Proposer Generated Resource

Introduction

Proposers familiar with the VLA's proposal submission process may recall the java-based General Observing Setup Tool, or GOST,  for setting up spectral-line resources. This tool is now obsolete and has been replaced with a modified version of the Resource Catalog Tool (RCT) to support proposals. Unlike GOST, the RCT is aware of all the tuning restrictions of the system.

This modified stand-alone version of the RCT, which differs slightly from the observer's RCT found in the OPT Suite, would be known as RCT-proposing, i.e., the RCT version to be used in conjunction with the Proposal Submission Tool - the PST. Like the PST, the RCT-proposing uses your my.nrao.edu account.

RCT-proposing should be used by proposers requesting spectral-line resources or non-default VLA WIDAR resources. Note that some spectral line science, such as high-redshift CO detections, can be achieved with selecting a default NRAO resource in the PST and the use of this RCT-proposing may not be necessary.

Once a custom resource is made with this tool, please download the Portable Document Format (PDF) that captures its parameters using the tool's interface (under the Validation tab). The generated PDF file should then be uploaded to the PST; note that the resource name, copied into the the PDF, should match the resource name entered in the PST.

If at anytime RCT-proposing does not load or freezes, try refreshing the webpage and if that does not help, contact the NRAO Science Helpdesk.

 

Guidelines

For Spectral Line proposals we provide the following two options in RCT-proposing:

  1. Setting up a resource using a Doppler position, i.e., the coordinates of an observing field (source) or near a group of fields, or
  2. Setting up a resource without the Doppler position (and Doppler Tuning) at the proposal submission phase. A reason to forgo using a Doppler position at this stage is to provide the convenience of uploading a "representative resource" for multiple observing fields that share the exact same spectral line resource setup, aside from the Doppler position. Observing with very different Doppler velocities, even for the same Doppler position, in general would not use a single representative resource due to the large shift in observing frequency.

Note, during the observation preparation stage of a Spectral Line resource, entering a Doppler position (and setting the Doppler tuning) is required. The advantage of specifying a (representative) Doppler position up-front (here, in the proposing stage, assuming it can be determined already) is that the final resource can easily be transferred to the observing stage. Especially when manually fine-tuning of the subbands and/or when adding extra continuum subbands, this will prevent having to recreate the resource and redo the manual edits again, starting from scratch at the observing stage.

 

Resource PDF Upload

Proposers will be required to upload one unique resource PDF to the PST, using RCT-proposing, per observing field/source or group of fields/sources and where the resource name used in the PST matches that from the PDF.

Single Source and/or Multi-band Proposals

  • Each receiver band and/or correlator setup will require a separate resource PDF upload, each with a distinctive descriptive name.

Multi-source Proposals

  • For multi-source proposals, you may consider forgoing the use of the Doppler position.
    • When all or a subset of sources can use the same resource, whether simple or complicated (see below), then supply one resource PDF per subset of sources for each receiver band and/or correlator setup.
    • Regardless of the number of sources, if the resource is simple (see for other, complicated resources below) for a given receiver band and/or correlator setup and applicable to all the sources (within small frequency differences due to their position and/or observing velocities), then one representative resource PDF may be uploaded to the PST.

Complicated Resource Setups

  • For complicated resources, please make one resource per source and upload their respective PDF files to the PST. Complicated resource setups include:
    • many spectral lines, and/or
    • more than two spectral lines requiring very wide (i.e., >=64 MHz equivalent) velocity coverage, and/or
    • requiring all 64 baseline board pairs, and/or
    • when a representative resource cannot capture the different needs of the science per source, and/or
    • when observing a sky tuning frequency close to, or crossing, 32 GHz (Ka-band) with the intention to actually use Doppler setting.

If there are many sources with each requiring a separate complicated resource setup as noted above, then please contact the NRAO Science Helpdesk well in advance for guidance.

 

Subband Considerations

Some restrictions and limitations to consider when adding continuum subbands to spectral line and frequency sweep resource setups.

Subbands narrower than 128 MHz can make use of recirculation. The use of recirculation would achieve the same channel separation as stacking a power-of-two in baseline board pairs. The benefit is that using recirculation in a subband requires fewer of the limited total number of baseline board pairs, which then can be used for additional purposes (like covering more lines, using narrower channel separations, or adding extra continuum subbands).

