PLUTÃO fotografado na oposição - 08/07/2016 - por Hélio C. Vital / RJ.
09/07/2016
Informações enviadas por e-mail pelo amigo Hélio Carvalho Vital / RJ, descrevem sua missão bem sucedida em fotografar PLUTÂO no céu do Rio de Janeiro, na noite de 08 de julho de 2016, utilizando seu telescópio Celestron C8 e sua câmera Canon Rebel T1i. Vejam o e-mail original e as desafiantes fotos abaixo:
Boa noite, amigos!
Comunico-lhes que tive sucesso em minha primeira tentativa na vida de fotografar Plutão. Foi na noite passada, quando ele estava em oposição.
Retransmito-lhes a mensagem que enviei para a Deborah Byrd do EarthSky.
Hi, Deborah!
I am sending you photos I took last night.
I succeeded in my first attempt to capture Pluto by using a camera attached to my C8.
The attached photos show it around 5:30 UTC (July 08), just some 7-8 hours after its opposition last night.
Description:
I attempted to photograph the very faint Pluto for the first time in my life last night as it was at opposition (magnitude 14.1), about one thousand times dimmer than the faintest star visible from Rio with the naked eye. In order to accomplish that challenging task, I attached my Canon EOS Rebel T1i camera to the primary focus of my Celestron 8 after running Skychart, a planetarium program, to get ephemeris data and plan the steps of my observation. I first aimed the C8 to Saturn and adjusted the setting circles of my C8 so that the coordinates of the planet could be read from them. Then I targeted Pi Sgr (m=2.88), currently located only 0.2° from Pluto, by moving the telescope to the right ascension and declination of the star. Finally, I shifted the C8 slightly to the coordinates of Pluto. I then took several shots using the highest speed of the camera (ISO 12800) with exposures ranging from 30 to 75 seconds. Photoscape was then used to improve contrast and sharpness of the photos. In order to ensure the planet had indeed be captured, I carefully compared the photos with images created by Skychart and I could pinpoint Pluto in most of them. I also found that stars up to one magnitude dimmer than Pluto had also be recorded.
What made my attempt of capturing Pluto from Rio successful? A combination of factors:
(1) A cloudless sky with excellent seeing and transparency conditions;
(2) The use of a telescope having approximately 800 times more light gathering power than the eye and using 57-time magnification;
(3) The use of a camera employing a very fast speed (12800 ASA) and long exposure times (30-75 seconds) to get as much light as possible;
(4) Post processing with Photoscape to improve sharpness and contrast, consequently highlighting details;
(5) Careful planning and some previous experience in this type of observation.
Many thanks for your kind attention!
Best wishes!
