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J/AJ/104/704  A VLA Search for Young Galactic Supernova Remnants (Sramek+, 1992)

A VLA Search for Young Galactic Supernova Remnants Sramek R.A., Cowen J.J., Roberts D.A., Goss W.M., Ekers R.D. <Astron. J. 104, 704 (1992)> =1992AJ....104..704S
ADC_Keywords: Supernova remnants; Surveys; Radio sources Description: This catalog contains the results of a galactic plane radio survey of possible very young supernova remnants. Of the 290 sources studied, only one possible SNR under 100 years old was identified. Table 1 summarizes the survey data. Table 2 is a compilation of the follow-up 6cm observations of 14 candidate shell sources. The search list was compiled from three surveys: Clark and Crawford (1974) at 408 MHz; Haynes et al (1979) at 5 GHz; Altenhoff et al (1978) at 4.9 GHz. The H110alpha radio recombination line survey of Downes et al. (1980A&AS...40..379D) was used to remove H II regions from the search list. A list of 500 SNR candidates was produced in this way. Limited observing time meant that only the brightest 290 of these sources were observed in late 1984. The authors conclude that only one of these is a possible very young SNR. Abstract: In the attempt to identify very young galactic supernova remnants (SNRs), 290 known compact (<2') galactic plane radio sources were observed at 20cm using the VLA in its 36 km configuration. The VLA observations described could detect supernovae with diameters between 5 and 20"; these would have an age of between 25 and 100 yr. Compact structure was detected in 168 (58%) of the 290 different sources observed; 73 sources (25%) were unresolved or slightly resolved point sources, 21 (7%) were single-well resolved, 56 (19%) were double, 18 (6%) were triple or complex. The large scale structure was completely resolved out for 122 (42%) of sources. Additional observations at 6cm with the VLA in the 11 km configuration were made of 14 sources with apparent shell structures that might have been characteristic of young SNRs. Low resolution observations were made at 20cm of 62 fields where the source was completely resolved out in the high resolution images. Only one source, G25.5+0.2, is a possible very young SNR. New H66_alpha recombination line observations place severe constrains on any thermal interpretation for this object. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 52 291 High resolution galactic plane radio SNR survey table2.dat 65 14 6cm observations of apparent shell structures table3.dat 41 62 Low resolution galactic plane radio SNR survey
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 6 F6.2 deg GLON Galactic Longitude (l2) 7- 11 F5.2 deg GLAT Galactic Latitude (b2) 13- 14 I2 h RAh *Right Ascension hours (1950) 15- 16 I2 min RAm *Right Ascension minutes (1950) 17- 20 F4.1 s RAs *Right Ascension seconds (1950) 21 A1 --- DE- *[± ]Declination sign (1950) 22- 23 I2 deg DEd *Declination degrees (1950) 24- 25 I2 arcmin DEm *Declination minutes (1950) 26- 27 I2 arcsec DEs *Declination seconds (1950) 29 A1 --- l_s20cm *[ <]Limit flag for 20cm flux 30- 34 F5.3 Jy s20cm *Peak 20cm flux density in 3'x3' box 36 A1 --- struct *[PSDCE]Radio structure of dominant source 38- 39 A2 --- obs *Epoch of observation 41 A1 --- ref *Reference of original survey 44- 45 A2 s newRAs *?New Right Ascension (seconds only) 47- 50 F4.1 arcmin newDEm *?New Declination (minutes only) 52 A1 --- note *?Notes
Note on RAh,RAm,RAs,DE-,DEd,DEm,DEs: Right Ascension and Declination (1950.0) as listed in the original survey catalog (see Ref column for survey reference) Note on l_s20cm: < indicates s20cm is approximate 5 sigma upper limit for fields in which the source is resolved out. Note on s20cm: Peak 20cm flux density on VLA image in a 3.0x3.0 arcmin box centered on the catalogued position. For double and complex sources the peak flux density refers only to the brightest component. No attempt was made to integrate flux densities. See the notes for related information. Note on struct: The radio structure of the dominant high brightness compact source. The symbols' meanings are as follows P = point sources or slightly resolved S = single extended source D = double source C = complex structure with several knots and/or filaments E = empty field - the catalog source is probably resolved out Note on obs: "A" observations were toward the galactic anticenter; "B" observations were toward the galactic center A1 = 29 Nov. 1984 A2 = 30 Nov. 1984 B1 = 7 Dec. 1984 B2 = 24 Dec. 1984 B3 = 28 Dec. 1984 Note on ref: 1 = Clark & Crawford 1974 2 = Haynes+ (1979) 3 = Altenhoff+ (1978) Note on newRAs: Improved right ascension seconds of time, if the peak of the compact structure is more than 0.5 arcmin from the catalogued position Note on newDEm: Improved declination arcminutes, if the peak of the compact structure is more than 0.5 arcmin from the catalogued position Note on note: A = improved positions and 6cm flux densities are given in Table 2 B = low resolution, wide field images were made at 20cm; see Table 3 1 = diameter about 45 arcsec 2 = other components about 30 arcsec to SE; 7 and 5 mJy peak 3 = other components about 30 arcsec to S; 5 mJy 4 = listed source is same as listed at l=21.05 5 = extended source 4 mJy; peak 45 arcsec to N; another 90 arcsec to NE
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 6 F6.2 deg GLON *Galactic Longitude (l2) 7- 11 F5.2 deg GLAT *Galactic Latitude (b2) 13- 14 I2 h RAh *?Right Ascension hours (1950) 15- 16 I2 min RAm *?Right Ascension minutes (1950) 17- 20 F4.1 s RAs *?Right Ascension seconds (1950) 21 A1 --- DE- *[± ]Declination sign (1950) 22- 23 I2 deg DEd *?Declination degrees (1950) 24- 25 I2 arcmin DEm *?Declination minutes (1950) 26- 27 I2 arcsec DEs *?Declination seconds (1950) 30- 34 F5.3 Jy s6cm Peak 6cm flux density 37- 41 F5.2 --- SpIndex *Spectral index between 6 and 20cm 44- 65 A22 --- MType *?Description of morphology of source
Note on GLON,GLAT: Galactic longitude and galactic latitude as derived from the original survey catalog Note on RAh,RAm,RAs,DE-,DEd,DEm,DEs: Right Ascension and Declination (1950.0) of the peak brightness of the source as determined by the 6cm observations Note on SpIndex: Spectral index between 6 and 20 cm wavelength using peak flux densities given in Table 1 and Table 2. Note on MType: Description of the source morphology, e.g. Shell, Point Source
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 6 F6.2 deg GLON *Galactic Longitude (l2) 7- 11 F5.2 deg GLAT *Galactic Latitude (b2) 13- 14 I2 h RAh *?Right Ascension hours (1950) 15- 16 I2 min RAm *?Right Ascension minutes (1950) 17- 20 F4.1 s RAs *?Right Ascension seconds (1950) 21 A1 --- DE- *[± ]Declination sign (1950) 22- 23 I2 deg DEd *?Declination degrees (1950) 24- 25 I2 arcmin DEm *?Declination minutes (1950) 26- 27 I2 arcsec DEs *?Declination seconds (1950) 29 A1 --- l_s20cm *[ <]Limit flag for 20cm flux 30- 34 F5.3 Jy s20cm *Peak 20cm flux density in 3'x3' box 36 A1 --- struct *[PSDCE]Radio structure of dominant source 38 A1 --- note1 *?Notes on general structure 40- 41 I2 --- note2 *?Notes on individual sources; "listed source described in the table; other comments refer to additional sources in the image. Positions and flux densities are for the brightness maxima.
