A Search for Intraday Variability in the Blazar PKS 2005-489

Rapid, multi-color optical monitoring carried out for a multiwavelengthcampaign during 22-27 August 2000 is presented for the bright and variable BLLac object PKS 2005-489. Previous multiwavelength monitoring campaigns of PKS2005-489 have found complex variability behavior both in flux density and inbroadband spectrum, with different modes and timescales from days to hours.During this campaign, PKS 2005-489 was observed to be in an unusual state,bright in the optical but faint in the X-ray, just prior to an X-ray flare thatbegan on 2 September 2000. PKS 2005-489 was also observed to have a flatteroptical spectrum than prior epochs. A linear increase in optical flux densitywas observed during the first 5.2 days of the campaign. However, intraday andcolor variability were not detected. The large discrepancy between the ratio ofX-ray to optical flux density observed during this campaign and that observedin prior epochs indicates a lack of long-term correlation between the twowavebands; and it illustrates that simple particle injection events in the jetare insufficient to explain the long-term variability behavior of this object.Twenty-three in-field standard stars are identified for future opticalmonitoring programs.Comment: Accepted, A