Custom Type Continuum Setup

On November 8, 2023, a new Resource Catalog Tool was introduced which changes the way custom resources are created. This section will cover the creation of a custom continuum resource. If you have questions or issues, please contact us through the NRAO Science Helpdesk.

Generate a Continuum Resource

If you prefer not to use an NRAO Default resource, for example for On-The-Fly Mapping observations, you may create a custom continuum resource in your personal catalog. These steps are applicable to wide band continuum resources for 8-bit and 3-bit instrument configurations. At any time you can click on the [?] icon to bring up a window with more information on the selected topic.

First, select the personal catalog/group you wish to create the resource in, then do the following to create an 8-bit or 3-bit resource.

FILE → CREATE NEW → INSTRUMENT CONFIGURATION

You will then be presented with the New Resource Wizard (Figure 3.7). Here you can select the type of resource (see the other sections on spectral line, frequency sweep, or manual setups), the array configuration, and give the resource a name.


Figure 3.7: New Resource Wizard.

Once you select Continuum, the Wizard will expand as indicated in Figure 3.8 below to give you more options. If you click on the Generate button before the Continuum options become available then this session of the OPT will crash. If that happens, please contact the NRAO Science Helpdesk so that this session can be terminated.


Figure 3.8: Expanded Wizard for Continuum setup

Here you will select the array configuration for the resource - this will adjust the Correlator Integration Time according to the NRAO default for that observing band. You can enter your desired value later. The Sampler Input Mode has two options: Two 1-GHz 8-bit samplers (A0/C0 and B0/D0) or Four 2-GHz 3-bit samplers (A1/C1, A2/C2, B1/D1, and B2/D2). Also specify a descriptive and useful name the resource. When all this has been done, click on the Generate button to create your new Continuum resource.

Important Note: After typing in any of the text fields, click somewhere else on the page (not in another field) to allow the entry to be applied (and saved to the data base) and always be patient when updating fields or navigating to different tabs.

A new 3-bit K-band continuum resource has been generated (Figure 3.9).


Figure 3.9: K-band resource created by Wizard.

8/3-bit Tab Information

Now that you have generated an 8/3-bit resource, we will walk you through the general layout of the tabs. With this knowledge, you will also be able to create a wide band continuum or frequency sweep resource. To create a spectral line resource, refer to the Spectral Line Resources section for a more detailed guide.

For both 8/3-bit instrument configurations you will see a graphical visual of the basebands at the top of the screen and under the Subbands tab. In addition, there is an information box located at the top right indicating the total Bl. BPs used, total data rate, total spectral points, total bandwidth, and capability mode, i.e., General Observing or Shared Risk. Figure 3.7 (above) is an example of the information you will be presented at the start of creating an 8-bit resource. Note, all completed actions made while working on a resource are automatically saved.

Basics Information Table

Near the top you will find the Basics info table (Figure 3.10) were you can change the name of the resource and the correlator integration time.

Figure 3:10 Continuum Basics info table.

Below is a description of the parameters in the Basics table.

Name	This should be distinctive from other resources and match the name of the corresponding resource used in the proposal. Do not use special characters and it is probably best to keep the name relatively short.
Correlator Integration Time (seconds)	The correlator integration time would have been set when the resource was initially created by selecting one of the array configurations. This can be modified in the table if you do not wish to use a default setting or if the default is no longer correct once the observing band has been determined. For more details, refer to the Time Resolution and Data Rates section of the Observational Status Summary (OSS).
Total Bl.BPs Used	This indicates the total baseline board pairs (BlBPs) used, which is a measure of the required correlator resources. The starting number will always be zero and will increase as lines and continuum subbands are added and when additional baseline board pairs are stacked on a line. The maximum number of available baseline board pairs is 64.
Total Data Rate	The data rate of the resource will increase with shorter correlator integration times and as lines and continuum subbands are added. Keep in mind the minimum and maximum data rates listed at Time Resolution and Data Rates.
Total Spectral Points	The total number of spectral points will increase as the number of requested BlBPs increases. The number of spectral points in a subband is the product of number of channels, number of polarizations and number of baseline board pairs. The total here is the sum over all subbands. For a more detailed explanation, refer to the Recirculation vs Baseline Board Pairs section of the OPT manual or the Spectral Line Resources section.
Total Bandwidth (GHz)	This will display the sum of all subband bandwidths across all basebands in GHz. This sum has no correction for overlapping subbands but note that overlapping subbands do not physically add to increasing continuum sensitivity.
Capability Mode	This will display the capability mode of a resource, e.g., general, shared risk, or resident shared risk observing. This will depend on the total data rate and certain other settings described in the OSS.
ID	This is the unique resource identification number.
Contact Support	Selecting this button will allow you to contact the NRAO Science Helpdesk while silently supplying data specific to this resource to the ticket.

Below is the description of each tab element / page in the resource.

