking. If your line is strong and you plan to apply off-line Doppler corrections, you must over sample your line with at least a factor 3 to 5 to be successful; see section A.3. Note that for Doppler tracking you need a velocity and reference frame, which you assign to the source in the SCT, or which you enter for each scan in the OPT.

Correlator integration time should be set in integer seconds equal or larger than one. The output data rate and your required field of view (limited by time averaging smearing) should guide you in what to enter.

The subband (total observing) bandwidth is selected by checking (ticking) the blue circle () for the output pairs for the correlator setting you require. This bandwidth will be divided in 256 frequency channels to provide your spectral resolution.

Click NRAO defaults in the left-hand side column to return to the NRAO defaults catalog. The table at the top of the main RCT editing or manipulation window (Figure 2.2) has a header line with obvious meanings. (If not, we should have supplied a fly-over help tool-tip for it; the tool-tip help shows up when the mouse hovers over the item for a second or so.) When you move the mouse over the headers you will see that they switch color to orange. Every table column with a header showing this behavior can be sorted by clicking the header. This is so for all other tools as well. A table with more than 25 entries may span multiple pages, but this catalog currently is too short to demonstrate this (see section 3.1.1). When a column is sorted, it will show a small orange arrow next to the header name, pointing up if the column is sorted in ascending order (going to larger values when going down in the table), and pointing down when the sorting is in descending order. A sorted table can be re-sorted in the opposite direction by clicking the column again (note that the header of a sorted column, the one with the arrow, might not change to the orange color anymore).

Figure 2.2: Web browser screen shot of the RCT when NRAO defaults is selected.

Each line in the table represents one resource with a name and some descriptive information. A line starts with a tick-box and an edit icon (). The tick-boxes can be used to select one or more entries in the catalog for copy/paste as described in the next section. A shortcut to select all, or to deselect all catalog entries on the current page can be found above the table. Selecting and copy/paste has to be redone for every page. The edit icon is used to access the details of the resource entry in the catalog, i.e., the specifics of the hardware and instrument configuration.

The NRAO defaults catalog (Figure 2.2) is a collection of hardware and instrument configurations (front-end receivers, correlator integration time plus observing/subband bandwidth and frequency channels, frequency tuning, etc.). They are expected to be good standards for continuum observations in the early EVLA era, i.e., using the receivers and correlator available to the observers during the OSRO program. These defaults are mostly useful for OSRO continuum bandwidth observations. They differ from the previous VLA NRAO defaults in frequency mainly because a larger instantaneous bandwidth is available: 256 MHz now versus 100 MHz before. The EVLA also has new and extended range receiver bands.

Note that NRAO defaults is in red italics, which means that this catalog is read-only. The plus-icon (, Figure 2.1) in front of the open book icon () indicates that this catalog includes sub-catalogs which are referred to as groups. A catalog does not need to contain groups, but at some point it may be more convenient to have them. If you click the plus-icon or NRAO defaults these groups will appear in the catalog tree and the plus-icon will change to a minus-icon. If you clicked on NRAO defaults, you will also see a table of contents of the highlighted NRAO defaults catalog in the main RCT window, the big field to the right hand side of the catalog column (Figure 2.1). This table list combines the contents of all groups and possible entries in the catalog that do not belong to a group (though in this case there are no such free-agent entries). Groups are, in this case, 2x 128 MHz Full pol (OSRO1) and Pointing setups. When highlighted or selected using the mouse button, the right-hand side window with the table of contents will only show (filter) the resources which were grouped in this sub-catalog. For example, selecting the 2x 128 MHz Full pol (OSRO1) group will now only list the NRAO default resources for continuum observations. Similarly, the Pointing setups will show the NRAO default resources for pointing scans in X, K, Ka and Q band (see below).