[Vlavlbausers] News for VLA/VLBA/HSA Proposers
Lori Appel
lappel at nrao.edu
Tue Sep 16 20:25:42 EDT 2008
News for VLA/VLBA/HSA Proposers, September 16, 2008
This posting may also be read on the web at
http://www.vla.nrao.edu/astro/guides/news
This "News" posting contains the following sections
General news
* Support for PhD dissertations using NRAO facilities
* Large proposals
News for VLA proposers
* General observing capabilities
* 74 MHz observing in the BnA and B configurations
* EVLA impact and availability
News for VLBA/HSA/VLBI proposers
* Regular proposal deadline is 2008 Oct 1 for trimester 2009-T1
* VLBA or HSA Proposals
* VLBA Observational Status Summary
* Proposals involving the EVN
* Global 3mm VLBI Proposals
------------------------------------------------------------------------
1. General News
a. Support for PhD dissertations using NRAO facilities
Students planning to use an NRAO telescope for their PhD dissertation
(particularly if more than one proposal will be required) should
submit a "Plan of Dissertation Research" of no more than 1000 words
with their first proposal. This plan can be referred to in later
proposals. At a minimum it should contain a thesis time line and an
estimate of the level of NRAO telescope resources needed. The plan
provides some assurance against a dissertation being impaired by
adverse referee comments on one proposal, when the referees do not see
the full scope of the project. This requirement applies to all three
of the NRAO major instruments: VLA, VLBA and GBT.
b. Large proposals
Large proposals to use NRAO instruments will be accepted at the
October 1, 2008, proposal deadline, and at all subsequent proposal
deadlines. There will no longer be separate, annual, calls for large
proposals. The definition of "large" and other policy issues relating
to the submission of large proposals is described in the Large
Proposal Policy
(http://www.nrao.edu/administration/directors_office/largeprop.shtml).
------------------------------------------------------------------------
2. News for VLA Proposers
a. General observing capabilities
The 1 October 2008 deadline is for the BnA (currently scheduled
between 23 January 2009 and 9 February 2009) and B configurations
(scheduled between 13 February 2009 and 18 May 2009). Proposals to use
the reconfiguration time from the A configuration to the BnA
configuration (12 January to 23 January 2008) and the reconfiguration
from the BnA to the B configuration (9 February 2009 to 13 February
2009) will also be reviewed. Proposers are encouraged to consider
proposals for projects that might fill gaps in the dynamic schedule,
i.e., one or more short (1-2 hour) observations covering a variety of
LSTs.
We are currently considering a plan to reverse the order of the
configuration cycles of the VLA/EVLA from the long-used D-> A-> B->
C-> D to D-> C-> B-> A-> D, beginning with the D configuration at the
end of 2009, to facilitate correlator commissioning and early science
with the EVLA. No decision has been taken as of this writing.
For the 1 October 2008 proposal deadline all VLA proposers must use
the NRAO Proposal Submission Tool (PST). A few minor modifications to
the PST have been made and will be in place starting 12:00 EDT
Wednesday, 17 September 2008, and accessible from NRAO Interactive
Services (http://my.nrao.edu). The PST can now upload a Plan of
Dissertation either within the Author's page for a specific proposal
or from a student's profile under user preferences. For more details
see the latest release notes
(https://wikio.nrao.edu/bin/view/Software/PSTReleaseNotesOct2008).
The number of EVLA antennas continues to increase at a rate of one
every two months. We have passed the point where more than half of the
antennas in the array are EVLA antennas. This has at least two major
consequences for users: (1) increased observing capabilities with
extended tuning ranges available at L, C, and K bands, as described
below; (2) revised observing and data reduction procedures are needed
when using the "transition" system. These are described in some detail
at the EVLA returns <http://www.vla.nrao.edu/astro/guides/evlareturn/>
web page and are outlined briefly under "EVLA impact and availability"
(section 2c(i)) below.
