From Idea to ALMA Project James Di Francesco Herzberg Institute of Astrophysics North American ALMA...

From Idea to ALMA Project James Di Francesco

Herzberg Institute of Astrophysics

North American ALMA Science Center(thanks to Mike Rupen, Gianni Comoretto & Ray

Escoffier)

TheAtacama Large

Millimetre Array(ALMA)

OutlineOutline

• ALMA CapabilitiesALMA Capabilities• Correlator ModesCorrelator Modes• Observing Tool (OT)Observing Tool (OT)• Proposal ProcessProposal Process• Early ScienceEarly Science

ALMA CapabilitiesALMA Capabilities• NumbersNumbers

1 2

4

58

10

9 mm

350 m

ALMA CapabilitiesALMA Capabilities• Frequency CoverageFrequency Coverage

ALMA CapabilitiesALMA Capabilities• Angular ResolutionAngular Resolution

- for 12-m array:for 12-m array: FWHMFWHM= 0.62”(max baseline[km])= 0.62”(max baseline[km])-1-1((/100 GHz)/100 GHz)-1-1

- 12-m antenna configurations will “breathe” from 12-m antenna configurations will “breathe” from maximum 200 m to maximum ~18 km baselinesmaximum 200 m to maximum ~18 km baselines - for ACA:for ACA: FWHMFWHM= 20.6”(= 20.6”(/100 GHz)/100 GHz)-1-1

- ACA antennas will be fixed in positionACA antennas will be fixed in position

ALMA CapabilitiesALMA Capabilities• Fields of ViewFields of View

= 62.9” (= 62.9” (/100 GHz)/100 GHz)--

1 1 [12m][12m]

FOV = 1.22 FOV = 1.22 ((/D)/D)

= 107.8” (= 107.8” (/100 /100 GHz)GHz)-1 -1 [7m][7m]

ALMA CapabilitiesALMA Capabilities• Fields of ViewFields of View

~4’~4’

Band 3 Band 3 (54”)(54”)

Band 6 (27”)Band 6 (27”)

Band 9 (9”)Band 9 (9”)

Band 7 (18”)Band 7 (18”)

FOV [12 m]FOV [12 m]

B68 ALMA single pointingB68 ALMA single pointing

ALMA CapabilitiesALMA Capabilities• Fields of View (Mosaics)Fields of View (Mosaics)

~4’~4’

Nyquist Nyquist Spacing Spacing

= 3= 3-1/2-1/2 ( (/D)/D)

= 29.75” x = 29.75” x ((/100 /100 GHz)GHz)-1-1

= expensive!= expensive!

OTF OTF mosaickingmosaicking to to come!come!

B68 ALMA 22-pointing mosaicB68 ALMA 22-pointing mosaic

ALMA CapabilitiesALMA Capabilities• Total Power RecoveryTotal Power Recovery (on scales >(on scales >/b/bminmin))

Method 1: ACA (or SMA??)Method 1: ACA (or SMA??) - fixed configuration, more - fixed configuration, more compact:compact: FWHMFWHM = 20.6”( = 20.6”(/100 GHz)/100 GHz)-1-1

- for similar SNR data, - for similar SNR data, tt(ACA) (ACA) = = nn x x tt(ALMA)(ALMA)Method 2: ACA 12 m antennas in TP modeMethod 2: ACA 12 m antennas in TP mode

- - FWHMFWHM = 12-m array FOVs (e.g., 54” in B3) = 12-m array FOVs (e.g., 54” in B3) - for similar SNR data, - for similar SNR data, tt(ACA-12) = (ACA-12) = nn x x tt(ALMA)(ALMA)

Method 3: build a ~25 m single dish (CCAT?)Method 3: build a ~25 m single dish (CCAT?)

ALMA CapabilitiesALMA Capabilities• PolarizationPolarization

- ALMA antennas have linearly polarized feeds,ALMA antennas have linearly polarized feeds, can recover can recover II, , QQ, , UU and and V V from observed X and Yfrom observed X and Y- not “free,” requires reducing band width by 2,not “free,” requires reducing band width by 2, some sensitivity some sensitivity - specs require <0.1% polarized flux error- specs require <0.1% polarized flux error**

- special calibration required (e.g., obs over many special calibration required (e.g., obs over many parallactic angles)parallactic angles)- needed for high dynamic range imagingneeded for high dynamic range imaging- Band 7 will have quarter-wave plates for precise Band 7 will have quarter-wave plates for precise polarimetric imaging (B5 only one polzn)polarimetric imaging (B5 only one polzn)

ALMA CapabilitiesALMA Capabilities• SensitivitySensitivity

http://www.eso.info/sci/facilities/alma/observing/tools/etc/

- also possible to combine ACA* with 12-m array!also possible to combine ACA* with 12-m array!

