Hi, I was wondering if there was already an estimate (or metric) for how long a given field is observable by the survey. I.e. how long is that patch of sky at high enough elevation etc to be included in the survey scheduler? Primarily I’m interested in how long the North Ecliptic Spur can be observed for each year compared to the typical Wide-Fast-Deep.
The MAF metrics will be looking at what was achieved, not what could be possible.
The key pieces of info you need are that we have a 20 degree altitude limit and are at a latitude of -30.2444 degrees.
Currently, we have a nominal 6-month observing season for all parts of the sky, regardless of how long it’s actually visible. This ends up varying a bit as some parts of the sky are over-subscribed relative to others. If there’s a good science case, we can alter the nominal observing season length for all or parts of the sky.
Ah cool, I think I am actually more interested in what was achieved rather than what was possible. I think what I meant to ask is how long the NES is observable, given that other parts of the survey may take priority during its window of observability and eat into that time. So it sounds like SeasonLengthMetric probably is what I’m looking for, thanks!
20 degrees altitude is an airmass (sec Z) of 2.92. Various discussions have suggested a likely survey airmass limit of more like 1.5 or even 1.4. That’s a practical altitude limit of 40-45 degrees. This may be extended to lower altitudes during the twilight survey, but with lessened survey depth.