Extinction photometry at Woomera

At one stage, Woomera was under consideration as a possible site for the southern hemisphere component of the Auger high-energy detector array. As a means of quantifying the clarity of the atmosphere above Woomera, extinction photometry was carried out at the Observatory.

At first, this was done with a photomultiplier tube attached to a Celestron C5 with a UG-1 filter on the front, for U-band data only. Later, the C14 and ST-6 were used with the UBVRI filter set for multi-filter measurements, although over a less extensive time span.

Compared with values found in the literature for extinction vlaues at major observatories around the world, Woomera fared very favourably, in spite of its low altitude above sea level. It does indeed have clear air, as is attested to by the very frequent appearance of the zodiacal light and, on occasion, the gegenschein.

Extinction co-efficient vs. wavelength : CCD-derived extinction values for Woomera.