Figure 3.11 Baseband Tab (click to enlarge)

Tab	Description
Basebands	From the Sampler Input Mode drop-down menu there are four available options: For 8-bit, the default sampler input mode is: Two 1-GHz 8-bit samplers (A0/C0 and B0/D0). For 3-bit, the default sampler input mode is: Four 2-GHz 3-bit samplers (A1/C1, A2/C2, B1/D1, and B2/D2). There are two 8/3-bit hybrid options (typically used for wide band continuum in the 3-bit basebands and spectral line in the 8-bit baseband for the high spectral resolution of the 8-bit system): Two 2-GHz 3-bit samplers (A1/C1 and A2/C2) and a single 1-GHz 8-bit sampler Single 1-GHz 8-bit sampler (A0/C0) and two 2-GHz 3-bit samplers (B1/D1, and B2/D2) The baseband center frequencies are set in the first table. The receiver band can be changed in the drop-down menu. If changed then the baseband center frequencies will update. Restrictions: For 3-bit, the baseband centers for A1/C1 and A2/C2 must be within about 2.5 GHz (same for B1/D1 and B2/D2), 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.

Figure 3.12 Subbands Tab (click to enlarge)

Tab	Description
Subbands	The basebands are empty. It is up to the observer to fill the basebands with subbands. For both 8/3-bit, you may edit the subbands as needed for your science goals. To edit the 8-bit subbands select the A0/C0 and B0/D0 tabs and to edit the 3-bit subbands select the A1/C1, A2/C2, B1/D1, and B2/D2 tabs (when applicable). All Subbands: Selecting the Fill or Delete button will fill all basebands with subbands or delete all subbands from all basebands. Selecting the All button will enable the Bulk Edit button, None, and Delete button. Note that there has to be at least one subband in the selected baseband for these buttons to work. Table will show the Baseband(s) with filled subbands, the Subbands in Basebands: Selecting the Add, Fill, or Delete button will add, fill, delete only the subbands within the selected baseband. Selecting the All button will enable the Bulk Edit button, None, and Delete button. Bulk Edit: The following parameters apply to both the All Subbands and Subbands in Basebands options: Bandwidth: Drop-down menu options ranging from 31.25 kHz to 128 MHz. Offset Freq from Center: Empty field to be filled in. Polarization: Drop-down menu options Full, Dual, Single: RR/XX, Single: LL/YY Array Summing: Drop-down menu options None (default), Pulsar, VLBI Bl. BPs: Drop-down menu options ranging from 1 to 63. Recirculation: Drop-down menu options: 1x, 2x, 4x, 8x, 16x, 32x, 64x Delete Selected Subbands: To enable, select all or some subbands by ticking the box in the right most column of the subbands, then click one of the Delete buttons in the Subbands in Baseband section. You may edit each subband individually by clicking on drop-down menus in the table. (If you hover your mouse over some of the column headers, an information box will pop-up.): BW (bandwidth): Drop-down menu options ranging from 31.25 kHz to 128 MHz. Snap To Grid and Fix To Baseband check boxes will be selected by default. Leave these selected for continuum subbands. These will be discussed in more detail in the spectral line section. Central Frequency: Drop-down menu. Polarization: Drop-down menu options Full, Dual, Single: RR/XX, Single: LL/YY Array Summing: Drop-down menu options None (default), Pulsar, and VLBI Bl. BPs (baseline board pairs): Drop-down menu options. Recirculation: Drop-down menu options. Priority: This options allows you to set the priority of each subband. The default is Essential, then there are options for Desired-1 through Desired-64 (most desired to least desired in ascending order). This is useful if you are requesting all 64 BlBPs and want to allow some edge subbands (or non-essential to your science) to be sacrificed so your observation can be run if not all 64 BlBPs are available in the correlator. The NRAO default resources which request all 64 BlBPs have sacrificial edge subbands selected. Comments: You may add text in this field. This it typically auto-filled when a spectral line is generated.

Figure 3.13 Special Modes Tab (click to enlarge)

Tab	Description
Special Modes	Pulsar: the default is set to None (standard Non-Pulsar Observing). This is only used for specific pulsar observing modes. Refer to the Pulsar section for more details. VDIF: the default recording is set to No. VDIF recording is only used for eLWA and radar observations. Refer to the VLA + LWA Observing section for more details. RFI Blanking: the default is set to No. Refer to the RFI Blanking section for more details.

Figure 3.14 Validation Tab (click to enlarge)

Tab	Description
Validation	This tab shows a summary of the instrument configuration you have created, a table of the Subband Grid Boundaries, and a table of the BlBPs in the correlator quadrants. If there is a problem with the resource, a warning or error message will appear in the interface feedback strip at the bottom.

Figure 3.15 Comments Tab (click to enlarge)

Tab	Description
Comments	This tab shows an entry field where you can add comments to your resource. Note that this comment field does not override the automatically generated comment for spectral line where the rest frequency of line is given.

Always double check your proposal to make sure your custom resource follows what you proposed to do.

If there is a need to modify the existing resource, after generating a resource and attaching it to scans in an SB in the OPT, rename or copy it to a new name and make the modifications in the resource with the new name. This adjusted resource has to be re-attached to the scans in the SB, replacing the faulty resource. The easiest way to do this is with the Bulk Edit Scans tab on the selected SB. Having a different name for the two resources is extremely useful in checking whether the edit was successful and whether scans with the old resource have been overlooked.