summer saturnalia

Still celebrating a summer Saturnalia.  I've had a run of the best seeing locally in several years.  It's a great time for planetary observing with Venus at sunset, Jupiter transiting at a gentlemanly 9 pm, Saturn near opposition around midnight, and then a blazing Mars rising in the east, approaching  opposition later this month.  

Here are more images from my recent capture of the Saturn's polar hexagon.  Infrared, up-sampling the video by a factor of 3.  

Saturn with north polar hexagon, infrared image 6/26/18 7:45 UTC

Here's a north polar projection, showing the hexagon:

The hexagon was not visible in my RGB image (click on image for full size):

Saturn RGB 6/26/18 7:45 UTC

Here, I've added infrared as luminance to bring out the hexagon in the RGB image.  You can also see that the banding on the disk is much more prominent in infrared (click on image for full size).

Saturn with north polar hexagon, RGB with IR luminance  6/26/18 7:45 UTC

Lastly, here's an annotated wider field:

The cause of the hexagon is still not clear.  One theory is that a hexagon forms where there is a steep variation in the speed and viscosity of atmospheric winds.  The hexagon was blue when it was discovered by the voyager probe in 1981, but has changed to a gold color.  More information on the hexagon at wikipedia.  

The north polar hexagon can only be imaged from earth when Saturn's north pole is tilted towards us.  It was maximally tilted towards us last year and will be tilting away for the next 15 years, when the south pole will be facing us, then begin tilting back.  So you can see the source of my urgency in capturing it.  

image details
celestron 11" Edge HD
ZWO ASI 290MM
zwo RGB filters, Baader IR pass "685" nm
processed in PIPP
upsampled 3x in autostakkert
sharpened in registax
combined in winjupos
6/26/18  07:45 UT
Eastbluff
Southern California

Eureka, The Hex!

neared Saturnian nirvana last night 
think i got a legit shot of the hexagon
if you look closely at the top dark ring, you can see the corners:

Saturn Infrared

image details
celestron 11" Edge HD
ZWO ASI290MM
Baader IR pass "685" nm
3 minute capture
FPS (avg.)=269
Shutter=3.532ms
Gain=351 (58%)
33% histogram
upsampled 2x in autostakkert
sharpened in registax
6/26/18  07:45 UT
Eastbluff

Southern California

Jellyfish, Supernova Remnant IC 443

The Jellyfish nebula is a large supernova remnant in the constellation Gemini. Hydrogen (Ha-red) and Oxygen (OIII-blue):

IC 443 in Ha and OIII
click for larger size

Here's a bright starless Ha version in jellyfish orientation with the "body" up top and "tendrils" reaching down:

Jellyfish Nebula Ha

The OIII signal is much more faint than the Ha, it was boosted in the above image to show the OIII detail. 

A darker version with the blue OIII barely visible

Blink comparing starless Ha and OIII versions:

IC 443 in hydrogen and oxygen

Note that in OIII it looks much more like an expanding ring of gas resulting from an explosion than Ha. 

Here are brighter versions of Ha:

IC 443 Ha

and OIII:

IC 443 OIII

The nebula is 50 arc minutes, larger than a full moon.

Now some of you crab nebula fans are probably asking where is the neutron star remnant? Is there a pulsar, pulsar wind?  The box lower left, is the location of a presumed pulsar--a spinning neutron star left over from the star that exploded:

The blinking spot is the approximate location of the pulsar.  

The thin filament seen in Ha (red) going to the left and upwards slightly, follows  the line of apparent motion of the neutron star superimposed on the pulsar wind (see below). 
There is still some debate as to whether this structure was responsible for the supernova due to it's off-center location.  The assumption is that it was an asymmetric blast. 

The Neutron star was only recently discovered.  It was not detected in visible light, but found by the Chandra X-ray observatory along with a surrounding pulsar wind nebula:

Chandra X-ray image

Though Chandra detected the x-ray source, pulsations were not detected.  The estimated period is 0.1-0.6 seconds, which was below the sensitivity of the equipment, i blinked it at .2 s ;)

The second box, upper right, looks like it might be a small planetary nebula.  

