From cwhite at NRAO.EDU  Fri Jun  1 15:05:21 2001
From: cwhite at NRAO.EDU (Carolyn White)
Date: Fri, 01 Jun 2001 15:05:21 -0400
Subject: [asac] [almanews] ALMA Memo 374 and 376 Released
Message-ID: <3B17E771.2041B066@nrao.edu>

ALMA Memo No. 374

Wide Field Imagings with the Atacama Large Millimter/Submillimeter Array

Koh-Ichiro Morita (Nobeyama Radio Observatory, NAOJ)

2001-05-29

Image quality of wide field observations with the ALMA has been studied with
imaging simulations. Results of the simulations showed that antenna pointing
errors are a serious problem for obtaining high quality images because they
make a large error in visibilities in the central (u,v) hole estimated by
mosaicing data processings. The ALMA Compact Array (ACA) with more than 10
smaller dishes (6-8m) can compensate this problem. However, a carefull
treatment of adding the data measured with the ACA to the data from the ALMA
is needed to obtain a significant improvement of imaging performances. The
ACA with 6m antennas has better imaging performances than that of the ACA
with 8 m antennas, although the difference between them is small for noisy
cases. Another option to realize high fidelity images for large objects is
to improve the pointing of some or all of the 12 m antennas.

View a pdf version of ALMA Memo 374.
http://www.alma.nrao.edu/memos/html-memos/alma374/memo374.pdf

Download a ps version of ALMA Memo 374.
http://www.alma.nrao.edu/memos/html-memos/alma374/memo374.ps

========================================================================

ALMA Memo #376

Integration of LO Drivers, Photonic Reference, and Central Reference
Generator

Eric W. Bryerton, William Shillue, Dorsey L. Thacker, Robert Freund, Andrea
Vaccari, James Jackson, Robert Long, Kamaljeet S. Saini, and Richard F.
Bradley

2001-05-18

These measurements represent the first test of a local-oscillator (LO)
driver based on a multiplied YIG-tuned oscillator (YTO) locked to a variable
frequency photonic mm-wave reference. The reference is provided as a
beatnote between two optical signals and is carried from a remote location
by 10 meters of optical fiber to a photomixer at the LO driver site. Phase
noise measurements were performed at about 80 GHz. A pre-prototype of the
Central Reference Generator (CRG) developed in Socorro was also used in the
tests as the fundamental reference from which all other sources were
synchronized.

View a pdf version of ALMA Memo 376.
http://www.alma.nrao.edu/memos/html-memos/alma376/memo376.pdf

Download a ps version of ALMA Memo 376.
http://www.alma.nrao.edu/memos/html-memos/alma376/memo376.ps
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From cwhite at NRAO.EDU  Tue Jun  5 08:21:59 2001
From: cwhite at NRAO.EDU (Carolyn White)
Date: Tue, 5 Jun 2001 08:21:59 -0400 (EDT)
Subject: [asac] [almanews] ALMA Memo 371 Released
Message-ID: <Pine.GSO.4.33.0106050821310.22025-100000@polaris.cv.nrao.edu>

ALMA Memo #371

Receiver Calibration Schemes for ALMA

S.Guilloteau (IRAM/ESO), R.Moreno (IRAM)<br>

04 June 2001</h2>

Keywords : Calibration, Receiver

We re-investigate the two receiver calibration schemes which have been
proposed for ALMA: dual loads located in the sub-reflector, or semi
transparent vane in front of the receiver. We show that the dual-load
system needs to switch with a cycle time of less than 0.1 second to be
efficient in the submillimeter regime. Moreover, integrations in excess of
20 seconds are required to get sufficient calibration accuracy at these
frequencies. The semi-transparent vane must have an absorption coefficient
of only 0.06--0.10 below 100 GHz, but is no longer required at frequencies
above 300 GHz. The vane transmission can be calibrated in 2-3 minutes by
measurement of an astronomical source (nearby quasar). Two vanes, with
absorption coefficient 0.06 and 0.12 respectively, are recommended to
minimize the calibration time. Given the simplicity of the vane system
(passive, slow device, in the receiver cabin), compared with the
complexity, speed and location of the dual-load system, we strongly
recommend that ALMA develops and adopts such a scheme for the receiver
calibration.


