Friday, June 26, 2015

planetary conjunctions: moon, venus, and late jupiter...saturn


After sunset on 6/21/15 there was a scenic arrangement of the crescent moon, venus, and jupiter--and it was clear (which has been problem here in June).  Though too wide to be captured in a telescope, I decided to turn my new mono planetary camera on the subjects. 


venus gave her usual inscrutable crescent:





Though very low in the sky I was able to get some detail on jupiter and lucky enough to catch the great red spot:


and the moon...well it's really big.  the widest field my planetary rig could manage was just a small section of the terminator:



a bit later i took crack at saturn:


while the moon has now wandered off, jupiter and venus will continue to close until tues 6/30/15 when they will be .3 degrees apart, and can be caught together in a medium power telescope field. 

Processing notes:
One of the problems with imaging jupiter with a mono camera is that it rotates so rapidly that the surface details move between red, green and blue filter images.  I used a software program called WinJupos to "derotate" the images for the RGB combine here are the rotating originals:


nexstar 8 GPS (8" SCT on alt azm mount)
ZWO ASI120MM-S
zwo RGB filters stacked in autostakkert, Drizzle 3x
wavelets in registax6 derotated and compbined in winJupos

red channel only was used for venus and the moon as it's less subject to atmospheric distortion due to poor seeing

RL deconvolution in maxim DL and finally reduced to 2x scale
except moon drizzle to 1.5x.

Monday, June 15, 2015

Saturn's out

prime viewing time for saturn
unfortunately i've been clouded out almost every night since Saturn's transit.

Here it is on the evening of 6/1



If you look closely you can see faint moons Tethys above and Dione below.

Also, if you look west after sunset later this week you should see a nice you should see a nice pairing of bright Venus and Jupiter along with the crescent moon.

http://www.skyandtelescope.com/observing/this-weeks-sky-at-a-glance-june-12-20/

interestingly, a year to the day from the first saturn of last season.

Imaging details:
nexstar 8 GPS (8" SCT on alt azm mount)
ZWO ASI120MM-S Camera
captured with firecapture @ 76 fps (exposure limited at 40% histogram with gain 82)
1 minute exposure for each color, zwo RGB filters
stacked in autostakkert, Drizzle 3x
sharpened in registax 6
RGB combine in maxim DL then RL deconvolution
downsized to 2x
6/2/15 fair seeing

~ (UT)=080100 (1 AM local 50 minutes past transit)


Tuesday, March 17, 2015

M76 in Nitrogen II Oxygen III and Helium II a rainbow in space

what's black and white and red all over?
...an image using an Ha filter. 

due to the abundance of hydrogen, you'll get some signal all the way from the highest energy to the lowest energy regions in a nebula right up to the ionization front, with rare exceptions.  thus hubble pallet images using SII, Ha, and OIII are typically teal and gold rather than red green and blue.

I chose a M76, a relatively bright planetary nebula with some detail, for the first image with my new narrower Helium II filter (4nm from chroma).

a quick blink of the mono channels for this one showed me that the brightest signal areas were not quite completely separated

which means a scientifically assigned color pallet will give the full spectrum...

a rainbow in space:

Helium II blue, (so faint it's stretched), Oxygen III linear green, Nitrogen II linear red

here's the color image with a log stretch which works quite well for bright planetaries with faint shells:

a healthy does of NII was applied as luminance

here's another variant with OIII assigned to teal rather than green:


mono NII


mono OIII


Helium II as blue with a green continuum filter as red and green (both new filters):


stretched blink


still looking for the pot of gold

8" LX200R, SX Trius 694 and QSI 660 binnedx2 to 0.8"/px
astrodon 3nm NII, 3nm OIII, chroma 4nm Helium II filters
ASA DDM60
NII 35x20min OIII 17x20min HeII 27x20 min
11/2014-2/2015
never enough exposure time...

Saturday, February 14, 2015

planetary nebula IC 418: a blue gem in a red cocoon

here's my first light with a new ccd camera: starlight xpress trius 694
believe it or not i've never used a filter wheel before
just manually screwed one filter on, imaged for a few nights, then went on to the next
not a big deal for super long narrow band imaging, but inconvenient for quick bright planetaries
so the filter wheel that came with the camera is more of a novelty to me
than the larger, more sensitive chip
thus a quick shot of a bright planetary as first light.

