Note: this is an
archived version which has been superseded. The current SNR
catalogue is at
http://www.mrao.cam.ac.uk/surveys/snrs/
A Catalogue of Galactic Supernova Remnants
(Version VI, 1996 August)
D.A. Green
Mullard Radio Astronomy Observatory
Cavendish Laboratory
Madingley Road
Cambridge CB3 0HE
UNITED KINGDOM
Contents.
Links from here.
This catalogue of Galactic supernova remnants (SNRs) is an updated version of
those presented in detail in Green (1984, 1988), in summary form in Green
(1991, 1996) - hereafter Versions I, II, III and IV respectively - and on
the World-Wide-Web (Version V, 1995 July). (Note that Version IV, although
published in 1996, was produced in 1993.)
This, the 1996 August version of the catalogue contains 215 SNRs (which is 21
more than in Version V), with about thousand references in the detailed
listings, plus notes on several dozen possible or probable remnants. For each
remnant in the catalogue the following parameters are given.
- Galactic Coordinates of the source centroid quoted to the
nearest tenth of a degree as is conventional.
- Other Names that are commonly used for the object. These
are given in parentheses if the remnant is only a part of the source. For some
object, notably the Crab Nebula, not all common names are given.
- Right Ascension and Declination of the source
centroid. The accuracy of the quoted values 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 respectively, whereas for larger remnants they are rounded to
coarser values, but are in every case sufficient to specify a point within the
boundary of the remnant. These coordinates are almost always deduced from radio
maps rather than from X-ray or optical observations, and are for B1950.0.
- Angular Size of the remnant, in arcminutes, 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 is quoted for the angular size of the more nearly
circular remnants, which is the diameter of a circle with an area equal to that
of the remnant, but for elongated remnants the product of two values is quoted,
and these are the major and minor axes of the remnant boundary modelled 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 its catalogue entry), 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.
- Flux Density of the remnant at 1 GHz in jansky. 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.
- Spectral Index of the integrated radio emission from the
remnant,
either a value that is quoted in 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 because there
is evidence that the spectral index varies across the face of the remnant or
that the integrated spectrum is curved, and in these cases the spectral index
is given as `varies' (refer to the description of the remnant and recent
references in the catalogue entry for more information). In some cases, for
example where the remnant is highly confused with thermal emission, the
spectral index is given as `?' since no value can be deduced with any
confidence.
- Type of the SNR, either `S', `F' or `C' if the remnant
shows a `shell', `filled-centre' or `composite' (or `combination') radio
structure (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.
In the detailed listings, for each remnant, notes on a
variety of topics are given. First, it is noted if other Galactic coordinates
have at times been used to label it (usually before good observations have
revealed the full extent of the object), if the SNR is thought to be the
remnant of a historical SN, or if the nature of the source as an SNR has been
questioned (in which case an appropriate reference is usually given later in
the entry). Brief descriptions of the remnant from the available radio, optical
and X-ray observations as applicable are then given, together with notes on
available distance determinations, and any point sources or pulsars in the
field of the object (although they may not necessarily be related to the
remnant). Finally, appropriate references to observations are given for each
remnant, complete with journal, volume, page, and a short description of what
information each paper contains (for radio observations these include the
telescopes used, the observing frequencies and resolutions, together with any
flux density determinations). These references are not complete, but
cover representative and recent observations of the remnant, and they should
themselves include references to earlier work. The references do not generally
include large observational surveys - of particular interest in this respect
are: the Effelsberg 100-m survey at 2.7 GHz of the Galactic plane 358°
< l < 240°, |b| < 5° by Reich et al. (1990) and Fürst
et al. (1990); reviews of the radio spectra of some SNRs by Kassim (1989) and
by Kovalenko, Pynzar' & Udal'tsov (1994); the Parkes 64-m survey at 2.4 GHz of
the Galactic plane 238° < l < 365°, |b| < 5° by
Duncan et al. (1995); reviews of Einstein X-ray imaging and FPCS
observations of Galactic SNRs by Seward (1990) and Lum et al. (1992)
respectively; surveys of IRAS observations of SNRs and their immediate
surroundings by Arendt (1989) and by Saken, Fesen & Shull (1992); and the
survey of HI emission towards SNRs by Koo & Heiles (1991).
