phrosty API

phrosty.imagesubtraction

phrosty.imagesubtraction.gz_and_ext(in_path, out_path)

Utility function that unzips the original file and turns

it into a single-extension FITS file.

Parameters:

• in_path (Path) – The input path of the file to unzip and flatten.

• out_path (Path) – The desired output path of the file that is unzipped and flattened, once it is saved.

Returns:

out_path – The output path of the file that has been unzipped and flattened.

Return type:

Path

phrosty.imagesubtraction.sky_subtract(inpath, skysubpath, detmaskpath, temp_dir=PosixPath('/tmp'), force=False)

Subtracts background, found with Source Extractor.

Parameters:

• inpath (Path) – Original FITS image

• skysubpath (Path) – Sky-subtracted FITS image

• detmaskpath (Path) – Detection Mask FITS Image. (Will be uint8, I think.)

• temp_dir (Path) – Already-existing directory where we can write a temporary file. (If the image is .gz compressed, source-extractor can’t handle that, so we have to write a decompressed version.)

• force (bool, default False) – If False, and outpath already exists, do nothing. If True, clobber the existing file and recalculate it.

Returns:

skyrms – Median of the skyrms image calculated by source-extractor

Return type:

float

phrosty.imagesubtraction.stampmaker(ra, dec, shape, imgpath, savedir=None, savename=None)

Make stamps.

Parameters:

• ra (float) – RA of center of stamp in degrees.

• dec (float) – Dec of center of stamp in degrees.

• shape (np.array) – Shape of stamp. must be a numpy array. e.g. np.array([100,100])

• imgpath (Path) – Path to image that stamp will be extracted from.

• savedir (Path) – Directory stamp will be saved to.

• savename (Path) – Base name of stamp filepath.

Returns:

savepath – Full savepath of stamp. Combined inputs “savedir/savename”.

Return type:

Path

phrosty.photometry

phrosty.photometry.ap_phot(scienceimage, coords, ap_r=9, method='subpixel', subpixels=5, merge_tables=True, **kwargs)

Does aperture photometry on the input science image and

specified coordinates.

Parameters:

• scienceimage (array-like) – Array containing science image.

• coords (astropy.table.Table) – Table with columns ‘x’ and ‘y’ representing pixel coordinates for the detected sources. Table can contain more than just ‘x’ and ‘y’, and this may be useful if you use merge_tables=True.

• ap_r (int, optional) – Aperture radius to use for aperture photometry. Defaults to 3.

• method (str, optional) – _description_. Defaults to ‘subpixel’.

• subpixels (int, optional) – _description_. Defaults to 5.

• merge_tables (boolean, optional) – If true, output is merged coords and results from aperture photometry. Defaults to True.

Returns:

Table containing results from aperture photometry.

Return type:

astropy.table.Table

phrosty.pipeline

class phrosty.pipeline.Pipeline(object_id, ra, dec, band, science_images, template_images, nprocs=1, nwrite=5, verbose=False)

Phrosty’s top-level pipeline

Create the a pipeline object.

Parameters:

• object_id (int)

• ra (float) – Position of transient in decimal degrees

• dec (float) – Position of transient in decimal degrees

• band (str) – One of R062, Z087, Y106, J129, H158, F184, K213

• science_images (list of tuple) – ( path_to_image, pointing, sca )

• template_images (list of tuple) – ( path_to_image, pointing, sca )

• nprocs (int, default 1) – Number of cpus for the CPU multiprocessing segments of the pipeline. (GPU segments will run a single process.)

• nwrite (int, default 5) – Number of asynchronous FITS writer processes.

align_and_pre_convolve(templ_image, sci_image)

Align and pre convolve a single template/science pair.

Parameters:

• sci_image (phrosty.Image) – The science (new) image.

• templ_image (phrosty.Image) – The template (ref) image that will be subtracted from sci_image.

get_stars(truthpath, nx=4088, ny=4088, transform=False, wcs=None)

Get the stars in the science images.

Optional to transform to another WCS.

get_zpt(zptimg, err, psf, band, stars, ap_r=4, zpt_plot=None, oid=None, sci_pointing=None, sci_sca=None)

Get the zeropoint based on the stars.

phot_at_coords(img, err, psf, pxcoords=(50, 50), ap_r=4)

Do photometry at forced set of pixel coordinates.

class phrosty.pipeline.PipelineImage(imagepath, pointing, sca, pipeline)

Holds a snappl.image.Image, with some other stuff the pipeline needs.

Create a PipelineImage

Parameters:

imagepathstr or Path

A path to the image. This will be passed on to an Image subclass constructor; which subclass depends on the config option photometry.phrosty.image_type

pointingstr or int

An identifier of the pointing of this image. Used e.g. to pull PSFs.

pipelinephrosty.pipeline.Pipeline

The pipeline that owns this image.

free()

Try to free memory. More might be done here.

get_psf(ra, dec)

Get the at the right spot on the image.

