https://www.eso.org/sci/meetings/2012/s … Baltay.pdf
The La Silla/QUEST Variability Survey
• Southern Hemisphere survey of ~20,000 square degrees (south of +25o declination)
• Repeated scans of the same area of the sky with a 2 day cadence to find variable and transient objects
• Scientific motivation
– Collect a large sample of well studied nearby supernovae for cosmological studies
– Search for Trans Neptunian Objects (TNO’s) and small planets in our solar system
– RRLyrae variable stars
– Other unusual transients
Instrumentation of the Survey
• The ESO 1 m Schmidt Telescope at the La Silla Observatory, available essentially full time to this survey except for the 10% potentially available to Chilean users.
• The 10 square degree QUEST Camera, permanently installed at the prime focus of the telescope
• A dedicated radio link to Cerro Tololo which we designed and built to allow real time transfer of 50 to
100 Gigabytes of data each night.
Survey Strategy
• Sensitivity to transients comes from repeated observations of a given area of sky
– 2 day cadence
– Area A on night 1, area B on night 2, area A on night 3, area B on night 4, etc etc
• To eliminate short time transients like asteroids, airplanes, cosmics etc cover each area twice a night with a one to two hour separation. These repeated scans provide sensitivity to Kuiper Belt Objects
• Use 60 second exposures in a single wide filter
• Typically cover 1500 sq degrees twice a night
• Program schedules observations each night
– Declinations between +20 and -25 degrees
– Less then 2 airmasses, more then 15o from galaxy
– Far enough east to be visible to followup for 60 days
Search for Trans Neptunian Objects
• Sensitivity to Trans Neptunian Objects, TNO’s (also called Kuiper Belt Objects, KBO’s) comes from repeated observations (two or three times a night) of the same area of the sky, look for objects moving with respect to background of distant stars
• So far found 65 new objects in our solar system beyond Neptune, some as big as half of Pluto
• Sensitive to objects down to mag 21.5
• One of the more interesting new objects is 2010 WG9, a distant body with an inclination exceeding 70 deg and a perihelion near the orbit of
Uranus
Survey running smoothly since Sept 2009
• Searched for TNO’s and transient stars, laid down reference frames in preparation for supernova search
– Covered 22,000 square degrees multiple times
