Note: this is an archived version which has been superseded. The current SNR catalogue is at http://www.mrao.cam.ac.uk/surveys/snrs/

G89.0+4.7     HB21

• Right Ascension: 20 45 00
• Declination: +50 35
• Size (/arcmin): 120×90
• Type: S
• Flux density at 1 GHz (/Jy): 220
• Spectral Index: 0.40

Radio: Distorted shell (4C50.52, an extragalactic double, is within the boundary of the remnant).

Optical: Filaments possibly associated.

X-ray: Centrally brightened.

Distance: Various associations imply 0.8 kpc.

References:

• Hirabayashi & Takahashi 1972, PASJ, 24, 231. 30-m dish at 4.2 GHz (11': S=160±40 Jy). ADS
• Willis 1973, A&A, 26, 237. NRAO 300-ft at 2.7 GHz (5': S=148±16 Jy), plus optical filaments. ADS
• Hill 1974, MNRAS, 169, 59. Half-Mile Telescope at 1.4 GHz (3'×3'.9). ADS
• Haslam et al. 1975, A&A, 39, 453. Effelsberg 100-m at 2.7 GHz (4'.4) ADS
• Fukui & Tatematsu 1988, in SNRISM, p261. CO observations of the vicinity (2'.7). ADS
• Tatematsu et al. 1990, A&A, 237, 189. DRAO at 408 MHz (3'.5×4'.5) and 1.4 GHz (1'.0×1'.3), including HI, plus CO observations of adjacent molecular cloud. ADS
• Biggs & Lyne 1996, MNRAS, 282, 691. Pulsar search. ADS
• Leahy & Aschenbach 1996, A&A, 315, 260. ROSAT observations. ADS
• Lorimer et al. 1998, A&A, 331, 1002. Pulsar search. ADS
• Koo et al. 2001, ApJ, 552, 175. NRAO 12-m and other CO observations (27" and 45") of eastern part. ADS
• Zhang et al. 2002, ApSS, 279, 355. 232 MHz (3'.8×4'.9: S=390±30 Jy), plus comparison with other data for spectral index studies. ADS
• Reich et al. 2003, A&A, 408, 961. Effelsberg 100-m at 863 MHz (14'.5: S=228±5 Jy). ADS
• Uyanıker et al. 2003, ApJ, 585, 785. DRAO at 1.4 GHz (1') including polarisation. ADS
• Byun et al. 2006, ApJ, 637, 283. CO observations of surroundings. ADS

Last updated: 26 Apr 2006