From: Saul Perlmutter (S_Perlmutter@lbl.gov)
Date: Wed Apr 13 2005 - 17:35:40 PDT
Hi HST Cluster SN team,
Here are some brief notes from the phone meeting on Monday, April 11 --
particularly for those who weren't able to call in:
1. We first discussed some organizational issues. We will set up a
web site at Berkeley, with a Wiki pages (editable web pages) so that we
can communicate with each other on this HST program. Among other
topics, we'll have a scheduling page so that people can indicate when
they are *not* available for a given phone meeting or in-person meeting
to make future planning easier. As of now the default meeting time,
when we call a phone meeting, is likely to be 9 AM on a Monday or
Tuesday.
2. We have already set up an email exploder (used for this email).
The address is:
3. The deadline for the Phase II observation schedule is a little over
a month from now, on May 13, and the budget is due a week later (if
submitted electronically). On the scheduling side this means that
each of the cluster groups needs to see if they have any clusters that
they would recommend substituting into our current list in the
proposal. We are likely to still be able to do substitutions later in
the HST cycle for targets that don't get scheduled till later, but then
we won't be able to trade them off against clusters that we start the
HST cycle with.
4. ***We agreed to have a phone meeting*** on
*** May 2 at 9 AM ***
to make first-cut decisions on substitutions for the cluster list. We
then will start preparing the Phase II schedule instructions based on
that list. Last minute changes in the following 10 days will still be
possible, but more time pressured. (And, as mentioned above, changes
later in the year will also be possible, but competing a smaller pool
of clusters for substitution.)
5. Looking at the 2-gyro availability schedule that we prepared at the
time of the proposal, the first clusters that are likely to get
observed are RCS0439-29, RCS0220-03, RCS0221-03, and RCS0337-28.
These would start in the beginning or middle of July, so we only have a
few months to prepare and test our systems to find the supernovae and
identify the properties of its host galaxy that will allow us to select
the z>~1 elliptical hosts. The supernova finding will be similar to
work that we have done before, but with a few new twists, so we will
begin testing that here at Berkeley. The host-galaxy study part of
the near-real-time pipeline will of course be quite different for this
project. The SN group and the cluster groups will have to work
closely to understand what tables of galaxy properties can be prepared
(and in what format) for rapid reference during the search, and how to
interpret them.
6. Howard pointed out that we should also do some quick galaxy
morphology studies of the first ACS images we get for each cluster, and
incorporate this information into the galaxy-property catalogs. Marc
said that we might be able to get the basic morphology parameters for
this with software developed by the ACS team. (Reminder to us: If a
supernova is already present in the first images then this morphology
won't always be correct for its host galaxy, at least not as first
measured by automated software.)
7. It will be helpful to have a pre-existing image for each cluster,
before the first data is collected, since this can be used to screen SN
candidates that are found early in the observing cadence. If possible
this should be z'-band, since this matches well the ACS 850LP response
that we will be using. For some clusters we already have ACS 850LP
data. As with the galaxy-properties catalogs, the cluster groups will
let the SN group know what they have available in the way of z' images.
8. Each of the cluster groups reported on what they are up to in terms
of finding more clusters and/or screening, refining the cluster lists
they already have. They are emailing in notes on these discussions,
which I will append to this message.
9. One note of interest from Chris Mullis was that his and Piero's
proposal to study the XMM cluster at z ~ 1.4 was awarded 12 NICMOS
"H"-band orbits. They will discuss with us how/if these can be
scheduled in such a way as to provide extra "free" data on any SNe
discovered in this cluster.
10. We also have to submit a budget request with the Phase II
deadline (a week later, May 20, if submitted electronically). I did a
little research and it appears that we can ask for money to perform the
several different analyses on the same data that we proposed for, even
though this will require more dollars per orbit than a more usual
proposal with one major analysis to do. Typical programs in the past
were awarded $3K/orbit (perhaps less for a simple but large program),
but more complex programs were awarded as much as $5K or $6K/orbit --
though perhaps not for very large programs(?). The important thing
will be to have written down very clear tasks that obviously must be
done to reach the science we proposed, and that justify the precise
expenses that we request. It would be helpful to get such lists of
tasks and expenses from everybody, with a rough goal of reaching
something around $2K/orbit or so for the cluster work as a starting
point (it will likely quickly go over). We should also think about
how to describe (and staff) work that we could do together across
cluster groups, and across the cluster-SN divide (like star-formation
history studies). Our first estimate of the cost for the SN part of
the program, comparing it to previous near-real-time programs, is a
little over $3K/orbit.
11. When we started to discuss the science we could do across the
cluster groups and also between the cluster and SN groups, we agreed
that it would be good to have a collaboration meeting once the data
starts coming in. The current thought is that we could organize one
in Berkeley late this summer.
<>12 . General congratulatory comments all around, and expressions
of excitement about the project and about having a chance to work
together on this.
Talk to you all again soon. Regards, --Saul
_______Notes from Howard Yee:_______
An issue in the cluster selection is the possibility that less evolved
clusters at z~1 may contain a large fraction of dusty galaxies.
Clusters that appear to be more evolved containfewer dusty galaxies
(based on some quick look Spitzer data). Hence, the RCS group will
examine the K-band data images and R-K color magnitude relation of a
large number of cluster candidates with z>~0.9 to ensure that the best
candidates have been choosen. We will look at both the appearance of
the clusters in K, and the tightness of the R-K coolor-magnitude
relation. Our group will at first focus on cluster in the 23 to 5 hr
RA range, as these are the targets that will likely be observed first.
In addition, attempts will be made to do cluster finding in the
RCS2 fields in the above RA range to look for very rich clusters for
possible substitution in the next three weeks. Because no additional
ancillary data on the RCS2 clusters will be available, only the most
spectacularly looking (e.g., evolved rich looking, strong lensing etc)
candiates will be considered as possible replacements.
_______Notes from Peter Eisenhardt:_______
We are recomputing phot-z's now, and will redo our cluster search
algorithm so as to have a refined list of candidates by about May 1.
We expect some Keck spectroscopy of our candidates, up to Adam
Stanford's run June 1 and 2. All of our targets are within a few
degrees of 14:30 + 34deg, so swapping them around a little even this
summer should still be fairly low impact on scheduling.
_______Notes from Megan Donahue:_______
For your notes, Mark Dickinson and I will be observing at the KPNO
4-meter on April 19-25 (6 nights), using Flamingos to search for
IR-counterparts to ROSAT X-ray cluster candidates lacking I-band
detections. We'll try to do a rough-and-dirty reduction of our data to
see if anything just leaps out at us, and if we find something at that
level we'll let you know. We'll have to work a little harder to pull
out redshift estimates, but if there are clusters in these fields,
they're z>1, and they'll be similar in Lx to other RDCS clusters at
z>1 (because they are similar Fx).
So we'll work hard to get the rough reductions done quickly, maybe even
at the telescope. If we find something, then it will be your call
whether to move it onto your target list. I'm hoping to repeat my
experience at finding MS1054-03 (that was from an I-band image at Las
Campanas, and I remember that image coming off the telescope, and I
wrote down, BIG cluster!) (Unfortunately ir-data needs a little more
massaging than i-band...)
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