Duty-Cycle Metrics
Introduction

This is a very brief introduction to the Duty-Cycle Metrics (hereafter "Metrics") program. The program aims to quantify how efficiently we provide observing time to the observers by measuring what fraction of a night is spent with the science detector recording photons from the sky. More details can be found on the Metrics home page.

The program extracts or calculates various relevant "events" relating to observing. These include start and stop times for images and spectra, guiding events, slewing events, etc. The sequence of these events then allows us to classify various time periods during the night as one of several observing "activities": slewing, science, calibration, focusing, etc.

The nightly timelineWeb page shows the events and activities for each night on each telescope. Menus and links at the top of each page allow you to navigate to other nights, or even to the nightlog summary for that night. You can select different start and stop times for the graphics to zoom in on a particularly interesting time period.

The top graphic shows the event timeline. Vertical bars show 12° twilights. The time between 12° twilights is the formal definition of the "night." No statistics are performed outside of this time frame.

The second graphic shows the translation of the event sequences into activities. There are some interesting effects you can see here, for example the reclassification of some images into "fine acquisition," particularly during LRIS slitmask observing. (See Keck I for Jan. 4, 2003 for an example.) Also, if no science data is taken on a target that shows a focus activity, the entire time during which the telescope was pointed at that star is classified as focus, not just the time during which the focus script was running. (The logic here being that if the OA did not have to focus, they would not have pointed at that star.) It is from these activities that the statistics are calculated.

Fig. 1. Events on K1 from UT 9:00 to 11:00 on 2003 Jan. 4. Note the narrow LRIS-B exposures in the top line just after 10:00. These are images taken in order to align a slitmask. At around 10:45 longer exposures begin. These are the slitmask spectra.

Fig. 2. Activities from the same time period as Fig. 1. Note that the slitmask alignment images do not show up as science. They have been reclassified as fine acquisition.

The third pie chart graphic shows the fraction of time spent in the various observing activities. The green "slice" is the important one that we want to maximize: the total time spent with the instrument's science shutter open and collecting data.

Caveats

There are some caveats to the system that you should keep in mind: