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ALMA Single Dish Pipeline Meeting
Jul 28-30 2014
Socorro New Mexico
Day 1: July 28
Note: Single Dish Observing Mode will change at start of cycle 3
Will include more efficient calibrations, including overheads.
Better and more flexibility in spatial sampling (5 X Beam along row, 3 X Beam perp)
How often are off's taken and where
In early science apply constant correction factor (fix comes in Feb 2015)
Scripted Pipeline apply factor of (1.2)
Need to understand exactly what happens here. Cat to give a summary tomorrow.
PROTO-DECISION: Based on understanding that this is an imaging only correction will apply as part of Scan Table to MS translation.
Perhaps better to only apply to the image (AI: Cat to clarify)
Single Dish Pipeline Overview:
T_sys solutions are the same derived from SDCAL2
Both versions are using the same code
Selection of channels is done manually in the script
ACTION: Automated pipeline stage needs commissioning
To Do: Add Edge channel flagging
We should actually Flag data
Adding Channel Flagger to Pipeline (Heuristic contact Eric V.)
DECISION: Compare get TP Sampling to detail plots in the inspect Data method.
What is the definition of the "off"
TP Sampling plot to go in weblog on the MS Splash Page (talk to Todd about the code, should we rewrite this or just use what they have.)
What gridding function should we be using in the imaging.
To Do: Commission the GJINK gridding function
SD Pipeline will for now use Prolate Sepheroidal
Cell size to be beam size / 9.0
convsupport = 6 (size of kernel) * Decision: Transition to making I image as output * To Do: Jansky to Kelvin Discussion *
DECISION: Increase number of edge points used as offs to 35%
QUESTION: What happens if the calibrator does not have the required 6 beams on edge? QA0 Fail!
Automated Flags: Edge Channels
Add Deterministic flagging stage
May need to flag atmospheric features.
Only in the Tsys plots
QUESTION: When should we make the transition to plot bandpass
(would need to create interferometric Tsys Cal table)
Day 2: July 29
Topics for further Discussion:
The factor of 1.2 will be applied in a special step in the pipeline to facilitate direct comparison with the scripted pipeline in Dec.
DECISION: To be implemented in single dish pipeline
DECISION: PI's must be warned that their data has the Nonlinearity correction issue and will not be processed via. standard pipeline.
DECISION: Official Pipeline will only handle the data that is taken after Feb.
Changes to the "OFFs":
An off and an off for the off
Not clear who has responsibility
Testing of the OFFs can we use the pipeline to help? Sounds like they have a script in place for now.
Future of Amp Cal:
Likely will ditch this ASAP (Cycle 3 is going to be the same)
May ditch Amp Cal altogether and just use a lookup table
Would require an Astro Holography run
Scanning in Az / El and other coordinate systems
Absolute Coordinates for off position
Calibration Efficiency (mitigation of overheads)
Would allow more Tsys at high frequency
Changes in scan length
Identification of subscan / rasters
DECISION: Heuristic based on time gaps and position gaps
Fast Scanning Modes?
True basket weaving (CSV-239)
Needed for Fast Scanning modes
Probably a cycle 5 target
Tsys Cal: What to do?
Can we take the interferometric Tsys cal and generate the SD:TsysCal from it
DECISION: To use interferometric Tsys table for flagging etc, then cross fill that to the SD:CalTable (including flags)
May not make it for 4.3, but perhaps for a November patch (?)
getFWHM2: Find half power (subtract and then do a root find) in a azimuthal average
Alternatively use a theoretical value:
Values in CASA repository are voltage, in AU they use the squares (complex2Square)
Kelvin to Jansky Conversion
Jy/K is coming from Amplitude calibrator
AI: Cat to define if the Jy/K is done before or after imaging.
Position of antenna is off in 4.2.2
Correct version is in 4.3
RECOMMENDATION: Only use PM antenna's on the ACA pad.
1.2 vs. 1.3 for the linearity correction
Average value of Tsys rather than spectral side <- Done by Bunyo
Use of weights in the imaging
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Topic revision: r6 - 2014-07-30,
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