Parameters:

• ra (float) – The coordinates in decimal degrees where we want the PSF.

• dec (float) – The coordinates in decimal degrees where we want the PSF.

phrosty.utils

phrosty.utils.get_corners(path=None, band=None, pointing=None, sca=None)

Retrieves the RA, dec of the corners of the specified SCA in degrees.

Parameters:

• band (str) – Roman filter.

• pointing (str) – Pointing ID.

• sca (str) – SCA ID.

Returns:

Tuple containing four numpy arrays, each with the RA and dec of the corner of the specified image in degrees.

Return type:

tuple

phrosty.utils.get_mjd(pointing, obseq_path=None)

Retrieve MJD of a given pointing.

Parameters:

• pointing (int) – Pointing ID.

• obseq_path (str, optional) – Path to obseq file Roman_TDS_obseq_11_6_23.fits.

Returns:

MJD of specified pointing.

Return type:

float

phrosty.utils.get_mjd_info(mjd_start=0, mjd_end=numpy.inf, return_inverse=False, obseq_path=None)

Get all pointings and corresponding filters between two MJDs.

Returns an astropy table with columns ‘filter’ and ‘pointing’. Does not return an ‘sca’ column because every sca belonging to a given pointing satisfies an MJD requirement.

Parameters:

• mjd_start (float, optional) – Start MJD, defaults to -np.inf

• mjd_end (float, optional) – End MJD, defaults to np.inf

• return_inverse (bool) – If true, returns all pointings outside the MJD range specified instead of inside.

• obseq_path (str, optional) – Path to obseq file Roman_TDS_obseq_11_6_23.fits.

Returns:

Astropy table with pointing numbers and corresponding filters that satisfy the MJD requirements.

Return type:

astropy.table.Table

phrosty.utils.get_mjd_limits(obseq_path=None)

Retrive the earliest and latest MJD in the simulations.

phrosty.utils.get_radec_limits(obseq_path=None)

Retrieve RA, dec limits (boresight coordinates).

phrosty.utils.get_roman_bands()

Get roman passbands.

Returns:

List of bands included in the Roman-DESC TDS simulations. :rtype: list

phrosty.utils.get_science(oid, band, infodir, returntype='list', verbose=False)

Get science images.

Science images are those images for a given OID actually contain the transient and also contain the RA/dec coordinates.

phrosty.utils.get_templates(oid, band, infodir, n_templates=1, returntype='list', verbose=False)

Get template images.

Template images are those images for a given OID do not actually contain the transient but do contain the RA/dec coordinates.

phrosty.utils.get_transient_info(oid)

Retrieve RA, Dec, MJD start, MJD end for specified object ID.

phrosty.utils.get_transient_mjd(oid)

Retrieve start and end dates of a transient based on its object ID.

phrosty.utils.get_transient_peakmjd(oid)

Retrieve z of a transient based on its object ID.

phrosty.utils.get_transient_radec(oid)

Retrieve RA, dec of a transient based on its object ID.

phrosty.utils.get_transient_zcmb(oid)

Retrieve z_CMB of a transient based on its object ID.

phrosty.utils.pointings_near_mjd(mjd, window=3, obseq_path=None)

Retrieve pointings near given MJD.

Parameters:

• mjd (float) – Central MJD to search around.

• window (float) – Number of days around central MJD to include in search.

• obseq_path (str, optional) – Path to obseq file Roman_TDS_obseq_11_6_23.fits.

Returns:

Pointings within specified MJD range.

Return type:

list

phrosty.utils.read_truth_txt(path=None, band=None, pointing=None, sca=None)

Reads in the txt versions of the truth files as convenient astropy tables.

Parameters:

• truthpath (str, optional) – Path to txt catalog version of truth file. If you do not provide this, you need to specify the arguments band, pointing, and sca.

• band (str, optional) – Roman filter. If you do not provide this, you need to provide truthpath.

• pointing (str, optional) – Pointing ID. If you do not provide this, you need to provide truthpath.

• sca (str, optional) – SCA ID. If you do not provide this, you need to provide truthpath.

Returns:

Astropy table with contents of the specified catalog txt file.

Return type:

astropy.table.Table

phrosty.utils.transform_to_wcs(wcs, path=None, band=None, pointing=None, sca=None)

“Transform world coordinates in a truth file to a new WCS.

Outputs pixel coordinates for the transformed coordinates. input wcs is an astropy wcs object.

phrosty.utils.transient_in_or_out(oid, start, end, band)

Retrieve pointings that contain and do not contain the specified SN, per the truth files by MJD.

transient_info_filepath is the output of make_object_table.

Returns a tuple of astropy tables (images with the SN, images without the SN).