2._CRD SETI_NP0 in_PRP 2020_CRD 
2020_CRD was_VBD the_AT0 first_ORD year_NN1 of_PRF the_AT0 pandemic_AJ0 ,_PUN the_AT0 lost_AJ0 year_NN1 ,_PUN the_AT0 year_NN1 of_PRF COVID_NN1 ._SENT Even_AV0 as_CJS I_PNP write_VVB this_DT0 in_PRP 2021_CRD ,_PUN many_DT0 facilities_NN2 are_VBB closed_VVN ,_PUN and_CJC much_DT0 of_PRF the_AT0 world_NN1 does_VDZ not_XX0 have_VHI access_NN1 to_PRP the_AT0 vaccines_NN2 that_CJT have_VHB allowed_VVN many_DT0 nations_NN2 to_TO0 begin_VVI re-opening_VVG and_CJC returning_VVG to_PRP normal_AJ0 ways_NN2 of_PRF research_NN1 ._SENT It_PNP is_VBZ likely_AJ0 this_DT0 review_NN1 would_VM0 have_VHI more_DT0 papers_NN2 to_TO0 cite_VVI without_PRP this_DT0 global_AJ0 tragedy_NN1 ._SENT 
Many_DT0 opportunities_NN2 for_PRP SETI_NP0 practitioners_NN2 to_TO0 meet_VVI and_CJC interact_VVI were_VBD lost_VVN ._SENT For_PRP instance_NN1 ,_PUN the_AT0 First_ORD Penn_NP0 State_NN1 SETI_NP0 symposium_NN1 ,_PUN intended_VVD to_TO0 be_VBI a_AT0 major_AJ0 ,_PUN annual_AJ0 ,_PUN international_AJ0 meeting_NN1 in_PRP the_AT0 field_NN1 ,_PUN was_VBD postponed_VVN to_PRP 2021_CRD (_PUL and_CJC then_AV0 later_AV0 to_PRP 2022_CRD )_PUR ._SENT That_DT0 symposium_NN1 was_VBD also_AV0 intended_VVN to_TO0 inaugurate_VVI the_AT0 Penn_NP0 State_NN1 Extraterrestrial_AJ0 Intelligence_NN1 Center_NN1 ,_PUN dedicated_VVN to_PRP research_NN1 ,_PUN training_NN1 ,_PUN curriculum_NN1 ,_PUN and_CJC fundraising_NN1 for_PRP the_AT0 field_NN1 ._SENT 
But_CJC ,_PUN being_VBG forced_VVN to_TO0 interact_VVI remotely_AV0 also_AV0 made_VVN the_AT0 world_NN1 a_AT0 little_AV0 smaller_AJC ._SENT The_AT0 Technoclimes_NP0 conference_NN1 in_PRP August_NP0 2020_CRD explored_VVD non-radio_AJ0 technosignatures_NN2 and_CJC produced_VVD many_DT0 new_AJ0 collaborations_NN2 ._SENT Two_CRD talk_VVB series_NN0 on_PRP technosignatures_NN2 ,_PUN the_AT0 NASA_NP0 Goddard_NP0 Technosignatures_NN2 Seminar_NN1 (_PUL led_VVN by_PRP Ravi_NP0 Kopparapu_NP0 )_PUR and_CJC the_AT0 PSETI_AJ0 Seminar_NN1 ,_PUN joined_VVD the_AT0 IAA_NP0 community_NN1 meeting_NN1 to_TO0 create_VVI a_AT0 trio_NN1 of_PRF worldwide_AJ0 "_PUQ SETI_NP0 colloquia_NN1 "_PUQ that_CJT anyone_PNI could_VM0 attend_VVI ._SENT 
There_EX0 was_VBD also_AV0 movement_NN1 on_PRP the_AT0 funding_NN1 front_NN1 ._SENT The_AT0 US_NP0 Congress_NN1 continued_VVD to_TO0 indicate_VVI that_CJT technosignatures_NN2 were_VBD properly_AV0 part_NN1 of_PRF NASA_NP0 's_POS portfolio_NN1 (_PUL although_CJS no_AT0 explicit_AJ0 funding_NN1 was_VBD allocated_VVN )_PUR ,_PUN the_AT0 Technoclimes_NP0 workshop_NN1 was_VBD supported_VVN by_PRP a_AT0 NASA_NP0 Exobiology_NN1 grant_NN1 ,_PUN and_CJC two_CRD NASA_NP0 Exoplanet_NN1 Research_NN1 Program_NN1 grants_NN2 were_VBD awarded_VVN to_PRP researchers_NN2 studying_VVG technosignatures_NN2 (_PUL Jean-Luc_NP0 Margot_NP0 at_PRP UCLA_NP0 and_CJC Ann_NP0 Marie_NP0 Cody_NP0 at_PRP the_AT0 SETI_NP0 Institute_NN1 )_PUR ._SENT Finally_AV0 ,_PUN the_AT0 Characterizing_AJ0 Atmospheric_AJ0 Technosignatures_NN2 (_PUL CATS_NN2 )_PUR effort_NN1 led_VVN by_PRP Adam_NP0 Frank_NP0 at_PRP the_AT0 University_NN1 of_PRF Rochester_NP0 was_VBD announced_VVN ,_PUN and_CJC its_DPS members_NN2 joined_VVD the_AT0 NExSS_NN1 research_NN1 coordination_NN1 network_NN1 at_PRP NASA_NP0 ._SENT 