The catalogue is available as a summary listing
of the parameters for each remnant, and as
detailed listings (with references) for each
object. Also see the list of
other names used for these SNRs, and
the list of abbreviations for journals,
proceedings and telescopes (both radio and X-ray) used in the detailed
listings.
The following objects, which were listed in Version I of the
catalogue were removed because they were no longer thought to be remnants, or
are poorly observed (see Version II for references and further details):
G2.4+1.4 (see also Gray 1994a; Goss & Lozinskaya 1995; Polcaro et al. 1995),
G41.9-4.1 (=CTB 73, PKS 1920+06), G47.6+6.1 (=CTB 63), G53.9+0.3
(part of HC40), G93.4+1.8 (=NRAO 655), G123.2+2.9, G194.7+0.4 (the
Origem Loop), G287.8-0.5 (see below), G322.3-1.2 (=Kes 24) and
G343.0-6.0 (see below).
G350.1-0.3, which was listed in Version II of the catalogue, was removed as
it is no longer thought to be a SNR (see Version III for details).
G358.4-1.9, which was listed in Version IV of the catalogue, was removed, as
following the discussion of Gray (1994a), as it is not clear that this is a
SNR.
In this version of the catalogue the following have been removed:
- G240.9-0.9, as Duncan et al. (1996) show that it is not a
distinct SNR;
- G299.0+0.2 and G328.0+0.3, following improved radio
observations, and comparisons with IRAS data by Whiteoak & Green (1996) which
showed that these are not SNRs.
The following objects, which have been reported as SNRs, but have not
been included in any of SNR catalogues, have subsequently been shown not to be
SNRs.
- G70.7+1.2, which was reported as a SNR by Reich et al.
(1985), but this has not been confirmed by later observations (see Green 1986;
de Muizon et al. 1988; Becker & Fesen 1988; Caswell 1988; Bally et al. 1989;
Phillips, Onello & Kulkarni 1993; Onello et al. 1995).
- G81.6+1.0 a possible SNR in W75 reported by Ward-Thompson &
Robson (1991). From the published data (see the observations in Wendker, Higgs
& Landecker 1991) it was noted in Version IV of the catalogue that this is thermal source not a
SNR, because of its thermal radio spectrum, and high infrared-to-radio emission
(see the subsequent discussion by Wendker et al. 1993).
- Green & Gull (1984) suggested that G227.1+1.0 as a very
young SNR, but subsequent observations (Channan et al. 1986; Green & Gull
1986) have shown that this is most likely an extragalactic source, not an SNR.
- A candidate SNR, G274.7-2.8, identified by Helfand & Channan
(1989), has been shown not to be a SNR by Caswell & Stewart (1991).
- G25.5+0.2, which was reported as a very young SNR by Cowan
et al. (1989), although this identification was not certain (see White &
Becker 1990; Green 1990; Zijlstra 1991). Sramek et al. (1992) report the
detection of recombination lines from this source (also see Subrahmanyan et al.
1993). Becklin et al. (1994) identify G25.5+0.2 as a ring nebula around a
luminous blue star.
- Most of the possible SNRs listed by Gorham (1990) - following
up SNR candidates suggested by Kassim (1988) - have been shown not to be SNRs
by Gorham, Kulkarni & Prince (1993).
Some entries in the catalogue have been renamed, due to
improved observations revealing a larger true extent for the object (G5.3-1.0
is now G5.4-1.2; G193.3-1.5 is now G192.8-1.1; G308.7+0.0 is now
incorporated into G308.8-0.1).
The following remnants were added to Version II of the catalogue:
G0.9+0.1, G1.9+0.3, G5.9+3.1, G6.4+4.0, G8.7-0.1, G16.8-1.1,
G18.9-1.1, G20.0-0.2, G27.8+0.6, G30.7+1.0, G31.5-0.6, G36.6-0.7,
G42.8+0.6, G45.7-0.4, G54.1+0.3, G73.9+0.9, G179.0+2.6, G312.4-0.4,
G357.7+0.3 and G359.1-0.9.
