Tuesday, September 5, 2017

2017 total solar eclipse composite images

First here's a different version of an image of the faint outer detail of the corona (be sure to click on images for full size): 
8/21/17 solar eclipse

Used a radial blur subtraction technique to enhance the contrast of the corona, compensating for some of the bright light from the inner corona scattered by clouds by bringing out more detail, especially the subtle loops lower left.    

An issue with images of the eclipse is that there is an extremely large range in brightness, more than can be encompassed by a picture on a video monitor or print out.  A "composite" image combines the faint detail from an image that over exposes the bright inner sections (see above) and the bright detail from an image that misses the faint detail.  

Here's my attempt at a composite:
8/21/17 solar eclipse composite


Unfortunately, all my attempts at compositing seemed to yield a mediocre version both the bright and the faint detail.  

Here are a few alternative versions, using tricks to provide maximum detail in both versions by inverting the color of one:
8/21/17 solar eclipse exclusion composite
8/21/17 solar eclipse inverted exclusion composite



Just for fun in the last set, I colored the bright detail red, which is appropriate as the chromosphere is actually red:


Image details:
DMK 51 web cam, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  Baader solar film, Fotga IR/UV cut filter.  The full field of view is approximately 96x72 arc minutes with a resolution of 3.6"/px.  video capture at 12 fps, aligned in autostakkert, wavelets in registax.
Casper Wyoming
42,50.9694N 106,15.5688W
8/21/2017

Sunday, August 27, 2017

2017 total solar eclipse images

partial phase, moon about to gobble up spots:
a few sunspots are noted in the photosphere, the bright visible surface of the sun.  

almost there...


"diamond ring"--final flash of direct sunlight at the start of totality (click for full size):


TOTALITY 
bright prominences in the chromosphere are visible with direct sunlight blocked:
8/21/2017 Total Solar Eclipse
with the bright photosphere hidden, prominences in the chromosphere can be seen.  the temperature increases from 6,000K F in the photosphere to up to 20,000K in the chromosphere.  

longer exposure brings out the outer corona, easily visible to the naked eye, note the magnetic field lines arcing out of the poles, and the subtle arcs lower left (click for full size):
8/21/2017 Total Solar Eclipse
click for full size
The temperature in the corona reaches 1,000,000 K, the reason for this remains unclear.  

Image details:
DMK 51 web cam, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  Baader solar film, Fotga IR/UV cut filter.  The full field of view is approximately 96x72 arc minutes with a resolution of 3.6"/px.  20 second video capture at 12 fps, aligned in autostakkert, wavelets in registax.
Casper Wyoming
42,50.9694N 106,15.5688W
8/21/2017

Saturday, July 29, 2017

saturn, so close to a hex

if you look at the top of the planet, you get a hint of an angular structure at the north pole, rather than a circle,
but i'm pretty sure it's artifact, not the polar hexagon which is smaller :(
Saturn 7/4/2017 7:45 UT

image details:
Meade LX850 12" f/8
televue 2x Barlow
FocalLength~4100mm
Resolution~0.19"

ASI120MM-S mono camera
ZWO RGB filters, Baader IR pass "685" nm
2 minute captures for each filter R G B
captures with firecapture @ ~22-55 fps
exposure 15-45ms ms per frame
stacked in autostakkert, combined in WinJupos, sharpened in registax 6

7/4/2017
Eastbluff, CA


Sunday, July 23, 2017

Solar rotation Active region 2665

like the earth, the sun itself rotates.  its period is once every 24 days at the equator, but only once every 35 days at the poles.  this was determined by watching sunspots rotate across the surface.  
This animation shows a group of sunspots (AR2665) rotating across the disc of the sun over the course of 9 days, from July 8th to the 16th 2017: 
Sun 7/8-16/2017, AR 2665
interestingly, today (7/23/2017) this "active region" lived up to its name and spat a gigantic coronal mass ejection out into space.  fortunately, it's facing away from us, though apparently right at mars, potentially affecting satellites there.  more at spaceweather.com
a few wacko preppers are predicting earthquakes as a result.  a more balanced perspective can be found here.  In any event, if a really big one of these things hits earth, our electronics are fried.  the active region should be rotating back towards us in about a week, hopefully bringing nothing more than a few auroras.   

Hydrogen alpha versions of this region at the beginning of the rotation can be seen in a previous post:
http://astrowhw.blogspot.com/2017/07/big-prominence-this-weekend.html

Image details:
DMK 51 web cam, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  Baader solar film, Tiffen 77 mm green and IR ND.6 filters.  The field of view is approximately 96x72 arc minutes.  20 second video capture at 12 fps, aligned in autostakkert, wavelets in registax.

