Wednesday, November 20, 2013

Comet ISON on 11-20-13

Five days have passed and this is the first morning it's been clear enough to try and grab photos of Comet ISON again. On the one hand Stellarium says that ISON has increased in brightness to mag ~3.75. On the other hand, it will be lower in the sky, arriving closer to dawn and combating a nearly full moon. All this means that it's effective brightness (measured as apparent extinction) will be about mag 4.75. So effectively it will be no better than five days ago, just lower in the sky. Which means that, given light pollution and haze, it's still not visible to the naked eye.

The good news is that I was able to photograph it back then, so I had high hopes for today. I trudged out at 5:45 (trying really really hard not to wake my fiance) pointed the camera in the right place and immediately started taking photographs. When the photos didn't show anything obvious I trudged back inside for the laptop and Stellarium to figure out exactly where to point the camera.

Because there are trees to the east I figured I had a relatively small window of opportunity - about 10 minutes around 6am before dawn started to interfere with my observing. I quickly found where I needed to be and starting snapping photos. I played with several settings from about 15 sec to as little as 2 seconds. I got my best results with my canon t5i at a 2 sec exposure with an ISO setting of about 1600. More than that and there was too much noise and background brightness. Go in the other direction and you get too much movement (long exposure time) or simply not enough photons (too low ISO). The camera also has a zoom lens (faux telephoto) which allowed me to get closer. I'll have to look up the specs on that if asked.

Anyways, here's the best of the bunch from this morning, courtesy of Flickr.  They are considerably embiggened there. Enjoy!

Comet ISON on 11-20-13

Comet ISON on 11-20-13

So basically, you can see the greenish coma and a little bit of the tail. Not bad for obviously hazy skies. I don't know if I'll get clear weather again, so this may be the last I see of ISON prior to its solar encounter.


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