It's been a while since the last post,
but I haven't stopped imaging the night sky. As the title suggests,
some have been more successful than others, but I have learned some
along the way. So, let's start with one of the more successful
images, then continue chronologically.
February 27, 2016
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| NGC2261 HUBBLES VARIABLE |
This image, of the cone looking thing,
is know as NGC 2261, AKA Hubble's Variable Nebula in the
constellation of Monoceros (Unicorn). Don't know where that one is,
you say? Well, it's near the brightest star in the sky Sirius...
which is also near one of the two most recognizable constellations in
the sky, Orion. It's a dim constellation, quite hard to spot,
actually. Anyway, the cause of the variability appears to be somewhat
uncertain, but possibly caused by dust drifting between the
illuminating star (R Mon, which is itself not directly visible) and
the nebula. If it is an illuminated nebula, that means it's a
reflecting nebula, meaning it's reflecting the light from the star.
In other words, it's not glowing (which would be an emission nebula).
It's about 2500 ly away and shines about magnitude 9. The variability
can be as much a 2 magnitudes.
One thing I didn't know in March, is
that I was going down a path of imaging dimmer and dimmer objects,
generally speaking, and the problems I was getting myself in for.
Hence, the failures and learning curve that eventually follows.
February 29, 2016
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| M79 |
I think this one is a successful image
as well. It's M79, in the constellation of Lepus (Rabbit), which is
just “under” (south) of Orion. It's a globular cluster of stars.
The interesting story of M79 is that it is probably an “extra
galactic” globular cluster. In other words, it was not formed in
our galaxy, the Milk Way. Although there is debate about this, it
appears it was formed in the “Canis Major Dwarf Galaxy”, which is
currently being absorbed into the Milky Way. (“Resistance is
futile”.... sorry Star Trek fans.) Anyway, it's about 41,000 light
years away from us and is considered about 11.7 billion years old,
which is younger than most of the globular clusters.
Also February 29, 2016
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| M105 |
This is where things start to go
downhill, as it were. After weeks of working on the situation,I think
I have finally figured out a
reasonable explanation: the problem is, I think, that the brightness
of the objects I'm imaging is so close to the brightness of the sky
glow (background light pollution) that normal image processing gets
“confused” and adds noise back into the image, making it almost
impossible to extract the image of the object I wanted to begin with.
It's rather like taking a picture of a polar bear in a snow storm and
then trying to get a clear image of the bear. M105 doesn't look like
the “typical” image of a galaxy. That's because it's an
elliptical galaxy. There are lots of these in the sky. M105 has a
brightness of magnitude 10.2, and a surface brightness of 11.3. In
the case of magnitudes, the higher the number, the dimmer the object.
It turns out that, with the skies I have at the Starlight
Observatory, a surface brightness of 11.3 is getting mighty close to
the limit of my equipment. That's my excuse, anyway. So, what's the
other fuzzy stuff in this image. There is something that looks rather
like the galaxy to the upper left of M105. It turns out that this is
a galaxy (NGC3384) that happens
to contain the quasar 1045+128. NGC3384 is just a little further from
us that M105, 38 million ly for 3384 vs. 32 million ly for M105. The
third, dimmer, galaxy, to the lower left of M105 is NGC3389. While
M105 and NGC3384 are part of the “local” Leo I group, NGC3384 is
not. It's about twice as far away.
March 4, 2016
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| M96 |
This is one I
consider mostly successful. This is M96, a galaxy that's about the
same distance from us as M105 and about the same brightness. As you
can see, it has a little more of a spiral structure. It's located a
little south of M105 in the sky. Whereas M105 is part of the Leo I
group, M96 is part of another group called, not to anyone's surprise,
the M96 group of galaxies.
March 7, 2016
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| M109 |
This is one more on the failure side.
The noise (graininess) is apparent and impossible to remove. This
galaxy is only a little dimmer than the ones above. Perhaps there was
some high cloudiness that I couldn't see? I don't know. I may try
this one again at a later time just to see if I can improve on this
one. At any rate, this is M109, found around the bowl of the Big
Dipper. M109 is a barred spiral galaxy that's about 60 million light
years away. By “barred”, that means there is a ”bar” of stars
that causes the galaxy to look somewhat like the Greek letter theta
,θ. There are also two more
galaxies in this image, but they are difficult to see. They are UGC
(for Uppsala General Catalogue of Galaxies) 6940, which is a tiny
fuzzy spot just south of M109, and UGC6969 to the left of M109. For a
little more information on UGC, see
April
3, 2016
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| M41 |
M41
is a large open cluster in Canis Major. The cluster is just south
(below) the star Sirius. It's bright at magnitude 4.5, and is about
2300 ly away. I covers an area of about the same size as the full
moon, about ½ degree. I consider this one a success as well.
April
3, 4, 5, 2016
Finally,
the challenge that caused me to decide I didn't have enough “signal”.
That means that the object was just too close to the sky glow. After
working for days trying different processing ideas, I finally decided
to look at the underlying raw images. What I found was that the
object was only just barely perceptible. The data couldn't be
stretched enough to bring the object forward from the background. It
would be pointless to show a raw image, but I can and will show what
the image looks like when it's just too dim to be separated from the
background. It looks like this.
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| M100 Noise apparent especially in corners (vignetting) |
The
image is of M100, a galaxy in Coma Berenices, which is just east
(left) of the constellation of Leo the Lion. It's about as bright
as some of the other galaxies shown above, but the difference is I
used 1 minute exposures (a total of 40 minutes worth) vs. 3 minute
exposures for most of the other galaxies. Looks really bad. However,
one night I shot 13 3 minute shots. It's the luminescence channel
only, but you can see the obvious difference. You can even see 5 more
galaxies in this image.
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| M100 3 minutes exposures, in black and white |
Well,
kids, that's it for now. I need to try some scope modifications to
help with the auto guiding, but hopefully I'll get more images soon.
A lot depends on the weather, which has been really bad (for
astronomy) for the last year.
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