2020_CRD is_VBZ also_AV0 a_AT0 notable_AJ0 landmark_NN1 for_PRP SETI_NP0 because_CJS it_PNP marks_VVZ the_AT0 target_NN1 for_PRP which_DTQ the_AT0 "_PUQ SETI_NP0 2020_CRD "_PUQ roadmap_NN1 was_VBD written_VVN ._SENT We_PNP have_VHB probably_AV0 made_VVN less_DT0 progress_NN1 than_CJS that_DT0 work_NN1 aspired_VVD to_PRP since_CJS then_AV0 ,_PUN but_CJC that_DT0 work_NN1 nonetheless_AV0 proved_VVD influential_AJ0 in_PRP directing_VVG radio_NN1 SETI_NP0 efforts_NN2 ,_PUN for_PRP instance_NN1 in_PRP the_AT0 development_NN1 of_PRF the_AT0 Allen_NP0 Telescope_NN1 Array_NN1 ,_PUN but_CJC also_AV0 for_PRP other_AJ0 efforts_NN2 such_DT0 as_PRP the_AT0 Square_NP0 Kilometer_NN1 Array_NN1 ._SENT 
2020_CRD had_VHD more_AV0 than_CJS its_DPS share_NN1 of_PRF SETI-specific_AJ0 tragedy_NN1 :_PUN in_PRP February_NP0 we_PNP lost_VVD Freeman_NP0 Dyson_NP0 ,_PUN one_CRD of_PRF the_AT0 pioneers_NN2 of_PRF the_AT0 field_NN1 ,_PUN at_PRP the_AT0 age_NN1 of_PRF 96_CRD ;_PUN and_CJC in_PRP December_NP0 the_AT0 instrument_NN1 platform_NN1 suspended_VVN above_PRP the_AT0 300-meter_AJ0 dish_NN1 of_PRF the_AT0 Arecibo_NP0 radio_NN1 telescope_NN1 collapsed_VVD ,_PUN destroying_VVG not_XX0 only_AV0 one_CRD of_PRF the_AT0 most_AV0 powerful_AJ0 and_CJC storied_AJ0 radio_NN1 telescopes_NN2 in_PRP the_AT0 world_NN1 ,_PUN but_CJC an_AT0 icon_NN1 of_PRF the_AT0 field_NN1 ._SENT 
3._CRD Results_NN2 from_PRP searches_NN2 (_PUL 7_CRD papers_NN2 )_PUR 
The_AT0 heart_NN1 of_PRF SETI_NP0 is_VBZ the_AT0 actual_AJ0 searches_NN2 ,_PUN and_CJC 2020_CRD brought_VVD several_DT0 new_AJ0 important_AJ0 results_NN2 and_CJC upper_AJ0 limits_NN2 ._SENT 
The_AT0 recent_AJ0 resurgence_NN1 of_PRF the_AT0 field_NN1 is_VBZ due_AJ0 in_PRP no_AT0 small_AJ0 part_NN1 to_PRP the_AT0 Breakthrough_NN1 Listen_VVB Initiative_NN1 ,_PUN which_DTQ has_VHZ injected_VVN funding_NN1 ,_PUN training_NN1 ,_PUN community_NN1 ,_PUN and_CJC energy_NN1 into_PRP SETI_NP0 ._SENT The_AT0 team_NN1 and_CJC its_DPS collaborators_NN2 published_VVD four_CRD new_AJ0 upper_AJ0 limits_NN2 in_PRP the_AT0 radio_NN1 ,_PUN making_VVG use_NN1 of_PRF the_AT0 extremely_AV0 high_AJ0 bandwidth_NN1 backends_NN2 at_PRP Green_NP0 Bank_NP0 and_CJC Parkes_NP0 ._SENT The_AT0 first_ORD was_VBD by_PRP Price_NP0 et_NP0 al._NP0 ,_PUN reporting_VVG null_AJ0 detections_NN2 for_PRP over_AV0 1300_CRD stars_NN2 over_PRP the_AT0 entire_AJ0 sky_NN1 in_PRP L_ZZ0 and_CJC S_ZZ0 bands_NN2 (_PUL 1_CRD –_PUN 3.5_CRD