Source Finding¶

Current in flint the aegeantools package is the only source finder supported. Even so, it is only used through a container as a CLI callable and not directly accessed via its private API.

There are two reasons where aegeantools is currently used:

1 - background and noise maps 2 - slim source finding

Background and noise estimation¶

There are weak links to the BANE program packaged in aegeantools. The computation of the bkg and rms maps through a rolling sigma-clipping boxcar function produces reliable and easily accessible direction-dependent diagnostics. In early versions of flint these were used as the basis of our clean mask creation routines. The rms map is also used when creating a summary field figure.

We note that in the latest version of aegeantools that there is an ongoing bug that can lead to a deadlock issue. For these reason we only expose the cores argument and have logic to ensure that the stripes BANE parameters it always one less than this.

class BANEOptions(BaseOptions):
    """Container for basic BANE related options. Only a subclass of BANE options are supported."""

    grid_size: tuple[int, int] | None = (16, 16)
    """The step interval of each box, in pixels"""
    box_size: tuple[int, int] | None = (196, 196)
    """The size of the box in pixels"""
    cores: int = 12
    """Number of cores to use. The number of stripes will be less than this number."""
    flint_use_fft: bool = False
    """Use flint's FFT BANE (``flint.bane``) instead of the container's BANE, rejecting pixels beyond 3 sigma as BANE does and with a tophat kernel for its box. ``grid_size`` and ``box_size`` are translated to it, with the step capped at 4, and ``cores`` is not used"""

Source finding¶

Flint offers the aegean source finding tool to be executed after BANE has been invoked. These two tools will always run sequentially. A limited set of aegean options have been exposed.

Importantly the intention here is to obtain a set of diagnostic results with minimal computation. The AegeanOptions exposed correspond to equivalent aegean CLI arguments. Do not that the default value of noconv is True – this mode does not handle the correlation of adjacent pixels.

class AegeanOptions(BaseOptions):
    """Container for basic aegean options. Only a subclass of aegean options are supported.

    Of note is the lack of a tables option (corresponding to --tables). This is dependent on knowing the base output name
    and relying on aegean to also append a suffix of sorts to the outputs. For that reason
    the aegean command generated will always create the table option.
    """

    nocov: bool = True
    """Whether aegean should attempt to model the co-variance of pixels. If true aegean does not. """
    maxsummits: int = 4
    """The maximum number of components an island is allowed to have before it is ignored. """
    autoload: bool = True
    """Attempt to load precomputed background and rms maps. """

Caution

The flint_aegean CLI will append options from both BANEOptions and AegeanOptions, and craft instances of these objects automatically. The default type of nocon and autoload will be translated to store_false options in argparse.ArgumentParser. If you want to use the quick version of aegean do not pass --noconv to the flint_aegean find CLI call.

Accessing via the CLI¶

The primary entry point for the source finding with aegean in flint is via flint_aegean:

A basic interface into aegean source finding routines.

usage: flint_aegean [-h] {find} ...

Positional Arguments¶

mode: Possible choices: find

Sub-commands¶

find¶

Run BANE with default options.

flint_aegean find [-h] [--grid-size GRID_SIZE GRID_SIZE]
                  [--box-size BOX_SIZE BOX_SIZE] [--cores CORES]
                  [--flint-use-fft] [--nocov] [--maxsummits MAXSUMMITS]
                  [--autoload]
                  image container

Positional Arguments¶

image: The image that BANE will process
container: Path to container with AegeanTools

Inputs for BANEOptions¶

--grid-size

The step interval of each box, in pixels

Default: (16, 16)

--box-size

The size of the box in pixels

Default: (196, 196)

--cores

Number of cores to use. The number of stripes will be less than this number.

Default: 12

--flint-use-fft

Use flint’s FFT BANE (flint.bane) instead of the container’s BANE, rejecting pixels beyond 3 sigma as BANE does and with a tophat kernel for its box. grid_size and box_size are translated to it, with the step capped at 4, and cores is not used

Default: False

Inputs for AegeanOptions¶

--nocov

Whether aegean should attempt to model the co-variance of pixels. If true aegean does not.

Default: True

--maxsummits

The maximum number of components an island is allowed to have before it is ignored.

Default: 4

--autoload

Attempt to load precomputed background and rms maps.

Default: True