The following remnants were added to Version III of the catalogue:
G4.2-3.5, G5.2-2.6, G6.1+1.2, G8.7-5.0, G13.5+0.2, G15.1-1.6,
G16.7+0.1, G17.4-2.3, G17.8-2.6, G30.7-2.0, G36.6+2.6, G43.9+1.6,
G59.8+1.2, G65.1+0.6, G68.6-1.2, G69.7+1.0, G279.0+1.1, G284.3-1.8
(=MSH 10-53), G358.4-1.9 and G359.0-0.9.
The following remnants were added to Version IV of the catalogue:
G59.5+0.1, G67.7+1.8, G84.9+0.5, G156.2+5.7, G318.9+0.4,
G322.5-0.1, G343.1-2.3, and G348.5-0.0.
The following remnants were added to Version V of the catalogue:
G1.0-0.1, G1.4-0.1, G3.7-0.2, G3.8+0.3, G28.8+1.5, G76.9+1.0,
G272.2-3.2, G341.2+0.9, G354.1+0.1, G355.6-0.0, G356.3-0.3,
G356.3-1.5 and G359.1+0.9.
The following remnants have been added to this version of the catalogue:
- G13.3-1.3 and G299.2-2.9, both identified from ROSAT
observations by Seward et al. (1995) and Busser, Egger & Aschenbach (1996)
respectively;
- G286.5-1.2, G289.7-0.3, G294.1-0.0, G299.6-0.5,
G301.4-1.0, G308.1-0.7, G310.6-0.3, G310.8-0.4, G315.9-0.0,
G317.3-0.2, G318.2+0.1, G320.6-1.6, G321.9-1.1, G327.4+1.0,
G329.7+0.4, G342.1+0.9, G343.1-0.7, G345.7-0.2, G349.2-0.1,
G351.7+0.8, G351.9-0.9 and G354.8-0.8, identified or confirmed as SNRs
from the MOST radio survey of Whiteoak & Green (1996).
The following are possible or probable SNRs for which further
observations are required to confirm their nature or parameters, or for which
observations are not yet in the published literature.
- A possible SNR near the Galactic centre reported by Ho et al.
(1985) from radio observations.
- Gosachinskii (1985) reported evidence for non-thermal
radio emission, presumably from SNRs, associated with several bright, thermal
Galactic sources (also see Odegard 1986, who questions the reliability of some
of Gosachinskii's results).
- G300.1+9.4, a possible SNR nearly 2° in diameter
reported by Dubner, Colomb & Giacani (1986) from radio observations.
- Routledge & Vaneldik (1988) report a possible faint shell SNR
nearly 2° in diameter at radio wavelengths, near the young pulsar PSR
1930+22 (see also Gómez-González & del Romero 1983, who report a smaller
(about 40 arcmin) possible SNR (G57.1+1.7) associated with this pulsar, and
see Caswell, Landecker & Feldman 1985 and Kovalenko 1989).
- G28.6-0.2, a possible SNR reported by Helfand et al. (1989)
from radio observations.
- Seven possible remnants (G45.9-0.1, G55.2+0.5, G63.7+1.1,
G71.6-0.5, G72.2-0.3, G83.0-0.2 and G85.2-1.2) of the eleven reported
by Taylor, Wallace & Goss (1992) from a radio survey of part of the Galactic
plane. (One of the other possible SNRs reported by Taylor et al., G76.9+0.9,
has now been included in the catalogue, but is called G76.9+1.0, see above.)
- A faint, poorly defined possible remnant G41.1+1.2 reported
by Gorham et al. (1993) from radio observations.
- G9.7-0.1, a possible SNR report by Frail, Kassim & Weiler
(1994) from radio observations.