GHz_NN0 )_PUR ._SENT Following_VVG the_AT0 methodology_NN1 suggested_VVN by_PRP Heller_NP0 and_CJC Pudritz_NP0 ,_PUN Sheikh_NP0 et_NP0 al._NP0 reported_VVD null_AJ0 results_NN2 in_PRP C_ZZ0 band_NN1 (_PUL 4_CRD –_PUN 8_CRD GHz_NN0 )_PUR for_PRP stars_NN2 in_PRP the_AT0 '_POS '_PUQ restricted_AJ0 Earth_NN1 Transit_NN1 Zone_NN1 '_POS '_PUQ ,_PUN i.e._AV0 the_AT0 region_NN1 of_PRF the_AT0 sky_NN1 that_CJT '_PUQ '_PUQ sees_VVZ '_POS '_PUQ Earth_NN1 transit_NN1 the_AT0 Sun_NN1 ._SENT Wlodarczyk-Sroka_NP0 et_NP0 al._NP0 extended_VVD the_AT0 upper_AJ0 limit_NN1 calculations_NN2 of_PRF previous_AJ0 searches_NN2 to_TO0 include_VVI all_DT0 of_PRF the_AT0 sources_NN2 in_PRP the_AT0 beam_NN1 (_PUL not_XX0 just_AV0 the_AT0 target_NN1 star_NN1 at_PRP the_AT0 center_NN1 )_PUR ._SENT And_CJC finally_AV0 ,_PUN Perez_NP0 et_NP0 al._NP0 reported_VVD null_AJ0 results_NN2 for_PRP the_AT0 Kepler-160_AJ0 system_NN1 ._SENT 
Overall_AV0 ,_PUN this_DT0 represents_VVZ both_AV0 a_AT0 substantial_AJ0 increase_NN1 in_PRP the_AT0 '_POS '_PUQ Cosmic_AJ0 Haystack_NP0 '_POS '_PUQ fraction_NN1 searched_VVD ,_PUN and_CJC the_AT0 deployment_NN1 of_PRF important_AJ0 new_AJ0 search_NN1 strategies_NN2 in_PRP the_AT0 radio_NN1 ._SENT 
The_AT0 Allen_NP0 Telescope_NN1 Array_NN1 (_PUL ATA_NP0 )_PUR continued_VVD its_DPS survey_NN1 of_PRF the_AT0 skies_NN2 ,_PUN publishing_VVG in_PRP 2020_CRD a_AT0 deep_AJ0 survey_NN1 and_CJC null_AJ0 result_NN1 of_PRF the_AT0 Wow_ITJ !_SENT Signal_NN1 field_NN1 ._SENT This_DT0 work_NN1 ,_PUN by_PRP Harp_NN1 et_NP0 al._NP0 ,_PUN scanned_VVD the_AT0 entire_AJ0 field_NN1 consistent_AJ0 with_PRP the_AT0 original_AJ0 signal_NN1 ,_PUN and_CJC included_VVD a_AT0 10_CRD MHz_NN0 bandwidth_NN1 and_CJC ∼100_CRD h_ZZ0 of_PRF observation_NN1 ,_PUN the_AT0 longest_AJS follow-up_NN1 yet_AV0 performed_VVN ._SENT It_PNP is_VBZ good_AJ0 to_TO0 see_VVI the_AT0 field_NN1 followed_VVD up_AVP in_PRP this_DT0 manner_NN1 to_TO0 search_VVI for_PRP potential_AJ0 repetitions_NN2 ._SENT 
Tremblay_NP0 and_CJC Tingay_NP0 reported_VVD on_PRP the_AT0 deepest_AJS narrowband_NN1 SETI_NP0 search_NN1 yet_AV0 with_PRP the_AT0 Murchison_NP0 Widefield_NP0 Array_NN1 (_PUL MWA_NP0 )_PUR ,_PUN this_DT0 time_NN1 of_PRF the_AT0 Vela_NP0 region_NN1 ._SENT These_DT0 low-frequency_AJ0 searches_NN2 explore_VVB very_AV0 large_AJ0 regions_NN2 of_PRF parameter_NN1 space_NN1 in_PRP the_AT0 Wright_NP0 et_NP0 al._NP0 Cosmic_AJ0 Haystack_NN1 formalism_NN1 ,_PUN thanks_NN2 to_PRP their_DPS sensitivity_NN1 and_CJC very_AV0 large_AJ0 fields_NN2 of_PRF view_NN1 ._SENT 
