Standards

RATCam Standards

Standard fields for RATCam are based on the Landolt series of standards (link to Landolt paper on NASA ADS). They are spaced every few hours of RA and are observed in all bands every two hours by the robotic control system. If you require standards beyond what are specified here you must request them explicitly on your Phase 2 sequence definition and will be charged the observing time for then.

Clicking the name of the field will bring up an image of the field with north at top and east to the left. All images are taken from the Digitised Sky Survey "POSS-1 Red" archives. Annotated stars' magnitudes are V-band, taken directly from the Landolt paper.

RINGO2 Standards

Two types of standard are necessary to reduce RINGO2 data. These are zero-polarized stars, and objects with known polarization. The zero-polarized standards are necessary to remove the instrumental polarization from the data. The polarized standards allow you to calibrate the effect of instrumental depolarization.

These standard star observations must be obtained at the same MOUNT (not SKY) position angle as the science data. In general we recommend using a MOUNT position angle of zero for all RINGO2 observations (science and standards). Calculation of a true sky position angle for your data (and hence polarization angle) is possible by using FITS keywords. In the FITS headers the sky position angle is stored in ROTSKYPA and the mechanical mount position in ROTANGLE.

Standards are spaced approximately every few hours of RA.

RISE 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.