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  2. Minute and second of arc - Wikipedia

    en.wikipedia.org/wiki/Minute_and_second_of_arc

    A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol ′, is a unit of angular measurement equal to ⁠ 1 / 60 ⁠ of one degree. [1] Since one degree is ⁠ 1 / 360 ⁠ of a turn, or complete rotation, one arcminute is ⁠ 1 / 21 600 ⁠ of a turn.

  3. Angular resolution - Wikipedia

    en.wikipedia.org/wiki/Angular_resolution

    The factor 1.22 is derived from a calculation of the position of the first dark circular ring surrounding the central Airy disc of the diffraction pattern. This number is more precisely 1.21966989... (OEIS: A245461), the first zero of the order-one Bessel function of the first kind divided by π.

  4. Stellar parallax - Wikipedia

    en.wikipedia.org/wiki/Stellar_parallax

    Very long baseline interferometry in the radio band can produce images with angular resolutions of about 1 milliarcsecond, and hence, for bright radio sources, the precision of parallax measurements made in the radio can easily exceed [dubious – discuss] those of optical telescopes like Gaia. These measurements tend to be sensitivity limited ...

  5. Millisecond - Wikipedia

    en.wikipedia.org/wiki/Millisecond

    1 millisecond – time taken for light to travel 204.19 km in a single mode fiber optic cable for a wavelength of 1550 nm (frequency: 193 THz). 1 millisecond – nerve conduction velocity (neuron signal firing) happens on the order of milliseconds; 1.000692286 milliseconds – time taken for light to travel 300 km in a vacuum

  6. International Celestial Reference System and its realizations

    en.wikipedia.org/wiki/International_Celestial...

    The positions of most are known to 1 milliarcsecond (mas) or better. [9] In August 1997, the International Astronomical Union resolved in Resolution B2 of its XXIIIrd General Assembly "that the Hipparcos Catalogue shall be the primary realization of the ICRS at optical wavelengths."

  7. AOL Mail

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    Get AOL Mail for FREE! Manage your email like never before with travel, photo & document views. Personalize your inbox with themes & tabs. You've Got Mail!

  8. Superluminal motion - Wikipedia

    en.wikipedia.org/wiki/Superluminal_motion

    The change in the source visibility that they measured for 3C 279, combined with changes in total flux density, indicated that a component first seen in 1969 had reached a diameter of about 1 milliarcsecond, implying expansion at an apparent velocity of at least twice the speed of light.

  9. AOL Mail for Verizon Customers - AOL Help

    help.aol.com/products/aol-mail-verizon

    1-800-358-4860. Get live expert help with your AOL needs—from email and passwords, technical questions, mobile email and more. AOL Mail for Verizon Customers.