Sunday, February 12, 2017

Something to see in Libra?

On the 8th of February, I woke up with the firm intention of getting some telescope observation time and bring home one or two sketches. At about 5:40, my first sketch was done and as always I took some time to contemplate the sky with just my eyes.

The circle shows the FOV
Scorpius was showing off its long and curvish figure while Virgo was reaching its zenith with Jupiter on board. I knew Libra should be in middle of those, but I could not trace well its shape. Then, I realized I had forgotten Libra and never had aimed my telescope at it. I guessed that after all the galactic and nebular show in Virgo and Scorpius, there was nothing left in Libra.   

I grabbed my phone, opened the Stellarium app and looked for Libra. My mobile version showed a shape that definitely did not look like a scale but more like a kite made with the stars Zubeneschamali, Zubenelgenubi, Brachium and Zuben Elakrab (all arabic names) and with some sort of tail from this last one star to 46 Lib. I personally like more the H.A. Rey´s version of Libra’s shape because it looks like a scale. To make the shape, he made use of two more stars  (39 and 40Lib) instead of 46 Lib.  A curious fact about Libra is that once it was considered part of the scorpion and in fact today, 3 of the names of its brightest stars refer to the claws of the scorpion.  
While I was comparing the visual information from my phone with the sky, I saw that there was a globular cluster of 8.52 magnitud in Libra called NGC 5897. I thought, “I haven’t heard of it, but I am going to give it a try.”  I aimed my findercope to the star Brachium and from there I star hopped a couple of grades to the east until I found 3 stars of 8th magnitude placed in a slightly curved row. In the view with the 40mm eyepiece the whole scenario looked like a number 7 (due to the horizontally flipped view). Right to the upper part of that particular asterism there was a ghosty circular patch of light at its left side. It was easy to see with low magnification even with direct vision, but it had nothing else to offer than the mere appearance of its existence among the background.

I was searching for this globular cluster and it seems to be the solitary globular cluster in Libra. Classified as class XI  (being I the most concentrated and XII the least concentrated) is in fact a loose globular cluster and probably that is why it looked so dim and ghosty in the eyepiece.

There is also more to see in Libra of course. Some double stars and the star Gliese 581 or HIP 74995 in Stellarium. This 10th magnitude star is the “sun” of a planetary system that contains Gliese 581g, a planet similar in size to the Earth, situated in the habitable zone of its star and that therefore could sustain life.

Happy stargazing,


Edited by: Jennifer Steinberg (editor in chief)


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