# Hubble's law

**Section:** Observed values of the Hubble constant

| Date published | Hubble constant (km/s)/Mpc | Observer | Citation | Remarks / methodology | - |
|---|---|---|---|---|---|
| after 1996 | - | - | - | - | - |
| before 1996 | 50–90 (est.) | - | - | - | - |
| 2019-03-28 | 68.0+4.2 −4.1 | Fermi-LAT | - | Gamma ray attenuation due to extragalactic light. Independent of the cosmic distance ladder and the cosmic microwave background. | - |
| 2019-03-18 | 74.03±1.42 | Hubble Space Telescope | - | Precision HST photometry of Cepheids in the Large Magellanic Cloud (LMC) reduce the uncertainty in the distance to the LMC from 2.5% to 1.3%. | - |
| 2019-02-08 | 67.78+0.91 −0.87 | Joseph Ryan et al. | - | Quasar angular size and baryon acoustic oscillations, assuming a flat LambdaCDM model. Alternative models result in different (generally lower) values for the Hubble constant. | - |
| 2018-11-06 | 67.77±1.30 | DES Collaboration | - | Supernova measurements using the inverse distance ladder method based on baryon acoustic oscillations. | - |
| 2018-09-05 | 72.5+2.1 −2.3 | H0LiCOW collaboration | - | Observations of multiply imaged quasars, independent of the cosmic distance ladder and independent of the cosmic microwave background measurements. | - |
| 2018-07-18 | 67.66±0.42 | Planck Mission | - | Final Planck 2018 results. | - |
| 2018-04-27 | 73.52±1.62 | Hubble Space Telescope and Gaia | - | Additional HST photometry of galactic Cepheids with early Gaia parallax measurements. The revised value increases tension with CMB measurements at the 3.8σ level. | - |
| 2018-02-22 | 73.45±1.66 | Hubble Space Telescope | - | Parallax measurements of galactic Cepheids for enhanced calibration of the distance ladder; the value suggests a discrepancy with CMB measurements at the 3.7σ level. | - |
| 2017-10-16 | 70.0+12.0 −8.0 | The LIGO Scientific Collaboration and The Virgo Collaboration | - | Measurement was independent of a cosmic ‘distance ladder'; the gravitational-wave analysis of a binary neutron star (BNS) merger GW170817 directly estimated the luminosity distance out to cosmological scales. | - |
| 2016-11-22 | 71.9+2.4 −3.0 | Hubble Space Telescope | - | Uses time delays between multiple images of distant variable sources produced by strong gravitational lensing. Collaboration known as Lenses in COSMOGRAIL's Wellspring (H0LiCOW). | - |
| 2016-08-04 | 76.2+3.4 −2.7 | Cosmicflows-3 | - | Comparing redshift to other distance methods, including Tully–Fisher, Cepheid variable, and Type Ia supernovae. A restrictive estimate from the data implies a more precise value of 75±2. | - |
| 2016-07-13 | 67.6+0.7 −0.6 | SDSS-III Baryon Oscillation Spectroscopic Survey | - | Baryon acoustic oscillations. An extended survey (eBOSS) began in 2014 and is expected to run through 2020. | - |
| 2016-05-17 | 73.24±1.74 | Hubble Space Telescope | - | Type Ia supernova, the uncertainty is expected to go down by a factor of more than two with upcoming Gaia measurements and other improvements. | - |
| 2015-02 | 67.74±0.46 | Planck Mission | - | Results from an analysis of Planck's full mission were made public on 1 December 2014 at a conference in Ferrara, Italy. | - |
| 2013-10-01 | 74.4±3.0 | Cosmicflows-2 | - | Comparing redshift to other distance methods, including Tully–Fisher, Cepheid variable, and Type Ia supernovae. | - |
| 2013-03-21 | 67.80±0.77 | Planck Mission | - | The ESA Planck Surveyor was launched in May 2009. Over a four-year period, it performed a significantly more detailed investigation of cosmic microwave radiation than earlier investigations using HEMT radiometers and bolometer technology to measure the CMB at a smaller scale than WMAP. | - |
| 2012-12-20 | 69.32±0.80 | WMAP (9 years), combined with other measurements. | - | - | - |
| 2010 | 70.4+1.3 −1.4 | WMAP (7 years), combined with other measurements. | - | These values arise from fitting a combination of WMAP and other cosmological data to the simplest version of the ΛCDM model. | - |
| 2010 | 71.0±2.5 | WMAP only (7 years). | - | - | - |
| 2009-02 | 70.5±1.3 | WMAP (5 years), combined with other measurements. | - | - | - |
| 2009-02 | 71.9+2.6 −2.7 | WMAP only (5 years) | - | - | - |
| 2007 | 70.4+1.5 −1.6 | WMAP (3 years), combined with other measurements. | - | - | - |
| 2006-08 | 76.9+10.7 −8.7 | Chandra X-ray Observatory | - | Combined Sunyaev–Zel'dovich effect and Chandra X-ray observations of galaxy clusters. Adjusted uncertainty in table from Planck Collaboration 2013. | - |
| 2001-05 | 72±8 | Hubble Space Telescope Key Project | - | This project established the most precise optical determination, consistent with a measurement of H0 based upon Sunyaev–Zel'dovich effect observations of many galaxy clusters having a similar accuracy. | - |
| after 1996 | - | - | - | - | - |
| before 1996 | 50–90 (est.) | - | - | - | - |
| early 1970s | ~55 (est.) | Allan Sandage and Gustav Tammann | - | - | - |
| 1958 | 75 (est.) | Allan Sandage | - | This was the first good estimate of H0, but it would be decades before a consensus was achieved. | - |
| 1956 | 180 | Humason, Mayall and Sandage | - | - | - |
| 1929 | 500 | Edwin Hubble, Hooker telescope | - | - | - |
| 1927 | 625 | Georges Lemaître | - | First measurement and interpretation as a sign of the expansion of the universe | - |