G18.9−1.1 ADS: search title/keyword/abstract or fulltext

• Right Ascension: 18 29 50
• Declination: −12 58
• Size (/arcmin): 33
• Type: C?
• Flux density at 1 GHz (/Jy): 37
• Spectral Index: 0.39

Notes: Has been called G18.95−1.1 and G18.94−1.04.

Radio: Non-thermal, diffuse partially limb-brightened, with central ridge.

Optical: Detected.

X-ray: Partial shell.

Point sources: Compact X-ray source, with diffuse nebula.

Distance: Optical absorption suggests 1.8 kpc, H₂ emission suggests 4.7 kpc, optical extinction suggests 3.1 kpc.

References:

• Fürst et al. 1985, Nature, 314, 720. Effelsberg 100-m at 4.75 GHz (2.′4: S=23.8 Jy), plus other flux densities. ADS
• Odegard 1986, AJ, 92, 1372. TPT at 57.5 MHz (7.′2×8.′0: S=82±15 Jy), plus review of flux densities. ADS
• Barnes & Turtle 1988, IAUCo, 101, 347. Molonglo at 408 MHz (2.′9×3.′1: S=58±9 Jy) and Parkes 64-m at 5 GHz (4.′1×4.′4: S=23±6 Jy). ADS
• Patnaik et al. 1988, Nature, 332, 136. Ooty at 327 MHz (0.′6×1.′6). ADS
• Fürst et al. 1989, A&A, 209, 361. Effelsberg 100-m at 4.75 GHz (2.′45: S=23.8 Jy) and VLA at 1.5 and 4.9 GHz (14″×19″), and Effelsberg 100-m at 1.4 GHz (9′) for HI. ADS
• Aschenbach et al. 1991, A&A, 246, L32. ROSAT observations. ADS
• Fürst et al. 1997, A&A, 319, 655. ROSAT observations, and Effelsberg 100-m at 10.6 GHz (1.′1). ADS
• Reich 2002, in NSPS, p1. Effelsberg 100-m at 10.6 GHz, including polarisation. ADS
• Harrus et al. 2004, ApJ, 603, 152. ROSAT and ASCA observations. ADS
• Tüllmann et al. 2010, ApJ, 720, 848. Chandra detection of compact source. ADS
• Sun et al. 2011, A&A, 536, A83. Urumqi 25-m at 5 GHz (9.′5: S=19.6±1.0 Jy) including polarisation and review of flux densities. ADS
• Stupar & Parker 2011, MNRAS, 414, 2282. Hα observations. ADS
• Froebrich et al. 2015, MNRAS, 454, 2586. H₂ IR observations. ADS
• Acero et al. 2016, ApJS, 224, 8. Fermi observations. ADS
• Shan et al. 2018, ApJS, 238, 35. Optical absorption for distance. ADS
• Lee et al. 2019, AJ, 157, 123. [FeII] and H₂ IR observations. ADS
• Lee et al. 2020, AJ, 160, 263. H₂ IR observations. ADS
• Wang et al. 2020, A&A, 639, A72. Optical extinction for distance. ADS
• Dokara et al. 2021, A&A, 651, A86. VLA at 4 to 8 GHz (18″) including polarisation, and Spitzer observations. ADS
• Bykov et al. 2022, A&A, 661, A19. eROSITA observations. ADS

Last updated: 4 Jan 2024

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