after seeing IC 418 listed as one of winter's best planataries in feb S&T
i decided to revisit the red planetary with narrow band filters
as my prior rgb effort yielded nothing but a red disk with a brighter spot in the center

so here it is in NII/OIII/OIII:



it's difficult to make out the central structure at native image scale
so i upsampled x2
for a final resolution of (EDIT: 0.2"/px)  (makes a difference to my eye)
straight linear stretch with a bit of RL deconvolution

in OIII there is a disk with a subtle central brightening:


here's the NII which shows a central star with an outer shell:


blink


difficult to say whether the mottling is noise or a hint of the spirograph pattern detected in the hubble image

interestingly combining the NII and OIII in a color image
seems to create an unsharp mask like effect
making the central OIII brightening (gem) more evident


prior effort (RGB 2007):


i also shot HeII subs but found only a very faint ring around the central star
seemed matched continuum filter images with equivalent exposure (accounting for bandwidth)
meaning it's either broadband glow or artifact such as reflections, corrector plate dust etc.

of course after imaging it i came across this on Jim Kaler's web site
indicating there are no HeII emissions:

http://stars.astro.illinois.edu/sow/ic418.html
"The low excitation nebula, with its relatively cool central star, does not exhibit He II emission lines (those of ionized helium), just those of He I (neutral helium)"
i believe this is taken from a 50 year old reference:
From L.H. Aller and J.B. Kaler, Astrophysical Journal vol. 140, p. 936, 1964.
so i'm a bit behind the times...

i also shot a 20 minute sub binned x2 in NII and OIII
and found no evidence of any other outer shell (didn't check Ha)


8" LX200R, SX Trius 694  0.4"/px
astrodon 3nm NII, 3nm OIII filters
NII 22x30s, OIII 20x30s
ASA DDM60
no AO no guiding
1/2/15

Thursday, February 12, 2015

Comet Lovejoy C/2014 Q2

caught a bright comet with an impressive tail in January:

The image frame is approximately 2 degrees wide, making this the longest comet tail I've captured as it clearly departs the frame.  Some images from dark skies show a tail spanning 19 degrees.  
This was shot through heavy light pollution and passing clouds (explaining the gaps in the star trails).  Nevertheless, the bright, twin tail structure is still visible.  
The comet was easily visible in binoculars, brighter than the andromeda galaxy, though i could not detect the tail.  
Here's a video of the individual frames complete with clouds and airplanes:
Note the comet tail follows the direction of the solar wind rather than the comet motion in this instance.   
Though fading a bit from peak brightness
It should still be visible early evening  in Andromeda this weekend with the new moon approaching

FS60C@ f/42. with SX H9C color camera and chroma light pollution filter.  60x2 minute exposures with mount tracking on comet (ASA DDM 60).  

Sunday, January 4, 2015

speaking of gas giants...Uranus

Uranus, seventh planet from the Sun. It has the third-largest radius and fourth-largest mass in the Solar System. Uranus is similar in composition to Neptune.  Along with Neptune, sometimes called an "ice giant" (prior post).  It has the coldest planetary atmosphere in the Solar System, with a minimum temperature −224 °C.  It has a complex, layered cloud structure, with water thought to make up the lowest clouds, and methane the uppermost layer of clouds.  At 20 a.u. it has an 84 year orbit.  Like other gas giants it spins rapidly, making one revolution in 17 hours.
Uranus has an axial tilt of 98°, so its axis of rotation is approximately parallel with the plane of the Solar System. This gives it bizarre seasonal changes. Combine this extreme tilt with it's 84 year orbit and you get a 21 year "night" at the pole during winter, compared to a 17 hour day at the equator during equinox.  
Like Neptune, there's not much to see visually.  Unlike Neptune, it can be seen with the unaided eye in dark locations.  At high power it can be seen as a small disk rather than a dot.  A slightly more green than Neptune.  A monster telescope or camera might detect several moons (see below), and possibly faint cloud formations.



The Hubble or flyby space craft can detect faint rings.

Saturday, January 3, 2015

Neptune overview

Neptune--eighth and farthest planet from the Sun (after Pluto’s demotion).  Along with Jupiter, Saturn and Uranus, a gas giant.  Smaller, but slightly more massive than its near-twin Uranus.  Uranus and Neptune are sometimes referred to as "ice giants" as they contain a higher proportion of "ices" such as water, ammonia, and methane.   Traces of methane in the outer atmosphere account for the planet's blue appearance.  At 30 au its orbit around the sun takes 165 years, so it’s not moving much in the sky from year to year. 
Discovered in 1846, Neptune was the first planet found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus suggested gravitational perturbation by another planet. There’s been controversy over credit for the discovery:
Interestingly, Galileo made the first recorded observation of Neptune, but apparently did not recognize it as a planet, though some have suggested that he was aware that it had moved relative to fixed stars. 

For visual astronomers, there’s not much to see except for the fact that at high power it can be seen as a small bluish disk rather than a dot.  It generally cannot be seen with the unaided eye.  Due to its distance, its apparent size is the smallest of the planets.  With dark skies or a camera you may be able to pick up a few moons.

Here’s an image of Neptune, the white spot to the right is its large moon triton:




With the Hubble or flyby space craft, surface storms and very faint rings have been detected.