This page (revision-76) was last changed on 07-Dec-2016 14:14 by BriazWearl

This page was created on 25-Jun-2008 06:03 by David R Williams

Only authorized users are allowed to rename pages.

Only authorized users are allowed to delete pages.

Page revision history

Version Date Modified Size Author Changes ... Change note
76 07-Dec-2016 14:14 10 KB BriazWearl to previous
75 11-Mar-2015 09:29 10 KB David R Williams to previous | to last
74 22-Jun-2010 16:19 10 KB David R Williams to previous | to last
73 19-May-2010 14:56 10 KB David R Williams to previous | to last
72 12-May-2010 23:12 10 KB David R Williams to previous | to last
71 12-May-2010 21:01 10 KB David R Williams to previous | to last
70 11-May-2010 15:52 10 KB David R Williams to previous | to last
69 11-May-2010 12:31 11 KB David R Williams to previous | to last
68 11-May-2010 12:29 10 KB David R Williams to previous | to last
67 11-May-2010 12:28 10 KB David R Williams to previous | to last
66 11-May-2010 12:28 10 KB David R Williams to previous | to last
65 11-May-2010 12:25 10 KB David R Williams to previous | to last
64 25-Jan-2010 14:31 9 KB David R Williams to previous | to last
63 25-Jan-2010 14:30 9 KB David R Williams to previous | to last
62 25-Jan-2010 14:21 9 KB David R Williams to previous | to last
61 19-May-2009 11:27 9 KB David R Williams to previous | to last

Page References

Incoming links Outgoing links
SbandObservingInfo
SbandObservingInfo

Version management

Difference between version and

At line 48 changed one line
There is often a substantial overlap between SAA and NGT events around the orbit. However, the phase of EUV night does not change phase in the orbit (whereas that of the SAA does). Therefore eclipses and SAA passes sometimes coincide (with night being the longer event), and sometimes do not overlap so much. However, there is almost always some overlap. (The exception to this is during the Golden Period, during which there are no SAA periods, but EUV nights continue to occur once per orbit).
There is often a substantial overlap between SAA and XTW (X-ray / EUV night) events around the orbit. However, the phase of EUV night does not change phase in the orbit, whereas that of the SAA does. Therefore nights and SAA passes sometimes coincide (with night being the longer event), and sometimes do not overlap so much. However, there is almost always some overlap. The exception to this is during the Golden Period, during which there are no SAA periods, but EUV nights continue to occur once per orbit.
At line 50 changed one line
As a result, a some parts of the day, the less-than-complete overlap of SAA and night means that the clear window for observing in such orbits can be shorter. Taking into account the buffers (summarised below) around orbital events, the distribution of clear observing windows, calculated from a typical mid-eclipse season OBEV file, ranged from 53 to 68 minutes, with a modal value of 61 minutes.
As a result, a some parts of the day, the less-than-complete overlap of SAA and night means that the clear window for observing in such orbits can be shorter. 2009 was the first year for which XTW calcluations were made for Hinode. So taking into account the buffers (summarised below) around orbital events, I recalculated the distribution of clear observing windows from the middle of eclipse season in 2009.
At line 52 added 6 lines
You can see from the histogram below that there are two distinct populations (ignore the very short windows at the far left: these are due to vanishingly small SAA events that occur shortly after larger events).
The main population follows a distribution ranging from 44 to 62 minutes, with a mode and median of around 53 minutes in length. The second population is on the far right, and corresponds to observing windows in the Golden Period where there are no SAAs, and these windows are 65 minutes long.
The sum of all this means that if you want to be of a single raster or study fitting in between eclipses, it needs to be no more than 44 minutes long (the minimum window length). However, if you are happy accepting some curtailment of the raster at one or both ends outside the Golden Period, in order to make full use of those windows that fall inside the Golden Period, then you might design a study to have maximum 65 minutes' duration. It is a gamble, obviously, because they aren't so well suited to the majority of the observing day, and cause difficulties in forecasting the telemetry that will be accumulated.
This page (revision-76) was last changed on 07-Dec-2016 14:14 by BriazWearlTop