Surveying Cosmic Time with the WIDAR Correlator National Radio Astronomy Observatory Galaxies through Cosmic Time – December 16-18, 2008 Surveying Cosmic Time with the WIDAR Correlator Michael P. Rupen Project Scientist for WIDAR

Introducing the EVLA

Overall EVLA Performance Goals Parameter VLA EVLA Factor Point Source Sensitivity (1-s, 12 hr.) 10 mJy 1 mJy 10 Maximum BW in each polarization 0.1 GHz 8 GHz 80 # of frequency channels at max. BW 16 16,384 1024 Maximum number of freq. channels 512 4,194,304 8192 Coarsest frequency resolution 50 MHz 2 MHz 25 Finest frequency resolution 381 Hz 0.12 Hz 3180 # of independent sub-correlators 2 64 32 (Log) Frequency Coverage (1 – 50 GHz) 22% 100% 5

MicroJy Sensitivity in 12 hours Green shows deepest image ever made (as of 1999) -- 1.9 microJy/bm at 8.5 GHz (152 hrs; Richards et al.) -- 3 hours with the EVLA! We are meeting (and exceeding, at high frequencies) almost all of these goals.

Full 1-50 GHz Frequency Coverage Additional EVLA Coverage Blue areas show existing coverage Green areas show new coverage Current Frequency Coverage

WIDAR correlator 8 GHz, full polarization, in one go 64 independent subband-pair correlators Can individually trade bandwidth for channels 128 MHz to 31.25 kHz 256 to 4096 channels Can link subband correlators for even more channels Independently tunable -- can target up to 64 individual lines (up to 128 in one polarization)

Wideband observations: full pol’n BW Dnu Dv Nch (GHz) (kHz) (km/sec) 1-2 1.024 31 6 131,076 2-4 2.048 125 12 65,536 4-8 4.096 500 25 32,768 8-12 16.5 12-18 6.144 2000/500 37/12 24,576 18-26.5 8.192 2000 27 16,384 26.5-40 13 40-50

64 different lines: 1 km/s, full polarization Band BW Nch Dnu Dv Vel.Cov. Total (GHz) (MHz) (kHz) (km/s) (km/sec) Nchan 1-2 4 2048 2.0 0.39 800 524,288 2-4 8 1024 7.8 0.78 320 262,144 4-8 400 8-12 16 512 31 0.94 480 131,072 12-18 0.63 18-26.5 0.41 210 26.5-40 32 256 125 1.1 282 65,536 40-50 0.83 213

The EVLA combines power and flexibility to allow you to tune the instrument to your science -- not the reverse.

The EVLA and Evolving Galaxies a few illustrative examples

Survey Speed I Time to observe 1 square degree to 40 microJy/beam rms doesn’t include overhead (--> x1.5, from NVSS) Rms chosen to ensure at least 20s/ptg (NVSS: 30s with 23.3s on-source) Note uv-coverage issues Assumes no overlap

Survey Speed II Square degrees observed per hour as a function of frequency, to an rms of 40 microJy/bm Assumptions as in last slide

Background sources: 12 hour integration Number of background sources in the primary beam in a 12-hour integration 1, 5, 150 sigma

Searching Hi-z Galaxies for CO emission Arp 220 at z = 8 VLA search: Restricted bands Covers 100 MHz (1000km/s) 100 MHz (1000 km/s) resolution EVLA search: All freqs. available Covers 8 GHz (80,000 km/s) 1 MHz (10 km/s) resolution

Nearby Galaxies Neutral hydrogen Rotation measures Spectral curvature (& absorption) Spectral curvature (& Faraday rotation) Neutral hydrogen for free!

Prototype Correlator 4 antennas 1 GHz @ 8-bits, RCP only 4-bit requantization 8 x 128 MHz subbands 1024 x 125 kHz per subband Dumptime 0.05-1 sec up to 7 MB/s 1 GB/hr with 1sec dumps

Final Correlator Racks installed & fully cabled up Begins open observations (VLA emulation modes) Jan 2010

3C84 @ 1.5 GHz 1244-1756 MHz 8192 x 62.5 kHz (13 km/s for local HI) 512 MHz

3C84 @ 1.5 GHz 1244-1756 MHz 8192 x 62.5 kHz (13 km/s for local HI) HI ABQ radars VLA polarizer satellites 512 MHz

3C84 @ 1.5 GHz 1244-1756 MHz 8192 x 62.5 kHz (13 km/s for local HI) HI ABQ radars VLA polarizer satellites Current VLA: 6.25 MHz @ 98 kHz 512 MHz

3C84 @ 1.5 GHz 1244-1756 MHz 8192 x 62.5 kHz (13 km/s for local HI) Final EVLA: 512 MHz (z=0-0.3) @ 7.8 kHz (1.7 km/s) HI ABQ radars VLA polarizer satellites Current VLA: 6.25 MHz @ 98 kHz 512 MHz

3C84 @ 1.5 GHz 1376-1384 MHz (one 8 MHz subband) 4096 x 1.95 kHz (0.4 km/s)

