[mmaimcal]BIWEEKLY CALENDAR OF THE ALMA PROJECT at NRAO

Al Wootten awootten at nrao.edu
Thu Sep 16 21:14:47 EDT 2004 

Folks

Your job is to find the errors before I send this out...
Thx,
Al

                        BIWEEKLY CALENDAR OF THE ALMA PROJECT at NRAO
                              September 13 - September 27, 2004


******************************** THIS BIWEEK ***************************
The Japan Negotiating Team, a committee of the ALMA Board, and
representatives of the Japanese National Institutes of Natural Science
(NINS) have reached a draft agreement with ESO and the National Science
Foundation concerning the construction of the Enhanced ALMA.
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The week of 27 September will bring the ALMA Science Advisory Committee 
to Charlottesville for their biannual face-to-face meeting on Monday and
Tuesday at the NTC.  Wednesday through Friday ALMA IPT leaders will meet
in Charlottesville.
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Past issues of this Calendar may be viewed at
http://www.cv.nrao.edu/~awootten/mmaimcal/ALMACalendars.html
*******************************************************************************

General Happenings

Chile:  SPdA:The ALMA camp has been completed with some door closers 
pending. Kitchen equipment has been installed. Work on the permanent 
access road continues.  A contractor has been selected for the initial 
construction of the ALMA  Array Operations Site (AOS) technical 
building. The foundation package includes the necessary excavation and 
the construction of the building foundation.
         Santiago:  A contract was negotiated for outfitting of the
temporary ALMA office in Santiago, Chile which will house the JAO and
Executive staff.

TUC: A successful review of the Local Oscillator (LO) was held 8
September in Tucson. The review focussed on the first LO synthesizer.

NAASC: NTSC versions of the ALMA DVD will arrive soon.  A new ALMA 
display was created for the DUSTY04 and AAS conferences.  A brochure for 
the AAS meeting is under development.  Updating of the ALMA and NAASC 
websites continues.

NTC:  Shipment of Cryostat No 1 from RAL to NTC is planned for 22nd Sep;
compressor and lines arrived 7th Sep.  Pre-production cartridge #1  for
Band 6 (1.3mm) has been assembled and RF tests will commence
next week.  Windows and filters received from IRAM will be installed in
the 1.3mm cartridge test cryostat this week.

ATF: The latest schedule information about the ATF test interferometer
shows that it is unlikely WVR tests can be preformed in the winter
period ‘04/’05.  Tests will focus on integration rather than
demonstration.
       Tests continue on the Vertex Prototype antenna.  Tests on the AEC
antenna await repairs.  It must be expected that the AEC antenna will
not be operational before the end of October.

AOC:  Second Vega 1 digitizer assembly received in Socorro.

DAILY CALENDAR (Times EDT )
Mon  13 September
9:30 AM-10:30 AM: NA Project Office Staff Meeting
10:30 AM-12:00 PM: JAO/IPT Teleconference
Tue  14
Wed  15
Thu  16
8:30 AM-10:00 AM: JAO Teleconference
Fri  17
Mon  20
9:30 AM-10:30 AM: NA Project Office Staff Meeting
Tue  21
10:30 AM-11:00 AM: Science IPT Telecon
2:00 PM-3:00 PM ALMA Board/NA Telecaucus
4:00 PM-5:00 PM: NAScienceIPT teleconference (open to all interested
                                 parties) (434)296-7082
                       Agenda: http://www.cv.nrao.edu/~awootten/mmaimcal/
Wed  22
Thu  23
8:00 AM-9:00 AM: ALMA Board Teleconference
8:30 AM-10:00 AM: JAO Teleconference
Fri  24
All day event: ALMA EU Meeting
Sat  25
Sun  26
****************************** UPCOMING EVENTS *************************
ALMA Calendar

     * 21 September -- ALMA/NA Telecaucus
     * 23 September -- ALMA Board Telecon
     * 24 September -- ALMA/EU Meeting, Garching
     * 27-28 September -- ASAC face-to-face meeting, Charlottesville
     * 29 Sept - 1 October -- face-to-face IPT Leads Meeting, CVille
     * 4-8 October -- The Cool Universe: Observing Cosmic Beginnings
                       Universidad Tecnica Federico Santa Maria,
                       Valparaiso, Chile
     * 11-12 Oct -- AMAC Meeting, Florence, Italy
     * 11-13 Oct -- New Windows on Star Formation in the Cosmos
                     University of Maryland, College Park, Maryland
     * 18-19 Oct --  PDR for the Tunable Filter Bank card; Bordeaux
     * 27-29 Oct -- Dusty and Molecular Universe Paris
     * 29 Oct -- ANASAC Telecon
     * 1 Nov -- ALMA JAO and Executives Face-to-face Meeting, Santiago
     * 2-3 Nov -- ALMA Board Face-to-face Meeting, OSF, near San Pedro 
de                      		Atacama
     * 2 December -- ALMA Board Telecon
     * 5-7 Jan 2005 -- UNSC URSI Boulder meeting Commission J
     * 6 Jan 2005 -- ANASAC Telecon
     * 11 Jan 2005 - ALMA Town Meeting, AAS San Diego
     * 27 Jan 2005 -- ALMA Board Telecon

