RISE

Introduction

RISE is a fast-readout camera developed in collaboration with the Queens University Belfast for the precision measurement of transiting exoplanet timing. The camera optics were designed by John Meaburn. Mechanical design work was done at Liverpool JMU, and mechanical and software build done at QUB. The CCD camera is an Andor DW485 using an E2V CCD 47-20 frame transfer device.

Specifications

  • Single fixed "V+R" filter comprising 3mm OG515 + 2mm KG3
  • Pixel Scale: 0.54 arcsec/pixel (unbinned)
  • Field of view 9.2 x 9.2 arcmin (11 arcmin unvignetted circle)
  • Minimum exposure Time 1.5 seconds (1x1 binning)
  • Minimum exposure Time 0.8 seconds (2x2 binning)
  • No readout overhead.
  • Gain (2x2 binning) 2.3 electrons/count
  • Read noise (2x2 binning) 10 electrons
  • Mean dark current (2x2 binning) 0.0143 counts/sec
  • Saturation Limit (1x1 binning) 20,000 counts
  • Saturation limit (2x2 binning) 40,000 counts

RISE field of view

Photometric Standards

As the majority of RISE data are taken for the purpose of relative photometry with secondary standards within the field of view, no routine nightly photometric standards are obtained for RISE. If you require standards you must request them explicitly on your Phase 2 sequence definition and will be charged the observing time for then.

Colour Terms

We will shortly make available colour dependant transforms between the V and R bands and the RISE natural photometric system. In the meantime this calculated filter transmission curve may be of some use.
RISE Filter transmission curve

Data Pipeline

All RISE data are run through a modified version of the RATCam data pipeline during the following working day after data taking. The pipeline debiases, removes a scaled dark frame and flat-fields the data using a library flat which is updated every few months. An automated email is sent when the data (along with the raw data) is then available to download in the normal fashion from the LT data archive.

Phase 1 information

RISE is now a common-user instrument. To calculate exposure times, use the 2x2 binned option for RATCam on the exposure time calculator. Note that no filter-change or readout time overheads need be applied when applying for RISE time; a simple 60 second slew overhead is all that is required. No filter changes are possible, and the readout speed is negligible.

Phase 2 information

In general we recommend 2x2 binning is used for all RISE observing due to the better linearity and cycle time in this mode. For bright targets you must be very careful of saturation and may well need to defocus the telescope. See also the detailed guidance on creating RISE observation sequences.