Roman Telescope: 3 RT Failures On Main Branch

It looks like we've hit a snag on the Roman telescope's main branch, with three recent regression tests (RT) failing. This issue stems from a change in the pmap file, specifically from roman_0042.pmap to roman_0043.pmap. These failures are making it a bit tricky to decipher the results of the regression tests on open pull requests, which is crucial for maintaining the stability and reliability of the Roman mission software. Understanding these failures is key to ensuring that future updates don't introduce regressions that could impact the telescope's operations or data analysis pipelines. The affected tests are test_elp_tvac.py::test_output_matches_truth, test_wfi_grism_pipeline.py::test_output_matches_truth, and test_wfi_grism_pipeline.py::test_repointed_matches_truth. The core of the problem lies in the values_changed dictionary, which clearly indicates that the context value within root['roman']['meta']['ref_file']['crds'] has been updated from roman_0042.pmap to roman_0043.pmap. This kind of change, while potentially necessary for updates or calibration improvements, can sometimes lead to unexpected behavior if not thoroughly tested across all relevant pipelines and test cases. The fact that these are regression tests means they are designed to catch exactly this type of subtle but impactful change. The goal here is to investigate why this specific pmap update is causing these three tests to fail and to determine the best course of action, whether it's adjusting the tests, understanding the impact of the pmap change, or rolling back if the change introduces unintended consequences. The spacetelescope and romancal communities will be particularly interested in how this is resolved, as it impacts the ongoing development and validation of the Roman mission's software. Ensuring the integrity of these regression tests is paramount for the success of the Roman Space Telescope.

The Impact of pmap Changes on Roman Telescope Regression Tests

The recent failures in the Roman telescope's regression tests are directly linked to an update in the pmap file, a critical component of the mission's calibration data system. The change from roman_0042.pmap to roman_0043.pmap signifies an alteration in the configuration or calibration files that the telescope's software relies on. Regression tests, like the ones that have failed, are specifically designed to compare the current output of the software against a known, correct baseline. When a test fails, it indicates that something has changed, and the current behavior no longer matches the expected behavior. In this scenario, the values_changed log provides a precise clue: {'new_value': 'roman_0043.pmap', 'old_value': 'roman_0042.pmap'}. This tells us that the reference file used for CRDS (Calibration Data Retrieval System) contexts has been updated. Such updates are common as new calibrations are developed, instrument characteristics are refined, or bugs are fixed. However, they can also introduce subtle differences that affect downstream processing. The fact that three specific tests are failing—test_elp_tvac.py::test_output_matches_truth, test_wfi_grism_pipeline.py::test_output_matches_truth, and test_wfi_grism_pipeline.py::test_repointed_matches_truth—suggests that the roman_0043.pmap change has a tangible impact on the Extended Light curve Processing (ELP) TVAC test and the Wide Field Instrument (WFI) grism pipeline, particularly concerning its output and re-pointed observations. Deciphering these failures is essential because the Roman Space Telescope relies on a highly accurate and consistent data processing pipeline. Any deviation from the expected output, even if introduced by an intended update, needs to be understood and validated. These RT failures are hindering the ability to confidently merge new code, as we can't easily tell if a failing PR is due to a genuine bug introduced by the PR or an issue stemming from the underlying pmap change. Therefore, a thorough investigation into why roman_0043.pmap is causing these specific discrepancies is paramount. This involves examining the exact differences introduced by the new pmap file and how those differences propagate through the ELP and WFI pipelines. The spacetelescope and romancal teams will need to collaborate closely to resolve this, ensuring that the Roman telescope's software remains robust and its scientific data remain pristine. The integrity of the Roman telescope's scientific output depends on such rigorous testing and diligent problem-solving.

