Mysterious absorption feature in field al

[ksi85]

While looking through the SiO Cube mosaic I found a strong double absorption feature in field al.

To understand if this feature is real I checked all the combined cubes for field al at that position and got the following spectra:

spw25:

spw 27:

spw 33:

spw 35:

HCO+:

HNCO:

It looks like all combined spws show these features. The two spectral absorption features are about ~13 km/s apart.

[ksi85]

Looking at the cubes of each configuration, the absorption feature is not clear at all and only visible in the spectrum of the ACA data (blue) and partly in the spectrum of the 12m data (orange):

The images do not show a clear absorption feature:

(12m upper left, ACA, upper right, TP lower left)

[ksi85]

There is also no clear continuum source at that position:

[ksi85]

Feature does not seem to be visible in Mopra data (HNCO as an example):

[ksi85]

circle center coordinates: l=0.5295240159, b=0.0882841052