SRDP > Known Issues

Known Issues

by Davis Murphy last modified Jun 18, 2019

ALMA Restores

The ALMA Restores are only available for 12m and ACA data that were pipeline calibrated in Cycle 5 and Cycle 6 (select Cycle 4 datasets processed in Cycle 5 may also be available). Data that were manually calibrated cannot be restored by this process and require a full download and execution of the calibration script. Single-dish (Total Power) datasets are also not supported for restoration at the present time.

Certain pipeline-processed projects that were sent for manual imaging can be restored via this process, but some additional flags may have been added during manual imaging and these will not be applied to the restored dataset. These flags may not be of significant consequence, but users should check if flagdata commands are present in the *scriptForImagingPrep.py included with the auxiliary package from the ALMA data archive.

ALMA Cube Imaging

ALMA Cube Imaging runs a modified recipe of the ALMA imaging pipeline to produce cubes with custom channel width, overall spectral width, and velocity or frequency-defined channels. Cleaning uses the same automasking procedure as the ALMA Imaging Pipeline and low signal-to-noise emission may not be fully encompassed within a clean mask. Imaging results for Cycle 5 data may differ from the archived products because ALMA Cube Imaging uses the most recent imaging pipeline and incorporates the recent improvements to functions such as continuum finding and automasking.

The same limitations of the restorations also apply.

VLA Restores

The VLA data and calibrations within the archive have not undergone rigorous Quality Assurance and flagging for observations executed prior to June 17, 2019 and even after this point not all data will have Quality Assurance. The flux calibration accuracy is not likely to be better than 10% and uncertainty could be higher, especially at frequencies > 20 GHz. Furthermore, portions of the science target data may have significant RFI that was not flagged by the pipeline and further flagging may be required to produce optimal images, especially for frequencies < 20 GHz.

Spectral line detection and imaging from restored datasets should not be regarded as science quality. The calibration pipeline uses RFI flagging throughout the spectral range that will flag spectral line data, also the statistical weighting of visibilities is optimized for continuum and will downweight emission lines. Users aiming to do spectral line science are advised to recalibrate the data using the pipeline recipe modified for spectral line data.

Archive

ALMA Cycle 0 data are not present in the archive interface, due to the way it was archived. If you require Cycle 0 data, please visit the ALMA Archive.

For ALMA data products other than the ASDM files and calibrated measurement sets, users must still visit the ALMA archive at the present time. We intend to make image products available in the future.

The proprietary periods for all data are properly enforced, however the icons denoting locked or proprietary data are not completely accurate.

Some ALMA projects may not be properly displayed in the NRAO archive due to problems with incorporating them into the index. If a user spots an inconsistency in the NRAO archive (e.g., missing execution blocks [EBs], missing MOUSes/SBNames, or any other issue) they are encouraged to submit a ticket to the NRAO helpdesk under the ‘Data Products’ Topic.