astrokat-helper

Helper respository for astrokat. Includes tools for analysing the astrokat output.

Install

First install astrokat. I.e. clone the repo, navigate there, and type pip install ., then go to this repo's root directory and repeat, pip install . . The python interpreter should then be able to execute all scripts found in here, and a new command when_is_patch_observable is installed.

Examples

new observation workflow

• Treat rising and setting completely separately.
• Make a reasonable guess of the scan LST range. For example, usually the second corner to rise/set is relevant for a rising/setting scan to start or end.
• Make a reasonable guess of the time it takes to calibrate before and after the scan.
• Prepare a yaml file for the scan but without calibrators.
• Look for calibration targets with astrokat-targets.py , i.e. run it on the scan corners (put those into a csv file). If needed extend the catalogue. Make sure to include the desired tags like gain pol bp and date and horizon.
• Select calibrators and add them to the yaml. The single-dish calibrators need to be observed on centre and shifted off-centre as described in the observation doc. The script scripts/yaml_checker.py runs a few checks on yaml files, it will also check that the single dish calibrator pointings are offset correctly.
• run astrokat-observe on the yaml for both ends of the LST range and check the output. Especially target elevation ranges are important. Fine tune the LST range and if needed, swap calibrators.
• Also double check yaml file using scripts/yaml_checker.py
• Once the yaml file is correct, create all desired mutations from it (e.g. shifted scan lines, with and without calibrators etc.)

targets

python astrokat-targets.py --infile ../../astrokat-helper/yaml/jan_2024/patch_1_targets.csv --horizon 35 --cat-path ../catalogues/ --cal-tags gain bp pol --datetime '2024-01-01 00:00'

The script scripts/corners_converter_angle_hourangle.py helps to convert degree RA/DEC coordinates into the format required by astrokat.

patch observability

Define a patch of the sky with right ascension and declination min/max values. You can display the dates when this patch will be drift-scannable with the script

when_is_patch_observable

The command line options can be displayed with when_is_patch_observable --help, and example usage is when_is_patch_observable --corners 6 20 -5 5 --date 2023-12-24 --buffer 30 --min_elevation 35 --max_elevation 50