**Table 3:** Ammonia line observations of comets at MPIfR and upper limits on the NH₃ column density.
Line	Frequency	$T_{\rm rms}$	$T_{99.7\%}$	$[ \int T_{\scriptscriptstyle{\rm MB}} \; {\rm d}v ]_{\rm max}~$ ^a	$\langle N(J,J) \rangle_{\rm max}~$ ^b	n(J,J) ^c	$\langle N(\hbox{NH}_3) \rangle_{\rm max}$
(J,J)		[mK]	[mK]	[mK km s^-1]	[10¹² cm^-2]		[10¹² cm^-2]
Comet C/2001 A2-B (LINEAR): 7 Jul. 2001 ( $\Delta t$ = 70 min, $\delta v = 1.4\hbox{ km s}^{-1}$ )
(1, 1)	23.69450	16	36	54	0.73	0.26	<2.8
(2, 2)	23.72263	16	30	45	0.46	0.18	<2.5
(3, 3)	23.87013	16	34	51	0.46	0.20	<2.3
(4, 4)	24.13942	15	30	45	0.38	0.05	<7.6
Lowest upper bound ^d							<2.3
Comet 153P/Ikeya-Zhang: 25 Apr. 2002 ^e ( $\Delta t$ = 53 min, $\delta v = 1.8\hbox{ km s}^{-1}$ )
(1, 1)	23.69450	12	40	77	1.04	0.26	<4.0
(2, 2)	23.72263	15	26	50	0.51	0.18	<2.8
(3, 3)	23.87013	16	40	77	0.69	0.20	<3.5
(4, 4)	24.13942	14	14	27	0.23	0.05	<4.6
Lowest upper bound ^d							<2.8
Comet C/2001 Q4 (NEAT): 8, 13, 17 May 2004 ( $\Delta t$ = 219 min, $\delta v = 1.7\hbox{ km s}^{-1}$ )
(1, 1)	23.69450	18	20	36	0.49	0.26	<1.9
(2, 2)	23.72263	19	28	51	0.52	0.18	<2.9
(3, 3)	23.87013	19	44	80	0.72	0.20	<3.6
(4, 4)	24.13942	23	20	36	0.31	0.05	<6.2
Lowest upper bound ^d							<1.9
Comet C/2002 T7 (LINEAR): 8, 13 May 2004 ( $\Delta t$ = 98 min, $\delta v = 1.9\hbox{ km s}^{-1}$ )
(1, 1)	23.69450	29	30	61	0.82	0.26	<3.2
(2, 2)	23.72263	29	82	166	1.69	0.18	<9.4
(3, 3)	23.87013	29	52	105	0.95	0.20	<4.8
(4, 4)	24.13942	47	80	162	1.37	0.05	<27.4
Lowest upper bound ^d							<3.2

^a $1.064 \cdot T_{99.7\%} \cdot \delta v$ with $\delta v$ values as given in the table.
^b From Eq. (1).
^c Defined in Eq. (2).
^d Lowest upper limit on $\langle N(\hbox{NH}_3) \rangle$ from the four lines observed.
^e Calculations based on the best single epoch of observations.

Source LaTeX | All tables | In the text

	1 Introduction
	2 Ammonia line observations
	3 Hydroxyl line observations
	4 Upper limits on NH₃ column densities and production rates
	5 Ammonia-to-water ratio
	6 Conclusions
	References