Use Case: Observing Preparation: Set Up to Observe a Single Field, Spectral Scan.

This ObsPrep usage scenario is based on the SSR use cases and it represents a possible use of the OT to set up an observing project. It should not be considered as a replacement of the UCs in the SSR Memo 11. It has been developed to aid in testing the ability of the design of the OT to support the specific case of the described observation setup.

Goal:   Define a program using the ALMA observing tool for a single field and a spectral scan.

Contact Author:   L. Testi

Role(s)/Actor(s):
Primary:   The observer (follows the basic course for this UseCase)
Secondaries:  
  Observing Preparation Tool
  Spectral Line Catalogs
  Source Catalogues and Databases
  DSS/2MASS Image Library
  Local User Resources (Catalogues, Images, Spectra)

Priority:   Critical

Performance:   Response to user inputs in near real time.

Frequency of Use:   Perform this ObsPrep Use Case for each target wich has been approved by the TAC for ALMA spectral scan observations.

Preconditions:

1. Proposal written by PI and submitted to ALMA TAC.
2. Project approved by the TAC for ALMA observations and ready for phase 2.
3. Project goals and constraint are:
   Primary Science Goal:
   Obtain a moderate resolution (~1-2 arcsec) spectral survey of a given target.
   Primary Science Constraints:
     -   Spatial Resolution <= 2
     -   Spectral Resolution: may depend on source type
     -   Range of Spatial Scales: few times the spatial resolution
     -   Line RMS: may depend on target and Freq range (same rms in the entire scan, but see warnings below)
     -   Continuum RMS: N/A
   

Basic Course:   Set up for Observations (User steps and OT responses)

NOTE: All steps in the Basic Course should be able to be saved in the micro-archive or as stand-alone disk file these can be saved & reloaded for later processing and/or share between different Co-I (e.g. via e-mail exchange).

1. Select Project Type:
   Choose Standard Imaging; Spectral Scan
   
2. Select Target: 
•  Source Name [Resolved by SIMBAD and coordinates presented] and/or enter name and coordinates manually [Galactic or Equ1950/2000]
• The user may want to specify the pointing position as offsets from the source coorinates 
  
3. Select Frequency or Wavelength range
• If cross bands or includes regions where the sensitivity is significantly degraded issue appropriate warnings to the used
  
4. If desired, view the primary beam  (or range) displayed on a DSS/2MASS or local image. If a DSS/2MASS image is requested, the FOV needs to be entered by the user. If a locally supplied image is to be used, the OT will display the supplied image [which must have a compatible header] 
5. The user may want to refine the pointing position using either the Visual Editor (e.g. click/drag with the mouse) or by changing the coordinates
   
6. Enter Spatial Resolution and Range of Scales:
   The OT should display the Primary Beam on the image and give feedback on whether one array configuration is enough and whether one or more pointings and ACA/TP measurements are required to cover the max scale range around the target. The user should be able to change the parameters and have immediate feedback. If multi-field/ACA/TP needed, then follow the appropriate test case.
   
7. Enter Spectral Resolution (Freq, V, or wl):
   The OT should display how many separate correlator/LO setups will be needed to cover the entire spectral region.
   
8. Enter Required RMS per resolution element:
   
   • This should be intended as the goal for all SBs in the programme.
   • The integration time of each SB may change significantly depending on the frequency Band and on the location within the Band
   • Warnings should be issued for SBs too close to the band edges (where sensitivity is significantly degraded and the integration time will become very large (Algorithm TBD)
   • It should be possible to flag Freq ranges to a total integration time per setup rather then to target RMS per setup.
     
10. The user reviews the default calibration choices:
      -   The OT can be required to show the calibration choices (calibrator, calibration options, integration times, duration of observing cycles, etc...)
      -   The advanced user can change the (allowed) parameters and receive warnings/feedback on the expected calibration accuracy. 
• It should be possible to select calibration choices as a function of frequency ranges (bands)
  
11. Required Feedback (TDB on where and when this feedback should be provided to the user):
      -   Beam information (expected beam ellipticity and axes)
      -   Total duration
      -   Weather constraints - stringency and likelihood to achieve - As a function of freq
      -   Configurations required - availability and timescales
      -   Warnings related to data quality (due to calibration scheme chosen) - As a function of freq
      -   Map sizes, data rate, total data volume - At freq extreemes and at any requested freq
      -   Scheduling Block breakdown
    

Postconditions:

1. User saves the observing setup on their local machine. It should be possible to save the project in the OT local micro-Archive or as an external file to share the work with other CoIs (via e-mail). The actual scheduling blocks (SBs) should also be saved to the local directory if desired by the user. Note: the 'saved file' for the OT and the SBs can be the same thing.
2. The user requests that the programme and associated SBs are validated.
3. If validated, User submits the complete programme and associated SBs from OT.

Issues to be Determined or Resolved:   Required feedback listed in point 10. of the Basic Course above.

Notes:   The relevant UCs from SSR Memo 11 are: 4.1 [part], 4.2.1, 4.2.2, 4.2.3, 4.2.6, 4.2.8

Last modified: 21aug03