Imaging

Brief Instructions for Calibrating UDB Data

Preparation

On pipeline, create a working directory in which the software will create any output, including the measurement set. Start CASA (takes a minute or so to load) and change to that directory

casa
cd /data1/dgary/solar/20170712_AR

Check if the UDB file you want already exists, in the appropriate subdirectory of /data1/eovsa/fits/UDB. If so, you can skip the next section.

Create a CASA UDBms file from a Miriad UDB file

In CASA, use task importeovsa:

default(importeovsa)

and set the input idbfiles to the scan or scans you wish to work with, as in this example:

idbfiles = '/data1/eovsa/fits/UDB/2017/UDB20170712183919'

You can check the inputs by

inp

You can change other inputs at this time, as desired, but the defaults are generally okay. Then to execute, type

go

A single scan takes about 1 minute using one CPU. The task will create a CASA measurement set under the current directory ended with "_scl.ms". In this case, it is "UDB20170712183919_scl.ms"

Find and Apply the Reference Calibration

At present, the task_calibeovsa script is not automatically loaded as a CASA task, so momentarily change to the appropriate folder and import the task, then change back to your desired folder:

cd /home/user/bchen/eovsa/suncasa/tasks/
import task_calibeovsa as tc
cd /data1/dgary/solar/20170712_AR
tc.calibeovsa('/data1/dgary/solar/20170712_AR/UDB20170712183919_scl.ms',flagant='13~15')

This should perform reference phase calibration and daily phase calibration, and write several calibration tables to /data1/eovsa/caltable/yyyymm/. By default (with docalib=True), it will also calibrate the CASA measurement set by writing a "CORRECTED" data column to the dataset. Also, it produces a standard frequency-synthesis image in Band 6-8 with natural weighting averaging over the entire duration of the measurement set, and save the original CASA image and registered fits file in heliocentric coordinates under /data1/bchen/solar/image/yyyy/mm/dd/. In the meantime, it creates a directory UDB20170712183919_scl.ms.flagversions (in the current directory) which includes the flag information (one can always undo or redo the flag using task "flagmanager").