From ccarilli@aoc.nrao.edu Tue Aug 6 09:42:52 2002 Date: Thu, 01 Aug 2002 08:34:21 -0600 From: Chris Carilli To: Steve Rawlings Subject: transients forms Joseph Lazio wrote: > Chris, > > Appended is the summary of the SKA concept evaluation by the Radio > Transients, Stellar End Products, and SETI Working Group. I realize > that you asked for a report for each Level 1 science goal in our WG. > However, in the process of evaluating and summarizing the designs, we > realized that there were a number of common requirements among our > three Level 1 goals. For that reason (and also partially to reduce > the number of reports being transmitted) we produced one summary. > > A related issue is that we also have evaluated the SKA design specs. > We suspect that our goals will evolve over time, based both on new > information and what is technically and fiscally possible, as might > the SKA design specs. Is there any mechanism for the SKA site to host > summaries of the WG's scientific requirements in a way that the WG > chairs can modify them as appropriate? If not, I will put something > on my NRL Web site. > > -- Joe > > -- > T. Joseph W. Lazio, Ph.D. voice: +1 202 404 6329 > Remote Sensing Division fax: +1 202 404 8894 > Naval Research Lab, Code 7213 Joseph.Lazio@nrl.navy.mil > Washington, DC 20375-5351 USA http://rsd-www.nrl.navy.mil/7213/lazio/ > > ------------------------------ > > ------------------------------------------------------------------------------ > Canada: LAR > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 20000 meet 1.4 GHz > > FoV sq.deg 1 1 meet 1.4 GHz, 19x19 FP array > > Multibeam > number [1] 1 ? many within FoV > beam sep (deg) 60[2] > # subarrays >~10 many? fail/meet? 1 LAR = subarray? > > response time s <10[3] 100 fail > > Freq range GHz 0.5 - >15 0.1-22 meet/exceed > > Correlator: > Bandwidth GHz 0.5+nu/2 4 fail > # spec channel 2048 > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short dt*df ~ 1 > 5 microseconds pulsar timing > > Configuration: > max baseline km 3000 > 50% area baseline > T_b sens K > > #independent IFs >10[4] 1 fail > max sep of IFs 9 GHz SETI > > DNR: > spatial 1E6 1e5 fail > spectral high SETI > polarization 1E4 > > # spatial pixels 1E8 > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > > Major problem(s): > > Spacings between 200 m and 1 km present an interesting challenge. > > Number of beams may be too limited. > > Correlator bandwidth is too small at high frequencies. > > Response time too long for some transient programs. > > Dynamic range too small. > > Careful site selection required in order to maximize fraction of the > Galactic plane that is visible. > > Possible Compromises: > > Supplement with other design(s) to access difficult baseline ranges > and solve other problems? > > Notes: > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large. > > total = 2 G$ (could decrease by factor 2 by decreasing > FoV by factor 4). Unblocked aperture => low sidelobes. > Loose collecting area with large zenith angle. 60 elements, 200m. > > ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ > China proposal: KARST > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 35000 exceed 30 elements > > FoV sq.deg 1 13x0.005 fail at 1.4 GHz > > Multibeam > number [1] 1 fail > beam sep (deg) 60[2] > # subarrays >~10 few fail/meet? 1 FAST = subarray? > > response time s <10[3] 100 fail > > Freq range GHz 0.5 - >15 0.3-6 fail > > Correlator: > Bandwidth GHz 0.5+nu/2 > # spec channel 2048 > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short dt*df ~ 1 > 5 microseconds pulsar timing > > Configuration: > max baseline km 3000 300 fail > 50% area baseline 30 > T_b sens K > > #independent IFs >10[4] > max sep of IFs 9 GHz SETI > > DNR: > spatial 1E6 1e5 fail > spectral high SETI > polarization 1E4 > > # spatial pixels 1E8 > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > Major problem(s): > > Limited number of beams over tiny FoV. > > Baseline and frequency coverage too small. > > Possible Compromises: > > Combination with other designs may solve some problems, but difficult > because of restriction to the karst region? > > Notes: > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large. > > limited sky coverage (68%), very limited FoV as proposed (could add > large