Subject: SOT: request for suggestions

From: Jan Rybak <[email-masked]>
Date: Tue, 22 May 2007 12:23:13 +0000 (UTC)

Dear Dr. Berger,

I apologize for my disturbing you for a moment but I would like to ask
you some questions as the SOT SSC.

Our group was granted by the DOT/LaPalma observing time in August 2007
(campaign web page with the proposal text is available at 
http://www.astro.sk/~choc/open/07_dot/07_dot.html).

We have already prepared and submitted a SOHO JOP proposal but it is
clear that after Aug 17 there will be no SOHO support available due to
the SOHO keyhole limitations.

Therefore, we work currently on a proposal for Hinode/EIS+SOT+XRT support 
of our g-b observations (or vice versa) for which we would like to apply 
(observing time since Aug 18).

Concerning the SOT part I would like to ask the following questions in advance.
Our idea is to operate SOT for few hours taking series of exposures like

- channels: BFI: G-band, Ca II H; NFI Fe I 630.25nm longitudinal magnetograms
- FOV: 1k x 2k (54" x 109")
- 12bit DPCM lossless data compression
- cadence: ~20s per filtergram (~60s per the sequence)
- time of day : 08:00-13:00 UT

Using data given at the SOT web page it seems that such program would provide
~800 kbps what is much more than the average data rate of only 300kbps.
This leads to just ~7000s of observations for one run.

Questions: - is this calculation correct?
           - can be the sequence (G-band, Ca II H, Fe I 630.25nm long. magnetograms)
             performed for several hours in such a run
           - is an alternative of ~3 bits/pixel the JPEG algorithm reasonable 
             (it gives ~5hours we in fact need) or is it really to much 
           - is it possible to ask for such time of runs - 5hours of data acqusition
             + downlik after it

You surely understand that we would like to keep all Hinode instruments observing
for the mentioned interval when we can expect better seeing conditions at LaPalma.
On the other hand we do not want to decrease cadence of filtergrams or number
of the selected channels. Therefore we would like to know your advice how to
handle this problem in an optimum way if possible.

With many thanks beforehand

Jan Rybak

TL, 22/5/07

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