DAP Known Issues¶

Persistent¶

LSF limitations¶

The DRP provides both pre- and post-pixelized Gaussian measurements of the instrumental line-spread function. Because it makes the most sense to use the pre-pixelized versions with pPXF, the DAP uses these pre-pixelized measurements for the dispersion calculations in both the stellar and ionized-gas velocity dispersions. A more in-depth analysis is needed to understand how these LSF changes affect the results.

Artifact effects on emission-line fitting¶

The DRP will inevitably miss some cosmic rays, and occasionally those cosmic rays will land on or near emission lines. This will play havoc with the emission-line fitter. Beyond possibly affecting the flux of the nearest line, it can also pull off all of the lines because the lines are forced to have the same velocity. An example of this in MPL-7/DR15 is 8134-9102 where a cosmic ray lands on [S II]6718 for e.g., spaxel (x,y) = (25,35). The cosmic-ray is slightly blueward of the [S II] center and leads to all the remaining lines being too far to the blue, as well as leading to incorrect fluxes and velocity dispersions.

Spectral indices¶

Both the spectral indices and their velocity-dispersion corrections are measured using the input (NSA) redshift, not the fitted stellar velocity. Specifically for the velocity-dispersion corrections, this means that there will be a velocity dependence of the correction that can be more significant that the correction for the velocity dispersion itself. The approach to the velocity dispersion corrections may be improved in future releases.

Flagging¶

There are still severe deficiencies in the flagging, in general. Measurements can exhibit pixel-to-pixel variations that are inconsistent with random error (because of the strong covariance between neighboring spaxels) or fiber-level deviations that are inconsistent with physical intuition. These issues tend to occur at low S/N, however, they might not all be caught by a simple S/N cut. Please consider the limited robustness of the flagging for your science goals. These limitations apply to essentially all derived products (kinematics, fluxes, indices, etc).

Uncertainties¶

Errors are generally “formal” errors determined either by the covariance (inverse Hessian) matrix provided by the optimization algorithm (stellar and emission-line kinematics) or a direct propagation of the error based on the inverse variances provided by the DRP (as for the emission-line moments and spectral indices). Idealized experiments and analysis of repeat observations have shown that the formal errors are within a factor of two of the statistical error. See the detailed assessments of the DAP uncertainties in the two main DAP papers: Westfall et al. (2019, AJ, 158, 231) and Belfiore et al. (2019, AJ, 158, 160).

MPL-9 (2.4.1)¶

Faults¶

The full report of the observations that faulted and the consolidated list of error messages can be found here (internal).

Of the 8130 attempted analyses, 73 did not successfully finish all three analysis approaches. In the 73 failures, the error can occur such that, e.g., the unbinned (SPX) processing finished but the Voronoi-binned results (VOR10) did not. Here are the number of MAPS files for each DAPTYPE:

`DAPTYPE`	\(N_{\rm cubes}\)
`SPX-MILESHC-MILESHC`	8097
`VOR10-MILESHC-MILESHC`	8089
`HYB10-MILESHC-MILESHC`	8057

The 33 observations that were unsuccessful for any analysis approach are:

8083-9101, 8148-3701, 8253-12705, 8309-3703, 8312-6101, 8332-12703,
8333-9101, 8438-12704, 8613-12702, 8626-9102, 8714-3703, 8715-12704,
8725-12705, 8941-12704, 8941-12705, 9024-6103, 9195-12704,
9485-12704, 9500-12702, 9508-12701, 9673-12703, 9673-9102,
9674-12703, 9674-12705, 9677-12703, 9677-12704, 9678-12704,
9678-9102, 10503-9101, 10505-6101, 10839-6103, 11014-12705,
11019-12703

The 8 observations that have SPX-MILESHC-MASTARHC results but none others are:

7443-3703, 8994-9102, 9024-12705, 9025-12702, 9888-9102, 11016-3704,
11823-3703, 11831-6104

The 32 observations that have all but the HYB10-MILESHC-MASTARHC output are:

8133-6102, 8141-12705, 8143-9102, 8147-6101, 8149-12701, 8263-12701,
8338-12704, 8485-12701, 8548-1901, 8568-12704, 8603-6102, 8615-12705,
8623-6103, 8933-12701, 8996-9101, 9025-12701, 9042-12704, 9044-9102,
9048-9101, 9050-6103, 9094-12704, 9094-6103, 9192-6103, 9863-6101,
9887-12705, 11025-6103, 11751-12703, 11757-12704, 11863-3703,
11941-12701, 11979-3704, 11982-3701

MPL-8 (2.3.0)¶

Faults¶

There were 32 observations that did not successfully finish all aspects of the MPL-8 run:

7443-3703, 7968-12703, 8133-6102, 8158-3703, 8309-3703, 8312-6101,
8320-3701, 8332-12704, 8462-6103, 8568-12704, 8616-3704, 8616-12705,
8626-9102, 8655-3702, 8935-12704, 8947-12704, 9025-12702, 9085-6104,
9183-12703, 9673-9102, 9673-12703, 9673-12704, 9674-12705,
9675-12705, 9677-12703, 9677-12704, 9862-12701, 9871-12704,
9874-9101, 9888-9102, 10498-12704, 10507-12705

In the 32 failures, the error may have occurred such that e.g., the unbinned (SPX) processing finished but the Voronoi-binned results (VOR10) did not. Here are the number of MAPS files for each DAPTYPE:

`DAPTYPE`	\(N_{\rm cubes}\)
`SPX-MILESHC-MILESHC`	6520
`VOR10-MILESHC-MILESHC`	6515
`HYB10-MILESHC-MILESHC`	6500

The 5 galaxies with SPX but no VOR10 output are:

7443-3703, 8158-3703, 8462-6103, 9025-12702, 9888-9102

The 15 galaxies with SPX and VOR10 but no HYB10 are:

7968-12703, 8133-6102, 8320-3701, 8332-12704, 8568-12704,
8616-12705, 8616-3704, 8655-3702, 8935-12704, 8947-12704, 9085-6104,
9183-12703, 9862-12701, 9874-9101, 10507-12705