<div dir="ltr"><div><div><div><div><div><div><div><div><div><div>Along a new thread, the _dim items had escaped my notice.<br></div>As discussed, the word "dimension" is confusing in this context<br></div>and people started wondering about units.<br></div>It is defined in the text as "number of samples".<br></div>It seems to me that better choices for "dim" would be:<br></div>len[gth], nsamp, num, nbr, or even npix (most samples will be pixels).<br><br></div>I also noticed that the time scale is completely missing from the<br></div>time axis. Anyone interested in accurate timing might want to know<br></div>what timescale the resource is using - TT, TDB, TAI, UTC, GPS, ...<br><br></div>Cheers,<br><br></div> - Arnold<br></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature"><div dir="ltr">-------------------------------------------------------------------------------------------------------------<br>Arnold H. Rots Chandra X-ray Science Center<br>Smithsonian Astrophysical Observatory tel: +1 617 496 7701<br>60 Garden Street, MS 67 fax: +1 617 495 7356<br>Cambridge, MA 02138 <a href="mailto:arots@cfa.harvard.edu" target="_blank">arots@cfa.harvard.edu</a><br>USA <a href="http://hea-www.harvard.edu/~arots/" target="_blank">http://hea-www.harvard.edu/~arots/</a><br>--------------------------------------------------------------------------------------------------------------<br><br></div></div></div>
<br><div class="gmail_quote">On Wed, Jul 15, 2015 at 9:43 AM, Arnold Rots <span dir="ltr"><<a href="mailto:arots@cfa.harvard.edu" target="_blank">arots@cfa.harvard.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div>This may get complicated.<br></div>In principle, I agree, but some axes may actually be binned, such as chip coordinates and pulse height...<span class="HOEnZb"><font color="#888888"><br><br></font></span></div><span class="HOEnZb"><font color="#888888"> - Arnold<br></font></span></div><div class="gmail_extra"><span class=""><br clear="all"><div><div><div dir="ltr">-------------------------------------------------------------------------------------------------------------<br>Arnold H. Rots Chandra X-ray Science Center<br>Smithsonian Astrophysical Observatory tel: <a href="tel:%2B1%20617%20496%207701" value="+16174967701" target="_blank">+1 617 496 7701</a><br>60 Garden Street, MS 67 fax: <a href="tel:%2B1%20617%20495%207356" value="+16174957356" target="_blank">+1 617 495 7356</a><br>Cambridge, MA 02138 <a href="mailto:arots@cfa.harvard.edu" target="_blank">arots@cfa.harvard.edu</a><br>USA <a href="http://hea-www.harvard.edu/~arots/" target="_blank">http://hea-www.harvard.edu/~arots/</a><br>--------------------------------------------------------------------------------------------------------------<br><br></div></div></div>
<br></span><div><div class="h5"><div class="gmail_quote">On Mon, Jul 13, 2015 at 8:45 AM, Laurent MICHEL <span dir="ltr"><<a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello,<br>
<br>
I do not think that t_dim is better suited than e_dim or s_dim to specify the number of events. Finally, an event is just a point within a 4dims space (S1/S2/E/T) and none of these axes has a special role.<br>
Considering that, I think the number of events should be reported in all *_dim columns. The ambiguity about binned axes or not is removed by the appropriate "dataproduct_type" value.<br>
<br>
Laurent<div><div><br>
<br>
Le 25/06/2015 03:06, Douglas Tody a écrit :<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On Wed, 24 Jun 2015, CresitelloDittmar, Mark wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
pg 25: Axes dimensions<br>
Outside of the pixelated image context, what values do these hold?<br>
For example, the sparse cube (ie: event list). do each of these hold<br>
the #events? or are s_dim1,s_dim2 == the span along that axis? and<br>
if so, in what frame?<br>
It seems that #events is closest to the description as the number of<br>
samples.<br>
</blockquote>
<br>
For event data which is not imaged, such as an event list, probably the<br>
best one can do is have t_dim specify the number of events. The spatial<br>
coverage would be specified with s_fov and the spectral coverage with<br>
em_min/max. The binning on the spatial and spectral axes is meaningless<br>
and should be zero. If a precomputed image for the observation is also<br>
provided, that would have all the dim values and would share the same<br>
obs_id.<br>
<br>
- Doug<br>
</blockquote>
<br></div></div><span><font color="#888888">
-- <br>
---- Laurent MICHEL Tel (33 0) 3 68 85 24 37<br>
Observatoire de Strasbourg Fax (33 0) 3 68 85 24 32<br>
11 Rue de l'Universite Mail <a href="mailto:laurent.michel@astro.unistra.fr" target="_blank">laurent.michel@astro.unistra.fr</a><br>
67000 Strasbourg (France) Web <a href="http://astro.u-strasbg.fr/~michel" rel="noreferrer" target="_blank">http://astro.u-strasbg.fr/~michel</a><br>
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