- Ten (G355.4+0.7, G356.6+0.1, G357.1-0.2, G358.1+1.0,
G358.5-0.9, G358.7+0.7, G359.2-1.1, G0.3+0.0, G3.1-0.6 and
G4.2+0.0) of the seventeen possible SNRs listed by Gray (1994b) from radio
observations near the Galactic centre (see also Dagkesamanskii, Kovalenko &
Udal'tsov 1994, who from radio observations also suggest a SNR, G0.4+0.1, in
the Galactic centre region which presumably related to G0.3+0.0 suggested by
Gray).
- G104.7+2.8, a possible SNR reported by Green & Joncas (1994)
from radio observations. However, recent observations at 10.7 GHz (W. Reich,
private communication) cast doubt on this identification, as they do not
support a non-thermal radio spectrum for the source.
- G310.6-0.2 and G310.8-0.4, two possible radio SNRs listed
by Whiteoak, Cram & Large (1994).
- G11.2-1.1, a possible SNR listed by Kovalenko, Pynzar' &
Udal'tsov (1994), based on unpublished radio studies (Trushkin 1988, preprint).
- Duncan et al. (1995) list 10 large-scale (1.5 to 10 degree),
and 22 smaller, low radio surface-brightness candidate SNRs.
- Whiteoak & Green (1996) list sixteen possible SNRs
(G308.4-1.4, G317.5+0.9, G319.9-0.7, G320.6-0.9, G322.7+0.1,
G322.9-0.0, G323.2-1.0, G324.1+0.1, G325.0-0.3, G331.8-0.0,
G337.2+0.1, G339.6-0.6, G345.1+0.2, G345.1-0.2, G348.8+1.1 and
G350.1-0.3) from their radio survey of much of the southern Galactic plane.
- G343.0-6.0 was listed in Version I as a SNR, identified
optically by Meaburn & Rovithis (1977). However, it was removed from the
catalogue in Version II as its extent is uncertain, and it has not been
identified at other wavelengths (also see Bedford et al. 1984; Meaburn et al.
1991).
- A possible SNR overlapping G296.1-0.5, identified from
optical (and X-ray) observations by Hutchings, Crampton & Cowley (1981).
- A SNR (G260.4-3.3) about 4 arcmin in diameter within the
Puppis A remnant identified optically by Winkler et al. (1989). This has not
been detected at radio wavelengths (Dubner et al. 1991).
- A possible SNR (G32.1+0.1) reported from optical spectroscopy
by Thompson, Djorgovski & de Carvalho (1991), following up radio and infrared
observations of Jones, Garwood & Dickey (1988).
- G203.2-12.3, a optical ring about 3 arcmin in diameter, which
was identified as a SNR by Winkler & Reipurth (1992).
- G75.5+2.4, a possible large (about 2°) old SNR in
Cygnus suggested by Nichols-Bohlin & Fesen (1993) from infra-red and optical
observations (see also Dewdney & Lozinskaya 1994).
- A possible optical SNR (G247.8+4.9) noted by Weinberger
(1995), which may be Balmer dominated.
- H1538-32 a large X-ray source in Lupus, near l=307°,
b=20° (Reigler, Agrawal & Gull 1980, see also Colomb, Dubner &
Giacani 1984) which is a possible old SNR;
- The Monogem ring, near l=203°, b=+12°, is a
possible old SNR (see Nousek et al. 1981; Plucinsky et al. 1996, and references
therein).
- X-ray emission in the Gum Nebula near l=250°,
b=0° (Leahy, Nousek & Garmire 1992, see also Reynolds 1976, Dubner
et al. 1992 and Duncan et al. 1996) which, together with optical spectra
indicate a possible old remnant;
- an X-ray enhancement due to an old SNR in Eridanus near
l=200°, b=-40° (Naranan et al. 1976, see also Burrows et al.
1993 and Snowden et al. 1995).
- G189.6+3.3, a faint, possible SNR overlapping G189.1+3.0
(=IC443) identified by Asaoka & Aschenbach (1994) from ROSAT X-ray
observations.
- G117.7+0.6, a faint shell of soft X-ray emission near CTB1
(=G116.9+0.2), which contains a pulsar (Hailey & Craig 1995).
