Oort's constants formulas on the wall of Witte Singel 58-C, Leiden (the Netherlands). <br><span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle A={\frac {1}{2}}\left({\frac {V_{0}}{R_{0}}}-{\frac {dv}{dr}}|_{R_{0}}\right)}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mi>A</mi><mo>=</mo><mrow class="MJX-TeXAtom-ORD"><mfrac><mn>1</mn><mn>2</mn></mfrac></mrow><mrow><mo>(</mo><mrow><mrow class="MJX-TeXAtom-ORD"><mfrac><msub><mi>V</mi><mrow class="MJX-TeXAtom-ORD"><mn>0</mn></mrow></msub><msub><mi>R</mi><mrow class="MJX-TeXAtom-ORD"><mn>0</mn></mrow></msub></mfrac></mrow><mo>−<!-- − --></mo><mrow class="MJX-TeXAtom-ORD"><mfrac><mrow><mi>d</mi><mi>v</mi></mrow><mrow><mi>d</mi><mi>r</mi></mrow></mfrac></mrow><msub><mrow class="MJX-TeXAtom-ORD"><mo stretchy="false">|</mo></mrow><mrow class="MJX-TeXAtom-ORD"><msub><mi>R</mi><mrow class="MJX-TeXAtom-ORD"><mn>0</mn></mrow></msub></mrow></msub></mrow><mo>)</mo></mrow></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle A={\frac {1}{2}}\left({\frac {V_{0}}{R_{0}}}-{\frac {dv}{dr}}|_{R_{0}}\right)}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/d38e208fe5e6a91d54effa5d0aa8c837ad3e3c70" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -2.505ex; width:23.281ex; height:6.176ex;" alt="{\displaystyle A={\frac {1}{2}}\left({\frac {V_{0}}{R_{0}}}-{\frac {dv}{dr}}|_{R_{0}}\right)}"></span>, <span class="mwe-math-element"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle B=-{\frac {1}{2}}\left({\frac {V_{0}}{R_{0}}}+{\frac {dv}{dr}}|_{R_{0}}\right)}"><semantics><mrow class="MJX-TeXAtom-ORD"><mstyle displaystyle="true" scriptlevel="0"><mi>B</mi><mo>=</mo><mo>−<!-- − --></mo><mrow class="MJX-TeXAtom-ORD"><mfrac><mn>1</mn><mn>2</mn></mfrac></mrow><mrow><mo>(</mo><mrow><mrow class="MJX-TeXAtom-ORD"><mfrac><msub><mi>V</mi><mrow class="MJX-TeXAtom-ORD"><mn>0</mn></mrow></msub><msub><mi>R</mi><mrow class="MJX-TeXAtom-ORD"><mn>0</mn></mrow></msub></mfrac></mrow><mo>+</mo><mrow class="MJX-TeXAtom-ORD"><mfrac><mrow><mi>d</mi><mi>v</mi></mrow><mrow><mi>d</mi><mi>r</mi></mrow></mfrac></mrow><msub><mrow class="MJX-TeXAtom-ORD"><mo stretchy="false">|</mo></mrow><mrow class="MJX-TeXAtom-ORD"><msub><mi>R</mi><mrow class="MJX-TeXAtom-ORD"><mn>0</mn></mrow></msub></mrow></msub></mrow><mo>)</mo></mrow></mstyle></mrow><annotation encoding="application/x-tex">{\displaystyle B=-{\frac {1}{2}}\left({\frac {V_{0}}{R_{0}}}+{\frac {dv}{dr}}|_{R_{0}}\right)}</annotation></semantics></math></span><img src="https://wikimedia.org/api/rest_v1/media/math/render/svg/cf1d7437edd8523c34ac437933fd08e3a9a91ddb" class="mwe-math-fallback-image-inline" aria-hidden="true" style="vertical-align: -2.505ex; width:25.11ex; height:6.176ex;" alt="{\displaystyle B=-{\frac {1}{2}}\left({\frac {V_{0}}{R_{0}}}+{\frac {dv}{dr}}|_{R_{0}}\right)}"></span>
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