Tuesday, July 18, 2017

jovian animation

on 6/17/17 Jupiter put on a show:
both io and ganymede transited jupiter's face while the great red spot was showing.  unfortunately, the seeing was not great.  here's what i salvaged:
Jupiter Ganymede, Io's shadow
6-18-2017 05:23 UT
the animation shows ganymede (upper left) rotating across the face of jupiter and then fade from view.  io has already begun its transit, but is lost in the northern equatorial belt.  just as ganymede fades from view, io's shadow races across from the left side.  towards the end you can again see a hint of ganymede again, (brownish spot) rotating across the surface up top.

here's shot from the night before with a bit better seeing, but no exciting events:
Jupiter
6/17/2017 05:28 UT
imaging notes
Poor seeing on the night of the animation
combining all the images in winjupos smoothed things out dramatically, 
but required way too much time in photoshop combining the win jupos and standard versions.  
The mono camera/filters do seem to give better color (previous night).  

image details:
Meade LX850 12" f/8
televue 2x Barlow
FocalLength~4100mm
Resolution~0.19"

for animation:
ZWO ASI120MC (color camera)
approximately 40x1 minute captures spaced by a minute
captures with firecapture @ ~134 fps
exposure 5 ms per frame

for still image:
ASI120MM-S mono camera
ZWO RGB filters
3x2 minute captures for each filter R G B
captures with firecapture @ ~190 fps
exposure 5 ms per frame
stacked in autostakkert, combined in WinJupos, sharpened in registax 6

6/17-18/2017
Eastbluff, CA



Tuesday, July 11, 2017

big prominence this weekend

variety pack of images:
solar prominence 7/8/17 (occulted)
Hydrogen alpha
H alpha composite
Ha exclusion
Ha colorized composite
full disk, full spectrum

image details:
full disk:
DMK 51 web cam, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  Baader solar film, Tiffen 77 mm green and IR ND.6 filters.  The field of view is approximately 96x72 arc minutes.  20 second video capture at 12 fps, aligned in autostakkert, wavelets in registax.

Eastbluff, CA 7/8/2017

Ha:
Lunt 60 PT double stacked
manually guided on a shaky alt-azm mount
ASI 120 MM-S camera
20 second video 57 fps.

Sunday, July 2, 2017

testing 4-5-6: summer sun, salvaged sunspot.

in testing a tracking mount for the eclipse, i encountered an unpleasant surprise: the sun is brighter in the summer!  so bright that the sun is now completely overexposed, blowing out any sunspots and surface detail.  a few more filters and voila granulation and a few small sun spots (click to see surface detail at full size):
Sun 6/24/2017
click for full size
Here's an image of the monster sunspot of October 2014 showing a close up of surface detail (click this link for more info on sunspots and granulation):  

AR 12912 10/25/2014
click for full size
salvaging sunspots:

A monster sunspot stole the show during the partial solar eclipse of 10/23/14 (see this link, and this link for more details on sunspots and granulation).  The sunspot was so big that i couldn't capture the whole thing in one frame except at a slow frame rate so i kludged together a mosaic.  several days later i imaged it again with the full field at slow frame rate, but for some reason the software wouldn't let me process it after i extracted the green channel (best contrast, see below).  gave it another shot with updated software and was able to pull out a nice image despite the low frame rate (12 fps).  

full disk filter discussion:
potential solutions to overexposure on the full disk:
1. additional filter in front of camera--too hard with takahashi adapters
2. stop down aperture--worked provisionally, but hate to throw out light
3. neutral density gel film in front of telescope--not optical quality so blurs image
4. larger filter in front of objective--an opportunity to test more filters :)
tested two types of filters: 
-0.6 neutral density IR blocking
the advantage of this is that IR is poorly focused by refractors so it blurs the image a bit, so blocking IR should give a sharper image.
-green filter
why green? turns out the solar granulation has the highest contrast with a green filter.  furthermore, refractors tend to handle green light best.   
fortunately, the 77 mm filters fit perfectly on the dewshield of my takahashi FS-60, though it's not threaded. 

results: both filters blocked enough light to prevent overexposure.  hard to say whether the ND or green filter gave a better image, but stacking the two gave the best results in terms of granulation contrast (subtle difference).  

Technical notes:
full disk:
DMK 51 web cam, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  Baader solar film, Tiffen 77 mm green and IR ND.6 filters.  The field of view is approximately 96x72 arc minutes.  20 second video capture at 12 fps, aligned in autostakkert, wavelets in registax.
Eastbluff, CA 6/24/2017
sun spot:
camera ZWO ASI 120 MC, telescope Celestron Nexstar 8 GPS (8" SCT), Baader film and IR/UV block filter.
20 second video at 13 fps, 5 ms exposure.
green channel extracted with PIPP, aligned in autostakkert, wavelets in registax.
Eastbluff, CA 10/25/2014