View a pdf version of ALMA Memo 371.
http://www.alma.nrao.edu/memos/html-memos/alma371/memo371.pdf

Download a ps version of ALMA Memo 371.
http://www.alma.nrao.edu/memos/html-memos/alma371/memo371.ps


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From lucas at iram.fr  Tue Jun  5 12:19:45 2001
From: lucas at iram.fr (Robert Lucas)
Date: Tue, 05 Jun 2001 18:19:45 +0200
Subject: [asac] Comments on the Canadian Software Proposal
Message-ID: <3B1D06A1.F613093@iraux2.iram.fr>

file:/home/lucas/ALMA/Software/SSR/canadaproposal.html
-- 
Robert LUCAS,            Institut de Radioastronomie Millimetrique
300 rue de la Piscine,  F-38406 St Martin d'Heres Cedex   (FRANCE)
Tel +33 (0)4 76 82 49 42                  Fax +33 (0)4 76 51 59 38 
E-mail: mailto:lucas at iram.fr                http://iram.fr/~lucas/
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From awootten at NRAO.EDU  Wed Jun 13 09:57:25 2001
From: awootten at NRAO.EDU (Al Wootten)
Date: Wed, 13 Jun 2001 09:57:25 -0400
Subject: [asac] ASAC telecon 14 June
Message-ID: <3B277145.4DBE6E8A@nrao.edu>

Agenda TBA but here are details for the call:
> MCI conference call has been booked.  Details for below:
> 
>  CALL DATE:        JUN-14-2001  (Thursday)
>  CALL TIME:        10:15 AM EASTERN TIME
>  USA #:            888-831-8982
>  International #:  +1-712-271-0922
>  PASSCODE:         ALMA
>  LEADER:           Dr. Al Wootten
> 
> All callers will need to know passcode and conference leaders name.


From awootten at NRAO.EDU  Wed Jun 13 14:53:30 2001
From: awootten at NRAO.EDU (Al Wootten)
Date: Wed, 13 Jun 2001 14:53:30 -0400 (EDT)
Subject: [asac] Agenda
Message-ID: <200106131853.OAA28350@polaris.cv.nrao.edu>

I have had trouble with the agenda URL so here it is in text.

 CALL DATE:    	   JUN-14-2001  (Thursday)
 CALL TIME:    	   10:15 AM EASTERN TIME
 USA #: 	   888-831-8982
 International #:  +1-712-271-0922
 PASSCODE:	   ALMA
 LEADER:           Dr. Al Wootten


 Telecon agenda items:
 
 
 1. Reports from the AMAC (Dick) and ACC (Bob) meetings
 
 2. ACA simulations (Ewine, Stephane)
 
 3. Toward a discussion on operations (Ewine)
 
 4. Plans for Chile meeting, i.p. science day (Leo)
 
 5. Calibration meeting: See  http://www.alma.ac.uk/calpdr
A list of relevant background materials, still in the format of the old agenda, is ready.  Note there are some new/draft memos linked to from this list.  
Please see:
      http://www.alma.ac.uk/calpdr/reading.html


From awootten at NRAO.EDU  Thu Jun 14 09:06:16 2001
From: awootten at NRAO.EDU (Al Wootten)
Date: Thu, 14 Jun 2001 09:06:16 -0400 (EDT)
Subject: [asac] Agenda
Message-ID: <200106141306.JAA20127@polaris.cv.nrao.edu>


 CALL DATE:    	   JUN-14-2001  (Thursday)
 CALL TIME:    	   10:15 AM EASTERN TIME
 USA #: 	   888-831-8982
 International #:  +1-712-271-0922
 PASSCODE:	   ALMA
 LEADER:           Dr. Al Wootten

Agenda with hyperlinks:
www.cv.nrao.edu/~awootten/mmaimcal/asac/asacjun01agenda.html
which includes links to the minutes of the last meeting and to the
calibration pdr readings.

