1 Introduction

Calculations done in the early 1980's demonstrated that luminous central stars of planetary nebulae could be stars undergoing a final helium shell flash. As reviewed by Iben & MacDonald (1994) the final helium shell flash brightens a white dwarf to AGB luminosity and results in a sudden change in abundances as the residual hydrogen envelope is consumed in the helium-burning convective shell. This process has been observed in V4334 Sgr (Sakurai's Object), and this star has been identified as a prototypical final helium shell flash object (Asplund et al. 1997). The list of similar objects is small, certainly less than 50, and perhaps as small as a few, depending on whether or not the R CrB stars are included (Clayton & De Marco 1997).

The only known star with behavior closely mimicing that of Sakurai's star is V605 Aql (Clayton & De Marco 1997). V605 Aql underwent brightening and fading in 1919-1923 with a light curve similar to that of Sakurai's star in 1996-1999. From 1924 through the early 1980's the visual faintness of V605 Aql as well as ignorance of its transient evolutionary state resulted in its being largely unobserved (Bidelman 1971; van den Bergh 1971). V605 Aql can be seen on the original Palomar sky survey as a faintly visible star on the red plate. Both V605 Aql and its associated planetary nebula A58 are obvious on a 5 m Hale image by van den Bergh (1971). However, the connection between the visually faint central star of A58 and V605 Aql, which was lost in 1923, was first made by Seitter (1985). At about the same time IRAS recovered V605 Aql as a bright point source ( 19158+0141) detected in all four bands, peaking at 41 Jy at 60 $\mu$m. V605 Aql was also observed as a bright and very red source by ISO with flux ranging from 0.5 Jy at 4.5 $\mu$m to 6.4 Jy at 14.5 $\mu$m (Kimeswenger et al. 1998).

Following the visual and far-infrared recovery of V605 Aql there has been considerable confusion about the identification of this star. This is reviewed by Kimeswenger et al. (2000) who present the first near-infrared image of the central star. To summarize, Herbig (1958) produced a finding chart accurate to a few arcseconds and noted a faint star on the Palomar sky survey at this position, but failed to note the presence of the (faint) planetary nebula. van der Veen et al. (1989) and Harrison (1996) later incorrectly identified V605 Aql as a star 35 $^{\prime\prime}$ from the center of the planetary nebula. As a result these papers reported near-infrared magnitudes far brighter than the correct values and these mistaken values have propagated in the literature. Kimeswenger et al. (2000) correctly identified V605 Aql and identified the nearby field star measured by van der Veen et al. (1989) and Harrison (1996).

Independent of the work of Kimeswenger et al. (2000) we attempted to observe the infrared spectrum of V605 Aql in June 2000. Following the Harrison (1996) paper we observed the incorrect star. We rapidly concluded that this star is not a final flash object and not the central star of A58. In order to identify the correct star we undertook wide field JHK imaging which is reported on here.