- G284.2-1.8 (=MSH 10-53), which was listed in early
SNR catalogues, but subsequently rejected because of its apparent thermal
spectrum (see Version II for details). Ruiz & May (1986) report optical and CO
radio observations that indicate the presence of shock-excited material in this
region, supporting the SNR identification, although the parameters of any SNR
are not well defined.
- G287.8-0.5, which is associated with eta Carinae, was
listed in Version I as a SNR, but was removed from the catalogue in Version II
as its parameters are uncertain (see Jones 1973, Retallack 1984, Tateyama,
Strauss & Kaufmann 1991, and the discussion in Version II).
- G359.2-0.8 (the `mouse'), near the Galactic centre, which has
been suggested as being analogous to the central region of CTB 80
(=G69.0+2.7) by Predehl & Kulkarni (1995).
Finally, it should be noted that some radio loops in the
Galactic plane (see Berkhuijsen 1973) may be parts of very large, old SNRs, but
they have not been included in the catalogue (see also Combi et al. 1995).
As noted in Versions II and IV of the catalogue, the following sources are
listed as SNRs, although, as discussed in each case, the identifications are
not certain: G5.4-1.2, G39.7-2.0 (=W50), G65.7+1.2 (=DA 495),
G69.0+2.7 (=CTB 80), G318.9+0.4 and G357.7-0.1. The nature of
G76.9+1.0 (an unusual radio source similar to G65.7+1.2 (=DA 495)), and
of G354.1+0.1 (which appears may be similar to G357.7-0.1 (=MHS
17-39)) are also uncertain (see Landecker, Higgs & Wendker 1993 and
Frail, Goss & Whiteoak 1994 respectively).
There are also some objects that have been identified as SNRs and are listed in
the catalogue, although they have been barely resolved in the available
observations, or are faint, and have not been well separated from confusing
background or nearby thermal emission, and their identification as SNRs, or at
least their parameters remain uncertain.
I am grateful to the many colleagues who have commented on the errors and
omissions in previous versions of the catalogue. No doubt errors remain in this
version, and I am always happy to receive feedback from users of the
catalogue.
This research has made use of the Bath Information & Data Services (BIDS) ISI
databse, NASA's Astrophysics Data System (ADS) Abstract Service, and the SIMBAD
database, operated by CDS, Strasbourg, France.
- Arendt R.G., 1989, ApJS, 70, 181.
- Asaoka I. & Aschenbach B., 1994, A&A, 284, 573.
- Bally J., Pound M.W., Stark A.A., Israel F., Hirano N.,
Kameya O., Sunada K., Hayashi M., Thronson H. & Hereld,
M., 1989, ApJ, 338, L65.
- Becker R.H. & Fesen R.A., 1988, ApJ, 334, L40.
- Becklin E.E., Zuckerman B., McLean I.S. & Geballe T., 1994,
ApJ, 430, 774.
- Bedford D.K., Elliott K.H., Ramsey B. & Meaburn J., 1984,
MNRAS, 210, 693.
- Berkhuijsen E.M., 1973, A&A, 24, 143.
- Burrows D.N., Singh K.P., Nousek J.A., Garmire G.P. & Good,
J., 1993, ApJ, 406, 97.
- Busser J.-U., Egger R. & Aschenbach B., 1996, A&A, 310, L1.
- Caswell J.L., 1988, in SNRISM, p269.
- Caswell J.L. & Stewart R.T., 1991, PASA, 9, 103.
- Caswell J.L., Landecker T.L. & Feldman P.A., 1988, AJ, 90, 488.
- Channan G.A., Helfand D.J., Spinrad H. & Ebneter K., 1986,
Nature, 320, 41.
- Colomb F.R., Dubner G.M. & Giacani E.B., 1984, A&A, 130, 294.
- Combi J.A., Testari J.C., Romero G.E. & Colomb F.R., 1995,
A&A, 296, 514.
