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Table 9

Observed line ratios in selected extragalactic objects and comparison to W49A.

Ratio APM 08279 NGC 253 W49A
Centre North East Southwest

HCN/HCO+ 4–3a 0.98 1.03 0.5 0.6 0.9 0.8
H13CN/H13CO+ 2–1 1.66–3.72b  ≈5c  ≈5c  ≈1.4c  ≈1.4c
HCN 4–3a/HNC 1–0 1.57 0.03–0.14b 2.0 1.0 0.9 1.4
H13CN/HN13C 2–1 2.29
HCN 4–3 / H13CN 2–1 0.42–0.56b
HCO+ 4–3 / H13CO+ 2–1 0.90–1.51b
HCO+ 4–3 / HC18O+ 2–1 2.60
DNC 2–1 / HNC 1–0 0.01–0.05b

Notes. 

(a)

J = 5–4 for APM 08279;

(b)

values for the two observed velocity components;

(c)

estimated from the 4−3 ratio (see text).

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