DAP Known Issues


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 ongoing to understand how these LSF changes affect the results (Law et al. 2020).

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.


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).


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-10 (3.0.1)


The full report of the observations that faulted and the consolidated list of error messages can be found in the MPL-10 error report (internal).

In total, there are 10529 DRP-produced data cubes. Of these, 488 did not have an input redshift, and were therefore not analyzed by the DAP; most (if not all) of these are the result of allocating bundles to empty sky for special observations (such as the mosaic of IC342).

Of the 10041 cubes that the DAP attempted to analyze, 42 caused faults during the analysis. These failures are mostly because the S/N required for either the stellar kinematics or emission-line fit was insufficient for any spectrum in the datacube. Of these, one cube successefully finished the SPX-MILESHC-MASTARHC2 analysis, but was unsuccessful for the other two types. Therefore, here are the number of completed MAPS files for each DAPTYPE:


\(N_{\rm cubes}\)







The 41 cubes that failed all DAPTYPEs are:

8479-6101, 8479-6102, 8479-12703, 8480-6102, 8480-12703,
8312-6101, 8953-6104, 9051-12704, 9051-6104, 9051-3704,
9673-6104, 9673-3701, 9673-3702, 9673-1902, 9673-1901, 9673-6101,
9673-6103, 9673-3703, 9673-3704, 9674-1902, 9674-6104, 9674-3701,
9674-1901, 9674-6101, 9674-3702, 9674-3703, 9674-3704, 9675-3701,
9675-3704, 9675-3702, 9675-1902, 9675-6104, 9675-6103, 9675-1901,
9675-3703, 9675-6101, 11987-6104, 11987-1901, 8587-12702,
8587-12701, 11828-1902

The cube that passed SPX-MILESHC-MASTARHC2, but failed the other two is:


Emission-line fluxes

Flipping between the plots here and here (see below), you’ll note that the \({\rm H}\alpha\) luminosity in the quiescent sequence seems to show a systematic shift to lower flux in MPL-10 compared with MPL-9. This likely has to do with the change in templates between MPL-9 and MPL-10; however, we’re investigating this further. Updates will be announced to the collaboration and posted here.


Comparison between the automatically generated plots from the DAPall file for MPL-9 (left) and MPL-10 (right) for the individual spaxel output (results for the other two binning schemes are comparable). MPL-10 seems to result in a systematic shift in the \({\rm H}\alpha\) luminosity in the quiescent sequence. Further information TBD.

MPL-9 (2.4.1)


The full report of the observations that faulted and the consolidated list of error messages can be found in the MPL-9 error report (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:


\(N_{\rm cubes}\)







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,

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)


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:


\(N_{\rm cubes}\)







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