J/A+A/662/A9 15 dense molecular cloud regions ALMA images (Ginsburg+, 2022)
ALMA-IMF II: Investigating the origin of stellar masses:
Continuum images and data processing.
Ginsburg A., Csengeri T., Galvan-Madrid R., Cunningham N.,
Alvarez-Gutierrez R.H., Baug T., Bonfand M., Bontemps S., Busquet G.,
Diaz-Gonzalez D.J., Fernandez-Lopez M., Guzman A., Herpin F., Liu H.,
Lopez-Sepulcre A., Louvet F., Maud L., Motte F., Nakamura F., Nony T.,
Olguin F.A., Pouteau Y., Sanhueza P., Stutz A.M., Towner A.P.M.
(The ALMA-IMF Consortium)
Armante M., Battersby C., Bronfman L., Braine J., Brouillet N.,
Chapillon E., Di Francesco J., Gusdorf A., Izumi N., Joncour I.,
Walker Lu X., Men'shchikov A., Menten K.M., Moraux E., Molet J., Mundy L.,
Nguyen Luong Q., Reyes-Reyes S.D., Robitaille J., Rosolowsky E.,
Sandoval-Garrido N.A., Svoboda B., Tatematsu K., Walker D.L., Whitworth A.,
Wu B., Wyrowski F.
<Astron. Astrophys. 662, A9 (2022)>
=2022A&A...662A...9G 2022A&A...662A...9G (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; H II regions ; Interstellar medium ;
Interferometry
Keywords: instrumentation: interferometers - stars: luminosity function -
mass function - ISM: structure - submillimeter: ISM -
stars: protostars - (ISM:) HII regions
Abstract:
We present the first data release of the ALMA-IMF Large Program, which
covers the 12m-array continuum calibration and imaging. The ALMA-IMF
Large Program is a survey of fifteen dense molecular cloud regions
spanning a range of evolutionary stages that aims to measure the core
mass function (CMF). We describe the data acquisition and calibration
done by the ALMA observatory and the subsequent calibration and
imaging we performed. The image products are combinations of multiple
12m array configurations created from a selection of the observed
bandwidth using multi-term, multi-frequency synthesis imaging and
deconvolution. The data products are self-calibrated and exhibit
substantial noise improvements over the images produced from the
delivered data. We compare different choices of continuum selection,
calibration parameters, and image weighting parameters, demonstrating
the utility and necessity of our additional processing work. Two
variants of continuum selection are used and will be distributed: the
"best-sensitivity" data, which include the full bandwidth, including
bright emission lines that contaminate the continuum, and "cleanest",
which select portions of the spectrum that are unaffected by line
emission. We present a preliminary analysis of the spectral indices of
the continuum data, showing that the ALMA products are able to clearly
distinguish free-free emission from dust emission, and that in some
cases we are able to identify optically thick emission sources. The
data products are made public with this release.
Description:
The FITS continuum images of the fields are distributed here.
The file types include:
.image.tt0.fits, .image.tt1.fits: The continuum image produced by CASA,
with two Taylor terms. tt0 is the constant component (the continuum),
tt1 is the slope. These images are not corrected by the primary beam
response pattern.
.model.tt0.fits, .model.tt1.fits: The model components used in the
clean. Like the images, these encode the two Taylor terms tt0 and tt1.
The model images are in Jy/pixel units and represent the best
estimation of a noise-free image.
.psf.tt0.fits, psf.tt1.fits: The point spread function for each Taylor
term.
.residual.tt0.fits, .residual.tt1.fits: The residual images, computed
from the image minus the convolution of the model with the PSF.
.mask.fits: The clean mask. Model components were only placed within
this mask. Note that with multiscale clean, it is still possible to
have nonzero model values outside the mask region, but all peaks were
contained within the mask. image.tt0.pbcor.fits: The primary-beam
correct Taylor term 0 continuum image.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
objects.dat 50 15 List of studied objects
list.dat 198 850 List of fits images
fits/* . 850 Individual fits images
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Byte-by-byte Description of file: objects.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.3 deg RAdeg Right ascension (J2000)
9- 15 F7.3 deg DEdeg Declination (J2000)
18- 25 A8 --- Name Name
27- 50 A24 --- SName Simbad name
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Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 55 A26 "datime" Obs.date Observation date
57- 67 E11.6 Hz Freq Observed frequency
69- 73 I5 Kibyte size Size of FITS file
75- 82 A8 --- Name Name
84-198 A115 --- FileName Name of FITS file, in subdirectory fits
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Acknowledgements:
Adam Ginsburg, adamginsburg(at)ufl.edu
(End) Patricia Vannier [CDS] 05-Oct-2021