!!!Observing with EIS with the new antenna

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!!About this page
This Wiki page deals with typical observing constraints that you need to bear in mind when making a proposal for observing with [Hinode EIS|Main].

!!!Practical constraints?
!!Time
!OP Periods
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.)

Since the transition to stable operations under the S-band antenna, typical OP Period durations have been two or three days.

Once solar activity begins to increase, and solar unpredictability increases accordingly, Hinode may consider more frequent (i.e., one-day-long) OP Periods.

!Eclipse Season
During eclipse season[#5], the line of sight between the spacecraft and the Sun grazes the Earth's atmosphere, causing attenuation (and ultimately complete absorption) of the light that would otherwise be seen by each of the instruments. This attenuation affects first the EUV and X-ray bands, then later the visible wavelength range.

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 begins about 10 minutes before the calculated entry into optical night (NGT_ENTRY) and ends about 10 minutes after exit (NGT_EXIT). Thus, the EIS operations team recommend that you leave a ten-minute buffer around s/c night in eclipse season.

!!Volume
Since moving to Hinode's S-band antenna for downlinks, the spacecraft typically can downlink something like 200 Mb[2] per 24 hours. This


!!Do you have examples of what kind of observations are best suited for EIS?
Yes :-)

Go over to the [Study4LowDataVolume] page on this Wiki for examples of programmes recently developed for EIS.


!!!Why can my old HOP no longer be run?
!!!How is the HOP process different?

!!Nomenclature
;__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.'' 
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__Other Notes__

[2|#2]: Remember, Mb stands for mega__bits__ (1024 × 1024 bits), as distinct from MB (for mega__bytes__). 1 MB = 8Mb.

[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.