However, SIMBAD lists a star cluster, molecular cloud, and bright nebula at this location--no planetary nebula:
Teutsch GN J0615.3+2253 -- Bright Nebula
  6 15 21.1 +22 53 27


Image details:
When I first shot it, I forgot that it was a supernova remnant and took a few test shots in SII and NII, only to find that they appeared to simply mirror the Ha with much weaker signal.
Despite imaging with narrower band width and 2x binning, the OIII is still much more faint than the Ha.
FS102, SX Trius 694 FL 627.3 mm, 1.49"/Pixel unbinned, reduced in photoshop to 3.9"/px
astrodon 5nm Ha, 3nm OIII filters
ASA DDM60
Ha 102x10 min + 20x10 min bx2
OIII 152x10 min bx2
total 45 hours 40 minutes ;)
1/14-2/23/2018, bortle white skies
eastbluff, CA

first Jupiter of the year 6/8/18 6 AM UTC good seeing

Here's my first jupiter of the year:

Jupiter and moons 2018-06-08-0512 UT

seeing was unusually good:

Jupiter 2018-06-08-0611_1 R-G-B

spent all last year tweaking equipment trying to get a good planetary image and got mush.  this year, first time out with older equipment i got lucky with good seeing, blowing away anything i did with my fine tuned rig last year :(

a few comparisons for imagers:
RGB camera up sampled 2x vs barlow:

RGB camera upsized x2

RGB camera 2x barlow

close, but very slight edge to the barlow

RGB camera barlowed 3x2 minute runs combined:

mono camera 1 minute x 2 each channel:

corrector fogged out before i could get a barlowed mono image :(


image details
celestron nexstar 8 GPS (8" SCT on a wedge)
wide view
ZWO ASI120MC
2 minutes with firecapture 5 ms exposures @ 21 fps
6/8/18 5:12 UTC

large view
ZWO ASI290MM
ZWO RGB filters,
2x60 second captures for each filter R G B
captures with firecapture ~5ms @ ~180 fps 30% histogram
6/8/18 6:11 UTC
stacked in autostakkert (upsampled x2), combined in WinJupos, sharpened in registax 6
final combine in photoshop

not shown: IR filter added little
adding small boxes closer to the edge in autostakkert, gave better peripheral detail

Eastbluff
Southern California

fiery prominence

hope others were able to get out and enjoy some sun today
looked very flame-like so i went with orange

Solar Prominence in Ha 5/28/2018

Image details:
Lunt 60 PT DS on manual alt-azm mount
ASI 290 MM
5 second video 99 fps
Shutter=5.0 ms
Eastbluff, CA 5/28/18 22:37 UT

re-revisiting the expanding crab nebula

here's my biennial addition to the crab nebula expansion from 2006 to 2016(17)
it appears as though the pulsar wind is outstripping the filaments, especially mid lower left:

This is an RGB image only as my earlier images were limited.
a wider version here shows a high proper motion star lower left:

Here’s is a composite of LRGB plus a touch of OIII luminance for the outer shell and faint jet up top:

M1 2016-17 LRGB OIII

Unlike most simple supernova remnants, the crab pulsar wind nebula is extremely rich in nitrogen.  so i elected to image it in NII, SII, and OIII.  Unfortunately, i didn't have time for Ha, but my impression is that the NII signal is similar to what one sees with a wide Ha filter due to the dominance of the NII.  The crab is probably not the best nebula for ultra narrow band imaging as rapid motion of the gas distorts the emission lines.  Here's a blink of the narrow band images:

The difficulty with creating a color narrow band image is that there's no apparent rhyme or reason to the SII signal, it makes no intuitive visual sense.  I tried a number of different color palettes...didn't like any of them.  then i created a blink of 3 different combinations and decided it was time to stop thinking, break out the lava lamp and play some hendrix:

Crab Nebula NII SII OIII combinations: NSO, SNO, NOS

OK coming back from outer space somewhat, here's an attempt to incorporate the SII data into a more traditional image, by coloring the SII gold/orange:

Crab Nebula LRGB NII SII OIII 2016-17

Lastly, a blink, of the narrow band images used above showing the addition of the SII in orange:

Crab Nebula NII red, SII orange, OIII blue

Last, but not least, if you haven't seen it, here's a very large/long animation i did in 2011 showing long and short term motion at the crab nebula as well as narrow band blinks (a bit grainy due to compression):
Large Animation File Link


Details:
2017
12/28/16-2/28/17
8" LX200R, SX Trius 694 and QSI 660 binned x2 to 0.8"/px, ASA DDM60
astrodon LRGB E SERIES GEN-II, NII 3 nm, SII 3nm, OIII 3 nm
L 239 x 1 min ;)
red 96 x 4 min, green 67 x 4 min, blue 67 x 4 min (included as pseudoluminance)
NII 19 x 20 min
SII 11 x 20 min
OIII 27 x 20 min

2015
11/26/14-3/9/15
8" LX200R, SX Trius 694 and QSI 660 binned x2 to 0.8"/px, ASA DDM60
astrodon LRGB E SERIES GEN-II, OIII 5 nm, chroma 540x50 nm filter (greenish continuum)
L 346 x 1 min ;)
red 33 x 4 min, green 22 x 4 min, blue 22 x 4 min (included as pseudoluminance)
OIII 24 x 20min
540x50 53 x 5min, 56 x 10min