Clear skies,
Al


From awootten at NRAO.EDU  Thu Jun 14 10:29:49 2001
From: awootten at NRAO.EDU (Al Wootten)
Date: Thu, 14 Jun 2001 10:29:49 -0400 (EDT)
Subject: [asac] AMAC members
Message-ID: <200106141429.KAA22707@polaris.cv.nrao.edu>


Sorry for not explaining the AMAC.  It is Alma Management Advisory Committee.
It replaces the MMA Oversight Committee and consists of that committee plus
5 additional European members, whose names I passed around.  Of course,
five Japanese members are expected to join in the near future.

 Arnold van Ardenne <ardenne at astron.nl>, ASTRON Chief of engineering
 Herwig Schopper <Herwig.Schopper at cern.ch>, Dir-Gen CERN (ret)
 John Credland <John.Credland at esa.int>, ESA executive scientific programs
 Robert Aymar <aymarr at itereu.de>, Head of ITER Project (fusion)
 Sergio Bertini <sbertini at intemanet.com>  executive (ret) in Italian 
       electronics firm, formerly radio astronomer at Arcetri

These join John Mather, Gerry Saunders, Dominic Tenorelli, Bob Wilson and
Gordon Chin, members of the MMAOC now the AMAC/US. 

Clear skies,
Al



From ewine at strw.leidenuniv.nl  Thu Jun 14 16:34:05 2001
From: ewine at strw.leidenuniv.nl (Ewine van Dishoeck)
Date: Thu, 14 Jun 2001 22:34:05 +0200
Subject: [asac] IMPORTANT; PLEASE RESPOND
Message-ID: <200106142034.WAA24605@nitrogen.strw.LeidenUniv.nl>

Dear ASAC-members,

First of all, I would like to extend our congratulations on behalf of the
entire ASAC to the project for the successful outcome of the E-ACC meeting!

===> Please read this message carefully: it contains information/questions on
new working groups and on the logistics of the ASAC meeting in Chile. PLEASE
RESPOND TO THE RELEVANT PEOPLE BY TUESDAY JUNE 19 <====

For those ASAC members who were not on the phone today: the good news is that
the three executives, including the NSF, agreed to submit budget requests
according to the "-10% option", rather than the "-20% option". If this level
of funding indeed comes through, it would be possible to implement all of our
high priority enhancements, i.e., the ACA, 4 additional receiver bands (1, 4 ,
8 and 10), and the enhanced/future correlator. However, the ball is now back
in the ASAC court: we have to convince the E-ACC of the feasibility and
scientific importance of the enhancements, especially of the ACA. We need to
do this by the date of the next E-ACC meeting, October 30-31 in Washington,
which means in practice that we need to formulate our recommendation at the
face-to-face meeting in Chile in September. In addition to our ASAC report, we
should produce a document with the scientific arguments for the enhancements.
For Bands 1, 4 and 8 and the enhanced/future correlator, we have already done
most of our homework, but we still need to add the ACA and Band 10 cases.
In addition, we need to adress some operational issues. As a result, we
have formed several working groups.


1. ACA issues
=============

The ACA case is particularly critical: it is the largest budget item,
of order $80M including receivers. Obviously, the executives are reluctant to
commit so much money unless they are convinced of its scientific importance
and feasibility. Recall that the previous simulations by various
groups have shown significant improvements in image fidelity, but that those
simulations did not yet include realistic atmospheric conditions, i.e.,
phase and amplitude errors. As Stephane argued last month, about 6 months
of work is needed to do the proper simulations. This will now have to be
shortened to about 2 months to get ready before the ASAC meeting.
Accordingly, we have formed a "tiger team" to deal with the ACA simulations,
consisting of:

  ACA tiger team (Stephane and Al to coordinate):
  ==============

  - Stephane, Frederic Gueth, Jerome Pety
  - Al, Mark Holdaway, Brian Butler
  - Morita-san
  - Patricia Monger
  - ASAC volunteers: Jack, Dick Crutcher, Pierre, Min Yun??TBC, Japanese TBD
                     ANY OTHER VOLUNTEERS??

