2011A&A...527A.102B

Query : 2011A&A...527A.102B

2011A&A...527A.102B - Astronomy and Astrophysics, volume 527A, 102-102 (2011/3-1)

Feasibility and performances of compressed sensing and sparse map-making with Herschel/PACS data.

BARBEY N., SAUVAGE M., STARCK J.-L., OTTENSAMER R. and CHANIAL P.

Abstract (from CDS):

The Herschel Space Observatory of ESA was launched in May 2009 and has been in operation ever since. From its distant orbit around L2, it needs to transmit a huge quantity of information through a very limited bandwidth. This is especially true for the PACS imaging camera, which needs to compress its data far more than what can be achieved with lossless compression. This is currently solved by including lossy averaging and rounding steps onboard. Recently, a new theory called compressed sensing has emerged from the statistics community. This theory makes use of the sparsity of natural (or astrophysical) images to optimize the acquisition scheme of the data needed to estimate those images. Thus, it can lead to high compression factors. A previous article by Bobin et al. (2008, IEEE J. Selected Topics Signal Process., 2, 718) has shown how the new theory could be applied to simulated Herschel/PACS data to solve the compression requirement of the instrument. In this article, we show that compressed sensing theory can indeed be successfully applied to actual Herschel/PACS data and significantly improves over the standard pipeline. To fully use the redundancy present in the data, we perform a full sky-map estimation and decompression at the same time, which cannot be done in most other compression methods. We also demonstrate that the various artifacts affecting the data (pink noise and glitches, whose behavior is a priori not very compatible with compressed sensing) can also be handled in this new framework. Finally, we compare the methods from the compressed sensing scheme and data acquired with the standard compression scheme. We discuss improvements that can be made on Earth for the creation of sky maps from the data.

Abstract Copyright: ∼

Journal keyword(s): instrumentation: photometers - methods: numerical - infrared: general - methods: observational

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024 		#notes
1 NGC 6946 H2G 20 34 52.332 +60 09 13.24   10.5       ~ 2527 2

Query : 2011A&A...527A.102B

Basic data :
NGC 6946 -- HII Galaxy
Origin of the objects types :

(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: 		G (2011MNRAS,APG,...), Rad (BWE,GB6,...), X (2E,RX,...), smm (JCMTSE,JCMTSF), IR (IRAS,PSCz), H2G (2013MNRAS), GiG ([CHM2007]), AG? (2020MNRAS), G? (2012ApJ)
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) : 		20 34 52.332 +60 09 13.24 (Infrared) [ ] C 2006AJ....131.1163S
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) : 		20 33 49.241 +59 58 48.27 [ ]
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) : 		095.718766 +11.672736 [ ]
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, ∼=unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz : 		V(km/s) 45 [7] / z(~) 0.000150 [0.000023] / cz 44.97 [6.90]
   D 2002LEDA.........0P
Syntax of morphological type is : mtype quality bibcode
  • mtype : Hubble morphological class (spirals, ellipticals, etc)
  • quality : flag of quality (A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the morphological type reference
Morphological type: 		Sc C 2019MNRAS.485.1477K
Syntax of angular size is : "maj-axis min-axis angle (wtype) quality bibcode"
  • maj-axis : major axis size (arc minutes)
  • min-axis : minor axis size (arc minutes)
  • angle : orientation angle (in degrees)
  • (wtype) : wavelength class for the origin of the angular size (Rad, mm, IR, Opt, UV, Xray, Gam)
  • quality : flag of quality of the angular size values ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the angular size reference
Angular size (arcmin): 		11.48 10.72 ~ (Opt) D 2003A&A...412...45P
Syntax of fluxes (or magnitudes) is : "filter-name (System) flux-value [error] quality MultVarFlags bibcode"
  • filter-name : U, B, V, R, I, G, J, H, K, u, g, r, i, z
  • (System) : may be AB (default is Vega)
  • flux-value : value of flux or magnitude
  • [error] : error value
  • quality : flag of quality of the flux value ( A=best quality -> E=worst quality, {� } =unknown quality)
  • MultVarFlags : Mult is zero or one char (J) for joined photometry ; Var can be zero or two chars (V[0-4])
  • bibcode : bibcode of the flux reference
Fluxes (4) :
B 10.5 [~] E ~
J 6.270 [0.025] C 2006AJ....131.1163S
H 5.913 [0.029] C 2006AJ....131.1163S
K 5.369 [0.034] C 2006AJ....131.1163S
SIMBAD within arcmin
', {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 Simbad points in this preview
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within arcsec The VizieR photometry tool allows for easy visualization of photometry points extracted around the Simbad position from photometry-enabled catalogues in VizieR.
The search radius has to be specified by the user. It is currently limited to a maximum of 30 arcsec. It depends mostly on the precision or quality of the coordinates (SIMBAD and VizieR catalogs), the resolution of the images from which the sources were extracted, source extent, and source crowding.
Suggestions are: crowded field: 0.5 to 1.5 arcsec, 3 arcsec otherwise; uncertain coordinates (SIMBAD quality E or coordinates without reference): 5 to 30 arsec (risky!). sed-help-icon
Some important notes on this object about identifications and objects associations.
notes:

Hierarchy : number of linked objects
whatever the membership probability is (see description here ) :

: 2
The count displayed here is the number of children objects.
The list obtained by clicking the button may be larger, as some children may be linked with different references or probability.

%This number is the number of distinct objets linked, by using this button, you will obtain all links (may be more than one) from that object to his children

: 442 		: 6 Display criteria :

The link on the acronym of the identifiers give access to the information for this acronym in the dictionary of nomenclature.
Identifiers (35) :
An access of full data is available using the icon Vizier near the identifier of the catalogue

NGC 6946 IRAS F20338+5958 RX J2034.9+6010 Z 304-6
APG 29 JCMTSE J203452.0+600913 SPB 263 Z 2033.8+5959
BWE 2033+5958 JCMTSF J203452.0+600913 TC 601 [CAB95] IRAS F20338+5958
2E 4389 LEDA 65001 UGC 11597 [CHM2007] HDC 1123 J203452.33+6009132
2E 2033.9+6000 2MASX J20345233+6009132 UZC J203452.8+600911 [CHM2007] LDC 1412 J203452.33+6009132
GB6 B2033+5959 MCG+10-29-006 WB 2033+5958 [M98c] 203348.8+595850
87GB 203349.0+595856 MY 203351.2+595835.0 WN B2033.8+5958C [NKB95] N6946
IRAS 20338+5958 MY 203351.2+600900.1 WN B2033.8+5958 [VDD93] 229
IRAS 20338+5959 PSCz Q20338+5958 2XMM J203452.4+600912

References (2527 between 1850 and 2024) (Total 2527)
Simbad bibliographic survey began in 1850 for stars (at least bright stars) and in 1983 for all other objects (outside the solar system).
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Collections of Measurements


velocities : 8    distance : 7   

   

Observing logs


herschel : 34    ISO : 81    IUE : 2    XMM : 8   

   

External archives :

Archive data at HEASARC - High-Energy Astrophysics Science Archive Research Center

Data at NED - NASA/IPAC Extragalactic Database : NGC 6946

Link by name to the catalogue in VizieR :

NGC 6946 APG 29 BWE 2033+5958 2E 4389 IRAS 20338+5958
IRAS 20338+5959 IRAS F20338+5958 2MASX J20345233+6009132 UGC 11597 WN B2033.8+5958C
WN B2033.8+5958

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