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https://github.com/loostrum/arts_tracking_beams
Create tracking beams from ARTS tied-array beam data
https://github.com/loostrum/arts_tracking_beams
Last synced: about 1 month ago
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Create tracking beams from ARTS tied-array beam data
- Host: GitHub
- URL: https://github.com/loostrum/arts_tracking_beams
- Owner: loostrum
- License: apache-2.0
- Created: 2020-08-28T15:27:59.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-06-17T17:52:29.000Z (7 months ago)
- Last Synced: 2024-08-09T21:23:07.095Z (5 months ago)
- Language: Python
- Size: 7.16 MB
- Stars: 2
- Watchers: 1
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Citation: CITATION.cff
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README
# ARTS tracking beams
[](https://zenodo.org/badge/latestdoi/291081079)
[](https://badge.fury.io/py/arts-tracking-beams)
[](https://codecov.io/gh/loostrum/arts_tracking_beams)
The Apertif Radio Transient System (ARTS) archive contains tied-array beam (TAB) data. The TABs have a time-dependent and
frequency-dependent pointing. This tool is able to convert the TAB data to a tracking beam (TB), which tracks a fixed point
on the sky over the course of an observation. Additionally, it can convert TAB data to Synthesised Beams (SBs),
which are suitable for transient searches.
## Dependencies
* python >= 3.6
* numpy >= 1.17
* astropy
* tqdm
## Installation
To install the latest release:
`pip install arts_tracking_beams`
To install the latest master branch:
`pip install git+https://github.com/loostrum/arts_tracking_beams`
## Usage
Basic usage of this package is described below. Tutorials are available at https://loostrum.github.io/arts_tracking_beams.
### Input data
First download the data set of interest from the Apertif Long-Term Archive (ALTA). Tools to find which pulsars are in the
field-of-view of a given Apertif pointing and to download the data are available as a separate
[python package](https://github.com/loostrum/arts_tools).
A data file from the archive is identified by three parameters: the task ID, compound beam (CB) index, and TAB index.
The file `ARTS200102003_CB00_TAB00.fits` would be the observation identified by task ID 200102003
(that is, the third observation on January 2nd, 2020), CB zero, TAB zero. A TB is created from the TABs of a single CB.
### Creating a tracking beam
A tracking beam (TB) is created from the TAB data with `arts_create_tracking_beam`.
The simplest use case is to create a tracking beam
from a folder which contains only one data set (i.e. the TABs of one CB of one observation), for a source with known
coordinates. For example, to create a tracking beam towards the Crab pulsar:
`arts_create_tracking_beam --input_folder /path/to/data/ --source 'PSR B0531+21'`
If there are multiple data sets in the input data folder, specify the task ID and/or CB index. Instead of the source name,
it is also possible to provide a RA and Dec. The name of the output FITS file is determined automatically from the input
source name or RA/Dec, but can also be specified manually. Using all of these options, an example command is:
`arts_create_tracking_beam --input_folder /path/to/data/ --taskid 200102003 --cb 0 --ra 05:34:32 --dec 22:00:52 --output tracking_beam.fits`
The TB creation consists of two steps:
1. Calculate the required TABs at each frequency and time
2. Reorder the data from the input TAB FITS files and create a new FITS file containing the TB.
The results of step 1 can be saved to disk with `--save_tab_indices`. To only calculate the TAB indices and
disable step 2 completely, use `--no_fits_output`.
To generate the FITS output from a TAB indices file on disk, use`--load_tab_indices /path/to/tab/index/file.txt`.
The script then loads the TAB indices and immediately goes to step 2.
There are a few more settings that can be customized. Run `arts_create_tracking_beam -h` for an overview of all options.
### Creating a synthesised beam
A synthesised beam (SB) is a type of beam that reorders the TABs as function of frequency, but *not* as function of time.
A single CB is covered by 71 SBs. Each SB is always made out of the same TABs. The SBs are used in the real-time
transient search that ARTS runs. The brightest transients may also be detectable in the archival data, so we here include
a tool to create the synthesised beams as well.
The synthesised beam tool, `arts_create_synthesised_beam`, works
in a very similar fashion as the tracking beam tool. An example command:
`arts_create_synthesised_beam --input_folder /path/to/data --sb 35`
Run `arts_create_synthesised_beam -h` for more options.