- Cowan J.J., Ekers R.D., Goss W.M., Sramek R.A., Roberts,
D.A. & Branch D., 1989, MNRAS, 241, 613.
- Dagkesamanskii R.D., Kovalenko A.V. & Udal'tsov V.A., 1994,
AR, 38, 23.
- de Muizon M., Strom R.G., Oort M.J.A., Claas J.J. & Braun R.,
1988, A&A, 193, 248.
- Dewdney P.E. & Lozinskaya T.A., 1994, AJ, 108, 2212.
- Dubner G.M., Colomb F.R. & Giacani E.B., 1986, AJ, 91, 343.
- Dubner G.M., Braun R., Winkler P.F. & Goss 1991, AJ, 101, 1466.
- Dubner G., Giacani E., Cappa de Nicolau C. & Regnoso E., 1992,
A&AS, 96, 505.
- Duncan A.R., Stewart R.T., Haynes R.F., Jones & K.L., 1995,
MNRAS, 277 36.
- Duncan A.R., Stewart R.T., Haynes R.F., Jones & K.L., 1996,
MNRAS, 280 252.
- Frail D.A., Goss W.M. & Whiteoak J.B.Z., 1994, ApJ, 437, 781.
- Frail D.A., Kassim N.E. & Weiler K.W., 1994, AJ, 107, 1120.
- Fürst E., Reich W., Reich P. & Reif K., 1990, A&AS, 85, 691.
- Gómez-González J. & del Romero A., 1983, A&A, 123, L5.
- Gorham P.W., 1990, ApJ, 364, 187.
- Gorham P.W., Kulkarni S.K. & Prince T.A., 1993, AJ, 105, 314.
- Gosachinskii, I.V., 1985, SvA, 29, 128.
- Goss W.M. & Lozinskaya T.A., 1995, ApJ, 439, 637.
- Gray A.D., 1994a, MNRAS, 270, 835.
- Gray A.D., 1994b, MNRAS, 270, 847.
- Green D.A., 1984, MNRAS, 209, 449 (Version I).
- Green D.A., 1986, MNRAS, 219, 39P.
- Green D.A., 1988, ASS, 148, 3 (Version II).
- Green D.A., 1990, AJ, 100, 1241.
- Green D.A., 1991, PASP, 103, 209 (Version III).
- Green D.A., 1996, in Supernovae and Supernova Remnants,
(proceedings of IAU Colloquium 145, Xi'an China, 1993 May 24--29),
eds McCray R. & Wang Z., (Cambridge University Press),
p.419 (Version IV).
- Green D.A. & Gull S.F., 1984, Nature, 312, 527.
- Green D.A. & Gull S.F., 1986, Nature, 320, 42.
- Green D.A. & Joncas G., 1994, A&AS, 104, 481.
- Hailey C.J. & Craig W.W., 1995, ApJ, 455, L151.
- Helfand D.J. & Channan G.A., 1989, AJ, 98, 1652.
- Helfand D., Velusamy T., Becker R.H. & Lockman F.J., 1989,
ApJ, 341, 151.
- Hutchings J.B., Crampton D. & Cowley P.A., 1981, AJ, 86, 871.
- Ho P.T., Jackson J.M., Barrett A.H. & Armstrong J.T., 1985,
ApJ, 288, 575.
- Jones B.B., 1973, AuJPh, 26, 545.
- Jones T.J., Garwood R. & Dickey J.M. 1988, ApJ, 328, 559.
- Kassim N.E., 1988, ApJ, 328, L55.
- Kassim N.E., 1989, ApJS, 71, 799.
- Koo B.-C. & Heiles C., 1991, ApJ, 382, 204.
- Kovalenko A.V., 1989, SvAL, 15, 144.
- Kovalenko A.V., Pynzar', A.V. & Udal'tsov V.A., 1994, AR, 38, 95.
- Landecker T.L., Higgs L.A. & Wendker H.I., 1993, A&A, 276, 522.
- Leahy D.A., Nousek J. & Garmire G., 1992, ApJ, 385, 561.
