FeedpositionsAnalyzer

A CHIME analyzer to calculate the East-West feed positions.

East-West positions are calculated from the fringe rates in eigenvectors. The eigenvectors of the visibility matrix are found in the archive, then orhtogonalized. To get the feed-positions in the UV plane we fourier transform the eigenvectors over the time axis. At the moment this Analyzer is supposed to run during the day to check for night transit data.

Metrics

dias_task_<task name>_ew_pos_residuals_analyzer_run_total

Counter for total number of task runs with each specific source.

Labels
source : Source transit name.

dias_data_<task name>_ew_pos_good_freq_total

How many frequencies out of 10 were good (EV ratio on vs off source smaller than 2)?

Labels
source : Source transit name.

dias_data_<task name>_bad_feeds_percent

How many feeds in percent are bad(position residuals are greater than N_SIGMA sigma / N_SIGMA * STD m)

Labels
freq : Frequency of data. source : Source transit name.

Output Data

File naming

<YYYYMMDD>_<SOURCE>_positions.h5
YYYYMMDD is the date of the beginning of the night, data was analyzed from and SOURCE is the name of the source transit (TAU_A, CYG_A or CAS_A).

Indexes

freq
Frequency Indexes.
input
Telescope input indexes.

Datasets

east_west_pos
Relative east-west feed positions in meters.
east_west_resid
Position residuals in meters.

Config Variables

dias.analyzers.feedpositions_analyzer.FeedpositionsAnalyzer.ref_feed_P1

The feed we reference the polarisation 1 data to. Default: 2.

Type:integer
dias.analyzers.feedpositions_analyzer.FeedpositionsAnalyzer.ref_feed_P2

The feed we reference the polarisation 1 data to. Default : 258.

Type:integer
dias.analyzers.feedpositions_analyzer.FeedpositionsAnalyzer.pad_fac_EW

By which factor we pad the data before performing the fourier transform. Default : 256.

Type:integer

Additionally, the config parameters of the base class are expected in the task file

dias.analyzer.Analyzer(name, write_dir, …) Base class for all dias analyzers.