CASU meeting Wednesday January 26th 11:30-13:00 CASU meeting area.
Present: JRL, MJI, STH, EGS, AKY, JPE, MR
Apologies: JCR, NAW, RGM
Agenda:
1. Actions from last meeting
2. Comments on WFAU minutes
3. Hardware update
4. Meetings and telecons
5. Data archives update
6. Optical/NIR processing
7. WFCAM update
8. VISTA update
9. AOB
Minutes
=======
1. Actions from the last meeting
--------------------------------
STH, MJI - No conclusions on the extinction dependence (though MJI and
STH have been looking at it), required before we can sign off the
calibration for Version 1.1 of the data products. It's very hard to
remove the residual scatter (0.1 mag) above E(B-V)=10. STH also
reminded us of the VISTA-WFCAM issue (delta-mag vs mag) which we still
don't understand. One obvious check will be the background subtraction
which STH will investigate by the next meeting.
>>>> ONGOING
EGS, MR - put the WFCAM illumination tables on the web.
STH, MJI - The WFCAM extinction calibration is closely linked to the
VISTA one above.
>>>> ONGOING
MJI - sumarry tables total exposure time column .. ** Didn't note
down anything here. **
AKY - liaised with UltraVISTA and found that they are doing their own
BGD subtraction. A revised action is now to get hold their latest
stacks and look at the differences with out processing - what can we
learn.
>>>> ONGOING
MJI - did indeed come up with a cunning plan to initiate the
processing of all of the VST data. Logic is to minimize work and, to
enable the best calibration.
STH, MJI - produced the first pass colour relation between VISTA I
(guider) and 2MASS infrared colours in time for tomorrows IOT
telecon. STH showed us some slides; encouragingly it looks like we can
predict i-band photometry to within 10% given JHK. The next steps will
be to improve the simple linear fits (they don't use the photometric
errors) and to test any extinction dependent effects. >>>> ONGOING
MJI - VMC meeting *** did anyone else go ? Did Mike ?
AKY - started to investigate the question of the evolution of the
flatfields (and possibly darks) with time: specifically concerning systematic
noise/feature changes, and rms noise properties.
>>>> ONGOING
MJI - managed to shut off the gas and stop the milk from burning. JRL
placed the list of affected frames in the README's
EGS - continued investigation of grouting: specifically, adding in the
monthly zeropoint information took out the residual (few percent)
offsets. Grouting now automatically takes out the detector-to-detector
zeropoints using the monthly calibration.
2. Comments on WFAU Minutes
---------------------------
MJI clarified with an email the differences between data products
versioned 1.0 and 1.1.
Also, MJD is a new column in the catalogues now (because of the
complexity involved in computing it - it's easier for us to produce
this on a source by source basis). This will be included as an update
from Version 1.0 to V1.1 in the tile release. JRL will make a pretty
picture for the VVV and the VMC.
>>>> JRL
3. Hardware Update
------------------
** JBOD for the expansion module ** MIKE can write this bit. 45 x 2TByte
disks - 80 TBytes of raid 6. Most of the cost is in the disks - 220
for 2TB
We had an APM power outage on 20th December - resulting in the loss of
a number of PSUs. We lost a day sorting out which ones had gone. And
used all our spares.
4. Meetings and Telecons
------------------------
VISTA IOT at 2pm UK time (JRL, MJI, AKY will all attend). STH has
circulated his investigation of optical-infrared photometry for the
VISTA autoguider to the IOT email list.
The VVV science meeting was held in Vina del Mar, Chile, though none
of us could attned. JRL (et all) will have a look through their
website to make sure we are on top of any issues arising.
MJI announced that there will be a VVV+VPHAS+EGAPS meeting at Herts
this July(ish) and asked if any of us were interested in attending.
