Sunday, February 26, 2017

crescent moon, hollywood style

What's wrong with this picture (click for full size)?

nothing really, except that the crescent is facing the wrong way. 

though few people can say which way the crescent moon should be facing

they have a visceral feeling that this isn't right.

when the moon is a thin crescent, it means that the sun is illuminating the side which is not facing us, so the moon has to appear very close to the sun in the sky: the crescent moon is seen just after sunset or just before sunrise, with the crescent facing down at the sun below the horizon (tips pointing up).  in the northern hemisphere it points down and to the right at sunset (looking west with sun setting in the southwest).  
you morning people may know that the crescent lies down and to the left in the east.  
it's the opposite in the southern hemisphere.
OK that was really confusing
here's a better description.  

for bad astronomy blogger Phil Plait, this knowledge turned his world upside down

he concluded that springfield must actually be in the southern hemisphere based on this scene from the elon musk episode of the simpsons.

the only way the crescent can be on the top of the moon is if you're standing on your head, or in outer space where up and down doesn't matter.  or perhaps some strange partial lunar eclipse.

i chose this orientation as the unnatural rotation gives it a spacey feel

kubrick was well aware of this:

by the way, here's one of the most over-the-top analyses of a movie i've ever seen
tons of fun

but for the clouds you may see the crescent moon in the next few nights
take a look and see what's missing from my image
to be continued...

-bill w

Technical notes:
web cam, DMK 51 and the tiny tak, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  The field of view is approximately 96x72 arc minutes.  Each image is a one minute video capture at approximately 12 fps, aligned in autostakkert, wavelets in registax.

Sunday, February 19, 2017

testing 1-2-3, preparing for the eclipse

testing out my imaging rig for the 8/21/17 total solar eclipse.  there will be a range of exposures so decided to shoot filtered midday sun, twilight moon, full moon.  Here are a few images (click on image for full size):
Sun white light filter 2-4-2017

Moon 2-4-2017
Moon 2-12-2017

Moon at twilight 1-30-2017 grey scale

Just for fun, i decided to simulate an eclipse with the images.
I selected the image closest to full and superimposed it on the solar image.
To my chagrin, the moon did not totally cover the sun--that whole perigee apogee thing--I'd created an annular eclipse.
so i had to use an image from another day when the moon was closer to the earth and large enough to completely cover the sun.
Here's the comparison illustrating variation in the apparent size of the moon during its orbit around the earth:
Lunar images superimposed on solar

Technical notes:
decided to go with my widest field webcam and shortest focal length scope with a web cam, DMK 51 and the tiny tak, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  The field of view is approximately 96x72 arc minutes.  Each image is a one minute video capture at approximately 12 fps, aligned in autostakkert, wavelets in registax.

Tuesday, February 14, 2017

heart of the heart

here's a close up of "the heart of the heart", 
dust and gas near open cluster Melotte 15,
in the center of IC 1805, the heart nebula (click for full size):

in a massive cloud of dust and hydrogen in the constellation Cassiopeia,  the dust began to clump. 
what caused the clumping? 
a supernova, gravitational interaction with a nearby galaxy, or maybe a cosmic butterfly.  
gravitational attraction caused the clumps to get more and more massive, generating so much pressure that the clumps burst into flames as nuclear fusion commenced.  stellar wind from the new star cluster caused the dust to move away with hydrogen glowing red at the heart-shaped edges. 
in the center of the heart nebula lies a psychedelic collection of dust pillars.  the tips of the pillars are anchored by dense collections of dust--stars to be, or perhaps that will never be, as the surrounding dust is blown away.

For obvious reasons, i prefer this one in a more natural color palette (above), but here's a version in the Hubble palette with hydrogen as green, sulfur as red and oxygen as blue:

lastly, here's an older wide field view of the heart nebula at low power as it's quite large, 5 times the apparent size of the full moon: 

heart nebula aka IC1805

click for full size, note the central star cluster and dust pillars.  

image details:
8" LX200R, SX Trius 694 binned x 2 to 0.8"/px
astrodon 3nm OIII, 3 nm SII, 5nm Ha filters
OIII 6x20 min bx2, 13x20 min bx4, SII 3 x 20 min bx2, 39x20 min bx4, Ha 12x 20 minutes bx2
Eastbluff, CA
in processing, i accidentally overlaid the hubble palette version on the conventional giving a hint of color to the highlights, seemed to work, so i left it.  the silky smooth background is not due to the massive exposure time, but rather aggressive use of topaz denoise.
heart nebula:
FS60C f/4.2 FR CS 10 nm Ha/Baader 8.5 nm Oiii filters, H9
Ha 12/19/08
Oiii 12/22/08-ruined by gradients re-shot 1/17/09
2 panel mosaic 12x5 min each panel
los alamitos, CA
bortle white skies, poor to fair seeing, good transparency for area