ALMA CapabilitiesALMA Capabilities• SensitivitySensitivity

- ultimately depends on spectral resolution (SR)ultimately depends on spectral resolution (SR) and this depends onand this depends on correlator configuration correlator configuration

- correlator is powerful but has finite capacity, has correlator is powerful but has finite capacity, has 4 quadrants that can be configured independently4 quadrants that can be configured independently

- correlator resources (filters, correlator planes)correlator resources (filters, correlator planes) allocated with trade-offs between band width,allocated with trade-offs between band width, no. of polarizations processed, sampling rate,no. of polarizations processed, sampling rate, and quantization level and quantization level

Correlator ModesCorrelator Modes


xij()

Correlators, um, Correlators, um, correlatecorrelatesignals from signals from antenna pairsantenna pairs

From the From the correlations, the correlations, the complex visibilities complex visibilities can be obtained by can be obtained by measuring themeasuring thereal and imaginary real and imaginary parts.parts.

Antenna 1


Antenna 1

Antenna 2


Antenna 1 Antenna 2

=0


Antenna 1 Antenna 2


Antenna 1Antenna 1 Antenna 2

=0.5



=1



=1.5



=2

Correlation of Ant 1 & Ant 2


For a monochromatic signal:

and the correlation function is

So we need only measure with



xI

xR

- xR and xI correspond to the amplitude and phaserespectively


- xR and xI are measured by adding measured by adding phase delays (phase delays ( = 1/4 = 1/4 ) to incoming signals, get ) to incoming signals, get RRijij((,,tt))

a complex correlatora complex correlator


- ALMA’s receivers are ALMA’s receivers are not not monochromaticmonochromatic, and deliver wide-band , and deliver wide-band signals to the correlatorsignals to the correlator

- to get to get spectraspectra, use the principle , use the principle that the Fourier Transform of a cross-that the Fourier Transform of a cross-correlation (lag) function is the correlation (lag) function is the frequency spectrum:frequency spectrum:

- SHORT LAGS LOW FREQUENCIESSHORT LAGS LOW FREQUENCIES- LONG LAGS HIGH FREQUENCIESLONG LAGS HIGH FREQUENCIES

Correlator ModesCorrelator Modes- baseband pairs from antennas are 2 baseband pairs from antennas are 2 GHz wideGHz wide- 4 baseband pairs are independently 4 baseband pairs are independently tunabletunable

LSB USB

12 3

4

4 GHz 8 GHz 4 GHz

o

e.g., Band 3: LO1

Correlator ModesCorrelator ModesThe ALMA Correlator:The ALMA Correlator: - 32 main racks with 3,000 printed - 32 main racks with 3,000 printed circuit cardscircuit cards - a total of 135,000 complex - a total of 135,000 complex integrated circuitsintegrated circuits - factor of 15,000 larger than the - factor of 15,000 larger than the VLA correlatorVLA correlator - overall system dissipation: - overall system dissipation: 170,000 W170,000 W

one quadrant

station rackcorrelator rackpowersupply

computer


- the ALMA Correlator is an “the ALMA Correlator is an “FXFFXF” ” design:design:

- - FF: divide incoming signal up to : divide incoming signal up to smaller chunks smaller chunks (sub-bands) using a Tunable (sub-bands) using a Tunable Filter Bank cardFilter Bank card - - XX: measure the cross-correlation : measure the cross-correlation function over a function over a range of lags, average over range of lags, average over timetime - - FF: Fourier Transform the CC : Fourier Transform the CC functions to obtainfunctions to obtain the frequency spectrum of each the frequency spectrum of each sub-bandsub-band - stitch together the sub-bands (if - stitch together the sub-bands (if necessary)necessary)


““F”F”

““X”X” ““F”F”

x4x4

ALMA Correlator Block DiagramALMA Correlator Block Diagram

Correlator ModesCorrelator Modes- Tunable Filter BankTunable Filter Bank (“F”) (“F”)