New EVLA antennas will not be outfitted with 12 - 18 GHz (U band)
receivers until the end of the construction project. The number of 15
GHz receivers in the array is therefore steadily declining as new EVLA
antennas are added, and this should be taken into account in
considerations of sensitivity, time requests, and uv-coverage. For
continuum observations the use of EVLA antennas at 18 GHz (at the low
frequency end of K-band) should be considered as an alternative to
using the 15 GHz receivers (see section 2c(i) below).
b. 74 MHz observing in the BnA and B configurations
As described in the May 16, 2008 News for Proposers (and see EVLA Memo
123 at
http://www.aoc.nrao.edu/evla/geninfo/memoseries/evlamemo123.pdf), we
have determined that having the 74 MHz dipoles installed causes a
temporal variation in the cross-polarization of order 1 - 2% at L-band
(1.0 - 2.0 GHz) on all antennas, with a timescale of about 1hour. We
will therefore assess whether to leave the 74 MHz dipoles mounted
through BnA configuration and into B configuration when the relative
pressure of 74 MHz and L-band polarimetry proposals has been established.
c. EVLA impact and availability
i. Short Term (March 2009 - August 2009)
At the beginning of this period there will be 20 EVLA antennas in the
array, rising to 23 in late summer 2009. A subset of the final WIDAR
correlator should be undergoing tests at the VLA site. The
availability of other hardware may limit the number of antennas
available to the VLA correlator to 20 beginning at some point during
this period. WIDAR commissioning and supported configurations may
have an impact on both the amount of observing time and user support
available during this period.
As more EVLA antennas come on line, we continue to caution that users
must be very careful in setting up and reducing their data in order to
obtain the best science during the transition period. Issues that are
important are described in detail at the EVLA returns
(http://www.vla.nrao.edu/astro/guides/evlareturn/)
web page. A few of the most important are summarized here:
1) Online Doppler tracking should be used only for projects employing
only EVLA antennas, such as those making use of the extended EVLA
tuning ranges. Online Doppler tracking should not be used if VLA-EVLA
baselines are included in an experiment because of phase jumps on
VLA-EVLA baselines introduced by the VLA Fluke synthesizers at any
change in frequency or bandwidth. For the same reason, phase
calibration must be included at any frequency or bandwidth change for
observations using both VLA and EVLA antennas.
2) The use of narrow-bandwidth modes on EVLA-EVLA baselines is
currently compromised by the aliasing of emission outside the band as
described on the EVLA returns web page. Please consult this web page
for latest information on post-processing compensation for the
aliasing effect. This problem will go away once the WIDAR correlator
is used for all antennas.
3) Some on-line flagging issues remain. In particular, there are some
cases in which the first few records of a scan are actually data from
the previous scan, but are not flagged by the online system. In
addition, the first 10 - 20 seconds after a change of band is often
bad and not flagged. Users should make sure to observe a calibration
source after a band change. The origins of the problems are known,
and software changes are underway to eliminate them. Until those
software changes occur - and are tested - users should critically
examine their data to find and flag such problems.
Ka-band (26.5-40 GHz) receivers have begun to be installed on the EVLA
antennas; currently there are two receivers on the array. After the
number of Ka-band receivers passes five currently planned for
November 2008), we plan to issue a call for shared-risk Ka-band
proposals, probably around January 2009. This may take the form of a
special call outside the normal proposal schedule. The number of
Ka-band antennas should increase from nine to 14 during the March -
August 2009 time period.
Extended tuning ranges are available on EVLA antennas at L-band
(1.0-2.0 GHz), C-band (4.2-7.7 GHz), and K-band (18.0-26.5 GHz). The
ranges outside the nominal VLA frequencies for C and L band
(especially the former) have poor sensitivity and polarization
performance, as compared with the nominal VLA frequencies. Further
details of the sensitivity as a function of frequency for these bands
can be found at the EVLA returns page
(http://www.vla.nrao.edu/astro/guides/evlareturn/) .
In addition to the increased tuning ranges on the EVLA antennas it is
now possible to tune the two IF pairs anywhere within the available
C-band simultaneously. IFs separated by up to 4 GHz at K-band
(18.0-26.5 GHz) and Q-band (40-50 GHz) are also possible.
In the March - August 2009 time period, we expect that several new
C-band receivers with newly designed ortho-mode transducers (OMTs)
will be installed on the array. Currently there are two such
receivers in the array, and there will be four by the end of October
2008. This number should increase from eight to 13 through the March
- August 2009 period. Receivers with new OMTs will have better
polarization performance and full sensitivity across the wide tuning
bands.