Perhaps_AV0 the_AT0 most_AV0 offbeat_AJ0 and_CJC unconventional_AJ0 search_NN1 of_PRF 2020_CRD was_VBD that_DT0 of_PRF Hippke_NP0 ,_PUN who_PNQ followed_VVD a_AT0 suggestion_NN1 by_PRP Hsu_NP0 and_CJC Zee_NP0 that_CJT there_EX0 could_VM0 be_VBI a_AT0 message_NN1 embedded_VVN in_PRP the_AT0 cosmic_AJ0 microwave_NN1 background_NN1 ,_PUN presumably_AV0 put_VVB there_AV0 intentionally_AV0 at_PRP the_AT0 observable_AJ0 universe_NN1 's_POS beginning_NN1 ._SENT Not_XX0 finding_VVG anything_PNI meaningful_AJ0 in_PRP the_AT0 power_NN1 spectrum_NN1 ,_PUN Hippke_NP0 helpfully_AV0 provides_VVZ a_AT0 1000-bit_AJ0 representation_NN1 of_PRF the_AT0 CMB_NP0 temperature_NN1 spectrum_NN1 for_PRP others_NN2 to_TO0 scrutinize_VVI for_PRP any_DT0 messages_NN2 that_CJT were_VBD not_XX0 apparent_AJ0 to_PRP him_PNP ._SENT 
4._CRD Search_NN1 methods_NN2 and_CJC instrumentation_NN1 (_PUL 16_CRD papers_NN2 )_PUR 
4.1_CRD ._SENT New_AJ0 instrumentation_NN1 
One_CRD of_PRF the_AT0 most_AV0 exciting_AJ0 projects_NN2 on_PRP the_AT0 horizon_NN1 is_VBZ PanoSETI_NP0 ,_PUN an_AT0 all-sky_AJ0 optical_AJ0 /_PUN NIR_NP0 fast_AJ0 transient_AJ0 project_NN1 designed_VVN to_TO0 search_VVI for_PRP pulsed_AJ0 laser_NN1 emission_NN1 ._SENT 2020_CRD saw_VVD significant_AJ0 progress_NN1 on_PRP the_AT0 PanoSETI_NP0 prototype_NN1 at_PRP Palomar_NP0 Observatory_NN1 ,_PUN as_CJS described_VVN in_PRP a_AT0 trio_NN1 of_PRF SPIE_NN1 papers_NN2 by_PRP Brown_NP0 et_NP0 al._NP0 (_PUL describing_VVG the_AT0 overall_AJ0 mechanical_AJ0 system_NN1 design_NN1 )_PUR Liu_NP0 et_NP0 al._NP0 (_PUL describing_VVG the_AT0 focal_AJ0 plane_NN1 electronics_NN1 and_CJC protocols_NN2 )_PUR ,_PUN and_CJC Maire_NP0 et_NP0 al._NP0 (_PUL showing_VVG on-sky_AJ0 results_NN2 and_CJC instrument_NN1 design_NN1 )_PUR ._SENT 
In_PRP addition_NN1 to_PRP being_VBG a_AT0 SETI_NP0 program_NN1 ,_PUN this_DT0 project_NN1 promises_VVZ to_TO0 open_VVI up_AVP new_AJ0 avenues_NN2 for_PRP research_NN1 in_PRP cosmic_AJ0 rays_NN2 ,_PUN as_CJS well_AV0 as_CJS the_AT0 potential_NN1 for_PRP serendipitous_AJ0 discoveries_NN2 in_PRP almost_AV0 completely_AV0 unexplored_AJ0 regions_NN2 of_PRF parameter_NN1 space_NN1 for_PRP fast_AV0 optical_AJ0 and_CJC NIR_NP0 transients_NN2 ._SENT 
Another_DT0 exciting_AJ0 new_AJ0 SETI_NP0 instrument_NN1 is_VBZ the_AT0 Five-hundred-meter_NN1 Aperture_NN1 Spherical_AJ0 radio_NN1 Telescope_NN1 (_PUL FAST_AJ0 )_PUR and_CJC its_DPS SERENDIP_NN1 VI_NP0 multi-beam_NN1 spectrometer_NN1 ,_PUN which_DTQ was_VBD declared_VVN fully_AV0 operational_AJ0 in_PRP January_NP0 ._SENT Li_NP0 et_NP0 al._NP0 described_VVD FAST_AV0 's_POS capabilities_NN2 and_CJC its_DPS partnership_NN1 with_PRP Breakthrough_NN1 Listen_VVB ,_PUN and_CJC Zhang_NP0 et_NP0 al._NP0 described_VVD the_AT0 first_ORD observations_NN2 and_CJC RFI_AJ0 mitigation_NN1 strategies_NN2 they_PNP employ_VVB ._SENT FAST_AV0 is_VBZ shaping_VVG up_AVP to_TO0 be_VBI a_AT0 worthy_AJ0 successor_NN1 to_PRP Arecibo_NP0 ._SENT 
4.2_CRD ._SENT Anomaly_NN1 detection_NN1 
Following_VVG up_AVP on_PRP suggestions_NN2 by_PRP Albrecht_NP0 and_CJC Balazs_NP0 ,_PUN Djorgovski_NP0 ,_PUN and_CJC others_NN2 to_TO0 search_VVI for_PRP highly_AV0 unusual_AJ0 events_NN2 in_PRP large_AJ0 sky_NN1 surveys_NN2 ,_PUN many_DT0 SETI_NP0 practitioners_NN2 have_VHB begun_VVN work_NN1 on_PRP anomaly-detection_NN1 or_CJC outlier_AJC analysis_NN1 as_CJS a_AT0 way_NN1 to_TO0 identify_VVI unexpected_AJ0 ,_PUN potentially_AV0 technological_AJ0 phenomena_NN2 ._SENT Singam_NP0 et_NP0 al._NP0 provided_VVD an_AT0 overview_NN1 of_PRF searches_NN2 for_PRP such_DT0 '_POS '_PUQ non-canonical_AJ0 astrophysical_AJ0 phenomena_NN2 '_POS '_PUQ and_CJC made_VVD suggestions_NN2 for_PRP them_PNP ._SENT 
Villarroel_NP0 et_NP0 al._NP0 described_VVD the_AT0 Vanishing_AJ0 and_CJC Appearing_VVG Sources_NN2 during_PRP a_AT0 Century_NN1 of_PRF Observations_NN2 project_NN1 (_PUL VASCO_NP0 )_PUR ,_PUN which_DTQ leverages_VVZ photographic_AJ0 and_CJC digital_AJ0 sky_NN1 surveys_NN2 across_PRP many_DT0 decades_NN2 to_TO0 search_VVI for_PRP star-like_AJ0 sources_NN2 that_CJT seem_VVB to_TO0 disappear_VVI or_CJC appear_VVI ._SENT The_AT0 survey_NN1 has_VHZ many_DT0 components_NN2 ,_PUN including_PRP hypothesis-driven_AJ0 searches_NN2 (_PUL for_PRP instance_NN1 for_PRP failed_AJ0 supernovae_NN2 )_PUR and_CJC serendipitous_AJ0 searches_NN2 driven_VVN by_PRP machine_NN1 learning_NN1 ._SENT Villarroel_NP0 et_NP0 al._NP0 describe_VVB the_AT0 citizen_NN1 science_NN1 component_NN1 of_PRF the_AT0 project_NN1 ._SENT 
De_NP0 la_NP0 Torre_NP0 explored_VVD the_AT0 challenges_NN2 of_PRF serendipitous_AJ0 detection_NN1 with_PRP neural_AJ0 networks_NN2 ,_PUN and_CJC the_AT0 role_NN1 of_PRF human_AJ0 cognition_NN1 and_CJC bias_NN1 in_PRP such_DT0 searches_NN2 ._SENT He_PNP compares_VVZ the_AT0 results_NN2 of_PRF a_AT0 neural_AJ0 network_NN1 to_PRP those_DT0 of_PRF human_AJ0 volunteers_NN2 identifying_VVG features_NN2 in_PRP imagery_NN1 ,_PUN and_CJC uses_VVZ the_AT0 bright_AJ0 spots_NN2 on_PRP Ceres_NP0 as_PRP an_AT0 example_NN1 ._SENT 
Brzycki_NP0 et_NP0 al._NP0 described_VVD using_VVG convolutional_AJ0 neural_AJ0 networks_NN2 to_TO0 identify_VVI and_CJC characterize_VVI narrow_AJ0 band_NN1 signals_NN2 in_PRP noisy_AJ0 data_NN0 with_PRP an_AT0 eye_NN1 towards_PRP radio_NN1 SETI_NP0 ._SENT Lesnikowski_NP0 et_NP0 al._NP0 described_VVD an_AT0 unsupervised_AJ0 neural_AJ0 network_NN1 to_TO0 analyze_VVI imagery_NN1 of_PRF the_AT0 moon_NN1 to_TO0 look_VVI for_PRP artifacts_NN2 and_CJC other_AJ0 anomalies_NN2 ,_PUN and_CJC shows_VVZ they_PNP can_VM0 recover_VVI the_AT0 obviously_AV0 artificial_AJ0 Apollo_NP0 15_CRD landing_NN1 site_NN1 with_PRP it_PNP ._SENT 
Finally_AV0 ,_PUN Giles_NP0 and_CJC Walkowicz_NP0 discussed_VVD an_AT0 outlier_AJC scoring_NN1 technique_NN1 for_PRP lightcurve_AJ0 data_NN0 as_PRP a_AT0 way_NN1 to_TO0 search_VVI for_PRP anomalies_NN2 and_CJC new_AJ0 phenomena_NN2 ,_PUN and_CJC produce_VVB such_DT0 scores_NN2 for_PRP millions_CRD of_PRF light_AJ0 curves_NN2 from_PRP the_AT0 Kepler_NP0 mission_NN1 ._SENT Such_DT0 work_NN1 is_VBZ useful_AJ0 for_PRP finding_VVG anomalies_NN2 such_DT0 as_PRP Boyajian_NP0 's_POS star_NN1 ,_PUN which_DTQ have_VHB proven_VVN interesting_AJ0 both_AV0 for_PRP SETI_NP0 and_CJC natural_AJ0 astrophysics_NN1 purposes_NN2 ._SENT 
