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At line 13 changed one line
An OP Period[Note 1] is the period of time during which an observing programme (''plan'') is defined. e.g. from 10:23 UT on 2008/05/02 to 11:19 UT on 2008/05/04. (The start and end of each OP period are determined by the pattern of ground-station contacts, which varies from day to day.)
An OP Period[1] is the period of time during which an observing programme (''plan'') is defined. e.g. from 10:23 UT on 2008/05/02 to 11:19 UT on 2008/05/04. (The start and end of each OP period are determined by the pattern of ground-station contacts, which varies from day to day.)
At line 20 changed one line
In order to have co-ordinated observations by its three instruments, Hinode points as a whole satellite (using its AOCS[Note 6]), either tracking a point to compensate for the (differential) rotation of the Sun, or focusing on a fixed point. Either way, changes in pointing by the s/c[Note 7] take time to stabilise. After approximately 90 seconds, Hinode can track or fix on a point with better than 1" accuracy, below the spatial resolution of EIS and XRT.
In order to have co-ordinated observations by its three instruments, Hinode points as a whole satellite (using its AOCS[6]), either tracking a point to compensate for the (differential) rotation of the Sun, or focusing on a fixed point. Either way, changes in pointing by the s/c[7] take time to stabilise. After approximately 90 seconds, Hinode can track or fix on a point with better than 1" accuracy, below the spatial resolution of EIS and XRT.
At line 29 changed one line
The duration of night-time is calculated for the visible band, and in the peak of eclipse season (around mid-July [Note 3]) this duration is about 20 minutes. EUV absorption (night ingress) begins about 10 minutes before the calculated entry into optical night (listed as NGT_ENTRY) and ends (night egress) in the EUV about 10 minutes after the optical band exit (NGT_EXIT). Thus, the EIS operations team recommend that you leave a __ten-minute buffer around s/c night__ in eclipse season where possible. Extended-duration observations
The duration of night-time is calculated for the visible band, and in the peak of eclipse season (around mid-July [3]) this duration is about 20 minutes. EUV absorption (night ingress) begins about 10 minutes before the calculated entry into optical night (listed as NGT_ENTRY) and ends (night egress) in the EUV about 10 minutes after the optical band exit (NGT_EXIT). Thus, the EIS operations team recommend that you leave a __ten-minute buffer around s/c night__ in eclipse season where possible. Extended-duration observations
At line 36 changed one line
On most orbits[Note 8], Hinode's orbit intercepts the South Atlantic Anomaly (SAA), a part of the geomagnetic environment where high-energy particles penetrate lower into the magnetosphere. During such passes, significantly more energetic particle hits (''cosmic rays'') are observed on the EIS detector images. These passes are calculated at the same time as other orbital events (such as Eclipse Season NGT events, when appropriate), and times vary each day. Such passes normally last approximately 15 to 20 minutes (although they can be calculated to last for as little as 30 seconds).
On most orbits[8], Hinode's orbit intercepts the South Atlantic Anomaly (SAA), a part of the geomagnetic environment where high-energy particles penetrate lower into the magnetosphere. During such passes, significantly more energetic particle hits (''cosmic rays'') are observed on the EIS detector images. These passes are calculated at the same time as other orbital events (such as Eclipse Season NGT events, when appropriate), and times vary each day. Such passes normally last approximately 15 to 20 minutes (although they can be calculated to last for as little as 30 seconds).
At line 72 changed one line
Since moving to Hinode's S-band antenna for downlinks, EIS typically can downlink something like 600 Mb[Note 2] per 24 hours. This is worked out by the total contact time at all ground-stations, in the coming OP Period, multiplied by the bandwidth to the ground[4]. Typical HOPs should be targeted to something like 250 Mb per day. __However__ , this is a rough guideline only, because the amount of telemetry that it's possible to downlink per day downlinked is quite variable, due to a number of practical factors.
Since moving to Hinode's S-band antenna for downlinks, EIS typically can downlink something like 600 Mb[2] per 24 hours. This is worked out by the total contact time at all ground-stations, in the coming OP Period, multiplied by the bandwidth to the ground[4]. Typical HOPs should be targeted to something like 250 Mb per day. __However__ , this is a rough guideline only, because the amount of telemetry that it's possible to downlink per day downlinked is quite variable, due to a number of practical factors.
At line 105 changed 2 lines
;__OP__:[Note 1|#1]''Operation Programme''
of each orbit. It lasts from late April until early September.''
;__OP__:[1|#1]''Operation Programme''
;__S-band antenna__:[4|#4] ''Hinode's secondary antenna, with a bandwidth of 262 kb/s.''
;__Eclipse Season__:[5|#5] ''The portion of the year where the sun is occluded by the Earth's atmosphere for a fraction of each orbit. It lasts from late April until early September.''
;__AOCS__:[6|#6] ''Attitude and Orbit Control System''
;__s/c__:[7|#7] ''abbreviation of'' spacecraft
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[Note 2|#2]: Remember, Mb stands for mega__bits__ (1024 × 1024 bits), as distinct from MB (for mega__bytes__). 1 MB = 8Mb.
[2|#2]: Remember, Mb stands for mega__bits__ (1024 × 1024 bits), as distinct from MB (for mega__bytes__). 1 MB = 8Mb.
At line 112 changed 6 lines
[Note 3|#3]: Is this correct? I know it's approximately true, since we start in late April, and come out of eclipse season in early September.
;__S-band antenna__:[Note 4|#4] ''Hinode's secondary antenna, with a bandwidth of 262 kb/s.''
;__Eclipse Season__:[Note 5|#5] ''The portion of the year where the sun is occluded by the Earth's atmosphere for a fraction
;__AOCS__:[Note 6|#6] ''Attitude and Orbit Control System''
;__s/c__:[Note 7|#7] ''abbreviation of'' spacecraft
[Note 8|#8]: Hinode's orbital period is 98.5 minutes
[3|#3]: Is this correct? I know it's approximately true, since we start in late April, and come out of eclipse season in early September.
[|#8]: Hinode's orbital period is 98.5 minutes
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