VLT quick views of spacecraft targets

The photo mosaic is based on a series of 3-minute exposures through a red filter, obtained with the VLT Test Camera in the evening of July 28, 1998. They were performed in a bright sky (5-day old Moon high in the sky) that resulted in some straylight due to internal reflections in the telescope. In the first three pictures (1 - 3), the very faint image of the comet (in the circles and somewhat elongated because of the motion) approaches a brighter background star from the right hand side. It is hardly visible in the next (4), since it is in front of this star, and in the last two images (5 - 6), it reappears on the left side of the star. At the time of the observations, Comet Wirtanen was 605 million kilometres (4.05 AU) from the Earth and 630 million kilometres (4.20 AU) from the Sun. The estimated magnitude is approx. 23 or beyond, i.e. over 100 times fainter than that of Wild 2.

This is a Six 3-min and one 6-min R (red) exposures with the VLT Test Camera on July 28, 1998. Mediocre observing conditions in bright moonlight. Picture no. 1 is a combination of two 3-min exposures; nos. 2 - 5 are single 3-min exposures; no. 6 is a 6-min exposure. The individual frames were rebinned (4x4 pixels), sky subtracted, noise and cosmics filtered, and shifted in order to center the comet. The fields shown measure approx. 27 x 27 arcsec. North is to the upper right; East is to the upper left.