  • 3-bit restrictions:  3-bit basebands cannot exceed 16 subbands per baseband.
  • 8-bit restrictions:  8-bit basebands cannot exceed 32 subbands per baseband.
    • Exceeding 16 subbands per baseband will trigger an alternate mode invoking additional hardware, known as data path 1 (DP1). 
    • DP1 can be invoked in two ways: automatically by the RCT or manually by the user.
    • More details and how to use more than 16 subbands per baseband can be found in the OPT manual (32 subbands per 8-bit baseband).

Note that using overlapping frequency coverage between the subbands/basebands does not physically yield any improvement to sensitivity; there is no scientific 'sqrt(N)' gain in deliberately creating identical subbands to improve signal-to-noise by averaging identical subbands together in the image.

Additional restrictions in the tuning of 8-bit or 3-bit sampler setups in K, Ka, and Q-band are described in the OPT manual.

 

Create a Catalog and a New Resource

When creating a new resource, proposers can organize their resources per project and/or observing semester by creating catalogs.

  • File → Create New → Catalog

Then create a new resource within the selected catalog.

  • File → Create New → Instrument Configuration

Please name the instrument configuration in RCT-proposing the same as the resource name used in the PST for this spectral line setup; this name will appear in the PDF that should be uploaded to the PST and will help identifying the frequency and correaltor  details with the corresponding intended resource.

 

Resource Setup Options

  • Spectral Line: This type will allow to make full use of recirculation and stacking of baselineboard pairs to obtain the highest spectral resolution on narrow chunks of frequency centered on specific rest frequencies and which are corrected for Doppler effects on the time and date of the actual observation. The proposer must generate several subbands each centered on a specified spectral line. This can be accomplished either manually or with the new automated setup. For details on how to setup this type of resource, refer to the Spectral Line Resource Setup for Proposers guide.
  • Frequency Sweep: (aka. line search or spectral scan) This type will allow to observe all or most of a 1GHz or 2GHz baseband in a contiguous chunk of frequency with higher and homogeneous spectral resolution (better than 2 MHz and typically in dual polarization) than the NRAO Default setups or the continuum option below will do. The proposer would cover one or more wide frequency ranges with a specified frequency resolution. The frequency can be specified in absolute observing frequency or by specifying a range around a spectral line. For details on how to setup this type of resource, refer to the Frequency Sweep Resource Setup for Proposers guide.
  • Continuum: This type will cover a wide frequency range with default frequency resolution appropriate for continuum sources (reproducing the NRAO defaults that can be modified, except that realfast is disabled). This type is likely more useful for OTF continuum observations (as the visibility integration time can be specified) than for line-specific work. Generating this resource is an updated version of the classic RCT custom continuum resource implementation. Refer to the OPT manual for more details.
  • Manual: This type will allow to setup any valid resource using the classic RCT resource setup implementation, step-by-step. Refer to the OPT manual for more details.

 

Import a Valid Legacy Resource

Note that for resources within this RCT-proposing you can simply copy/paste resources within the same catalog, or between different catalogs, and there is no need to export/import. If resources are copied, please make sure to give the pasted version its own unique descriptive name.

However, if you have an existing resource created for a previous observation in the RCT, you may export that resource from the RCT and import it into the RCT-proposing catalog. Consider giving the imported resource its own new name, especially if edits are made after importing.

  • Log into the OPT tool suite and select to view the Instrument configurations (RCT). Then in the RCT, select the resource you wish to export and then select at the top:
    • File → Export Resource (this will export an xml file)
    • Alternatively the resource can be exported from the resource-specific validation page (select Download XML)
  • Log in to RCT-proposing. In RCT-proposing, select a resource catalog then select at the top:
    • File → Import Resource → Browse (select the xml file you want to import/upload) → Upload → Done (if using Firefox)

(If you are using Firefox you will be required to select the Done button after selecting Upload to complete the import. Otherwise, selecting Upload will complete the import.)

Note, the resource must be valid in the RCT for it to successfully export. If it is not valid then you will be required to recreate the resource in the RCT-proposing interface. For legacy spectral line resource setups that are somehow not valid, export the lines as a text file from the Lines tab. Recreate the spectral line resource in the RCT-proposing using the imported lines text file.

 

Export a Valid RCT-proposing Resource

Once you have created a valid resource in RCT-proposing, uploaded it to the PST as part of your proposal, and your proposal has been approved, you may export the resource(s) for use in the RCT/OPT. However, if the resource is a spectral line setup the Doppler position must be defined. If not, the RCT will not import the resource from the RCT-proposing xml file. 

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