G6.4−0.1     W28

• Right Ascension: 18 00 30
• Declination: −23 26
• Size (/arcmin): 48
• Type: C
• Flux density at 1 GHz (/Jy): 310
• Spectral Index: varies

Notes: Has been called G6.6−0.2.

Radio: Several non-thermal sources in a ring, with flat spectrum core.

Optical: Diffuse emission.

X-ray: Diffuse emission from most of the remnant.

Point sources: Young pulsar near edge of remnant, but not thought to be related.

Distance: HI observations suggest 1.9 kpc.

References:

• Kundu & Velusamy 1972, A&A, 20, 237. NRAO 140-ft at 10 GHz (3'). ADS
• van den Bergh et al. 1973, ApJS, 26, 19. Optical observations. ADS
• Dickel & Milne 1976, AuJPh, 29, 435. Comparison of earlier Parkes 64-m maps at 2.7 GHz (8'.4) and 5 GHz (4'.4). ADS
• Dopita et al. 1977, ApJ, 214, 179. Some optical line ratios. ADS
• Altenhoff et al. 1979, A&AS, 35, 23. Effelsberg 100-m at 4.9 GHz (2'.6). ADS
• Lozinskaya 1981, SvAL, 7, 17. Mean optical velocity. ADS
• Andrews et al. 1983, ApJ, 266, 684. VLA at 1.4 GHz (8'') 4.9 GHz (3'') and 15 GHz (1'') of central region only, plus Einstein image of central region. ADS
• Bohigas et al. 1983, RMxAA, 8, 155. Optical spectra. ADS
• Odenwald et al. 1984, ApJ, 279, 162. Nearby IR source. ADS
• Andrews et al. 1985, AJ, 90, 310. VLA of central component. ADS
• Long et al. 1991, ApJ, 373, 567. Einstein and optical observations. ADS
• Kassim 1992, AJ, 103, 943. VLA at 327 MHz (3'.1×4'.4: S=660 Jy). ADS
• Kaspi et al. 1993, ApJ, 409, L57. Pulsar association. ADS
• Frail et al. 1993, Nature, 365, 136. VLA at 327 MHz (smoothed to 65''), plus pulsar association. ADS
• Frail et al. 1994, ApJ, 424, L111. VLA of associated OH masers. ADS
• Esposito et al. 1996, ApJ, 461, 820. Possible associated γ-ray emission. ADS
• Frail et al. 1996, AJ, 111, 1651. OH maser emission. ADS
• Biggs & Lyne 1996, MNRAS, 282, 691. Pulsar search. ADS
• Claussen et al. 1997, ApJ, 489, 143. VLA of OH masers. ADS
• Claussen et al. 1999, ApJ, 522, 349. High resolution observations of OH masers. ADS
• Arikawa et al. 1999, PASJ, 51, L7. Observations of shocked CO. ADS
• Yusef-Zadeh et al. 2000, ApJ, 540, 842. VLA at 327 MHz (2'.6×5'.5) and 1.48 GHz (40''×65''). ADS
• Dubner et al. 2000, AJ, 120, 1933. VLA at 328 MHz (97''×52'': S=425±40 Jy) and 1415 MHz (88''×48'': S=246±20 Jy), and comparison with other observations. ADS
• Reach & Rho 2000, ApJ, 544, 843. ISO observations of interactions with surroundings. ADS
   also see: Reach & Rho 2001, ApJ, 558, 943. Erratum. ADS
• Rowell et al. 2000, A&A, 359, 337. Upper limit on high energy γ-rays. ADS
• Douvion et al. 2001, A&A, 373, 281. ISO observations. ADS
• Roberts et al. 2001, ApJS, 133, 451. ASCA observations. ADS
• Velázquez et al. 2002, AJ, 124, 2145. Parkes 64-m at 1.4 GHz (15') for HI. ADS
• Rho & Borkowski 2002, ApJ, 575, 201. ROSAT and ASCA observations. ADS
• Claussen et al. 2002, ApJ, 580, 909. Observations of nearby source. ADS
• Yusef-Zadeh et al. 2003, ApJ, 583, 267. OH observations. ADS
• Caswell 2004, MNRAS, 349, 99. ATCA at 1.7 GHz of associated OH masers. ADS
• Mavromatakis et al. 2004, A&A, 426, 567. Optical observations. ADS
• Reach et al. 2005, ApJ, 618, 297. Molecular lines and near IR observations. ADS
• Hoffman et al. 2005, ApJ, 620, 257. OH maser observations. ADS
• Kawasaki et al. 2005, ApJ, 631, 935. ASCA observations. ADS
• Neufeld et al. 2007, ApJ, 664, 890. Spitzer observations. ADS
• Aharonian et al. 2008, A&A, 481, 401. γ-ray observations. ADS
• Casandjian & Grenier 2008, A&A, 489, 849. γ-ray observations. ADS
• Hewitt et al. 2008, ApJ, 683, 189. GBT at 1.6 and 1.7 GHz for OH masers. ADS
• Guilani et al. 2010, A&A, 516, L11. γ-ray observations. ADS
• Marquez-Lopez & Phillips 2010, MNRAS, 407, 94. Mid-IR observations. ADS
• Abdo et al. 2010, ApJ, 718, 348. Fermi observations. ADS
• Yuan & Neufeld 2011, ApJ, 726, 76. Spitzer observations. ADS
• Sawada et al. 2012, PASJ, 64, 81. Suzaku observations. ADS
• Nichols et al. 2012, MNRAS, 419, 251. CO observations of selected regions. ADS
• Gusdorf et al. 2012, A&A, 542, L19. CO observations of regions in NE. ADS

Last updated: 23 May 2014