**Table 2:** Comparative abundances of "CHO'' molecules in comet Hale-Bopp and in the Galactic Centre Sgr B2(N).
Molecule	Relative abundance
	C/1995 O1^a	Sgr B2(N)^b
	$\times 100$	$\times 10^7$
H₂CO	${\approx} 1^{c}$	>0.005
CH₃OH	2.4	2.
CH₃CHO	0.025	0.002
c-C₂H₄O	<0.2	0.001
C₂H₅OH	<0.1	0.01
HCOOH	0.09	0.001
CH₃COOH	<0.06	$\approx$ 0.01
HCOOCH₃	0.08	0.01
CH₂OHCHO	<0.04	0.0007-0.0011
HOCH₂CH₂OH	0.25	0.0008-0.0015

^a Cometary abundances are given relative to H₂O. They are taken from Bockelée-Morvan et al. (2000), Crovisier et al. (2004) and from the present work.
^b Abundances are given relative to H₂assuming N[H₂] = $2.8 \times 10^{24}$ cm^-2. They are taken from Nummelin et al. (2000), from Mehringer et al. (1997) for CH₃COOH, from Hollis et al. (2000, 2001, 2002) for glycolaldehyde and ethylene glycol. Since the spatial distributions of the molecules differ, these relative abundances must be considered with some caution.
^c Cometary formaldehyde is mainly coming from an extended source. Less than 0.07% relative to water is coming directly from the nucleus according to Wink et al. (1999).

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