Note on GLON,GLAT: Galactic longitude and galactic latitude as derived from the original survey catalog Note on RAh,RAm,RAs,DE-,DEd,DEm,DEs: Right Ascension and Declination (1950.0) of the peak brightness of the source as determined by the low resolution VLA 20cm observations Note on l_s20cm: < indicates s20cm is approximate 5 sigma upper limit for fields that remain completely resolved. Note on s20cm: Peak 20cm flux density. For double and complex sources the peak flux density refers only to the brightest component. No attempt was made to integrate flux densities. See the notes for related information. Note on struct: Classification of the radio structure of the dominant high brightness compact source. The symbols' meanings are as follows: P = point sources or slightly resolved S = single extended source D = double source C = complex structure with several knots and/or filaments E = empty field - the catalog source is probably resolved out Note on note1: A = Extended low brightness emission in addition to the compact structure indicated by the classification. B = Possible shell structure Note on note2: 1 = compact source, 1.40 Jy peak, at RA=18h00m37s, DE=24d22.9' 2 = double source, 0.25 Jy peak, at RA=18h03m19s, DE=-21d38' 3 = single, 0.162 Jy, at RA=18h06m46s, DE=-19d27.0' 4 = other weak knots nearby 5 = point source, 0.58 Jy, at RA=18h31m41s, DE=-07d57.1' 6 = point source, 0.15 Jy, at RA=18h37m57s 7 = another point source. 0.12 Jy, at RA=18h40m19s, DE=-04d17' 8 = listed double 30" separation, well resolved components. 9 = correction applied, FWZI about 1.1 arcmin. 10 = G29.7-0.3 is 15 arcmin to NW 11 = point source, 1.17 Jy, at RA=18h47m23s, DE=-01d36.4' 12 = point source, 0.43 Jy, at RA=18h44m59s, DE=-01d16.0' 13 = double source, 0.17 Jy, at RA=18h49m34s, DE=-00d04.5' 14 = point source, 0.53 Jy, at RA=18h49m14s, DE=-00d31.9' 15 = extended emission region 3' FWZI, offset 4'S of point source 16 = point source, 0.32 Jy, at RA=18h57m47s, DE=-03d59.0' tailed (shell?) source, .26 Jy peak, at RA 18h58m33s, DE=04d07.7' 17 = extended emission region 4' FWZI, offset 8' N of catalogued position 18 = listed double source has 0.5' separation 19 = listed double source has 0.6' separation 20 = listed double source has 1.5' separation 21 = point source, 0.23 Jy, at RA=07h18m27s, DE=-15d13.9' listed double source has 20" separation 22 = listed source has extended, 2.3' FWZI 23 = listed source has diameter 45" FWZI 24 = listed double source has 30" separation 25 = listed double source has 45" separation 26 = listed double source has 20" separation 27 = extended, partial shell source, 1.04 Jy peak, at RA=17h16m04s, DE=-37d07.8' 28 = extended, complex source, 1.1 Jy peak, centered on RA=17h17m30s, DE=-35d43' 29 = extended, complex source, 2.4 Jy peak, centered on RA=17h21m27s, DE=-34d08' 30 = broad structure with many knots and filaments seen on image; heavily resolved 31 = partial shell source, 0.15 Jy peak, at RA=17h28m11s, DE=-33d31.5', 2.5' diameter FWZI 32 = very extended diffuse emission over 8' diameter area 33 = heavily confused by SGR A * about 20' to north
Acknowledgements: These tables were originally prepared via OCR and proofread by Heinz Andernach in October 1998. Further checks of the files were made by him in July 2000, some minor errors were found in Table 1 and corrected. References: Altenhoff W.J., et al., 1978, A&AS, 35, 23 =1978A&AS...35...23A Clark D.H., Crawford D.F., 1974, AuJP, 27, 713 =1974AuJP...27..713C Downes D., et al., 1980, A&AS, 40, 379 =1980A&AS...40..379D Haynes R.F., et al., 1979, AuJPS, 48,1 =1979AuJPS..48....1H
(End) James E. Gass [SSDOO/ADC] 18-Aug-2000
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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