- Lum K.S.K., Canizares C.R., Clark S.W., Coyne J.M.,
Markert T.H., Saez P.J., Schattenburg M.L. & Winkler P.F.,
1992, ApJS, 78, 423.
- Meaburn J. & Rovithis P., 1977, ApSS, 46, L7.
- Meaburn J., Goudis C., Solomos N. & Laspias V., 1991, A&A, 252,
291.
- Naranan S., Shulman S., Friedman H. & Fritz G., 1993.
ApJ, 208, 718.
- Nichols-Bohlin J. & Fesen R.A., 1993, AJ, 105, 672.
- Nousek J.A., Cowie L.L., Hu E., Lindblad C.J. & Garmire G.P.,
1981, ApJ, 248, 152.
- Odegard N., 1986, AJ, 92, 1372.
- Onello J.S., DePree C.G., Phillips J.A. & Goss W.M., 1995,
ApJ, 449, L127.
- Phillips J.A., Onello J.S. & Kulkarni S.R., 1993,
ApJ, 415, 143.
- Polcaro V.F., Rossi C., Norci L. & Viotti R., 1995, A&A, 303, 211.
- Plucinsky P.P., Snowden S.L., Aschenbach B., Eggar R., Edgar R.J,
McCammon D., 1996, ApJ, 463, 224.
- Predehl P. & Kulkarni S.R., 1995, A&A, 294, L29.
- Reich W., Fürst E., Altenhoff W.J., Reich P. &
Junkes N., 1985, A&A, 151, L10.
- Reich W., Fürst E., Reich P. & Reif K., 1990, A&AS, 85, 633.
- Reigler G.R., Agrawal P.C. & Gull S.F., 1988, ApJ, 235, L71.
- Retallack D.S., 1983, MNRAS, 204, 669.
- Reynolds R., 1976, ApJ, 206, 679.
- Routledge D. & Vaneldik J.F., 1988, ApJ, 326, 751.
- Ruiz M.T. & May J., 1987, ApJ, 309, 667.
- Saken J.M., Fesen R.A. & Shull J.M., 1992, ApJS, 81, 715.
- Seward F.D., 1990, ApJS, 73, 781.
- Seward F.D., Dame T.M., Fesen R.A. & Aschenbach B., 1995,
ApJ, 449, 681.
- Snowden S.L., Burrows D.N., Sanders W.T., Aschenbach B. &
Pfeffermann E., 1995, ApJ, 439, 399.
- Sramek R.A., Cowan J.J., Roberts D.A., Goss W.M. & Ekers R.D.,
1992, AJ, 104, 705.
- Subrahmanyan R., Ekers R.D., Wilson W.E., Goss W.M. & Allen,
D.A., 1993, MNRAS, 263, 868.
- Tateyama C.E., Strauss F.M. & Kaufmann P., 1991, MNRAS, 249, 716.
- Taylor A.R., Wallace B.J. & Goss W.M., 1992, AJ, 103, 931.
- Thompson D.J., Djorgovski S. & de Carvalho R.R., 1991, PASP, 103,
487.
- Ward-Thompson D. & Robson, 1991, MNRAS, 248, 670.
- Weinberger R., 1995, PASP, 107, 58.
- Wendker H.I., Higgs L.A. & Landecker T.L., 1991, A&A, 241, 551.
- Wendker H.I., Higgs L.A., Landecker T.L. & Ward-Thompson D.,
1993, MNRAS, 263, 543.
- White R.L. & Becker R.H., 1990, MNRAS, 244, 12P.
- Whiteoak J.B.Z., Cram L.E. & Large M.I., 1994, MNRAS, 269, 294.
- Whiteoak J.B.Z. & Green A.J., 1996, A&AS, 118, 329.
- Winkler P.F. & Reipurth B., 1992, ApJ, 389, L25.
- Winkler P.F., Kirshner R.P., Hughes J.P. & Heathcote S.R.
1989, Nature, 337, 48.
- Zijlstra A.A., 1991, MNRAS, 248, 11P.
Dave Green/MRAO, Cambridge, UK/D.A.Green@mrao.cam.ac.uk