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<div class="moz-cite-prefix"><br>
Hi Jelte, Gijs, all,<br>
<br>
please find attached a plot where the Francesco's procedure
mag_lim difference with respect the expected values
(Deltamag=m_lim-m_ex) are plotted against the FWHM in all the 52
fields. There is a trend with the FWHM as expected and definitely
the mean discrepancy is larger than 0.3 mag in general. The
situation with the i' band is particularly worrisome and Francesco
has double checked that there is nothing wrong there.<br>
<br>
We will possibly have a final assessment on the i-band images
after the final QC. We are planning to possibly experiment a
little more in the catalog space, however it might be the case to
check some different coadd combining method.<br>
<br>
Cheers,<br>
<br>
Nicola <br>
<br>
On 11/22/12 12:00 PM, Jelte de Jong wrote:<br>
</div>
<blockquote cite="mid:50AE05DF.1020503@strw.leidenuniv.nl"
type="cite">
<meta content="text/html; charset=ISO-8859-1"
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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
moz-do-not-send="true" 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>
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<br>
<pre class="moz-signature" cols="72">--
Dr. Jelte T. A. de Jong
Sterrewacht Leiden
Leiden University, Leiden, the Netherlands
E: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:jelte@strw.leidenuniv.nl">jelte@strw.leidenuniv.nl</a>
T: +31-(0)715275818
W: jelte.jdejong.net
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<br>
<br>
<pre class="moz-signature" cols="72">--
Nicola R. Napolitano
Research Astronomer
INAF - Observatory of Capodimonte
Salita Moiariello, 16, 80131, Napoli (Italy)
phone: +39 081 5575509; fax: +39 081 456710
email: <a class="moz-txt-link-abbreviated" href="mailto:napolita@na.astro.it">napolita@na.astro.it</a>
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