Feder Observatory

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Looking at Galaxies and Stumbling Upon Supernovae! 0

Posted on May 08, 2013 by Juan

Sometimes it is just fun to look at the sky.  On the evening of May 6-7, Beau, Nathan, and I looked at a couple of galaxies just to see what we could see in some deep exposures.  Hypothetically, I had two goals.

  1. I wanted science images to test Dr. Craig’s data reduction scripts on.  Up until now, Dr. Craig’s scripts for cleaning up the Feder data (e.g. – fixing the FITS headers, adding an astrometric solution, etc) had only been run by Dr. Craig.  So this was the test to see if they could run on my own computer.  We had a few problems, but all in all, his scripts cleaned up this data nicely.
  2. Secondly, I wanted to get an image of an edge-on galaxy to provide a comparison light profile to one that one of our students is working on with the much more face-on galaxy M101.  

A Edge-On Galaxy and a Surprise Guest!

For these reasons, I shot images in B, V, and R of M65.  The combined exposure time was 360 seconds in R, 360 seconds in V, and 900 seconds in B.  While I did reduce the data properly, removing bias and dark current and applying the flat-fielding corrections, this was my first attempt to merge such images into a single color image, so the fidelity of the color image may be a bit bogus.  In any case, here it is, a color composite image of M65 as shot at the Feder observatory on a night with mixed seeing.

M65 (Composite Color)(Click on Image for Full Resolution Version)

I really like how this image of M65 came out, especially how clear the dust lanes and spiral arms are.  Not as impressive as other people’s images of M65, but I was happy.  Unknown to me at the time, it turns out M65 had a supernova discovered in it on March 20, now designated Supernova SN2013an.  Zooming in, we can clearly see it…


A Much Fainter Galaxy with an Expected Visitor

Since we had to wait a little bit for M65 to rise high enough to be at a lower airmass, we took the opportunity to push the limits of the Feder 16-inch by taking images of the supernova candidate announced in the  Astronomer’s Telegram #5051.  This was the intended supernova image of the evening!  The Astronomers Telegram noted a “bright” supernova candidate in UGC 9379 which was at an airmass of 1.28 at the start of the night and getting better as the night went on.  This galaxy is relatively faint so we shot exposures adding up to 600 seconds in R, 900 seconds in V, and 1800 seconds in B.  Here is the resulting color composite image (again, I don’t trust the color fidelity):

UGC9379 with SN Candidate (Composite Color)(Click on Image for Full Resolution Version)

During that 10 minutes of exposures in the R band, a satellite flew through the field of view, thus the streak on the left side of the image.  

The galaxy UGC 9379 was very clearly visible in the R and V bandpass images, but was just barely visible in the B bandpass, despite the long exposure.  That said, the supernova was quite visible in all bandpasses and possibly most distinct in the B bandpass.  This color difference between the galaxy and the supernova is quite visible in this color composite image.

So there you have it, we intended to look at one supernova and two galaxies, and we got a second supernova as well!

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