- divides up the input 2 GHz - divides up the input 2 GHz baseband pairs intobaseband pairs into 32 sub-bands, each 62.5 MHz wide32 sub-bands, each 62.5 MHz wide - each sub-band can be tuned - each sub-band can be tuned independently withinindependently within the 2 GHz basebandthe 2 GHz baseband - allows quadrant to work - allows quadrant to work simultaneously on many simultaneously on many pieces of baseband pieces of baseband - no. of filters used determines - no. of filters used determines band width:band width: e.g., 32 filters e.g., 32 filters 2 GHz 2 GHz 1 filter 1 filter 62.5 MHz 62.5 MHz (NB: 2 filters used for 31.25 (NB: 2 filters used for 31.25 MHz)MHz)


- Correlator PlanesCorrelator Planes (“X”) (“X”)

- 32 planes per quadrant- 32 planes per quadrant - process the outputs from filters- process the outputs from filters - e.g., one plane used for each 62.5 - e.g., one plane used for each 62.5 MHz sub-band,MHz sub-band, - or, the output of fewer filters - or, the output of fewer filters can be “stretched” can be “stretched” across many planes to obtain across many planes to obtain higher spectral higher spectral resolution (SR)resolution (SR)

- e.g., for 2 GHz (32 filters), get - e.g., for 2 GHz (32 filters), get 244 kHz SR244 kHz SR for 250 MHz (4 filters), for 250 MHz (4 filters), get 30 kHz SRget 30 kHz SR

Correlator ModesCorrelator Modes- a quick side-discussion on - a quick side-discussion on digitizationdigitization: :

- - SamplingSampling: signals (: signals (vv((tt)),, 0 ≤ 0 ≤ ≤ ≤ ) are ) are lossless if sampled lossless if sampled at the Nyquist rate, at the Nyquist rate, tt < 1/2( < 1/2())

- - QuantizationQuantization: chosen level (2-bit, 4-: chosen level (2-bit, 4-bit) can induce bit) can induce offsets (noise), offsets (noise), vv((tt)) vv((tt)) + +

- higher sampling rate and quantization - higher sampling rate and quantization level better level better reproduce input signal, improves S/N, reproduce input signal, improves S/N, at a cost to at a cost to SR (correlator resources)SR (correlator resources)

- can choose sampling rate (1N or 2N, for - can choose sampling rate (1N or 2N, for factor 2 SR) and factor 2 SR) and quantization level (2-, (3-), 4-bit, for quantization level (2-, (3-), 4-bit, for factor 4 SR)factor 4 SR)

Correlator ModesCorrelator Modes1. Time Division Modes1. Time Division Modes - total band width of 2 GHz - total band width of 2 GHz (continuum only)(continuum only) - filters divide up 1 ms of - filters divide up 1 ms of integration into 32integration into 32 smaller time blockssmaller time blocks - planes process each time block, - planes process each time block, allows fasterallows faster integration times of 16 msintegration times of 16 ms - only Nyquist sampling possible- only Nyquist sampling possible - SR depends on no. of polzns (1, 2 - SR depends on no. of polzns (1, 2 or 4) and or 4) and quantization level (2-bit or 3-quantization level (2-bit or 3-bit)bit) - e.g., 128 x 15.6 MHz SR for 2 - e.g., 128 x 15.6 MHz SR for 2 polznspolzns


Example of Time Division Modes (Band 6):Example of Time Division Modes (Band 6):

- 1 quadrant observes 2 GHz of LSB (230-232 1 quadrant observes 2 GHz of LSB (230-232 GHz), 2 polzns,GHz), 2 polzns, 2-bit, Nyq., get 2-bit, Nyq., get 128 spectral points each 128 spectral points each 15.6 MHz wide15.6 MHz wide

- 1 quadrant observes 2 GHz of LSB (232-234 1 quadrant observes 2 GHz of LSB (232-234 GHz), 4 polzns, GHz), 4 polzns, 2-bit, Nyq., get 2-bit, Nyq., get 64 spectral points each 64 spectral points each 31.25 MHz wide31.25 MHz wide

- 1 quadrant observes 2 GHz of USB (246-248 1 quadrant observes 2 GHz of USB (246-248 GHz), 2 polzns, GHz), 2 polzns, 2-bit, Nyq., get 2-bit, Nyq., get 128 spectral points each 128 spectral points each 15.6 MHz wide15.6 MHz wide

- 1 quadrant observes 2 GHz of USB (248-250 1 quadrant observes 2 GHz of USB (248-250 GHz), 4 polzns, GHz), 4 polzns, 2-bit, Nyq., get 2-bit, Nyq., get 64 spectral points each 64 spectral points each 31.25 MHz wide31.25 MHz wide