>>>> ALL
** SOMEONE attended a meeting about ESO Phase III documentation at
SOMEWHERE on SOME DAY. **Didn;t this happen last month ? There is
an action on each PI to write SOME STUFF down by 31st March
2011. Relevant to this, we summarised what we understand each of
the surveys is doing, where we know:
UV, Video - are both doing their own thing
VMC - are submitting tiles + catalogues, via WFAU
VVV - is submitting the the same but from CASU
VIKING - nobody knows
VHS - are almost certainly submitting products from CASU
MJI and EGS attended the UKIDSS science meeting at the RAS this
January. The saw some good stuff, including discovery of a redshift
7.03 quasar: Nature submitted, Warren et al.
MJI and JPE attended the VMC meeting in Munich. Science is being done
- mostly SFH and variability.
5. Data archives update
------------------------
All going very nicely.
6. Optical/NIR processing
--------------------------
EGS has fallen a little behind on UVEX and IPHAS.. presumably due to
his VISTA overload. JRL expressed his interest in the OMEGACAM header
structure. STH has a large volume of CFH data on h and chi Per to
process. (Mike warned about the illumination correction. Apparently
the problem has been fixed .. recently - Version B.5 is supposed to
fixed.)
We are expecting to receive updated survey management plans in the
near future from the VST team.
The Kepler field imaging project will be starting this summer.
EGS mentioned that he would like some updates for fitsio_merge
specific to the iphas data, including an upgrade to include all the
apertures. He volunteered himself to do it basically.
7. WFCAM update
----------------
There has been very little data due to bad weather (correlation with
going automatic?). Ice has been present on the cryostat window for the
last week - half a mag of throughput and brighter sky in K. This is
being fixed now. Mike has taken over the processing since
mid-December. All data are reduced up to today, and released to the
end of Novemember, and all transfers are up to date.
We note that Chris Davis has taken up new duties with JCMT, and would
like to thank him for all his hard work throughout the lifetime of
WFCAM, and to wish him the very best. At the same time we say a big
hello to Watson Varricatt as our new interface.
8. VISTA update
----------------
We have received data up until 12th January. Although 3 nights are
missing. The third disk was hiding in the bottom of the box, see? So
it was sent back. A replacement has now been requested.
Processing is now about to start with the January data. But this won't be
released until we have reached version 1.1. Release-wise we have
completed V1.0 up until the end of November.
We talked about the changes between V1.0 and V1.1. MJI clarified that
the changes all involve catalogues: the images themselves do not
change at all (i.e. the pixel values), except the images will be
called V1.1. But some of the calibration information in the image
headers will change, accordingly:
V1.1 Dec-Jan will have slightly different astrometric
distortion coefficients - now the telescope has settled
through the focus changes. Note that the wavelength dependence
is verified to be zero. The residuals are well below the
100mas requirement.
The classifier has been slightly updated (NB this will affect
the pawprint catalogues), and involves a small tweak to the
model used to estimate the total flux. This means the products
are more robut in terms of the aperture corrections. This
helps with grouting for example - as we are more robust to
seeing variation.
We will rerun the photometric calibration with the revised
color equations and extinction corrections - this is the
main holdup at present. And then we can do the monthly corrections for
chip-to-cip offsets and illumination corrections to the
photcal. Detector-to-detector offsets are of order 1% in Z,
and smaller in other filters.
Other changes are keyword propagation: NICOM, and the header
will properly reflect ICRS (although a redundant Equinox
keyword will still preserve FK5 to ensure backwards
compatability).
Most of these changes are dirven by trying to have excellent
tiles. The next step will be rigorous testing of V1.1 vs V1.0
catalogues. We need to organise who does what: Mike will start us off
- and then will pass it on to one the youngsters. He pointed out the
very useful aperture correction diagnostic plot - plotting apcor vs
number for each detector at the pawprint level.
>>>> MJI, EGS, AKY
** something about ESO OB STATUS is not changing. So just ignore it and trust the data. Nothing for us to do here.**
**Interesting question over marginally good-enough pawprints which when combined give marginally no good enough tiles.**
Median position angle of the fitted ellipse added to the
classifier. And output to the catalogues headers. Convention N->E
JRL loves VISTA - just for the record.
9. CASUHELPs
-------------
**Saturated stars keeps coming up. Look in the code in
CASUTools. And see article.
AOB
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The small toilet is broken.