Observations of standard stars are routinely acquired to enable the photometric calibration of science data, as well as to monitor the performance of the network’s telescopes. The data from these observations are available to all in the Science Archive. The proposal code for these observations is “Photometric standards”. In the image headers, the observations have OBSTYPE = STANDARD, so the BANZAI-processed file names have a “s91” suffix, rather than the “e91” given to OBSTYPE = EXPOSE.
Scheduling
Observations of standard stars are attempted every night with every imager.
- Standard star observations are scheduled during morning astronomical twilight, i.e. from solar altitude = -12° to -9°.
- Standard star observations are inserted into gaps in the scheduling of science observations. To make the scheduling flexible, the observation durations are short: only two filters per observation per night are scheduled. The actual duration depends on which filters are selected.
- Observations with Johnson-Cousins (UBVRI) and Sloan (u’g’r’i’zs) filters are scheduled on alternating nights. The default exposure times are as follows:
- Johnson-Cousins: U = 180s, B = 90s, V = 60s, R = 60s, I = 60s.
- Sloan: u’ = 160s, g’ = 80s, r’ = 60s, i’ = 60s, zs = 80s.
- Requests for observations of standard stars outside of the fields in the table below should be submitted to LCO's Science Support.
Standard Fields
All of the routinely observed standard star fields are found in the collection assembled by Landolt (1992) and augmented by Landolt (2009). The RAs and DECs given in the table below indicate the field center coordinates in J2000.0 of the 10’ x 10’ field-of-view of the Spectral cameras.