The ACA tiger team will meet at/following the Cambridge calibration PDR where
it will formulate a detailed plan. It will post weekly updates on the WWW
and report at our monthly telecons. The role of the ASAC members of the tiger
team is to keep a critical eye on the methods, progress and results, so that we
are not faced with surprises at the face-to-face meeting.

In addition, the ASAC is requested to provide science examples for the ACA.
Besides using the generic testcases from the model library, we need to
convince the E-ACC on scientific grounds. PLEASE SEND SUGGESTIONS TO ME BY
JUNE 29.
 

2. Band 10 science case
=======================

We need to argue the Band 10 science case along the lines of the Band 1, 4 and
8 cases.

ASAC volunteers: Yamamoto??? Japanese TBD, Ewine, 
                 NEED A NORTH AMERICAN VOLUNTEER


3. Operations
=============

The E-AEC has requested ASAC input on the operations from the pure scientific
point of view: how would the astronomers like to use ALMA, both experts
and non-experts? What should be the tasks of the regional data centers
and that in Chile? There is some useful material on this subject, including
the recent ESO operations document, which will be sent to you by hardcopy
in the near future.


  Operations working group:
  -------------------------

 - Neal (coordinator), Christine, Peter Shaver, John Richer, Roy, Leo
   Bronfman, Nick??? TBC, Japanese TBD
   ANY OTHER VOLUNTEERS??

The output of the working group should be a short document to be used as
starting point for our discussion in Chile. Neal will draft a statement of work.


4. Enhanced/future correlator
=============================

There will be a 1-week working group meeting between Japan/EU/NA representatives
to discuss the future/enhanced correlator late July/early August. The ASAC
should re-iterate its guidelines beforehand. Rafael will summarize our
recommendations to date and circulate them before our July telecon.


5. Chile meeting
================


a. Science day
--------------

An ASAC scientific organizing committee for the science day on September 13
has been formed consisting of:

 - Leo (coordinator), Pierre, Al, Tetsuo, Ewine

Plans will be circulated by early July.


b. Logistics
-----------

PLEASE FILL OUT THE FORM BELOW AND RETURN TO LEO

Leo will provide representative timetables for travel from Santiago to
San Pedro and return. Partcipants should check flights to Chile as soon
as possible, since they fill up rapidly. Most flights from the US arrive
in the morning, allowing plenty of time to travel to San Pedro the same
day. They usually leave in the evening from Santiago. The science
program will end around tea time on September 13, so that people can
fly back the same evening.

We will investigate whether to make a block booking on the flight from
Calama-Santiago September 10, or whether it is cheaper/easier to combine
with your international ticket. Leo will send the relevant flight number
and time.


6. SUMMARY
==========

JUNE 19: DEADLINE FOR ASAC VOLUNTEERS FOR ACA, BAND 10 and OPERATIONS WORKING 
         GROUPS
         SEND NAMES TO EWINE

JUNE 29: DEADLINE FOR ACA SCIENCE EXAMPLE SUGGESTIONS
         SEND MATERIAL TO EWINE, WITH COPIES TO STEPHANE AND AL

A.S.A.P.: SEND LODGING REQUESTS FOR CHILE TO LEO BRONFMAN
          


Obviously, we have a busy few months ahead, but also a wonderful opportunity
to define the ALMA that we scientists would like to have!

Many thanks in advance for your efforts,

Ewine

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

    Chile lodging information
    =========================


  ***** PLEASE RETURN TO leo at das.uchile.edu  A.S.A.P. *****


Name:

E-mail:


- I will go to San Pedro/Chajnantor: Yes/No

    If Yes: I need lodging for the nights of Sept. 8: Yes/No    
                                             Sept. 9: Yes/No

    Accompanying persons: Yes/No
                   

- I will attend the ASAC meeting in Santiago: Yes/No

    If Yes: I need lodging for the nights of Sept. 10: Yes/No    
                                             Sept. 11: Yes/No
                                             Sept. 12: Yes/No
                                             Sept. 13: Yes/No
   Accompanying persons: Yes/No


- Any dietary restrictions:

- Any comments/special needs:


From ewine at strw.leidenuniv.nl  Sat Jun 16 12:28:09 2001
From: ewine at strw.leidenuniv.nl (Ewine van Dishoeck)
Date: Sat, 16 Jun 2001 18:28:09 +0200
Subject: [asac] Correction and Request
Message-ID: <200106161628.SAA11987@nitrogen.strw.LeidenUniv.nl>

Dear ASAC members,

One correction and one more request:

- Correction: Leo's e-mail address is: leo at das.uchile.cl
              Please send the Chile lodging form to him a.s.a.p.