Correlator ModesCorrelator Modes2. Frequency Division Modes2. Frequency Division Modes - filters used to obtain 31.25 MHz - filters used to obtain 31.25 MHz - 2 GHz BWs,- 2 GHz BWs, all planes work on filtered BW all planes work on filtered BW to improve SRto improve SR - spectral resolution (SR) depends - spectral resolution (SR) depends on:on: - no of polarizations (1, 2, - no of polarizations (1, 2, or 4)or 4) - quantization level (2-bit - quantization level (2-bit or 4-bit)*or 4-bit)* - sampling rate (1 Nyq. or 2 - sampling rate (1 Nyq. or 2 Nyq.)Nyq.) - 1 spectral “window” per quadrant- 1 spectral “window” per quadrant - slower integration times: 64-512 - slower integration times: 64-512 msms

* Correlation efficiency is 0.88 for 2-bit x 2-bit, * Correlation efficiency is 0.88 for 2-bit x 2-bit, increases to 0.94 (2N) or 0.99 (4-bit), yielding increases to 0.94 (2N) or 0.99 (4-bit), yielding respectively 14% and 27% reductions in observing time.respectively 14% and 27% reductions in observing time.





Example of Frequency Division Modes (Band 6):Example of Frequency Division Modes (Band 6):

- 1 quadrant observes (in USB) 1 quadrant observes (in USB) CO 2-1 at CO 2-1 at 230.538 GHz230.538 GHz over over 125 MHz; mode 61 yields 512 spectral points 125 MHz; mode 61 yields 512 spectral points with 0.32 with 0.32 km skm s-1-1 resolution, 2 polzns, 4-bit, 2 x resolution, 2 polzns, 4-bit, 2 x Nyq.Nyq.

- 1 quadrant observes (in LSB) 1 quadrant observes (in LSB) CC1818O 2-1 at O 2-1 at 219.560 GHz219.560 GHz over over 31.25 MHz; mode 63 yields 1024 spectral 31.25 MHz; mode 63 yields 1024 spectral points with 0.04 points with 0.04 km skm s-1-1 resolution, 2 polzns, 4-bin, 2 x resolution, 2 polzns, 4-bin, 2 x Nyq.Nyq.

- 2 quadrants observe 2 quadrants observe continuumcontinuum over 2 GHz over 2 GHz each (one in each (one in USB, one in LSB) in time division mode; USB, one in LSB) in time division mode; mode 69 yields 128 mode 69 yields 128 spectral points, 20.4 km sspectral points, 20.4 km s-1-1 resolution, 2 resolution, 2 polzns, 2-bit, Nyq.polzns, 2-bit, Nyq.

Correlator ModesCorrelator Modes3. Multiple Region Modes3. Multiple Region Modes - for frequency division modes with - for frequency division modes with BWs of BWs of 125 MHz - 1 GHz, can divide up 125 MHz - 1 GHz, can divide up BW…BW… - allows multiple lines within BW - allows multiple lines within BW to be observedto be observed simultaneously within the 2 GHz simultaneously within the 2 GHz baseband, if:baseband, if: - region BW must be a multiple - region BW must be a multiple of 62.5 MHzof 62.5 MHz - other parameters (SR, no. of - other parameters (SR, no. of polzns, quant.polzns, quant. level and sampling rate) must level and sampling rate) must be the be the samesame for all regionsfor all regions - trade-off between no. of regions - trade-off between no. of regions and SR!and SR!

Correlator ModesCorrelator ModesExample of Multiple Region Modes (Band 6):Example of Multiple Region Modes (Band 6):

- 1 quadrant observes (in USB) uses mode 47, 1 quadrant observes (in USB) uses mode 47, 125 GHz BW, 125 GHz BW, 1024 spectral points at 0.16 km s1024 spectral points at 0.16 km s-1-1 SR, 2 SR, 2 polzns, 4-bit, Nyq.: polzns, 4-bit, Nyq.: 1/4 for 1/4 for CO 2-1 at 230.5 GHzCO 2-1 at 230.5 GHz,, 1/4 for 1/4 for NN22D+ 3-2 at 231.3 GHzD+ 3-2 at 231.3 GHz,, 1/4 for 1/4 for CHCH33OH 8OH 8-1-1-7-700 E at 229.8 E at 229.8 GHzGHz,, 1/4 for 1/4 for SOSO22 11(5,7) - 12(4,8) at 11(5,7) - 12(4,8) at 229.3 GHz229.3 GHz, , for 4 windows each with 256 spectral points for 4 windows each with 256 spectral points (BW: 164 km s(BW: 164 km s-1-1))

