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Dear Francesco,<br>
<br>
the limiting mags, as written in the original proposal, are the
following:<br>
u: 24.8<br>
g: 25.4<br>
r: 25.2<br>
i: 24.2<br>
(see also for example on the KiDS website:
<a class="moz-txt-link-freetext" href="http://kids.strw.leidenuniv.nl/techspecs.php">http://kids.strw.leidenuniv.nl/techspecs.php</a>).<br>
<br>
Seems to me that we're off by about 0.4 mag, of which 0.3 is
probably attributable to the decrease of throughput of the system
due to mirror reflectivity? <br>
Btw, we should be able to see this by looking at the limiting mags
as function of observation date. Would be interesting to verify
this.<br>
<br>
Cheers,<br>
Jelte<br>
<br>
<div class="moz-cite-prefix">On 22/11/12 09:53, Francesco La Barbera
wrote:<br>
</div>
<blockquote
cite="mid:CAOnmKXdg198O_bZP3P=Mb5eBjAoAWT-t6mR0=acfoq=x5hqVVg@mail.gmail.com"
type="cite">Dear Gijs, et al.,<br>
<br>
<div class="gmail_quote">On Thu, Nov 22, 2012 at 6:44 AM, Gijs
Verdoes Kleijn <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:verdoes@astro.rug.nl" target="_blank">verdoes@astro.rug.nl</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Dear
Francesco et al,<br>
<br>
Many thanks for the input Francesco. I bring this conversation
now into the mailinglist space to ease following the
discussion.
<div class="im"><br>
</div>
</blockquote>
<div><br>
</div>
<div>OK! </div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
I ran the procedure for all 52 fields. The procedure
produces a single plot, with SNR as a function<br>
of 2'' diameter mag. One example is attached here, for the
field KIDS_185.0_1.5.r.<br>
Black points are all good (flag==0) objects in the field.
In red you can see the median trend, while<br>
the blue curve is the analytic fit<br>
p_1*flux/(p_2*flux+p_3)<br>
where p_1, p_2, and p_3 are free fitting parameters.<br>
</blockquote>
</div>
Looks good! Could you share the script you are using? Then
Hugo and I will make a python version of it as part of the QC
script for sourcelists.<br>
<br>
</blockquote>
<div><br>
</div>
<div>I'm attaching here the fortran program, which is part of
KIDSCAT now. In order to compile it, you</div>
<div>need the port library+pgplot. Binary versions of these
libraries were already included in the first KIDSCAT internal
release. You should have them already, otherwise, pls, just
lemme know.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
The series of 4 (5?) curves are due to discrete steps in
integration times due to the dither pattern, right?<br>
The displacement in magnitude seem in rough agreement with
that idea:<br>
>>> -2.5*math.log10(4/5.)<br>
0.24227503252014099<br>
>>> -2.5*math.log10(3/5.)<br>
0.55462187404089092<br>
>>> -2.5*math.log10(1/5.)<br>
1.7474250108400469<br>
>>> -2.5*math.log10(2/5.)<br>
0.99485002168009395
<div class="im"><br>
<br>
</div>
</blockquote>
<div>Yup, different patterns correspond to objects in regions
with different texp (because of dithering). </div>
<div>Your figures further confirm this. </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
The analytic fit is used to compute the typical mag
corresponding to SNR_LIMIT=5 (see dashed and<br>
solid black lines in the plot). This is our limiting mag.<br>
The procedure also computes the same kind of limit but for
different SNR_LIMIT(i.e. 10 and 15). These<br>
values are stored in an ascii file (MLIM.dat), into the
subdirectory OUTPUT_RES.<br>
</blockquote>
</div>
Good. Please store the analytic fit parameters as well. Those
will come in handy.
<div class="im"><br>
</div>
</blockquote>
<div>Done. In the ascii file MLIM.dat, we also have now a third
column with p_i.</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
I made some tests according to what we mentioned some time
ago:<br>
1) I can confirm that computing SNR from either FLUXERR or
MAGERR doesn't make any difference at all (just a sanity
check);<br>
</blockquote>
</div>
Good.
<div class="im"><br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
2) using different detection tresholds does not change
significantly the mag lim estimates; the second attached
plot<br>
shows the effect of decreasing DETECT_TRESH from 2.5 to
2.0 for the same fit as in the example. The mag lim goes<br>
from 24.77 to 24.78!!<br>
</blockquote>
</div>
Good to know MAG_APER at 2" diameter is very insensitive to
this change in DETECT_THRESH. That might be different for
e..g, MAG_ISO. For now I think it is enough to restrict the
lim. mag. analysis to MAG_APER with 2". For those we have
predictions we can compare to (in KiDS proposal). KiDS team
meeting is a good opportunity if/how we need to extend the
lim. mag. analysis.<br>
</blockquote>
<div><br>
</div>
<div>Could you kindly provide us the predictions (the ones in
hte porposal) for different wavebands ? We (Nicola+me) are
performing a systematic comparison to predicted mag_lim's, and
want to be sure to use correct values. </div>
<div> </div>
<div>Of course, the meeting will be an excellenet opportunity to
discuss possible extensions....</div>
<div><br>
</div>
<div>Cheers!</div>
<div>F.</div>
<div><br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Best wishes, Gijs
<div class="HOEnZb">
<div class="h5"><br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
Pls, lemme know whatever comment/suggestion you have.
Also, do we want/need compute other limiting mags<br>
(e.g. using MAGAUTO/different apertures)???<br>
<br>
Cheers,<br>
Francesco<br>
<br>
</blockquote>
<br>
</div>
</div>
<span class="HOEnZb"><font color="#888888">
-- <br>
--------------------------------------------------------------------<br>
|dr Gijs Verdoes Kleijn | astronomer
|<br>
|<a moz-do-not-send="true"
href="mailto:e-mail%3Averdoes@astro.rug.nl"
target="_blank">e-mail:verdoes@astro.rug.nl</a> |
OmegaCEN / Kapteyn Institute / |<br>
|www:<a moz-do-not-send="true"
href="http://www.astro.rug.nl/%7Everdoes"
target="_blank">www.astro.rug.nl/~verdoes</a> |
Target |<br>
|tel: <a moz-do-not-send="true"
href="tel:%2B31-50-3638326" value="+31503638326"
target="_blank">+31-50-3638326</a> |
University of Groningen |<br>
|mobile: <a moz-do-not-send="true"
href="tel:%2B31-654658050" value="+31654658050"
target="_blank">+31-654658050</a> | postal
address: |<br>
| | Kapteyn Astronomical
Institute |<br>
| | Postbus 800, 9700 AV,
Groningen|<br>
| | The Netherlands
|<br>
--------------------------------------------------------------------<br>
<br>
</font></span></blockquote>
</div>
<br>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<br>
<pre wrap="">_______________________________________________
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Dr. Jelte T. A. de Jong
Sterrewacht Leiden
Leiden University, Leiden, the Netherlands
E: <a class="moz-txt-link-abbreviated" href="mailto:jelte@strw.leidenuniv.nl">jelte@strw.leidenuniv.nl</a>
T: +31-(0)715275818
W: jelte.jdejong.net
</pre>
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