We present optical spectra of 403 stars and quasi-stellar objects in order to obtain distance limits
towards intermediate- and high-velocity clouds (IHVCs), including new Fibre-fed Extended
Range Optical Spectrograph (FEROS) observations plus archival ELODIE, FEROS, High
Resolution Echelle Spectrometer (HIRES) and Ultraviolet and Visual Echelle Spectrograph
(UVES) data. The non-detection of Ca II K interstellar (IS) absorption at a velocity of −130
to −60 km s−1 towards HDE 248894 (d ∼ 3 kpc) and HDE 256725 (d ∼ 8 kpc) in data at
signal-to-noise ratio (S/N) > 450 provides a new firm lower distance limit of 8 kpc for the
anti-centre shell HVC. Similarly, the non-detection of Ca II K IS absorption towards HD 86248
at S/N ∼ 500 places a lower distance limit of 7.6 kpc for Complex EP, unsurprising since this
feature is probably related to the Magellanic System. The lack of detection of Na I D at S/N =
35 towards Mrk 595 puts an improved upper limit for the Na I column density of log (NNaD <)
10.95 cm−2 towards this part of the Cohen Stream where Ca II was detected by Wakker et al.
Absorption at ∼ −40 km s−1 is detected in Na I D towards the Galactic star PG 0039+049
at S/N = 75, placing a firm upper distance limit of 1 kpc for the intermediate-velocity cloud
south (IVS), where a tentative detection had previously been obtained by Centurion et al. Ca ´ II
K and Na I D absorption is detected at −53 km s−1 towards HD 93521, which confirms the
upper distance limit of 2.4 kpc for part of the IV arch complex obtained using the International
Ultraviolet Explorer (IUE) data by Danly. Towards HD 216411 in Complex H a non-detection
in Na D towards gas with log(NH I) = 20.69 cm−2 puts a lower distance limit of 6.6 kpc
towards this HVC complex. Additionally, Na I D absorption is detected at −43.7 km s−1 in the
star HD 218915 at a distance of 5.0 kpc in gas in the same region of the sky as Complex H.
Finally, the Na I/Ca II and Ca II/H I ratios of the current sample are found to lie in the range
observed for previous studies of IHVCs.