{"id":115,"date":"2016-01-19T14:12:09","date_gmt":"2016-01-19T14:12:09","guid":{"rendered":"http:\/\/www.astronotas.org\/messier\/?p=115"},"modified":"2023-12-09T14:45:41","modified_gmt":"2023-12-09T18:45:41","slug":"m21","status":"publish","type":"post","link":"https:\/\/www.astronotas.org\/messier\/m21\/","title":{"rendered":"Messier 21"},"content":{"rendered":"\n
\"M21\"<\/a><\/figure>\n\n\n\n

Objeto: M21<\/strong><\/p>\n\n\n\n

Constelaci\u00f3n: Sagittarius
Fecha: 1992.05.31 | Hora: n\/a UT
Lugar: Sumidero, Aguas Buenas, PR<\/p>\n\n\n\n

Tipo de objeto: C\u00famulo abierto, clase D
Nombre: NGC 6531
Magnitud: 5.9 | Tama\u00f1o: 12′
A.R. 18h04.6m | Dec. \u201322\u00b030′
\u00c9poca: 2000.0<\/p>\n\n\n\n

Instrumento: Meade MTS-SN 6
Ocular: 6 mm ortosc\u00f3pico | Aumento: 127x
Campo aparente: 45\u00b0 | Campo actual: 21′
Otros:<\/p>\n\n\n\n

Carta en Uranometr\u00eda 2000.0: 339<\/p>\n\n\n\n

\"M21\"<\/a>
REU program\/NOAO\/AURA\/NSF [origen<\/a>] <\/figcaption><\/figure>\n\n\n\n

Descripci\u00f3n<\/h3>\n\n\n\n

Espa\u00f1ol: <\/strong>M21 es un c\u00famulo abierto, o gal\u00e1ctico, en la constelaci\u00f3n de Sagitario, a menos de 1\u00b0 de M20, al Nebulosa Tr\u00edfida, parte de la cual se puede ver dentro del campo de visi\u00f3n del ocular de 30x. A mayor magnificaci\u00f3n, esta se pierde, dejando solamente a M21. El \u00e1rea donde se localiza este peque\u00f1o c\u00famulo est\u00e1 poblada por infinidad de estrellas, que se ven tenues al fondo de la imagen. Son tantas (estamos mirando al centro de la galaxia) que apenas pueden distinguirse, causando una impresi\u00f3n granulosa-nebulosa de fondo. Las estrellas de este c\u00famulo se ven entre blancas y amarillentas. Al centro, se distingue una estrella doble.<\/p>\n\n\n\n

English: <\/b>M21 is an open, or galactic, cluster in Sagittarius, less than 1\u00b0 from M20, the Trifid Nebula, partially viewed in the same field of view at 30x. At higher magnification, M20 is no longer visible, leaving M21 alone. The area where the cluster is located is full of stars that seem faint in the background. There are so many (we’re looking at the heart of the galaxy) that they are hardly distinguishable, creating a granulous-nebulous impression. The stars in this cluster look white and yellowish. There’s a double star in the center.<\/p>\n\n\n\n

\"M20<\/a>
M20 y M21. REU program\/NOAO\/AURA\/NSF. [origen<\/a>] <\/figcaption><\/figure>\n\n\n\n

Cometarios de Messier en 1771:<\/strong> La misma noche determin\u00e9 la posici\u00f3n de dos c\u00famulos de estrellas que est\u00e1n cerca el uno del otro, un poco arriba de la ecl\u00edptica, entre el arco del Sagitario y el pie derecho de Ofiuco: la estrella conocida m\u00e1s cercana de estos dos c\u00famulos es la und\u00e9cima de la constelaci\u00f3n del Sagitario, de s\u00e9ptima magnitud, seg\u00fan el cat\u00e1logo de Flamsteed: las estrellas de estos dos c\u00famulos son, de la octava a la novena magnitud, rodeados de nebulosidad. Determin\u00e9 sus posiciones. Ascensi\u00f3n recta de primer c\u00famulo, 267\u00b0 4′ 5″, su declinaci\u00f3n 22\u00b0 59′ 10″ meridional. Ascensi\u00f3n recta del segundo, 267\u00b0 31′ 35″, su declinaci\u00f3n, 22\u00b0 31′ 25″ meridional.<\/p>\n\n\n\n

Comentarios de Messier en 1783:<\/strong> C\u00famulo de estrellas, cerca del precedente; la estrella conocida m\u00e1s cercana de estos dos c\u00famulos es la und\u00e9cima del Sagitario, de s\u00e9ptima magnitud, seg\u00fan Flamsteed. Las estrellas de estos dos c\u00famulos son de la octava a la novena magnitud, rodeados de nebulosidad.<\/p>\n\n\n\n

Mapa para localizar a M21<\/strong><\/p>\n\n\n\n

\"Mapa
Haga click para agrandar.<\/figcaption><\/figure>\n","protected":false},"excerpt":{"rendered":"

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