- Request: New documents have been posted at the WWW site of the Calibration
           PDR in Cambridge in the last week. Please read these carefully.
           Those ASAC members not attending the meeting may want to send 
           comments before the meeting to Stephane or Al. For links, see

           http://www.cv.nrao.edu/~awootten/mmaimcal/asac/asacjun01agenda.html

Many thanks!

Ewine

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

    Chile lodging information
    =========================


  ***** PLEASE RETURN TO leo at das.uchile.cl  A.S.A.P. *****


Name:

E-mail:


- I will go to San Pedro/Chajnantor: Yes/No

    If Yes: I need lodging for the nights of Sept. 8: Yes/No    
                                             Sept. 9: Yes/No

    Accompanying persons: Yes/No
                   

- I will attend the ASAC meeting in Santiago: Yes/No

    If Yes: I need lodging for the nights of Sept. 10: Yes/No    
                                             Sept. 11: Yes/No
                                             Sept. 12: Yes/No
                                             Sept. 13: Yes/No
   Accompanying persons: Yes/No


- Any dietary restrictions:

- Any comments/special needs:



From awootten at NRAO.EDU  Mon Jun 18 14:31:30 2001
From: awootten at NRAO.EDU (Al Wootten)
Date: Mon, 18 Jun 2001 14:31:30 -0400 (EDT)
Subject: [asac] [almanews] ALMA Memo 365  Released
Message-ID: <200106181831.OAA16879@polaris.cv.nrao.edu>

ALMA Memo #365

Atmospheric Phase Stability at Chajnantor and Pampa la Bola

Bryan J. Butler and Simon J. E. Radford
National Radio Astronomy Observatory

Seiichi Sakamoto
National Astronomical Observatory of Japan

Kotaro Kohno
Nobeyama Radio Observatory

2001-Jun-06

Atmospheric phase stability has been measured at Chajnantor (e.g., Radford &
Holdaway 1998) and Pampa la Bola (e.g., Ishiguro 1998) for many years now
with Site Test Interferometers (STIs - see Ishiguro et al. 1989; Radford et
al. 1996). A preliminary analysis of these data showed Chajnantor had
smaller phase fluctuations than Pampa la Bola (Holdaway et al. 1997), but
only 6 weeks worth of data were included in that analysis. Given the more
extensive data set available now, it seems appropriate to make a more
complete comparison.


View a pdf version of ALMA Memo 365.
http://www.alma.nrao.edu/memos/html-memos/alma365/memo365.pdf

Download a ps version of ALMA Memo 365.
http://www.alma.nrao.edu/memos/html-memos/alma365/memo365.ps


============================================================================
=
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From tetsuo.hasegawa at nao.ac.jp  Tue Jun 19 00:44:33 2001
From: tetsuo.hasegawa at nao.ac.jp (Tetsuo Hasegawa)
Date: Tue, 19 Jun 2001 13:44:33 +0900
Subject: [asac] IMPORTANT; PLEASE RESPOND
In-Reply-To: <200106142034.WAA24605@nitrogen.strw.LeidenUniv.nl>
References: <200106142034.WAA24605@nitrogen.strw.LeidenUniv.nl>
Message-ID: <p04320403b75483764ffb@[133.40.220.182]>

Dear ASAC members,

Attached EXCEL file is a list of candidate science examples that may or may 
not benefit ACA.  It is an outcome of a brainstorming among Japanese 
scientists including Kotaro Kohno, Ryohei Kawabe, Ken'ichi Tatematsu, 
Naomasa Nakai, Koh-Ichiro Morita and myself.  The "Y" in the column under 
the title "Is ACA beneficial?" means a possibility that ACA may bring its 
scientific benefit to the program, provided that the object is bright 
enough so that the dynamic range of the image is not limited by statistical 
noise.  The actual merit of ACA needs to be evaluated more carefully for 
each example taking actual surface brightness and structure into account.

