Thursday, December 18, 2014

Bode’s nebulae M81 and M82

A quest for dark skies in Lijiang, China.

Since my last entry in September I hadn’t had the opportunity to work on the blog because I had been busy with preparations for traveling to China. I arrived at our new home on the 25th of October and since that day, I had been busy moving in and setting into a new style of life here.


The sky here (at least at this time of the year) is so clear and clean, not only at night but also in the day, that as soon as I could be done with the moving in (at least the most important things) I went outside to enjoy the landscape and the stars. Here is a picture I took of the majestic Jade Dragon Snow Mountain at the north of the city.


The first night I went outside at around 20:00 hours. I took the binoculars with me just to perform a quick scan of the sky. I looked at Saggitarius to “test the sky” trying to spot an easy target, but I realized something was wrong with the Binos. I saw the image duplicated and there was a difference between the vertical position of the stars when looking through each eyepiece individually.   Well, I felt hopeless at first, but then, after some research, I found the solution to the problem: the binoculars needed collimation. I spent almost 1 week getting them collimated.  After some reading about how to do that, I got the appropiate screwdriver and glue (It should not have been that complicated, but I didn’t know the Chinese words to get it) and finally I performed the collimation.  By the end of November I was once again  ready to take a trip to the stars.

On the 23th of November at 05:00 hours, I took the binoculars and my notebook to an open space in middle of our apartment complex. There, the sky could be seen all around, but there were a few direct lights around. The sun would not rise until 07:00 so I had enough time to find and sketch. With a sky Bortle 5-6 I was able to see enough stars with my only eyes to start to searching. The star a Uma (Dubhe) was about 35 degrees from the horizon avoiding a good amount of light pollution and the seeing was good. Starting from Dubhe, I moved the binoculars to the west and by following a pattern of stars I had seen previously in my tablet, I saw both Galaxies.  They both seemed dimmer than the stars around, but because of the high FOV in the binoculars, there was enough contrast between the Galaxies and the sky. M81 seemed like a oval patch with a differentiated core, while M82 (Cigar Galaxy) seemed dimmer than M81 just a curved line patch. I could not see the recently discovered supernova in it, but I was still impressed to see Cigar Galaxy for the first time.

I had seen M81 once from a small town located 2 hours from Bogotá. The sky there was also Bortle 5-6, but the Plough wouldn’t go any higher in the sky and it was just over the lights of the nearby city that with only 150,000 people, shined more brightly than the one I am actually living in in China now that has about 800,000 people.  At that time I could only see M81 galaxy’s core as a fuzzy and tiny spot. With averted vision I could see it better and also I perceived a very dim oval shape around. At that time I had to use a black sheet covering my head because there was a strong source of direct light above the house: a powerful streetlight. I also I could not have good eye adaptation therefore the image I saw of M81 was poor compared with my most recent observation.

Sometimes, the external conditions plays against a good observation (humidity, temperature, location, LP) so it is not only how big are the optics being used that determines how good the observation is. I feel blessed that now I have better conditions close to my home and there is a big hope to find a really dark sky not far from here.

Hope you can enjoy the sketches and now I can say: Welcome to China!!!



LG. 



Edited by Jennifer Steinberg (editor in chief)





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