Browse this table... |
SNRGREEN - Green Catalog of Galactic SNRs (December 2001 Version) |
HEASARC Archive |
This December 2001 version of the catalogue contains 231 SNRs, which is 6 more than listed in the previous version, which this version replaces in the HEASARC database. The basic summary data included in this catalogue for each SNR are its designation, position, angular size (in arcminutes), type, flux density at 1 GHz, spectral index, and any other names by which it is known. Notes on these parameters, on possible remnants not included, and on questionable SNRs that are listed in this catalogue, are given in the full version of the catalogue on the World-Wide-Web at http://www.mrao.cam.ac.uk/surveys/snrs/
It should be noted that there are serious selection effects which apply to the identification of Galactic SNRs (see Green 1991), so that great care should be taken if these data are used in statistical studies.
Green, D.A., MNRAS, 209, 449 (1984) =1984MNRAS.209..449G (Paper I). Green, D.A., ApSS, 148, 3, (1988) =1988APSS..148....3G (Paper II). Green, D.A., PASP, 103, 209 (1991) =1991PASP..103..209G (Paper III). Green D.A., 1996, in Supernovae and Supernova Remnants, (Proceedings of IAU Colloquium 145), eds McCray R. & Wang Z., (Cambridge University Press), p. 419 (Paper IV). Green D.A., 1998, A Catalogue of Galactic Supernova Remnants, 1998 September version <Mullard Radio Astronomy Observatory, Cambridge, United Kingdom (1998)> Green D.A., 2000, A Catalogue of Galactic Supernova Remnants, 2000 August version <Mullard Radio Astronomy Observatory, Cavendish Laboratory, Cambridge, United Kingdom (2000)> Green D.A., 2001, A Catalogue of Galactic Supernova Remnants, 2001 December version <Mullard Radio Astronomy Observatory, Cambridge, United Kingdom (2001)>
Name
The catalog designation of the remnant given with the
`SNR` prefix and the LII and BII coordinates to the nearest 0.1 degrees
in the way recommended by the Dictionary of Astronomical Nomenclature and
recognized by SIMBAD. Notice that this supercedes the `old' nomenclature
which used a 'G' prefix (and which was in fact used in the CDS table from
which this present database was constructed).
RA
The Right Ascension of the remnant. The accuracy of the quoted positions
depends on the size of the remnant; for small remnants they are to the nearest
few seconds of time and the nearest minute of arc for RA and Dec, respectively,
but for larger remnants they are rounded to coarser values. They are in every
case sufficient to specify a point within the boundary of the remnant. These
coordinates are generally deduced from radio maps rather than from X-ray or
optical observations, and were given in the original catalog in J2000 equator.
Dec
The Declination of the remnant. The accuracy of the quoted positions
depends on the size of the remnant; for small remnants they are to the nearest
few seconds of time and the nearest minute of arc for RA and Dec, respectively,
but for larger remnants they are rounded to coarser values. They are in every
case sufficient to specify a point within the boundary of the remnant. These
coordinates are generally deduced from radio maps rather than from X-ray or
optical observations, and were given in the original catalog in J2000 equator.
LII
The galactic longitude of the remnant.
BII
The galactic latitude of the remnant.
Major_Diameter
The major diameter of the remnant, in arcminutes. The
angular size information is usually taken from the highest resolution radio
map available, although, for some barely resolved sources that are thought to
be SNRs, the only available size is that from Gaussian models after
deconvolution with the observed beam size. The boundary of most remnants
approximates reasonably well to a circle or an ellipse. A single value
(placed in the major diameter field) is quoted for the angular size of the
more nearly circular remnants, being the diameter of a circle with an area
equal to that of the remnant, but, for elongated remnants, both major and
minor diameters are given, these being the major and minor axes of the remnant
boundary modeled as an ellipse. In a few cases an ellipse is not a satisfactory
description of the boundary of the object (refer to the description of the
individual object given in the full catalogue entry in the World-Wide Web
version of the SNR Catalog at http://www.mrao.cam.ac.uk/surveys/snrs/ ),
although an angular size is still quoted for information. For `filled-centre'
remnants, the size quoted is for the largest extent of the observed radio
emission, not, as at times has been used, the half-width of the centrally
brightened peak.
Minor_Diameter
The minor diameter of the remnant, in arcminutes. The
angular size information is usually taken from the highest resolution radio
map available, although, for some barely resolved sources that are thought to
be SNRs, the only available size is that from Gaussian models after
deconvolution with the observed beam size. The boundary of most remnants
approximates reasonably well to a circle or an ellipse. A single value
(placed in the major diameter field) is quoted for the angular size of the
more nearly circular remnants, being the diameter of a circle with an area
equal to that of the remnant, but, for elongated remnants, both major and
minor diameters are given, these being the major and minor axes of the remnant
boundary modeled as an ellipse. In a few cases an ellipse is not a satisfactory
description of the boundary of the object (refer to the description of the
individual object given in the full catalogue entry in the World-Wide Web
version of the SNR Catalog at http://www.mrao.cam.ac.uk/surveys/snrs/ ),
although an angular size is still quoted for information. For `filled-centre'
remnants, the size quoted is for the largest extent of the observed radio
emission, not, as at times has been used, the half-width of the centrally
brightened peak.
Flag_Major_Diameter
This flag is set to '?' if there is uncertainty in
the quoted angular size information.
Type
The morphological type of the SNR, either "S", "F" or "C" according to
whether the remnant shows a "shell", "filled-center" or "composite" (or
"combination") radio structure, respectively, (or "S?", "F?" or "C?",
respectively, if there is some uncertainty), or "?" in several cases
where an object is conventionally regarded as an SNR even though its nature is
poorly known or not well understood.
Limit_Flux_1_GHz
This flag is set to '>' if the quoted 1 GHz flux density
is a lower limit.
Flux_1_GHz
The flux density of the remnant at 1 GHz, in milliJanskies
(mJy). This is not a measured value, but that deduced from the observed radio
frequency spectrum of the source. The frequency of 1 GHz is chosen because
flux density measurements at frequencies both above and below this value
are usually available.
Flag_Flux_1_GHz
This flag is set to '?' if the quoted 1 GHz flux density
is considered uncertain.
Spectral_Index
The radio spectral index {alpha} where S({nu}), the
flux density at frequency nu, is proprtional to {nu}^-{alpha}.
The spectral index of the integrated radio emission from the remnant
is either a value quoted from the literature, or one deduced from the
available integrated flux densities of the remnant. For several SNRs a
simple spectral model is not adequate to describe their radio emission,
either because the spectral index varies across the face of the remnant or
because the integrated spectrum is curved, and in these cases the
parameter flag_spectral_index (q.v.) is set to 'V'. In some cases, for
example where the remnant is highly confused with thermal emission, the
parameter flag_spectral_index (q.v.) is set to '?' since either no
value can be deduced with any confidence, or only an uncertain value
can be deduced.
Flag_Spectral_Index
This flag is set to 'V' if a simple spectral model is
not adequate to describe the remnants's radio emission, either because the
spectral index varies across the face of the remnant or because the integrated
spectrum is curved, or is set to '?' for cases where the remnant's emission
is highly confused with thermal emission, so that either no
value can be deduced with any confidence, or only an uncertain value
can be deduced.
Alt_Names
Up to three alternate commonly used name for the remnant.
A name that is given in parentheses indicates that the remnant is only a part
of the source. For some objects, notably the Crab Nebula, not all common names
are given.
Class
The BROWSE classification code populated using the type parameter.