We hope that this list serves as a starting point toward our clear and 
objective evaluation of the scientific merit of ACA.

With best,

Tetuso

At 22:34 +0200 01.6.14, Ewine van Dishoeck wrote:
>In addition, the ASAC is requested to provide science examples for the ACA.
>Besides using the generic testcases from the model library, we need to
>convince the E-ACC on scientific grounds. PLEASE SEND SUGGESTIONS TO ME BY
>JUNE 29.
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-- 
_______________________________________________________________
Tetsuo HASEGAWA, D. Sc.   <tetsuo.hasegawa at nao.ac.jp>
ALMA-J Project Scientist
Professor, National Astronomical Observatory of Japan
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Phone +81-422-34-3780 / FAX +81-422-34-3764
_______________________________________________________________

From tetsuo.hasegawa at nao.ac.jp  Tue Jun 19 22:44:38 2001
From: tetsuo.hasegawa at nao.ac.jp (Tetsuo Hasegawa)
Date: Wed, 20 Jun 2001 11:44:38 +0900
Subject: [asac] Re: Three examples for ACA evaluation
In-Reply-To: <200106190658.IAA17132@strw.LeidenUniv.nl>
References: <200106190658.IAA17132@strw.LeidenUniv.nl>
Message-ID: <p04320402b755ab71e6b2@[133.40.220.182]>

Dear Ewine and ASAC members,

Based on discussions with Yasuo Fukui and my colleagues in the ALMA-J 
office, I choose the following three examples as appropriate to measure the 
possible benefit from ACA out of the table I sent yesterday:

Example 1: Extended protostellar envelopes --- How accurate can ALMA images 
reproduce its radial profile?

Example 2: Multiple dense cores in a GMC at a distance of LMC --- How 
accurate can an ALMA image reproduce the extended diffuse component and the 
mass function of the cores embedded therein?

Example 3: Face-on disk galaxies at small to intermediate distances --- How 
accurate can ALMA images reproduce the extended disk component and the 
brightness of the arms and the interarm regions?

We understand that there are many other important subjects for ALMA. 
However, the above examples should serve as a good set of benchmarks for a 
single peak+envelope system (Example 1), a multiple and random peaks+common 
envelope system (Example 2), and an extended structure with quasi-periodic 
patterns (Example 3).  We will encounter similar situations in various 
observational programs with ALMA.

We may wish to ratio images taken at different frequencies to get spatial 
maps of the spectral index in the continuum or the line intensity ratios. 
In the Example 3, we may also measure the arm/interarm contrast.  For these 
purposes, we should evaluate the accuracy (or fidelity) of the reproduced 
image in reference to the in-situ brightness of the original image, i.e., 
in terms of images showing the fractional error
[(reproduced intensity) - (original intensity)]/(original intensity),
at least at two different observing frequencies for the same model source.

The actual observations will be made both in continuum and in line, but 
simulating only continuum observations should be sufficient for the current 
purpose.

With best,

Tetsuo

At 8:58 +0200 01.6.19, Ewine van Dishoeck wrote:
>Dear Tetsuo,
>
>Many thanks for the input on the ACA science examples. It is very good to see
>that the Japanese community is so actively thinking about ALMA programs!
>
>Which of the 2-3 programs would you consider as the highest priority for the
>ACA?
>
>With best regards,
>
>Ewine

-- 
_______________________________________________________________
Tetsuo HASEGAWA, D. Sc.   <tetsuo.hasegawa at nao.ac.jp>
ALMA-J Project Scientist
Professor, National Astronomical Observatory of Japan
2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
Phone +81-422-34-3780 / FAX +81-422-34-3764
_______________________________________________________________


From soliver at tuc.nrao.edu  Wed Jun 20 18:26:19 2001
From: soliver at tuc.nrao.edu (Stacy Oliver)
Date: Wed, 20 Jun 2001 15:26:19 -0700
Subject: [asac] [almanews] ALMA Memo 378 Released
Message-ID: <NFBBIFMFOKJLFHFJACADCEHACAAA.soliver@tuc.nrao.edu>