Pinpointing the Failing Tests and Their Significance

The three regression tests that have unfortunately failed on the Roman telescope's main branch are test_elp_tvac.py::test_output_matches_truth, test_wfi_grism_pipeline.py::test_output_matches_truth, and test_wfi_grism_pipeline.py::test_repointed_matches_truth. Each of these tests plays a distinct but vital role in validating the Roman telescope's data processing capabilities. test_elp_tvac.py::test_output_matches_truth: This test is part of the Extended Light curve Processing (ELP) suite and specifically targets the output of the Extended mission's TVAC (Thermal Vacuum) simulation. TVAC tests are crucial for verifying how an instrument performs under simulated space conditions. The _output_matches_truth suffix indicates that this test compares the actual output generated by the ELP pipeline against a pre-defined 'truth' file – a known, correct result. A failure here means that the processing of ELP data, possibly related to light curve generation or other extended mission products, has deviated from the expected outcome after the pmap update. This could affect how scientists analyze transient events or other time-dependent phenomena observed by Roman. test_wfi_grism_pipeline.py::test_output_matches_truth: This test focuses on the Wide Field Instrument (WFI) and its grism (a grating prism) spectroscopy capabilities. Grisms allow the telescope to capture spectral information along with imaging. The _output_matches_truth part again signifies a comparison between the current WFI grism pipeline output and a golden truth file. A failure suggests that the processing of grism data from the WFI, which is critical for determining the redshift and composition of celestial objects, has changed in an unpredicted way. This could impact the accuracy of spectral measurements derived from WFI grism observations. test_wfi_grism_pipeline.py::test_repointed_matches_truth: This test also pertains to the WFI grism pipeline but specifically addresses scenarios where the telescope has been re-pointed during an observation. Re-pointing is a common maneuver for astronomical instruments, allowing them to observe different targets or regions of the sky. Verifying that the grism pipeline performs correctly after a re-point is essential for ensuring data consistency across multiple slews. A failure here indicates that the WFI grism pipeline's output is not as expected when the telescope changes its orientation, which could lead to artifacts or inaccuracies in scientific products derived from such observations. The common thread linking these failures is the upgrade of the CRDS context file from roman_0042.pmap to roman_0043.pmap. This single change is having a cascading effect across different instrument modes and processing pipelines. It underscores the interconnectedness of the Roman telescope's software and the importance of meticulous regression testing. The spacetelescope and romancal communities must work together to diagnose whether the roman_0043.pmap file is correct and the tests need adjustment, or if the pmap change has introduced a genuine issue that needs to be fixed within the pipeline code itself. Without resolving these RT failures, the confidence in the main branch's stability is undermined, making it harder to proceed with further development for the Roman Space Telescope.

Navigating the pmap Update: roman_0042.pmap vs. roman_0043.pmap

The crux of the recent Roman telescope regression test failures lies in the transition from roman_0042.pmap to roman_0043.pmap. This seemingly minor version increment in the pmap file signifies a potentially significant update to the underlying calibration data or configuration used by the Roman mission's software, specifically within the CRDS (Calibration Data Retrieval System) framework. The CRDS plays a pivotal role in ensuring that the correct calibration files are applied to the raw science data based on the observation's metadata. When this system is invoked, it consults a pmap (parameter map) file, which acts as a central registry, pointing to specific versions of calibration files, often organized by context. The change from roman_0042.pmap to roman_0043.pmap means that the CRDS will now be referencing a different set of calibration files or a different configuration for applying them. This could involve updates to reference pixel masks, gain settings, wavelength solutions, flat fields, or any other parameter critical for accurate data reduction. The fact that this update has triggered failures in the test_output_matches_truth and test_repointed_matches_truth tests for both the ELP and WFI grism pipelines highlights the pervasive impact of calibration changes. It suggests that the new calibration files referenced by roman_0043.pmap are leading to subtle, yet detectable, differences in the processed data compared to what was expected based on roman_0042.pmap. For scientists relying on the Roman telescope's data, these differences could manifest in variations in measured fluxes, spectral features, or image characteristics. The challenge now is to determine the root cause of these discrepancies. Is the roman_0043.pmap file itself correctly generated and representative of the latest understanding of the instrument's behavior? Or has the change in pmap inadvertently exposed a latent issue within the ELP or WFI processing pipelines that wasn't apparent with the older calibration files? This investigation requires a deep dive into the specifics of what changed between the two pmap versions. Detailed comparisons of the calibration files pointed to by each pmap are necessary. Furthermore, understanding the exact algorithms within the ELP and WFI pipelines that are sensitive to these calibration changes is crucial. The spacetelescope and romancal development teams will need to collaborate closely to meticulously analyze the output differences and trace them back to their origin. This might involve regenerating test data with the new pmap and comparing it element by element with the old results, or even running specific diagnostic tests on the calibration files themselves. Resolving these RT failures is not just about fixing broken tests; it's about ensuring the scientific integrity of the Roman telescope's data products and maintaining confidence in the mission's software infrastructure. The Roman Space Telescope's success hinges on the reliability of its data, making this calibration update and its subsequent testing a critical milestone in its development lifecycle.

Conclusion: Upholding Roman Telescope's Data Integrity

The recent regression test failures on the Roman telescope's main branch, triggered by the pmap file update from roman_0042.pmap to roman_0043.pmap, serve as a critical reminder of the complexities involved in maintaining a cutting-edge astronomical instrument's software. These failures in the ELP TVAC and WFI grism pipeline tests underscore the sensitivity of the data processing workflows to even seemingly minor changes in calibration references. The core challenge lies in discerning whether the new pmap file introduces a genuine regression or if the existing tests need refinement to accommodate updated instrumental characteristics. The spacetelescope and romancal communities are now tasked with a thorough investigation, involving detailed comparisons of calibration files and pipeline behavior. This process is vital for ensuring that the Roman telescope continues to deliver scientifically accurate and reliable data. Ultimately, the successful resolution of these RT failures will bolster confidence in the main branch's stability and pave the way for future advancements. For those interested in the technical underpinnings of space missions and the rigorous testing required, I recommend exploring resources from organizations like the Space Telescope Science Institute (STScI) itself, which provides extensive documentation and updates on the Hubble and Roman Space Telescopes. Additionally, the ESA (European Space Agency) often publishes valuable insights into space mission operations and data processing standards, offering a broader perspective on the challenges and triumphs of astronomical exploration.