FP arrays), no discussion of correlator/IF. total = 0.85 G$. > > ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ > European Design: Integrated Aperture Arrays > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 10500 fail at 1.4 GHz > lower at large elev > FoV sq.deg 1 1 meet at 1.4 GHz > > Multibeam > number [1] 8 fail > beam sep (deg) 60[2] 90 meet > # subarrays >~10 many meet > > response time s <10[3] < 1 meet? 60s for sources > at > 45deg tilt > > Freq range GHz 0.5 - >15 0.15 - 1.5 fail > > Correlator: > Bandwidth GHz 0.5+nu/2 0.2 fail > # spec channel 2048 2x4096 meet/exceed > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short dt*df ~ 1 > 5 microseconds pulsar timing > > Configuration: > max baseline km 3000 2000 fail extendable? > 50% area baseline 100 > T_b sens K > > #independent IFs >10[4] 3 fail > max sep of IFs GHz 9 1 fail SETI > > DNR: > spatial 1E6 > spectral high SETI > polarization 1E4 > > # spatial pixels 1E8 > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > Major problem(s): outline the major design problem(s) wrt science goal > > Restricted sky coverage and effective collecting area at low > elevations. > > Acceptable level of risk of decreased scientific performance if > politically-required technology innovation does not meet expectations? > > Possible Compromises: > > Notes: > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large. > > Full sky coverage requires retilting tiles in 3 steps. > Cost = 0.78 G$. > > ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ > India: Preloaded parabolic dishes > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 20000 meet 1.4 GHz, less > at high/lower freq > FoV sq.deg 1 1 meet at 1.4 GHz, full Xcorr > of inner array > Multibeam > number [1] 1 ? many within PB > beam sep (deg) 60[2] > # subarrays >~10 many meet > > response time s <10[3] 60 fail > > Freq range GHz 0.5 - >15 0.15-10 fail > > Correlator: > Bandwidth GHz 0.5+nu/2 > # spec channel 2048 > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short dt*df ~ 1 > 5 microseconds pulsar timing > > Configuration: > max baseline km 3000 > 50% area baseline > T_b sens K > > #independent IFs >10[4] > max sep of IFs 9 GHz SETI > > DNR: > spatial 1E6 1e6 meet > spectral high SETI > polarization 1E4 1e4 meet > > # spatial pixels 1E8 > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > Major problem(s): outline the major design problem(s) wrt science goal > > Does putting dipoles around aperture lead to increased scattering and > higher system temperature? > > Possible Compromises: > > Notes: > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large. > > Array design parallels US, only different is elements. > total for antennas = 0.5 G$. > Max freq. can be increased using panels instead of wire mesh. > > ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ > Australia 1: Refracting concentrators > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 20000 meet 1.4 GHz, lower > at high/lower freq > FoV sq.deg 1 3.6 exceed at 1.4 GHz, full Xcorr > of inner array > Multibeam > number [1] 2 fail > beam sep (deg) 60[2] 150 meet > # subarrays >~10 many meet > > response time s <10[3] 60 fail > > Freq range GHz 0.5 - >15 0.1-5 fail > > Correlator (dual pol) > Bandwidth GHz 0.5+nu/2 1.5 fail > # spec channel 2048 2x4096 meet/exceed full BW > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short dt*df ~ 1 > 5 microseconds pulsar timing > > Configuration: > max baseline km 3000 3000 meet > 50% area baseline 4 > T_b sens K 0.7 at 0.1"res > > #independent IFs >10[4] 4 fail > max sep of IFs 9 GHz SETI > > DNR: > spatial 1E6 > spectral high SETI > polarization 1E4 > > # spatial pixels 1E8 > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > Major problem(s): outline the major design problem(s) wrt science goal > > Limited number of beams and frequency coverage. > > Possible Compromises: > > Notes: > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large. > > Similar in concept to US design but with Luneberg lenses as > elements. Allows for widely spaced, multiple beams on sky. Each beam > needs own Rx/feed support/drive, so eventually blockage becomes > issue. Current proposal has 2 beams for 1.4 G$. > Lens technology is a major uncertainty. > > ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ > Australia 2: Cylindrical Reflector > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 20000 meet > > FoV sq.deg 1 1 meet at 1.4 GHz > > Multibeam > number [1] 8 fail > beam sep (deg) 60[2] 40x1 fail/meet at 1.4 GHz > # subarrays >~10 many meet > > response time s <10[3] 60 fail/meet msec for objects > in 40deg FoV > Freq range GHz 0.5 - >15 0.1-9 fail > > Correlator (dual pol): > Bandwidth GHz 0.5+nu/2 2.4 fail > # spec channel 2048 2x4096 meet/exceed > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short dt*df ~ 1 > 5 microseconds pulsar timing > > Configuration: > max baseline km 3000 10000 exceed > 50% area baseline 40 > T_b sens K > > #independent IFs >10[4] > max sep of IFs 9 GHz SETI > > DNR: > spatial 1E6 1e6 meet > spectral high SETI > polarization 1E4 > > # spatial pixels 1E8 > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > Major problem(s): outline the major design problem(s) wrt science goal > > Possible Compromises: > > Notes: total cost = 1G$ > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large. > > ------------------------------------------------------------------------------ > ------------------------------------------------------------------------------ > USA proposal: N/d > ------------------------------------------------------------------------------ > Level 1 science program: Radio Transients, Stellar End Products, and SETI > We have grouped these Level 1 science goals together because > they share a number of common requirements, which have the > effect of opening new areas of parameter space. The science > goals are > (1) The first unbiased survey of the variable/transient radio > sky at centimeter wavelengths; > (2) Conduct a Galactic pulsar census with the aim of detecting > all of the pulsars in the Galaxy beamed toward us; and > (3) Measure or constrain the luminosity function of ETI > transmitters at microwave frequencies. > > Spec Requirement Design fail/meet/exceed comments > ---- ----------- ------- ---------------- -------- > A/T m^2/K 20000 20000 meet 1.2 to 11 GHz, less > at high/lower freq > FoV sq.deg 1 1 meet at 1.4 GHz, full Xcorr > of inner array > Multibeam > number [1] 1 ? many within PB > beam sep (deg) 60[2] > # subarrays >~10 many meet > > response time s <10[3] 60 fail > > Freq range GHz 0.5 - >15 0.15-34 exceed > > Correlator: > Bandwidth GHz 0.5+nu/2 3.2 fail > # spec channel 2048 1.6e4 exceed full BW > ~ 1 Hz channels SETI (but restricted BW) > sampling time s short short meet unit t-BW > 5 microseconds meet? pulsar timing > > Configuration: > max baseline km 3000 5000 exceed > 50% area baseline 35 > T_b sens K 1 at 0.1"res > > #independent IFs >10[4] 4 > max sep of IFs 9 GHz full band meet? > > DNR: > spatial 1E6 1e6 meet > spectral high SETI > polarization 1E4 1e4 meet > > # spatial pixels 1E8 5e10 exceed > > ----------------- > Special requirements: > > Real-time RFI excision should not exclude real celestial transients or > pulsars. > > Multiple, phased-up subarrays (a.k.a. tied subarrays) for real-time > processing (e.g., coincidence testing) or increased sky coverage. > > Pulsar and SETI programs require dt*df ~ 1. SETI requires small df. > Pulsars, and those transient programs that exploit scintillation > (e.g., IDV), require small dt. > > A buffer for ex post facto "real-time" processing of the phased-up > array or subarrays. > > Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > > Substantial fraction (> 50%) of Galactic plane should be visible at > full (or nearly so) sensitivity. > > Major problem(s): outline the major design problem(s) wrt science goal > > Possible Compromises: > > Notes: total = 1.8 G$. Collecting area is 1/2 (SKA). > [1] Instantaneous access to the full FoV via multiple simultaneous pencil > beams (or equivalent correlator capability). > [2] We require large separation between (primary) beams in order to > conduct programs such as pulsar timing or watching transient > evolution. We do not necessarily require the full G/T of the > SKA for these programs so achieving this requirement via > subarraying is acceptable. > [3] Requirement relaxed from Bologna report. Response time of 100 s > could be tolerated for pulsar work. > [4] Assumes SETI receives 10; number may be lower if bandwidth of IFs > sufficiently large.