ALMA Memo #378

A 200-300 GHz SIS Mixer-Preamplifier with 8 GHz IF Bandwidth

E. F. Lauria, A. R. Kerr, M. W. Pospieszalski, S.-K. Pan, J. E. Effland, A.
W. Lichtenberger

2001-Jun-07


Initial results are presented for a 200-300 GHz SIS mixer/preamplifier with
an IF bandwidth of 8 GHz. The mixer uses Nb/Al-oxide/Nb tunnel junctions in
a circuit with low IF capacitance and inductance. The mixer block mounts
directly on the body of a three-stage 4-12 GHz preamplifier which uses
discrete InP HFET devices. Mixer bias is provided through the input circuit
of the preamplifier. At a LO frequency of 230 GHz, the measured mixer-preamp
gain is 30-35 dB, and the DSB receiver noise temperature is 45-57 K across
the whole IF band. The preamp alone has 40 dB of gain, and dissipates 7.7
mW. With four amplifiers required in each ALMA cartridge, there is concern
that the cooling capacity currently planned for ALMA receivers will be
marginal. This mixer/preamplifier has demonstrated that an IF bandwidth of 8
GHz is indeed achievable for ALMA Band 6.


View a pdf version of ALMA Memo 378.
http://www.alma.nrao.edu/memos/html-memos/alma378/memo378.pdf

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From cwhite at NRAO.EDU  Thu Jun 21 08:40:47 2001
From: cwhite at NRAO.EDU (Carolyn White)
Date: Thu, 21 Jun 2001 08:40:47 -0400
Subject: [Fwd: [asac] [almanews] ALMA Memo 378 Released]
Message-ID: <3B31EB4F.11CA5B0@nrao.edu>


-- 
Carolyn White
National Radio Astronomy Observatory
520 Edgemont Road
Charlottesville, VA 22903
804-296-0224
Fax:  804-296-0278
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From bachiller at oan.es  Fri Jun 22 06:30:56 2001
From: bachiller at oan.es (Rafael Bachiller)
Date: Fri, 22 Jun 2001 12:30:56 +0200
Subject: [asac] ASAC: Enhanced/Future Correlator Guidelines
Message-ID: <200106220830.KAA21493@baal.oan.es>



Dear ASAC members,

Following your suggestion at the last ASAC teleconference, I have drafted 
a summary of recent ASAC recommendations concerning the ALMA Enhanced/Future 
Correlator. This should provide a guideline to the Enhanced/Future Correlator 
working teams which will meet by next July.

Please send me your comments and suggestions as soon as possible, so I can 
incorporate them before the next teleconference.

With best regards,
                          Rafael

                          bachiller at oan.es


==========================================================================


ASAC Guidelines for the ALMA Enhanced/Future Correlator

The following specifications and goals should be taken into account 
by the European, Japanese and North American teams working in the design 
of an Enhanced/Future Correlator for ALMA.

In general terms, the ASAC stresses that the Enhanced Correlator 
developments should be guided by the goals of achieving 
          (a) high number of channels in wide band modes
          (b) high configuration flexibility
          (c) high sensitivity
          (d) high spectral resolution, and 
          (e) power consumption as low as possible.

As in previous occasions, the ASAC strongly encourages a tight collaboration
of the different teams to optimize the design and to select the best possible
architecture and manufacturing method within the budget limits.

What follows is a summary of the requirements and goals which were 
put forward by the ASAC at recent meetings. 

1.- In addition to the final total number of 12m antennas, the Enhanced/Future
Correlator must accommodate the ALMA Compact Array.

2.- A total number of about 8000 channels is the minimum required.
This seems sufficient for most astronomical observations. 
Observations using multiple sub-bands and polarizations would accordingly 
have less channels available per product (sub-band and/or polarization). 
A good, more ambitious, goal would be to obtain 4000 to 8000 channels 
per product. Nevertheless, if the total number of channels were significantly 
larger than 8000, there should be ways of selecting or compressing them for
further processing.