******************************* TECHNICAL NEWS *************************
ALMA Memo No. 503 Antenna Position Determination: Observational Methods 
and Atmospheric Limits          John Conway  (Onsala Space Observatory, 
Sweden)

We discuss the accuracy to which ALMA antenna relative positions can be
determined via astronomical observations of phase and delay toward 
multiple strong calibrators. We show that delay induced phase gradients 
across the bandpass can be used to resolve turn ambiguities so that 
accurate delays can estimated from the phase. At low frequencies this 
demands only modest stability of the bandpass phase. For this and other 
reasons we argue that 90GHz is the best frequency for position 
calibration observations. The proposed specification for short time 
instrumental phase stability is adequate for antenna position 
determination. We discuss in detail the effect of the wet troposphere 
and derive how position errors scale with baseline length in the case of 
single-baseline calibration. We then generalise to a full calibration of 
the whole array. It is found that the resulting position errors between 
two antennas is the same as if these two antennas participated in there 
own single baseline calibration. We find that because of the geometry 
and the need to solve for instrumental phase that even on short 
baselines the rms error on the vertical or z-component is twice as large 
as for the x and y components. In addition for >1km baselines while the 
x and y rms errors rapidly saturate the z components rms errors continue 
to increase. Some uncertainly in estimating errors on long baselines 
comes from our lack of knowledge of the outer scale of turbulence at the 
site. The effects of systematic gradients in the zenith wet or dry delay 
and methods of calibration are briefly considered.  We propose that when 
in the intermediate 'zoom' array configurations an initial calibration 
of the moved antennas is made in late afternoon lasting 30minutes. Later 
in the early hours of the morning, when phase stability is best, we 
propose a 30 - 60 minute calibration of the whole array. Because
of the need to apply phase corrections for antenna positions 
retro-actively even continuum data should always be stored in spectral 
line mode with channel widths <1 GHz. Final pipelining for the highest 
dynamic range imaging may have to wait for up to 12 hours until good 
antenna positions are obtained. With good 'a priori' positioning of 
antennas on pads and/or the acceptance of delayed pipelining as the norm 
after reconfiguration the first late-afternoon calibration might be 
avoided. For the smallest configurations we expect that the troposphere 
will not be a limitation on achieving the proposed goal of 100 microns 
relative positioning on all baselines. For larger configurations we 
estimate that while most baselines will achieve the target accuracy 
those baselines to recently moved antennas will have much
larger errors. Further work is required to understand the effects of 
this on imaging and astrometry.

View a pdf version of ALMA Memo #503.
http://www.alma.nrao.edu/memos/html-memos/alma503/memo503.pdf
-------------------------------------
LAMA Memo No. 808  How To Tune ALMA:  An Example
Larry R. D'Addario         Dated:   2004-Sep-07

This note describes the process of setting up the LO system of the
ALMA telescope so as to obtain a desired sky frequency and bandwidth.
It does this by way of a specific example for which the calculation
and control steps are given in detail.  One example cannot cover all
possible cases, but comments are included about how some steps might
be different.  This description is based on the system design that is
now current, but some details are subject to change.

LAMA Memo index page, with general information and links to all memos:
http://www.tuc.nrao.edu/lamaMemos
This memo, PDF format:
http://www.tuc.nrao.edu/lamaMemos/lamaMemo808.pdf (56 KB)
*******************************ALSO OF INTEREST************************

******************************************************************************* 

Please send information for upcoming calendars by Friday evening of the
preceding biweekly period to Janet Bauer or Al Wootten via e-mail
(jbauer at nrao.edu or awootten at nrao.edu).

The calendar will be issued between late Friday and sometime on Monday 
by e-mail to all NRAO scientific staff members and anyone else 
interested. A specific mailing list, alma-info, has been created for 
anyone wishing to receive it.  Past issues are now available at 
http://www.cv.nrao.edu/~awootten/mmaimcal/ALMACalendars.html

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