KFPA Astrid Pointing Modes
Modification Request #? (C04 2009)
Effective use of the KFPA requires regular peaking on a bright radio source and
and adjusting the sub-reflector position to focus the telescope.
The Astrid procedures used perform these tasks must be updated.
This MR concerns extension of the existing Astrid point and focus modes to
explicitly allow the observer to select the SIGNAL and REFERENCE beams.
This extension requires Astrid to develop a model for the angular locations
of all beams.
Our planed approach, for the near term, is to update the dual beam
procedures for the KFPA use, by allowing the observer to explicitly
select SIGNAL and REFERENCE beams. Later MRs will request more optimum
use of the KFPA array for pointing and focus observations.
We have described KPFA pointing and focus plans for commissioning
The document describes re-configuration of the existing Astrid procedures
and a new pointing mode to allow checking the relative gain of the
Astrid shall command pointing and focus observations with observer specified
signal and reference beams.
The Peak and Focus procedures requiring updates are:
For brevity, we describe these procedures collectively as Peak and Focus observations.
A standard set of optional parameters should be added to all astrid procedures
concerned with pointing and focus. The parameters are the indexes to the beams to be used
for different rolls in the peak and focus process. Since future procedures will allow
different combinations of beams for different functions, below we suggest a general
syntax for specifing all beams used in a particular process.
For Peak and Focus, the initial requirements are only to supply single beams for signal
and reference. Initially, the KFPA Peak and Focus algorithms will be identical to those
used for the current K band, dual beam receiver. That is, the system will
center the point and focus observations on the Signal beam and subtract
the reference beam intensity, as an estimate of system and sky temperature.
The Astrid analysis code must compute/fit the expected signal contributions
due to the source occasionally being present in the REF beam during
Peak observations, as is currently done.
The Peak and Focus observations can be made more efficient by use of several
beams for estimation of the REF signals. The REF signal could be the average
(or better median) of the OTHER beams, for a better estimate of the off source
The options needed for spectral line mapping, SIG=ALL, REF=OTHERS,
etc, are not used, but are noted for completeness. The spectral line
mapping routines will require specification of SIG beams, if the
observer will configure the spectrometer for multiple spectral bands.
The SIG and REF parameters are optional. The default values for SIG are the
center beam (feed 1) and the beam due east of that beam (feed 2) (East defined
when the telescope is at azimuth = 0, due North).
- SIG=I, where I is index to one of beams in the array (range 1 to N) (ie SIG=1)
- SIG=I,J,K,L, where I,J,K,L are indicies to beams in the array (ie SIG=1,2,3,4)
- SIG=ALL, where ALL indicates all beams should be configured for the observations
- REF=M, where M is the index of another of the beams for sky subtraction (ie REF=2)
- REF=OTHERS, where OTHERS indicates all beams not in the SIG list.
5. Example Usage
#Astrid Script to point and focus the telescope before a spectral line observation.
#09AUG19 GIL Revised as an example for MR
#09FEB01 GIL KFPA single pixel tests
#First put in your sources
#!!!!!!!!!!!!!!!!! be sure that this is the correct setup !!!!!!!
Peak(sourceName #source name
, Offset("Encoder", "00:12:00", 0) #offset Az
, Offset("Encoder", 0, "00:12:00") #offset El
, 30 #time
, SIG=1 #signal beam
, REF=2) #reference beam
#note that future versions c
Focus(sourceName,-120.0, 240.0, 60.0 # object, start, length in mm, time
, SIG=2 #signal beam
, REF=5) #reference beam
Example of new sequence of calls to the revised Peak and Focus routines.
6. Deployment Checklist
Steps in the deployment checklist.
7. Test Plan
7.1 Internal Testing
The software group must fill out this section
This section covers things like unit testing, simulator testing, and any other tests required to make sure this MR is ready for sponsor/integration/regression testing.
The sponsor testing for these procedures will be repeated execution of the modified
procedures, listed above, for three types of radio of sources, bright, moderate and weak intensities.
These test observations will be carried out in modest weather conditions, (neither perfectly clear
nor rainy). Predicted zenith atmospheric tau should be in the range .05 to .1
The sponsor testing will include making peak observations with each beam of the array
selected as the SIG beam and also each beam of the array selected as REF beam (but not
all combinations (only 7 tests, not 7*6/2 = 21 peaks per source type).
7.3 Integration/Regression Tests
What do the integration/regression testers need to do in order to test this MR.
Software Group will add this section
|| To the best of my knowledge, the request in this MR is complete. I have thought through this request, and believe it to be an important feature to implement or bug to fix.
|| I acknowledge that I have validated the completed code according to the acceptance tests.
|| - Glen Langston - 2009 August 19
|| - name - date
| Approved by Sponsor
|| - name - date
| Approved by CCC
|| - name - date
| Accepted/Delivered by Sponsor
|| - name - date
%X% if MR is not complete (will display )
%Y% if MR is complete (will display )
CCC Discussion Area--
-- GlenLangston - 2009-08-19