3.- Three-bit digitizing format and three-bit (or even four-bit) correlation 
format are recommended to obtain high sensitivity by diminishing quantization 
losses.

4.- A highest spectral resolution of 5 kHz is required.
This corresponds to 0.05 km/s at 30 GHz, which is necessary, e.g., 
for the observation of lines in cold dark molecular clouds.

5.- A reasonable goal for the Enhanced/Future Correlator is to provide 
16 sub-bands (in total, not per polarization). Note that the equivalent 
number of sub-bands in the Baseline Correlator is 8. 

6.- ALMA will have the ability to be split in different logically-independent
sub-arrays, and to observe at a maximum of 4 different frequencies. 
The Enhanced/Future Correlator should be able to accommodate at least 
16 independent sub-arrays, which is the number provided by the Baseline 
Correlator.

7.- For solar (continuum) observations, minimum integration times of 1 msec 
are required. For spectral line observations, the fastest integration period 
should be made compatible with the minimum dump time. In side band separation 
mode, integration times of the order of 120 msec should be possible.







From ewine at strw.leidenuniv.nl  Sat Jun 30 09:53:21 2001
From: ewine at strw.leidenuniv.nl (ewine at strw.leidenuniv.nl)
Date: Sat, 30 Jun 2001 15:53:21 +0200 (MEST)
Subject: [asac] Chile lodging
Message-ID: <200106301353.PAA13700@deuterium.strw.leidenuniv.nl>

Dear ASAC members,

Below please find the list of registrations so far for the Chile meeting. A
number of people have not yet registered. Can you do so a.s.a.p., especially
if you want to go to Chajnantor? Rooms in San Pedro are very limited. In fact,
there are only 6 spots left on a shared-room basis (see message Leo below)!


For flights coming back Calama on the 10'th, ask your travel agent
to book:

 LA  151  10SEP CJC-SCL 1910   2155


Finally,  please let me know of any specific ACA science examples by Tuesday
July 3, if you have not done so already.

With best wishes,

Ewine


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

Registration dd. June 29 from Leo Bronfman


S. Radford, San Pedro=yes
P. Shaver, yes
Y. Chikada, yes         
G. Blake, yes + 1
D. Emerson, yes + 1 (maybe)
H. Matsuo, yes
R. Kurtz, yes
M. Yun does not come
R. Lucas, yes
R. Bachiller, yes
J. Richer, yes
C. Wilson, yes
J. Payne, yes
K. Tatematsu - his own arrangements for San Pedro
E. van Dishoek, yes
M. Walmsley, no
N. Evans, yes + 1
L. Bronfman, yes

I booked 12 double rooms at Hosteria Don Tomas, in San
Pedro, right after the meeting in Florence. That was all
 what I could do,  because school
vacations start in Chile that very day, and the town was
booked. For previous days there is no problem - this is for
people that want to go early to San Pedro. 

We have 15 ASAC people going to San Pedro , three of them
with accompanying person. They will use 3 double rooms.
So we have 9 double rooms  for the 
remaining  12 people. Six people would be alone and
6 persons would have to share rooms the night of Sept 9th
(the problematic one).  Thus, if people keep registering for San Pedro,  
we have an absolute limit of six more persons, in a shared
room basis. I hope everyone has made up his/her mind by
now. 

All the best,

Leo

PS would you kindly circulate the above list so as to know
if there are any lost registrations



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

    Chile lodging information
    =========================


  ***** PLEASE RETURN TO leo at das.uchile.cl  A.S.A.P. *****


Name:

E-mail:


- I will go to San Pedro/Chajnantor: Yes/No

    If Yes: I need lodging for the nights of Sept. 8: Yes/No    
                                             Sept. 9: Yes/No

    Accompanying persons: Yes/No
                   

- I will attend the ASAC meeting in Santiago: Yes/No

    If Yes: I need lodging for the nights of Sept. 10: Yes/No    
                                             Sept. 11: Yes/No
                                             Sept. 12: Yes/No
                                             Sept. 13: Yes/No
   Accompanying persons: Yes/No


- Any dietary restrictions:

- Any comments/special needs: