USNO Astrometry. Ralph Gaume, U.S. Naval Observatory. Commission 8. August 29, IAU XXVIII General Assembly

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1 USNO Astrometry Ralph Gaume, U.S. Naval Observatory Commission 8 August 29, 2012 IAU XXVIII General Assembly

2 Overview Discuss and present status of USNO astrometric catalogs and astrometric observing programs

3 ICRF2 By resolution, the XXVII GA of the IAU adopted ICRF2 as the fundamental realization of the ICRS ICRF2: 30 years of VLBI observations Catalog contains coordinates of 3414 extragalactic objects (~5 x ICRF1)

4 ICRF2 S/X: 8.4 GHz, 3.6cm: 3414 sources Ecliptic 40 µas floor. ~1200 obj. well observed, ~2000 survey session only 28 Aug 2012 C.S. Jacobs Credit: Ma et al, eds. Fey, Gordon, Jacobs, IERS Tech. Note 35, Germany,

5 ICRF2 By resolution, the XXVII GA of the IAU adopted ICRF2 as the fundamental realization of the ICRS ICRF2: 30 years of VLBI observations Catalog contains coordinates of 3414 extragalactic objects (~5 x ICRF1) Noise floor 40 microas (~6 x better than ICRF1) Axis stability ~10 microas (2 x better than ICRF1) 295 new defining sources Minimal source structure Improved position stability More uniform sky distribution IERS Technical Note 35, machine-readable catalog

6 Prospects for Next Radio Reference Frame IAU Division 1 working group Produce detailed implementation and execution plan for next generation Radio Reference Frame. Improved data sets, improved models, global VLBI arrays, potentially incorporate higher frequency observations Report plan to Division I at XXIX GA Goal: Produce next Radio Reference Frame for adoption at XXX GA

7 Celestial Reference Frame (CRF) Hipparcos remains as the primary optical realization of the ICRS (by resolution of the XXIII GA of the IAU) But Hipparcos has degraded considerably from accuracy at central epoch ( ) By resolution, the XXVII GA of the IAU Resolves that the IERS, together with other relevant organizations continue efforts to improve and densify high accuracy reference frames defined at other wavelengths and continue to improve ties between these reference frames and ICRF2.

8 Bright Stars: NPOI Navy Precision Optical Interferometer (NPOI) First light, 1994 USNO-NPOI Astrometric Catalog (UNAC) 100+ star astrometric catalog, brighter than 6 th Mv Approx 16 mas astrometric accuracy Preliminary version of catalog by end of 2012 Planning underway to incorporate 4 x 1.8m Keck outriggers Improve limiting magnitude Potential improvement of astrometric accuracy (longer baselines)

9 Bright Stars: JMAPS Joint Milli-Arcsecond Pathfinder Survey (JMAPS) USNO bright star space mission 1 mas New technology: SiC telescope, CMOS- Hybrid detectors Future uncertain, currently no path to flight Funding removed, byproduct of US federal budget pressures Instrument flight parts being delivered Telescope, flight detectors, focal plane, some instrument integration and

10 UCAC & URAT USNO CCD Astrograph Catalog (UCAC) Observed Four versions of the catalog: UCAC 1-4 UCAC4 released this month USNO Robotic Astrometric Telescope (URAT) Utilizes same objective lens, but modern camera, redesigned telescope, upgraded mount Observations have started from

11 Fainter Star Catalogs USNO faint star catalogs: Naval Observatory Merged Astrometric Dataset (NOMAD) Simple merge of Hipparcos, Tycho, UCAC, USNO B Will be updated On line: POC: Dr. Dave Monet (dgm@nofs.navy.mil) USNO will be producing catalogs from current/future astrometric and non-astrometric surveys Prototyping global solution algorithms