- 1 quadrant observes (in LSB) 1 quadrant observes (in LSB) CC1818O 2-1, O 2-1, 1313CO CO 2-1, SO 52-1, SO 566-4-455 and and CHCH33OH 8OH 800-7-711 E E also in mode 47, as above also in mode 47, as above

- 2 quadrants: LSB/USB 2 quadrants: LSB/USB continuumcontinuum in time in time division mode (69)division mode (69)

Correlator ModesCorrelator Modes4. Multi-resolution Modes4. Multi-resolution Modes - implement frequency division modes - implement frequency division modes over fewer over fewer than 32 correlator planesthan 32 correlator planes - correlator resources can be fully - correlator resources can be fully divided up for divided up for multiple windows with different multiple windows with different SRSR - allows zoom in into features seen - allows zoom in into features seen in wide bandin wide band - lower SR for a given BW- lower SR for a given BW - only 2-bit quantization available, - only 2-bit quantization available, mostly 1 Nyq.mostly 1 Nyq. available (three 2 Nyq. Modes)available (three 2 Nyq. Modes) - no more than 16 filters can be - no more than 16 filters can be used!used!


* na = correlator fraction cannot maintain BW with minimum * na = correlator fraction cannot maintain BW with minimum feasible resolutionfeasible resolution

Correlator ModesCorrelator ModesExample of Multi-Resolution Modes (Band 6):Example of Multi-Resolution Modes (Band 6):

- 1 quadrant observes (in USB) uses:1 quadrant observes (in USB) uses: - mode 3, 500 GHz BW with 8 planes, - mode 3, 500 GHz BW with 8 planes, gets 2048 spectral gets 2048 spectral points, 1 polzn, 2-bit, Nyq. points, 1 polzn, 2-bit, Nyq. (wide-(wide-band?)band?) - mode 6, 62.5 MHz BW with 8 planes, - mode 6, 62.5 MHz BW with 8 planes, gets 2048 spectralgets 2048 spectral points, 1 polzn, 2-bit, Nyq. points, 1 polzn, 2-bit, Nyq. (CO (CO 2-1)2-1) - mode 25, 31.25 MHz BW with 16 planes, - mode 25, 31.25 MHz BW with 16 planes, gets 4096 spec.gets 4096 spec. points, 1 polzn, 2-bit, 2 x Nyq. points, 1 polzn, 2-bit, 2 x Nyq. (N(N22DD++ 3-2) 3-2) - windows put anywhere in the 2 GHz - windows put anywhere in the 2 GHz input basebandinput baseband - total BW used < 1 GHz (16 filters; - total BW used < 1 GHz (16 filters; NB: if mode 2 isNB: if mode 2 is included, filters are shared; BW of included, filters are shared; BW of m2 window < 1 GHz)m2 window < 1 GHz)

each of other 3 quadrants are set up each of other 3 quadrants are set up independently!independently!

This is all very challenging, but it is This is all very challenging, but it is important to figure it all out before important to figure it all out before proposals are written!proposals are written!

““I think anyone who does not take full advantage of the I think anyone who does not take full advantage of the correlator deserves to be publicly ridiculed.”correlator deserves to be publicly ridiculed.” - - AnonymousAnonymous

ALMA Observing ToolALMA Observing Tool - the interface for planning ALMA - the interface for planning ALMA observationsobservations - will be used to define “minimally - will be used to define “minimally schedulable schedulable blocks” (MSBs) for execution at blocks” (MSBs) for execution at ALMAALMA - contains:- contains: - - sensitivity calculator toolsensitivity calculator tool - - calibrator selection toolcalibrator selection tool - - pointing visualization toolspointing visualization tools - - spectral region visualization toolsspectral region visualization tools

- not yet ready for prime time (this - not yet ready for prime time (this workshop):workshop): http://www.roe.ac.uk/ukatc/projects/alma/almaot/UT5.0/webhttp://www.roe.ac.uk/ukatc/projects/alma/almaot/UT5.0/webstart.htmlstart.html