4.3_CRD ._SENT Other_AJ0 methodology_NN1 
Michaud_NP0 et_NP0 al._NP0 reviewed_VVD the_AT0 case_NN1 for_PRP preserving_VVG the_AT0 lunar_AJ0 farside_NN1 for_PRP radio_NN1 astronomy_NN1 and_CJC radio_NN1 SETI_NP0 ,_PUN to_TO0 take_VVI advantage_NN1 of_PRF what_DTQ is_VBZ (_PUL today_AV0 )_PUR a_AT0 region_NN1 free_AJ0 from_PRP terrestrial_AJ0 radio_NN1 frequency_NN1 interference_NN1 ._SENT 
Sandora_NP0 and_CJC Silk_NP0 outlined_VVD a_AT0 Bayesian_AJ0 framework_NN1 for_PRP designing_VVG and_CJC interpreting_VVG results_NN2 from_PRP searches_NN2 for_PRP biosignatures_NN2 and_CJC technosignatures_NN2 ._SENT Haqq-Misra_NP0 et_NP0 al._NP0 argued_VVD that_CJT the_AT0 relative_AJ0 abundance_NN1 of_PRF technosignatures_NN2 versus_PRP biosignatures_NN2 detected_VVN in_PRP future_AJ0 astronomical_AJ0 surveys_NN2 with_PRP space_NN1 telescopes_NN2 will_VM0 help_VVI determine_VVI whether_CJS the_AT0 '_POS '_PUQ Great_AJ0 Filter_NN1 '_PUQ '_POS (_PUL which_DTQ they_PNP define_VVB as_PRP the_AT0 '_POS '_PUQ hardest_AJS step_NN1 in_PRP planetary_AJ0 evolution_NN1 '_POS '_PUQ )_PUR is_VBZ in_PRP our_DPS past_NN1 or_CJC future_NN1 ._SENT 
Finally_AV0 ,_PUN Seto_NP0 and_CJC Kashiyama_NP0 presented_VVD an_AT0 analysis_NN1 of_PRF stellar_AJ0 motions_NN2 and_CJC their_DPS uncertainties_NN2 from_PRP Gaia_NP0 for_PRP use_NN1 in_PRP targeting_VVG METI_AJ0 signals_NN2 ,_PUN which_DTQ might_VM0 be_VBI useful_AJ0 for_PRP SETI_NP0 as_CJS well_AV0 ._SENT 
5._CRD Target_NN1 and_CJC frequency_NN1 selection_NN1 (_PUL 8_CRD papers_NN2 )_PUR 
The_AT0 Cosmic_AJ0 Haystack_NN1 is_VBZ large_AJ0 ,_PUN and_CJC so_AV0 narrowing_VVG down_AVP the_AT0 best_AJS targets_NN2 and_CJC frequencies_NN2 to_TO0 check_VVI is_VBZ essential_AJ0 ._SENT 
This_DT0 problem_NN1 of_PRF finding_VVG someone_PNI also_AV0 looking_VVG for_PRP you_PNP is_VBZ a_AT0 game_NN1 introduced_VVN to_PRP game_NN1 theory_NN1 by_PRP Thomas_NP0 Schelling_NP0 ,_PUN who_PNQ actually_AV0 used_VVD Cocconi_NP0 and_CJC Morrison_NP0 as_PRP an_AT0 example_NN1 of_PRF his_DPS point_NN1 ._SENT In_PRP [_PUL 36_CRD ]_PUR I_PNP described_VVD and_CJC formalized_VVD this_DT0 connection_NN1 of_PRF target_NN1 and_CJC frequency_NN1 selection_NN1 as_PRP a_AT0 hunt_NN1 for_PRP '_POS '_PUQ Schelling_NP0 points_NN2 '_POS '_PUQ and_CJC applied_VVD the_AT0 idea_NN1 to_PRP the_AT0 suggestion_NN1 of_PRF Planck_NP0 that_CJT his_DPS eponymous_AJ0 units_NN2 would_VM0 be_VBI truly_AV0 universal_AJ0 ,_PUN known_VVN even_AV0 to_PRP alien_AJ0 species_NN0 ._SENT The_AT0 resulting_AJ0 lists_NN2 of_PRF frequencies_NN2 to_TO0 check_VVI (_PUL across_PRP the_AT0 electromagnetic_AJ0 spectrum_NN1 )_PUR are_VBB arguably_AV0 still_AV0 too_AV0 anthropocentric_AJ0 and_CJC arbitrary_AJ0 ,_PUN but_CJC are_VBB nonetheless_AV0 small_AJ0 enough_AV0 in_PRP number_NN1 to_TO0 add_VVI to_PRP the_AT0 lists_NN2 of_PRF '_POS '_PUQ magic_AJ0 frequencies_NN2 '_PUQ '_POS to_TO0 search_VVI at_PRP ._SENT 
Another_DT0 Schelling_NP0 point_NN1 is_VBZ when_AVQ to_TO0 look_VVI ._SENT Gray_NP0 argued_VVD that_CJT an_AT0 efficient_AJ0 transmission_NN1 strategy_NN1 is_VBZ to_TO0 broadcast_VVI continuously_AV0 from_PRP a_AT0 fixed_AJ0 point_NN1 and_CJC direction_NN1 on_PRP a_AT0 planetary_AJ0 surface_NN1 ._SENT The_AT0 result_NN1 would_VM0 be_VBI that_CJT signals_NN2 would_VM0 repeat_VVI every_AT0 planetary_AJ0 rotation_NN1 ._SENT Gray_NP0 's_POS application_NN1 here_AV0 is_VBZ to_PRP the_AT0 Wow_ITJ !_SENT Signal_NN1 (_PUL and_CJC indeed_AV0 this_DT0 motivated_AJ0 Harp_NN1 et_NP0 al._NP0 above_AV0 )_PUR but_CJC more_AV0 generally_AV0 is_VBZ that_CJT similar_AJ0 '_POS '_PUQ one-off_AJ0 '_PUQ '_POS signals_NN2 should_VM0 be_VBI prioritized_VVN for_PRP re-observation_NN1 ._SENT 
We_PNP also_AV0 need_VVB to_TO0 know_VVI where_AVQ to_TO0 look_VVI ._SENT Caballero_NP0 attempted_VVD to_TO0 identify_VVI the_AT0 most_AV0 likely_AJ0 stars_NN2 in_PRP the_AT0 Wow_ITJ !_SENT Signal_NN1 region_NN1 of_PRF the_AT0 sky_NN1 to_TO0 host_VVI life_NN1 ._SENT Kaltenegger_NP0 and_CJC Pepper_NP0 used_VVD the_AT0 Gaia_NP0 DR2_NN1 catalog_NN1 to_TO0 extend_VVI the_AT0 work_NN1 of_PRF Heller_NP0 and_CJC Pudritz_NP0 to_TO0 identify_VVI new_AJ0 Earth_NN1 Transit_NN1 Zone_NN1 stars_NN2 ._SENT 
Arguments_NN2 for_PRP searches_NN2 for_PRP artifacts_NN2 within_PRP the_AT0 solar_AJ0 system_NN1 are_VBB as_AV0 old_AJ0 as_CJS modern_AJ0 SETI_NP0 ,_PUN but_CJC the_AT0 idea_NN1 seems_VVZ to_TO0 have_VHI new_AJ0 resonance_NN1 these_DT0 days_NN2 ._SENT Gertz_NP0 made_VVD one_CRD such_DT0 argument_NN1 ,_PUN and_CJC includes_VVZ some_DT0 suggestions_NN2 for_PRP how_AVQ to_TO0 search_VVI ._SENT 
Developing_AJ0 ideas_NN2 by_PRP Wolfe_NP0 ,_PUN Turnbull_NP0 and_CJC Tarter_NP0 ,_PUN and_CJC others_NN2 ,_PUN Gertz_NP0 made_VVD a_AT0 good_AJ0 argument_NN1 that_CJT white_AJ0 dwarfs_NN2 ,_PUN evolved_AJ0 stars_NN2 ,_PUN and_CJC similar_AJ0 objects_NN2 ,_PUN while_CJS presumably_AV0 poor_AJ0 targets_NN2 for_PRP searches_NN2 for_PRP biosignatures_NN2 ,_PUN are_VBB actually_AV0 good_AJ0 targets_NN2 for_PRP technosignature_NN1 searches_NN2 because_CJS they_PNP have_VHB given_VVN rise_NN1 to_PRP a_AT0 technological_AJ0 species_NN0 that_CJT has_VHZ outlived_VVN its_DPS host_NN1 planet_NN1 ._SENT 
