2010A&A...518L.105M -
Astronomy and Astrophysics, volume 518, L105-105 (2010/7-2)
Direct estimate of cirrus noise in Herschel HI-GAL images.
MARTIN P.G., MIVILLE-DESCHENES M.-A., ROY A., BERNARD J.-P., MOLINARI S., BILLOT N., BRUNT C., CALZOLETTI L., DI GIORGIO A.M., ELIA D., FAUSTINI F., JONCAS G., MOTTRAM J.C., NATOLI P., NORIEGA-CRESPO A., PALADINI R., ROBITAILLE J.-F., STRAFELLA F., TRAFICANTE A. and VENEZIANI M.
Abstract (from CDS):
In Herschel images of the Galactic plane and many star forming regions, a major factor limiting our ability to extract faint compact sources is cirrus confusion noise, operationally defined as the ``statistical error to be expected in photometric measurements due to confusion in a background of fluctuating surface brightness''. The histogram of the flux densities of extracted sources shows a distinctive faint-end cutoff below which the catalog suffers from incompleteness and the flux densities become unreliable. This empirical cutoff should be closely related to the estimated cirrus noise and we show that this is the case. We compute the cirrus noise directly, both on Herschel images from which the bright sources have been removed and on simulated images of cirrus with statistically similar fluctuations. We connect these direct estimates with those from power spectrum analysis, which has been used extensively to predict the cirrus noise and provides insight into how it depends on various statistical properties and photometric operational parameters. We report multi-wavelength power spectra of diffuse Galactic dust emission from HI-GAL observations at 70 to 500µm within Galactic plane fields at l=30 ° and l=59 °. We find that the exponent of the power spectrum is about -3. At 250µm, the amplitude of the power spectrum increases roughly as the square of the median brightness of the map and so the expected cirrus noise scales linearly with the median brightness. For a given region, the wavelength dependence of the amplitude can be described by the square of the spectral energy distribution (SED) of the dust emission. Generally, the confusion noise will be a worse problem at longer wavelengths, because of the combination of lower angular resolution and the rising power spectrum of cirrus toward lower spatial frequencies, but the photometric signal to noise will also depend on the relative SED of the source compared to the cirrus.
Abstract Copyright:
∼
Journal keyword(s):
ISM: structure - ISM: general - stars: formation - stars: protostars - submillimeter: ISM - infrared: ISM
(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases
Other object types:
MoC
()
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
bibcode : bibcode of the coordinates reference
ICRS
coord.
(ep=J2000) :
01 52 29.6 +87 40 31
[
]
D
~
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
bibcode : bibcode of the coordinates reference
FK4
coord.
(ep=B1950 eq=1950) :
01 38 22.4 +87 25 33
[
]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
ra dec : right ascension and declination (unit and frame defined according to your Output Options)
Grey values are increasing the original precision due to the computation of frame transformations
(wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
[error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
position angle (in degrees North celestial pole to East)
quality : flag of quality
E ≥ 10"
D : 1-10" (and some old data)
C : 0.1-1"
B : 0.01-0.1" + 2MASS, Tyc
A : VLBI, Hipparcos
bibcode : bibcode of the coordinates reference
Gal
coord.
(ep=J2000) :
123.6064 +24.8839
[
]
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects">
Overlay
points in this preview
All
(CDSPortal)
Send to
Hierarchy :
number of linked objects
whatever the membership probability is
(see description
here
)
:
The link on the acronym of the identifiers give access to the
information for this acronym in the dictionary of nomenclature.
Identifiers (3) :
An access of full data is available using the icon Vizier near the identifier of the catalogue
References (76 between 1850 and 2024) (Total 76)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
Follow
new references on this object
Annotations :
Annotations allow a user to add a note or report an error concerning the astronomical object and its data. It requires registration to post a note. See description . Please, have a look at Best practices. The list of all annotations to SIMBAD objects can be found here .
To bookmark this query, right click on this link: simbad:objects in 2010A&A...518L.105M and select 'bookmark this link' or equivalent in the popup menu