1. Observing project: Molecules in absorption at z ~ 1
Source PKS

2. PKS1830-211 z=0.88582 Frye et al 97 2 images, + Einstein ring
But 2 absorbing systems,
one at z=0.19 seen in HI

3. Two components, covering each one image of the source
as confirmed by PdB (Wiklind & Combes 1998)
Slight temporal variability

4. Measuring the continuum of A and B
Possible without resolving the source and separating the
2images, since the absorption in A is optically thick A
A +B

5. Monitoring, measure of H0
The single dish (without resolving the 2 images) can follow
the intensity of the two, since they are absorbing at two V
Monitoring during 3 years (1h per week)
==> delay of 24+5 days, H0 = km/s/Mpc

6. Measure of Tmb (z) Low excitation (diffuse gas) Tex ~Tmb
The case for PKS
Several transitions give the same
result (slightly lower, due to a microlens)
From UV H2 lines
Srianand et al 2000

7. Variation of constants
Kaluza-Klein theories, Strings and M-theory, predict
variations of α = e2/hc fine structure constant
Heterodyne resolution R=106
Method of Alkali doublet
of many multiplet
Webb et al (2001)
Appears to have a variation, at
high z only
Murphy et al (2001)
Δ α / α =( )10-5