Execution Block ID uid://A001/X15a0/X180 Sgr_A_st_al_03_7M

[keflavich]

Sgr_A_st_al_03_7M uid://A001/X15a0/X180

• [x] Observations completed?

• [x] Delivered?

• [x] Downloaded? (specify where)

  • [x] hipergator
  • [x] hipergator pipeline run
  • Pipeline Run 20220604T040117
  • Pipeline Run 20220604T004206
  • Pipeline Run 20220604T000833

• [ ] Weblog unpacked

• [x] Weblog Quality Assessment?

• Extra Weblog Sgr_A_st_al_03_7M_0 -> pipeline-20220604T040117, Extra Weblog Sgr_A_st_al_03_7M_1 -> pipeline-20220527T210152

• [x] Imaging: Continuum

• [x] Imaging: Lines

  • [x] SPW16 H13CN
  • [x] SPW18 H13CO+/SiO
  • [x] SPW20 HCO+
  • [x] SPW22 HNCO
  • [x] SPW24 Cont 1
  • [x] SPW26 Cont 2

Product Links:

• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw18.cube.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16.cube.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw26.cube.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw20.cube.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw22.cube.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw24.cube.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw18.mfs.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16.mfs.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw26.mfs.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw22.mfs.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw24.mfs.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw20.mfs.I.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16_18_20_22_24_26.cont.I.pb.tt0.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16_18_20_22_24_26.cont.I.tt1.pbcor.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16_18_20_22_24_26.cont.I.alpha.error.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16_18_20_22_24_26.cont.I.alpha.fits
• member.uid___A001_X15a0_X180.Sgr_A_star_sci.spw16_18_20_22_24_26.cont.I.tt0.pbcor.fits

Reprocessed Product Links:

• uid___A001_X15a0_X180.s12_0.Sgr_A_star_sci.spw18.cube.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s12_0.Sgr_A_star_sci.spw24.cube.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s12_0.Sgr_A_star_sci.spw20.cube.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s12_0.Sgr_A_star_sci.spw16.cube.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s12_0.Sgr_A_star_sci.spw22.cube.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s12_0.Sgr_A_star_sci.spw26.cube.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s8_0.Sgr_A_star_sci.spw18.mfs.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s8_0.Sgr_A_star_sci.spw24.mfs.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s8_0.Sgr_A_star_sci.spw22.mfs.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s8_0.Sgr_A_star_sci.spw26.mfs.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s8_0.Sgr_A_star_sci.spw20.mfs.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s8_0.Sgr_A_star_sci.spw16.mfs.I.iter1.image.pbcor.fits
• uid___A001_X15a0_X180.s36_0.Sgr_A_star_sci.spw16_18_20_22_24_26.cont.I.iter1.image.tt0.pbcor.fits

[d-l-walker]

I've had a quick look through the weblog for this, and the main thing that stands out is that the automasking failed in the cube imaging. I can't see any glaring issues with the actual data, so I'm not sure what's causing this yet. The most obvious thing is this warning:

Warning! Source Sgr_A_star is an odd-shaped mosaic -- there is no mosaic field at the image phasecenter and imaging is likely to fail. The phasecenter of nearest pointing to the image center is ICRS 17:46:26.4396 -028.28.49.281

It seems like CASA doesn't like the shape of this mosaic, and explicitly warns that imaging may fail. So I guess this is the culprit? Can we get around this with manual imaging/custom imaging parameters?

Other than this I don't see any major issues in the weblog.

[snlongmore]

I mentioned this issue in ALMA Heldesk ticket 19313

[keflavich]

Needs reimaging with the psfphasecenter keyword set to a location within the imaged area.

[xinglunju]

@d-l-walker Dan, you will self-assign this issue and work on the re-imaging, right? Is it ok if I assign it to myself too so that a student use this SB to get some experience of weblog review?

[d-l-walker]

@xinglunju of course, that'd be great!

[d-l-walker]

Small, underwhelming update: I've been trying to re-image this for a while now to fix the issues with the PSF being outside of the mosaic.

• The good news is that this is an easy fix to just explicitly place the PSF in the centre of the mosaic (rather than the centre of the image).
• The bad news is that I'm struggling to make sense of the data -- the images that I'm getting look very different to those delivered, in that there is very little emission, and the values are like 1e6-7x too low.
  • I figured this was an issue with the calibration restoration, so I downloaded the raw data via Globus and restored the calibration myself. Unfortunately this didn't solve the issue and the images still don't look right. I've attached some screenshots below to demonstrate this. These just show the continuum, but the issues are the same for the cubes too.
  • I'll continue to think about this and try to figure out what's going on ...

Original PL pb-corrected continuum

Reprocessed pb-corrected continuum: note the lack of structure and significant difference in values in the colorbar

[xinglunju]

@d-l-walker I used to find similar issues when imaging large VLA mosaics, and it is the 'gridder' keyword in tclean, standard vs. mosaic (the latter should be used). No sure if it is the same issue in your case...

[d-l-walker]

Hi @xinglunju, thanks for the suggestion. In this case I am already using gridder='mosaic'. In fact, I have tried running the exact tclean command used by the pipeline, leaving every parameter unchanged, yet I still get the same issue.

[keflavich]

@d-l-walker perhaps post a log from the imaging run and we can discuss it on the telecon?

[d-l-walker]

Here's the log from a test I did this morning where I ran the same tclean command as the PL to create a dirty continuum image: https://www.dropbox.com/s/s1m17wna5mal932/casa-20220720-081325.log?dl=0

[d-l-walker]

I've finished re-processing this now. As mentioned in this week's telecon, the problem with the low fluxes was to do with the datacolumn in mstransform. I was copying the commands from the original weblog, where data was selected. I just had to change this to corrected and all was fixed.

This recleaning was to fix the issue with the bad PSF and failed automasking due to the PSF being placed outside of the mosaic as a result of the weird mosaic shape. I tried using the psfphasecenter parameter to do this, but tclean failed no matter what I tried. I've passed this along internally to the appropriate people. The workaround solution I used was to:

• Place the standard phasecenter near the centre of the mosaic (rather than image centre)
• Increase the imsize to account for the offset introduced with the new phasecenter
• Crop all images post-cleaning to remove unnecessary blank pixels

This isn't the most efficient solution, but hey, it worked ... I'll update the override tclean commands file soon with the parameters used.

@keflavich I've added all of the output files for the continuum + all SPWs, along with FITS files for the .image & .image.pbcor files in /upload/Sgr_A_st_al_03_7M_reclean/. The destination for transfer is /rawdata/2021.1.00172.L/science_goal.uid___A001_X1590_X30a8/group.uid___A001_X1590_X30a9/member.uid___A001_X15a0_X180/.

Here's a preview of the peak intensity maps for each SPW (16 -> 26). All are scaled to the HNCO (SPW 22, bottom left). Residuals and masks look good. I'm happy with the results, so I've marked this as 'Done'.

[keflavich]

I moved the files over.