dfreproject: A Python package for astronomical reprojection

Fuente: arXiv
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Main Authors: Rhea, Carter Lee, Van Dokkum, Pieter, Janssens, Steven R., Pasha, Imad, Abraham, Roberto, Bowman, William P, Lokhorst, Deborah, Chen, Seery
Format: Preprint
Published: 2025
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author Rhea, Carter Lee
Van Dokkum, Pieter
Janssens, Steven R.
Pasha, Imad
Abraham, Roberto
Bowman, William P
Lokhorst, Deborah
Chen, Seery
author_facet Rhea, Carter Lee
Van Dokkum, Pieter
Janssens, Steven R.
Pasha, Imad
Abraham, Roberto
Bowman, William P
Lokhorst, Deborah
Chen, Seery
contents Deep astronomical images are often constructed by digitially stacking many individual sub-exposures. Each sub-exposure is expected to show small differences in the positions of stars and other objects in the field, due to the movement of the celestial bodies, changes/imperfections in the opto-mechanical imaging train, and other factors. To maximize image quality, one must ensure that each sub-exposure is aligned to a common frame of reference prior to stacking. This is done by reprojecting each exposure onto a common target grid defined using a World Coordinate System (WCS) that is defined by mapping the known angular positions of reference objects to their observed spatial positions on each image. The transformations needed to reproject images involve complicated trigonometric expressions which can be slow to compute, so reprojection can be a major bottleneck in image processing pipelines. To make astronomical reprojections faster to implement in pipelines, we have written `dfreproject`, a Python package of GPU-optimized functions for this purpose. The package's functions break down coordinate transformations using Gnomonic projections to define pixel-by-pixel shifts from the source to the target plane. The package also provides tools for interpolating a source image onto a target plane with a single function call. This module follows the FITS and SIP formats laid out in the seminal papers. Compared to common alternatives, `dfreproject`'s routines result in speedups of up to 20X when run on a GPU and 10X when run on a CPU.
format Preprint
id arxiv_https___arxiv_org_abs_2505_03932
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle dfreproject: A Python package for astronomical reprojection
Rhea, Carter Lee
Van Dokkum, Pieter
Janssens, Steven R.
Pasha, Imad
Abraham, Roberto
Bowman, William P
Lokhorst, Deborah
Chen, Seery
Instrumentation and Methods for Astrophysics
Deep astronomical images are often constructed by digitially stacking many individual sub-exposures. Each sub-exposure is expected to show small differences in the positions of stars and other objects in the field, due to the movement of the celestial bodies, changes/imperfections in the opto-mechanical imaging train, and other factors. To maximize image quality, one must ensure that each sub-exposure is aligned to a common frame of reference prior to stacking. This is done by reprojecting each exposure onto a common target grid defined using a World Coordinate System (WCS) that is defined by mapping the known angular positions of reference objects to their observed spatial positions on each image. The transformations needed to reproject images involve complicated trigonometric expressions which can be slow to compute, so reprojection can be a major bottleneck in image processing pipelines. To make astronomical reprojections faster to implement in pipelines, we have written `dfreproject`, a Python package of GPU-optimized functions for this purpose. The package's functions break down coordinate transformations using Gnomonic projections to define pixel-by-pixel shifts from the source to the target plane. The package also provides tools for interpolating a source image onto a target plane with a single function call. This module follows the FITS and SIP formats laid out in the seminal papers. Compared to common alternatives, `dfreproject`'s routines result in speedups of up to 20X when run on a GPU and 10X when run on a CPU.
title dfreproject: A Python package for astronomical reprojection
topic Instrumentation and Methods for Astrophysics
url https://arxiv.org/abs/2505.03932