Proposal ProcessProposal Process

- a Call for Proposals will be likely a Call for Proposals will be likely issued annually, issued annually, will detail available modeswill detail available modes- “- “Phase IPhase I” prepared using ALMA ” prepared using ALMA Observing ToolObserving Tool- proposal review process is not yet proposal review process is not yet solid, probablysolid, probably a single Proposal Review Committee a single Proposal Review Committee with subject with subject sub-panels will meet and offer sub-panels will meet and offer recommendationsrecommendations- these recommendations are harmonized these recommendations are harmonized withwith partner share by a higher committeepartner share by a higher committeepartner of PI will be charged for partner of PI will be charged for observing timeobserving timetime allocated, work on “time allocated, work on “Phase IIPhase II” ” proposal withproposal with ARC support ARC support

Proposal ProcessProposal Process

Å@0 Call for Proposals

Å@Phase I Proposal Phase I Support

Technical review2 Scientific Review

4 Å@

6 Phase II Program Phase II Support

8 Observation

Archive ArchiveArchive and data delivery

Data Reduction Reduction Support

Publish

Reduction Support

Months since CfP

DSOARC

Publish

User

Proposal Review Committee

Database Astronomer Public Data(1yr after obs)

Å@

Data Reduction

RejectedAccepted

Early ScienceEarly Science

What about Early Science?What about Early Science?

- “shared-risk” observing, ie., no - “shared-risk” observing, ie., no guaranteesguarantees - 33% of available time over 1 year, - 33% of available time over 1 year, time shared time shared with ALMA commissioning teamwith ALMA commissioning team

- - Timeline:Timeline: - Decision point: - Decision point: Q2 2010Q2 2010 - Call for Proposals issued: - Call for Proposals issued: Q4 Q4 20102010 - Proposals due: - Proposals due: Q1 2011?Q1 2011? - Observations: - Observations: Q3 2011 - Q3 2012Q3 2011 - Q3 2012

Early ScienceEarly Science

- at least at least sixteensixteen 12 m antennas fully 12 m antennas fully commissionedcommissioned- Bands 3, 6, 7, 9Bands 3, 6, 7, 9 on all antennas on all antennas (some 4, 8?)(some 4, 8?)- baselines out to - baselines out to 1 km1 km- single fields + pointed mosaicssingle fields + pointed mosaics- basic set of spectral modes (basic set of spectral modes (7, 9, 7, 9, 12, 18, 7012, 18, 70))- linear/circular polzn of compact linear/circular polzn of compact sourcessources- SD mapping of extended objects in OTF SD mapping of extended objects in OTF modemode- calibration to levels comparable to calibration to levels comparable to existing arraysexisting arrays- software for proposal preparation, software for proposal preparation, planning and planning and execution + off-line data reductionexecution + off-line data reduction

Further ReadingFurther Reading- ALMA CapabilitiesALMA Capabilities - - http://www.eso.org/sci/facilities/alma/observinghttp://www.eso.org/sci/facilities/alma/observing

- Correlator ModesCorrelator Modes - “Synthesis Imaging in Radio Astronomy II,” ASP - “Synthesis Imaging in Radio Astronomy II,” ASP Vol. 180, proceedings Vol. 180, proceedings of NRAO Aperture Synthesis School, chapter on of NRAO Aperture Synthesis School, chapter on correlatorscorrelators

- M. Rupen’s talk on Correlators from same - M. Rupen’s talk on Correlators from same (available on-line on (available on-line on NRAO website: NRAO website: http://www.nrao.edu/meetings/synthimwksp.shtml))

- Escoffier, R. P. et al., “The ALMA Correlator” - Escoffier, R. P. et al., “The ALMA Correlator” 2007, A&A, 462, 8102007, A&A, 462, 810

- ALMA Memo 556, “Observational Modes Supported by - ALMA Memo 556, “Observational Modes Supported by the ALMA the ALMA Correlator”Correlator”

http://www.nrao.edu/meetings/synthimwksp.shtml

From Idea to ALMA From Idea to ALMA ProjectProject

• Given the unprecedented capabilities Given the unprecedented capabilities of ALMA, the time to start thinking of ALMA, the time to start thinking of science is of science is NOW!NOW!

• ALMA’s correlator is particularly ALMA’s correlator is particularly complex, requiring careful planning to complex, requiring careful planning to exploit its potential (OT will help)exploit its potential (OT will help)

• Early Science will commence in Early Science will commence in Q3 Q3 20112011, even then ALMA will be the most , even then ALMA will be the most sensitive and flexible mm-array on the sensitive and flexible mm-array on the planetplanet

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