SkyCam

Introduction

"SkyCam" is a project to provide simultaneous wide field observations with normal LT data taking. All data taken with SkyCamA and SkyCamT is immediately public to all and may be used for any non-commercial scientific or educational purpose. Data taken with SkyCamZ remains proprietary. Please contact the LT group if you require access to that data.

Specification

At present the system consists of three cameras:

• SkyCamA - an "all sky" camera on a fixed mount inside the LT enclosure. This uses a 4.5mm fisheye lens to provide near all-sky coverage down to about 6th magnitude. It is capable of detecting reasonably thin cirrus cloud and is most likely useful for checking for the presence of clouds affecting data etc.
• SkyCamT - a "medium field" camera mounted on the LT mount which parallel points with the telescope. This uses a 35mm focal length lens to provide a 21° field of view and can detect sources down to about 12th magnitude. The pixel scale is 73.4 arcsec/pixel.
• SkyCamZ - a "zoomed field" camera mounted on the LT mount which parallel points with the telescope. This uses an Orion Optics AG8 telescope to provide a 1° field of view with a pixel scale of 3 arcsec/pixel and can detect sources down to about 18th magnitude.

All cameras use Andor ikon-M DU934N-BV cameras equipped with a 1024x1024 pixel, back illuminated and anti-reflection coated CCD running at -40°C. There are no filters in the system. A quantum efficiency curve is presented below:

Pipeline

When the enclosure is open, data is taken automatically once per minute with a 10 second exposure time. All data is automatically dark subtracted and flat-fielded and a world coordinate system fitted. SkycamZ data remains proprietary, but SkyCamA and SkyCamT data is then immediately publicly released both as JPEG and FITS files here. In addition both browsable and searchable image archives are available.

Sensitivity

Testing of SkyCamT has shown it is capable of repeatable photometry to a few hundredths of a magnitude for objects of around 8th magnitude. No testing has yet been done at fainter magnitudes. The lightcurve below of RR Lyrae (period about 1.1 days) was constructed from two images per night obtained over a six week period and shows the quality of data that can be expected. The scatter in the lightcurve is dominated by variability in the object from phase to phase rather than the skycam data itself.