Continuum: Missing, contamination

[keflavich]

Several fields were noted to have remaining contamination or missing continuum even after our QA process.

• ag: contamination
• y: contamination
• ai: contamination
• ao: missing continuum

[SpacialTree]

• ah: emission seems consistent
  

• g: consistent
  

• n: continuum emission seems weaker in the spw25_27 image (bottom right)
  
  

• w: seems consistent
  

• j:feature in the reimaged mosaic that isn’t in the other images, region with star formation in it is variable w/ some continuum sources visible in some images and not in others
  
  
  

• m: it looks like there is something off field over on the side, is that real? Complicated field as it includes part of Sgr B2. continuum mosaic looks a little different in one region.
  
  

• i: star formation-y region seems fine, but up closer to Sgr B2 there is a spw25_27 thing that doesn’t seem to show up as much (there’s a filamentary thing, but nothing round-ish) in spw33_35
  
  
  

[keflavich]

Thanks @SpacialTree . My takeaway from your report is that field j aggregate needs reimaging, but the rest it's less clear - I don't think the remaining artifacts are caused by continuum mis-selection

[xinglunju]

For all plots, the panels are reimaged mosaic (top left), spw33_35 (top right), pipline mosaic (bottom left), spw25_27 (bottom right)

• f (cmz06): looks good
  

• o (cmz15): looks good.
  

• af (cmz32): looks good.
  

• r (cmz18): looks good.
  

• am (cmz39): looks good.
  

• a (cmz01): looks good.
  

• v (cmz22): on a second look, the northern edge of the spw33_35 image looks wrong. Maybe some issues of weighting that down weight those pointings when we mosaic them? This has been noted by @keflavich in Execution Block ID uid://A001/X15a0/X11e Sgr_A_st_v_03_TM1 #235 (comment)
  

[ksi85]

Since I couldn't find the 12m_continuum_mosaic.fits on Globus, I am doing the comparison with the other three files only. (Happy to re-do once I am back from holidays in two weeks)
Plots are reimaged mosaic (upper left), spw25_27 (upper right), spw33_35 (lower left)

z:
One point source only in spw25_27 (cyan circle)
One point source not (or not as strong) in spw25_27 (yellow circle)

al:
Point source not in spw33_35 (cyan circle)

ar:
Point source not in spw25_27 (or barely visible) (cyan circle)

Fields b, ak, u and an seem fine.
Often, the emission in spw25_27 is stronger (and the negative bowls deeper) than for spw33_35.

[keflavich]

I'm not sure what to make of that source in field 'z'. It's not the kind of artifact we were dealing with earlier - i.e., it's not missing continuum or contaminated continuum. Similar statement about al. I wonder if we're just losing sources on the edge of fields?

The missing source in ar 25_27 looks OK to me - that's just higher noise / bigger beam smearing out the source

[keflavich]

@ksi85 When you have a chance, could you compare the non-mosaic images for z and al to their neighbors?

[ksi85]

Will do, but can only do it in two weeks. On holidays from tomorrow. Adam Ginsburg ***@***.***> schrieb am Fr., 2. Aug. 2024, 16:58:

…

@ksi85 <https://github.com/ksi85> When you have a chance, could you compare the non-mosaic images for z and al to their neighbors? — Reply to this email directly, view it on GitHub <#425 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AW6XNSUQ5O3KQMPPU7BBUWTZPONARAVCNFSM6AAAAABL2S55B6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDENRVGU4TCNBZGM> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[d-l-walker]

aa

Overall looks pretty consistent, though there is a blob near the cursor in the upper right (below Sgr A*) that is present in 25_27 & the combined image, but not in 33_35

ai

Point sources and bright features seem consistent, but there is larger scale, diffuse emission towards the centre that is more prominent in the combined image compared to the separate 25_27/33_35 ???

aq

Seems fairly consistent despite the difficult region. Diffuse emission/ripples more prominent in 25_27 vs. 33_35.

h

Seems consistent. Not much going on here.

p

Seems consistent. Some of the fainter compact sources are harder to see in 25_27, but they are there.

q

Looks consistent. A bit more diffuse emission in 25_27 again.

x

Generally OK. There are two very faint blobs near the cursor that are brighter in 25_27.

[keflavich]

There was a problem @mpound noted in ao in the last WP1 meeting. I investigated it a little here:
#41 (comment)

The problem is that I double-corrected for the LSRK->TOPO conversion. When recording the line-containing frequencies, I had already converted from LSRK -> TOPO. Then, when I applied the line selection in the continuum creation step, I assumed the frequencies were in LSRK.

The solution is - unfortunately - to re-run everything again. It's a simple fix, but won't be instantaneous.

[keflavich]

The good of this problem is: it only affects regions with large LSRK<->TOPO offsets. The bad is... it affects everything.