We also expect that in this time frame the installation of S-band (2-4
GHz) receivers will have begun on the EVLA and testing of this new
observing capability will be underway. S-band receivers will be
available for shared-risk observing when there are at least 5
available, currently anticipated for mid-late 2009.
Note that JObserve cannot be used directly to make observe files for
the new tuning ranges or for the new frequency bands (Ka and S). Users
wishing to take advantage of the new tuning ranges of these new bands
should check the EVLA returns web page for further information. A new
observation preparation tool (OPT) is currently undergoing final
testing, in preparation for observers who are successful for the
shared-risk Ka -band call. The OPT will also be used for the
EVLA+WIDAR in the long term; capabilities for WIDAR are currently
being designed and implemented.
ii. Medium Term (September 2009 - May 2010)
By the end of 2009 approximately 24 EVLA antennas are scheduled to be
available. It is likely that we will decommission the remaining VLA
antennas in the array sometime during this term. Depending on how the
WIDAR commissioning is progressing, the VLA correlator may also be
decommissioned in this time frame.
The configuration schedule may be modified during 2009 to accommodate
WIDAR and other EVLA commissioning. Consideration is also being given
to reversing the current order of VLA configurations (see "General
observing capabilities", above). Users should not assume that the
regular configuration cycle will necessarily be maintained throughout
2009.
iii. Long Term (2010 - 2012)
In late 2010, the primary EVLA retrofit will be completed, although
not all the frequency bands will be installed on all antennas. The
wide-band K, Q, Ka, and C band receiver systems are expected to be
completed by this time. Open shared-risk observing is expected to
begin in 2011 using the full WIDAR correlator.
------------------------------------------------------------------------
3. News For VLBA/HSA/VLBI Proposers
a. Proposal Deadline is 2008 Oct 1 for Trimester 2009-T1
This deadline applies to regular observing proposals requesting
- the Very Long Baseline Array (VLBA), alone or with affiliate(s)
http://www.vlba.nrao.edu/astro/
- the High Sensitivity Array (HSA)
http://www.nrao.edu/HSA/
- the European VLBI Network (EVN)
http://www.evlbi.org/
- Global cm VLBI (EVN+VLBA) in the Feb/Mar session
- Global 3mm VLBI in the May session
http://www.mpifr-bonn.mpg.de/div/vlbi/globalmm/
This deadline also applies to large observing proposals requesting the
VLBA, alone or with other NRAO resources.
http://www.nrao.edu/administration/directors_office/largeprop.shtml
b. VLBA or HSA Proposals
Proposal preparation and submission are via the NRAO Interactive
Services http://my.nrao.edu/ . For the 1 October 2008 deadline,
VLBA/HSA proposals may *only* be submitted using the online proposal
submission tool. VLBA/HSA proposals may *not* be submitted via the
LaTex template and e-mail. Students planning to use an NRAO telescope
for their PhD dissertation must submit a "Plan of Dissertation
Research" of no more than 1000 words with their first proposal. At a
minimum it should contain a thesis timeline and an estimate of the
level of NRAO telescope resources needed. The plan can be submitted
via the NRAO Interactive Services http://my.nrao.edu/ .
c. VLBA Observational Status Summary
NRAO has produced an updated version of its comprehensive document
"VLBA Observational Status Summary". Significant changes include a
revision of the 22 GHz sensitivity values based on the recently
completed upgrade funded by MPIfR; new values for the continuum
sensitivity at 23.8 GHz, slightly off the water line; and updated
information on recording and correlator systems. The updated document
can be found in
html http://www.vlba.nrao.edu/astro/obstatus/current/
pdf http://www.vlba.nrao.edu/astro/obstatus/current/obssum.pdf
or ps http://www.vlba.nrao.edu/astro/obstatus/current/obssum.ps
formats.
d. Proposals Involving the EVN
For all classes of proposals involving the EVN, *only* the on-line
tool NorthStar http://proposal.jive.nl should be used to prepare and
submit proposals. This includes Global
cm VLBI (EVN+VLBA) proposals.
e. Global 3mm VLBI Proposals
Proposal preparation is via the LaTeX template
http://www.nrao.edu/administration/directors_office/vlba-gvlbi.shtml .
Proposal submission is via e-mail to propsoc at nrao.edu and
propvlbi at mpifr-bonn.mpg.de.
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