Tuesday, January 17, 2017

a sharper eye, NGC 6751 in NII Ha OIII

The glowing eye nebula, NGC 6751 really looks like an eye to me, complete with a pupil, iris, and reflected light.  Yes, it's a bit blood-shot:
RGB image, 2007
I re-shot the planetary nebula with narrow band filters (nitrogen-red, hydrogen-green, and oxygen-blue) and a newer camera with larger image scale :)

this image shows faint red jets to the sides
these did not enhance as dramatically in NII compared to Ha as typical red FLIERS do.
there is however,  an unusual line of red NII enhancing pillars crossing just above the center.
also a hint of structured filaments/pillars surrounding the clearing around the central star

lots more detail, but perhaps less eye-like

progressively aggressive stretches of the OIII image shows at least 2 faint outer shells:

also a very faint smudge to the lower right.
This paper, in part based on this super deep image confirm the presence of the outer shells, one of which is interacting with the interstellar medium.  The smudge to the lower right is apparently not part of the planetary nebula.

image details:
8" LX200R, SX Trius 694 0.4"/px
astrodon 3nm OIII, 3 nm NII, 5nm Ha filters
OIII 10 x 5 min, NII 10 x 5 min, Ha 6 x 5 minutes
unusually good seeing.  
The image is rotated south up to match the older image.  
Eastbluff, CA

no calibration ;)

a random field star showed a hint of OIII nebulosity around it when stretched aggressively
HD 177793
19 06 22.52288 -06 04 28.5941
wondering if it's a small planetary (or just my imagination)
there is a fair amount of random nebulosity in the field
couldn't find anything on it in SIMBAD

not sure how else to check
HD 177793

Tuesday, January 3, 2017

fun with a spectroscope, planetary nebula NGC 6886, a tiny saturn nebula

NGC 6886 is a stellate planetary nebula--it's so small it can't be distinguished from a star. 

Here's a grey-scale image which basically looks like a field of stars:

blinking this with an image using an OIII filter reveals the planetary nebula:

it appears to be a star, but gets brighter compared to the surrounding stars with the filter indicating OIII emission, a characteristic of planetary nebulae (see previous post)

here's an image of the field using a filter with a diffraction grating which separates the light into its spectrum:

most stars yield a broad streak of light (left of star) with dark absorption lines corresponding to various elements ionizing as they absorb light.  the location of the absorption lines can be likened to the fingerprint of the star, showing which elements/ions are present and helping to classify the star.

here's a typical spectrum with a few characteristic absorption lines:

another star with a mess of broad absorption lines characteristic not of elements, but various metallic molecules, many involving titanium, which is another story:

a close look at a blink of the spectrum compared to the luminance shows two "new stars" appearing
in the spectral image (left side):

this is the planetary nebula, without a typical stellar spectrum, but rather very specific emission lines:

the brightest is OIII, oxygen; the second brightest Ha and NII (hydrogen and nitrogen).
the faint lines to the right of OIII are Hydrogen beta and Helium II--not a great target for Helium imaging

lastly, here's a very high resolution image (0.2"/pixel) taken with NII and OIII filters

"Clearly" showing a tiny bipolar planetary nebula resembling the Saturn nebula

happy new year

bill w

more on the spectroscope

image details:
8" LX200R, SX Trius 694 0.4"/px
final nebula image upsampled to .2"/px
astrodon 3nm OIII, 3 nm NII, rainbow optics filter
OIII 33 x 5 min, NII 22 x 5 min, luminance 11 x 30 sec, spectrum 13 x 5 minutes
eastbluff, CA

no calibration ;)

Sunday, October 2, 2016

open cluster Messier 29, the pants cluster?

M 29 is an open cluster in cygnus:

relatively bright, an easy target for a small telescope or binoculars
the 5 brightest stars are B0 giants, 160,000 times brighter than the sun

a wider field caught some faint nebulosity 

(upper right, click on images below for full size):

so i shot some Hydrogen alpha images

to dress it up:

in doing a web search on this
i came across (trigger warning) this bizarre image  which links to a youtube video

by British astronomer Pete Lawrence. 
apparently pants is slang for "not good" and normally refers to "underpants".

anyway what he's getting at is that it's not the most impressive cluster out there.
part of the reason for this is that intervening dust obscures the light from these stars by a factor of 1000.  furthermore, the cluster sits in  cygnus, a section of the sky very rich in background stars.  

that being said, in my long focal length SCT (high power/narrow field) it's a nicely defined object whereas most open clusters are too big to be encompassed by the SCT's field

i shot it mainly as a test of my short focal length refractor
which didn't turn out that well as evidenced by these ugly distorted stars in the corners that i had to crop out:

Imaging details:
Takahashi FS-60C F/4.2
Starlight Xpress Trius 694 3.7"/px
astrodon 5nm Ha, RGB E-series filters
Ha 36x5 min, RGB 20x1 minute each channel

Eastbluff, CA