Ćirković_NP0 and_CJC Vukotić_NP0 argued_VVD that_CJT M_ZZ0 dwarfs_NN2 are_VBB poor_AJ0 targets_NN2 for_PRP radio_NN1 SETI_NP0 ,_PUN because_CJS their_DPS frequent_AJ0 flaring_NN1 would_VM0 interfere_VVI with_PRP the_AT0 development_NN1 of_PRF radio_NN1 technology_NN1 on_PRP their_DPS planets_NN2 (_PUL although_CJS I_PNP wonder_VVB whether_CJS the_AT0 presence_NN1 of_PRF a_AT0 powerful_AJ0 and_CJC important_AJ0 radio_NN1 source_NN1 like_PRP a_AT0 flaring_AJ0 star_NN1 nearby_AV0 would_VM0 not_XX0 increase_VVI the_AT0 likelihood_NN1 of_PRF the_AT0 development_NN1 of_PRF such_DT0 technology_NN1 )_PUR ._SENT 
Finally_AV0 ,_PUN Lacki_NP0 et_NP0 al._NP0 produced_VVD a_AT0 remarkable_AJ0 catalog_NN1 of_PRF '_POS '_PUQ one_CRD of_PRF everything_PNI '_POS '_PUQ ,_PUN a_AT0 list_NN1 of_PRF an_AT0 example_NN1 of_PRF every_AT0 major_AJ0 kind_NN1 of_PRF astronomical_AJ0 object_NN1 and_CJC superlative_AJ0 ._SENT Interesting_AJ0 in_PRP its_DPS own_DT0 right_NN1 beyond_PRP SETI_NP0 ,_PUN this_DT0 '_POS '_PUQ exotica_NN1 catalog_NN1 '_POS '_PUQ for_PRP Breakthrough_NN1 Listen_VVB also_AV0 provides_VVZ a_AT0 target_NN1 list_NN1 for_PRP investigation_NN1 into_PRP whether_CJS any_DT0 of_PRF these_DT0 presumably_AV0 natural_AJ0 kinds_NN2 of_PRF objects_NN2 is_VBZ actually_AV0 an_AT0 example_NN1 of_PRF or_CJC influenced_VVN by_PRP technology_NN1 on_PRP large_AJ0 scales_NN2 ._SENT 
6._CRD Development_NN1 of_PRF technosignatures_NN2 (_PUL 15_CRD papers_NN2 )_PUR 
6.1_CRD ._SENT The_AT0 axes_NN2 of_PRF merit_NN1 
Many_DT0 technosignatures_NN2 across_PRP a_AT0 range_NN1 of_PRF scales_NN2 and_CJC detection_NN1 strategies_NN2 have_VHB been_VBN proposed_VVN ,_PUN and_CJC it_PNP remains_VVZ unclear_AJ0 which_DTQ are_VBB the_AT0 most_AV0 promising_AJ0 ._SENT 
The_AT0 literature_NN1 has_VHZ long_AV0 seen_VVN papers_NN2 arguing_VVG for_PRP various_AJ0 criteria_NN2 of_PRF merit_NN1 when_CJS weighing_VVG technosignatures_NN2 ._SENT Indeed_AV0 ,_PUN within_PRP two_CRD years_NN2 of_PRF Cocconi_NP0 and_CJC Morrison_NP0 's_POS foundational_AJ0 article_NN1 arguing_VVG for_PRP radio_NN1 communication_NN1 as_PRP an_AT0 ideal_AJ0 technosignature_NN1 ,_PUN Dyson_NP0 ,_PUN Bracewell_NP0 ,_PUN and_CJC Schwartz_NP0 and_CJC Townes_NP0 all_AV0 argued_VVN for_PRP others_NN2 on_PRP various_AJ0 grounds_NN2 ._SENT For_PRP a_AT0 good_AJ0 example_NN1 ,_PUN see_VVB the_AT0 discussion_NN1 of_PRF Shostak_NP0 ,_PUN who_PNQ made_VVD the_AT0 case_NN1 for_PRP artifacts_NN2 over_PRP radio_NN1 transmissions_NN2 ._SENT 
At_PRP the_AT0 NASA_NP0 Technosignatures_NN2 Workshop_NN1 in_PRP 2018_CRD ,_PUN Sofia_NP0 Sheikh_NP0 compiled_VVD many_DT0 of_PRF these_DT0 criteria_NN2 into_PRP a_AT0 single_AJ0 diagram_NN1 she_PNP called_VVD the_AT0 '_POS '_PUQ axes_NN2 of_PRF merit_NN1 '_POS '_PUQ for_PRP technosignature_NN1 search_NN1 ._SENT This_DT0 helpfully_AV0 compiled_VVN various_AJ0 arguments_NN2 about_PRP detectability_NN1 ,_PUN contrivance_NN1 ,_PUN longevity_NN1 ,_PUN and_CJC so_AV0 on_AVP into_PRP a_AT0 single_AJ0 ,_PUN qualitative_AJ0 ,_PUN somewhat_AV0 subjective_AJ0 framework_NN1 ._SENT 