3C84 @ 1.5 GHz 8 x 8 MHz subbands 8 x 4096 channels Zoomed in here! Avg’d x2 (3.9 kHz) or x64 (470 kHz) Zoomed in here! Tau~0.15 Tau~0.21 32 km/s 17 km/s 1382.95 MHz 1420.35 MHz Tau~0.003 430 km/s 1395.5 MHz

3C84 @ 1.5 GHz 8 x 8 MHz subbands 8 x 4096 channels Zoomed in here! Avg’d x2 (3.9 kHz) or x64 (470 kHz) Zoomed in here! Full EVLA: 64 independently tunable subband pairs Different bandwidth & resolution for each subband pair Tau~0.15 Tau~0.21 32 km/s 17 km/s 1382.95 MHz 1420.35 MHz Tau~0.003 430 km/s 1395.5 MHz

3C84 @ 22 GHz 21988-23012 MHz 8192 x 125 kHz (1.7 km/s) 1 GHz

3C84 @ 22 GHz 1 GHz 21988-23012 MHz 8192 x 125 kHz (1.7 km/s) Full EVLA: 8 GHz (BWR 1.5:1) Full pol’n 8192 x 1 MHz (14 km/s) 1 GHz

Orion water masers 8 x 64 MHz, 2048 channels 1.4% shown here 31.25 kHz/channel (0.4 km/s) 1.4% shown here

Example: massive star-forming region H71a H70a H69a H68a H67a H66a H65a H64a H63a H62a Example from Claire Chandler

Example: massive star-forming region 32 molecular density/temp. tracers @ 0.2 km/s 8 RRL @ 1 km/s 3 GHz (24 x 128 MHz) left over for continuum 18-26.5 GHz

Example: massive star-forming region 32 molecular density/temp. tracers @ 0.2 km/s 8 RRL @ 1 km/s 3 GHz (24 x 128 MHz) left over for continuum 22.6-24.6 GHz

Schedule

EVLA and You Now 2009 Expanded tuning ranges 3-antenna Prototype Correlator (more anon) 2009 Ka band 10-antenna WIDAR0 3-bit samplers

EVLA and You Jan 2010 Open Shared Risk Observing Turn off VLA correlator WIDAR in “VLA emulation mode” (2 x 128 MHz subband pairs) Re-cycle configurations: Dvla-Dwidar-C-B-A (data rates!) Resident Shared Risk Observing ?

Receiver upgrades

OSRO WIDAR modes (1) Continuum applications and spectro-polarimetry Two independently-tunable sub-bands (IFs), full polarization, each with bandwidth 128/2n MHz (n=0,..,12), 64 channels Sub-band BW (MHz) Number of poln. products channels/poln product Channel width (kHz) Channel width (kms-1 at 1 GHz) Total velocity coverage 128 4 64 2000 600/n(GHz) 38,400/n(GHz) 1000 300 19,200 32 500 150 9,600 16 250 75 4,800 8 125 37.5 2,400 62.5 19 1,200 2 31.25 9.4 600 1 15.625 4.7 0.5 7.813 2.3 0.25 3.906 1.2 0.125 1.953 0.59 0.0625 0.977 0.29 18.75 0.03125 0.488 0.15 9.375

OSRO WIDAR modes (2) Spectral line applications One tunable sub-band (IF), dual polarization, with bandwidth 128/2n MHz (n=0,..,12), 256 channels Sub-band BW (MHz) Number of poln. products channels/poln product Channel width (kHz) Channel width (kms-1 at 1 GHz) Total velocity coverage 128 2 256 500 150/n(GHz) 38,400/n(GHz) 64 250 75 19,200 32 125 37.5 9,600 16 62.5 19 4,800 8 31.25 9.4 2,400 4 15.625 4.7 1,200 7.813 2.3 600 1 3.906 1.2 300 0.5 1.953 0.59 150 0.25 0.977 0.29 0.125 0.488 0.15 0.0625 0.244 0.073 18.75 0.03125 0.122 0.037 9.375

Having fun with WIDAR

Demonstration Observations What can we do with the PTC that will get the whole astronomical community fired up?

Demonstration Observations Prototype correlator 3 antennas 1 GHz, 1 pol’n, 8192 channels 0.1-1 sec dumps (possibly 10msec…) Short observations -- up to 10 hours See handout for detailed specifications

Demonstration Observations Write up a proposal (a few paragraphs) by tomorrow (Wednesday) morning Put it in the box (appearing soon, just outside the auditorium) Or e-mail to jvangork@astro.columbia.edu or mrupen@nrao.edu SOC will review these (with technical advice as needed) and pick one (or more!) to be observed No guarantees, but we’ll aim at the end of the year Raw & processed data put up on the conference web site (note VLA archive!) Correlator tee shirt to the winner, if I get around to designing one Winner(s) announced by the end of the meeting WIDAR0 (10 antenna, 256-640 MHz, full pol’n) ideas also welcome