2013
1/12/2013-3/4/2013
8" LX200R @ 0.6"/px, SX AO, Astrodon OIII 5nm, IDAS LPR filters SX H9/H9C
RGB(IDAS) 14x20 min, luminance 35x5 min with idas, 35x5 min unfiltered, plus RGB pseudoluminance
OIII 19x20 min

2010
12/6/2010-2/6/2011
8" LX200R, SX AO, Astrodon OIII 5nm IDAS LPR, SX H9/H9C
RGB 31x20 min, luminance 205x5 min plus RGB pseudoluminance, OIII 47x10 min binnned x2

2008
forgot the details there was too much star trailing for me to complete the initial processing.
aborted HaRGB

2006
1/2,3,5/06
nexstar 8 GPS, IDAS LPR filter, f/6.3 FR, SXV H9C
120x1 min, 240x30 sec (unguided)

spikes and a detective story

Here's an image of open cluster M 25 taken with a small refractor.

Open Cluster M 25

^{An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring (wikipedia).  Most of the stars have the same appearance, though there can be variation.  Many open clusters are visually large objects in the sky, best seen with a small telescope or binoculars.}  

diffraction spikes are those pretty lines that you see radiating from bright stars in photographs. interestingly, the spikes are not inherent to the starlight, but rather an artifact of light interacting with the optical system used to capture the image.

reflecting telescopes typically have the most prominent diffraction spikes, large cross shaped lines emanating from bright stars.  they are caused by cross bars in the light path used to hold a secondary mirror in place.

the classic vertical and horizontal line are created by "spider vanes' 
which hold a secondary mirror in place in many types of reflecting telescopes
wikipedia diffraction spikes

refracting telescopes (lenses only, no mirrors) have no such obstacles in the light path, they produce the "cleanest" stars without prominent diffraction spikes.

a few use curved spiders in their reflectors to minimize the effect, but they can have issues:

destinycomp.com

as you can imagine amateur telescope makers have tried all kinds of different curved shapes (modeling with fourier-transforms) to minimize the effect.  while curved shapes can mitigate the effect, they scatter a small amount of light throughout the field.  so many prefer straight spiders with spikes and a cleaner surrounding field.

^{I know what you're thinking now: wait a minute.  the brighter stars in your image have diffraction spikes which are caused by cross-bars suspending the secondary mirror of a reflecting telescope, but you said this was taken with a small refractor.  What is this, some sort of misguided...}

April fools, I Photoshopped  the image, adding the spikes in to accentuate the stars in the cluster. 

some find the spikes aesthetically pleasing and will actually add them into their image by stringing fishing line across the front of the telescope, or using photoshop as I did above.  

A Detective Story:
Having an image selected for the astronomy picture of the day (APOD) is the pinnacle of amateur astronomy.  If you look at the caption for the APOD for 1/12/17, you'll see the following cryptic message:
"Editor's Note: The NGC 891 image used in today's APOD posting has been replaced and the credit corrected to indicate the author of the original work."        
Apparently, an amateur astronomer from Italy who had been boasting that his images taken with modest equipment were comparable to those of the major observatories (thanks to his excellent technique) posted the image that was originally selected.  It turned out, the image was plagiarized.  The astronomer had taken an older image from the Mount Lemmon Observatory and photoshopped it into his image.  

How did they catch him?  take another look at my December image below.  This was just a star test, an image of a bright star (Capella) slightly out of focus used to to diagnose a problem in my optical train (telescope, filters, filter wheel, off-axis guider, camera...).  looked pretty cool so i figured i'd share it:

Capella star test

The telescope used to take this shot doesn't have crossbars, so you don't see a single set of large diffraction spikes, but if you brighten it up like this, you see hundreds of tiny spikes radiating out from the star.  if you look closely, you can see a slightly more prominent set of lines going vertically and horizontally.  the vertical and horizontal line are caused by the rectangular architecture of the camera while the myriad surrounding spikes result from subtle irregularities such as dust on the lenses.  

Here's an image of a bright set of stars taken with a refractor.  The brightest set of stars have pairs of lines 120 degrees apart.  These are caused by 3 clips holding the lenses in place:

Omicron-1 Cygni, the Patriotic Triple 6/09

Thus, the pattern of lines around a star reveal the instrument used, just as ballistics on a bullet can be linked to a gun.  

The "author" of the original APOD image, claimed to have used a telescope that does not have crossbars, but the diffraction pattern around the stars in the plagiarized image exactly matched the diffraction pattern in the observatory image with large diffraction spikes.  someone thought the image looked familiar and compared the two...

why someone would do this is beyond me, but apparently it's not that uncommon. 

more sordid details here:


the smoking gun image comparing the two: