2017 eclipse warm up images and techniques 1

almost all publications on eclipse imaging say something like: "for your first total eclipse forget about taking photos, just watch".  sound advice, but i've been honing my solar imaging techniques for several years...

i posed the dilemma to my astroimaging group: 
veteran eclipse chaser Dave Kodama got a puzzled look on his face and simply said, "if there's no picture, it didn't happen".

though far from a proponent of organization for organization's sake, i realized this was going to take some  preparation. 

There are many accounts of photographers missing the total eclipse by forgetting to take solar filters off, or forgetting to replace the filter, leading to fried equipment.  Mindful of this i ran two complete dry runs of the imaging session from my imaging location at the same time of day. 


Here's an animation of one of the sessions.  note the slight rotation of the sunspots across the solar surface even over the course of a few hours:

Sun 8/18/2017

Here's the image from the day before, excitement growing as a second sunspot grouping rotates into view:

Sun 8/20/17

ironically, my best full disk white light image of the sun was taken on 8/21/17, only to be overshadowed by eclipse images :)

Sun 8/21/2017

note two separate sunspot groupings and well defined surface granulation.

colorized:

IMAGING TECHNIQUES:

in an excellent ebook on photographing the eclipse, Alan Dyer gave a comprehensive list of imaging techniques ordered by level of complexity.  my approach (webcam, laptop, close up telescope, tracking mount) seemed to be over the top, making preparation a must.  

Starting in January i began working out an imaging rig, field of view, and processing techniques for the sun and moon in white light. 


next i tested filters, finally concluding that green + an IR/UV block gave the best detail on sunspots and surface granulation.  however, at the 11th hour i decided to dispense with the green filter in order to minimize the fiddle factor, as imaging totality with a green filter would block the red light of the solar prominences and switching would complicate the process. 


Then to the mount.  after numerous tests with a simple manual alt-azm mount were moderately successful, Alan Smallbone gave a mount review, and talked some sense into me. so i switched to a simple polar aligned single axis tracking mount.  streamlining the imaging process.  

single axis tracking mount, mylar laptop cover bottom

focus during solar imaging has always been problematic for me.  the problem is that bright sunlight makes it almost impossible to view the image on a reflective laptop screen.  i'd typically bake with my head and laptop under a blanket while trying to focus, reaching blindly for the focus knob.  2 solutions:
-a laptop "tent" or lapdome complete with a shade to block light reflecting up from the ground (also wear a dark shirt)

Lapdome, note shade between keyboard and screen blocking reflected light from the ground, secondary mylar cover in background

-a mylar drop cloth.  most mylar "space blankets" are too thin to block all the light.  i found a thicker version that did the trick, light weight, easy to pack.  placing the blanket over my head and laptop blocked out stray light, and reflected radiant energy keeping things cooler.  

tuned laptop: new battery so it would last thru the eclipse and "custom water cooling" to keep it from overheating during a long imaging session in hot weather.

Laptop intake fan, bottom of laptop

filter box elevating laptop, improving airflow:

custom water cooling:

frozen water bottle

condensing unit:

towel containing condensation

laptop ran cooler like this in hot weather than it did in an air conditioned airport sitting flat on a table.  

Image details:
DMK 51 web cam, Takahashi FS-60C, 60 mm aperture at f/4.2 with a reducer.  Skywatcher star adventurer tracking mount.  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.
-cell phone Droid Turbo ;)
Casper Wyoming
42,50.9694N 106,15.5688W
8/18,20,21/2017

2017 solar eclipse epiphenomena

During a total solar eclipse, bright stars and planets can be seen as the sky darkens

Here's a wider field shot of the eclipse i took with a DSLR using a long focal length lens:

8/21/2017 solar eclipse Casper, Wyoming

if you look closely, you can see the star Regulus (corrected from Rigel) to the left of the lower spike.
here's a much brighter (and noisier) version for folks with dark monitors who can't see the star:

unfortunately, i missed focus by a bit so i'm unable to combine this with the sharper telescopic images. spent a long time trying to sharpen/salvage it, but eventually just left it as is, right out of the camera, looks OK at this scale

other eclipse epiphenomena:

-first contact
anticipation grows, but not much changes as the moon's shadow first touches the right edge of the sun:

as the sun is gradually devoured by the black disk of the moon, a number of effects are noted:


-it looks really cool (through appropriate filters)

8/21/2017 eclipse partial phases, filtered

-the sky darkens and the temperature drops measurably
Jean Kodama charted a 16 degree F drop in temperature and captured an amazing pinhole projection (see below):

http://astrocamera.net/2017/0821/pinhole.htm

-very bright stars and planets become visible during the day
venus was evident before totality. i did not see Rigel, but didn't really look for it (see image above)

-subtle abnormalities can be detected in shadows
edges perpendicular to the crescent becoming slightly fuzzy compared to edges parallel to the crescent:

note difference in shadow edges at index

-pinhole or circular projections of the sun show a crescent instead of a circle (note these solar projections don't require a total eclipse, only partial phases):

shadow selfie sun in hand

crescent projected through hand held in a circle

Jean Kodama's amazing pinhole projection

more details including time lapse projection available here:
http://astrocamera.net/2017/0821/pinhole.htm


-shadowbands--strange waves of shadow can be seen moving on bright areas of the ground shortly before and after totality
saw them on the sidewalk while looking down at my laptop ;)

-unusual behavior from local wildlife
heard reports of rodents burrowing at the start of totality, birds chirping and settling in trees, dogs howling; a rooster crowing as the sun reappeared.

i did hear some cat calls.

Residence Inn staff given an hour off to watch the eclipse

Image details:
-totality wider field:
Nikon D-60, AF-S DX NIKKOR 55-300mm f/4.5-5.6G ED VR, f/5.6 300 mm 1/20" iso 400
-partial phases:
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.
-cell phone Droid Turbo ;)
Casper Wyoming
42,50.9694N 106,15.5688W
8/21/2017

great american eclipse shot: casper wyoming travelogue

I chose Casper Wyoming for the eclipse for several reasons:

1 historically it had the greatest chance of clear skies at that time and date of any region on the eclipse track

2 it has a local airport making it easy to get in and out, important given dire predictions of crowds traffic jams and gas shortages

After a smooth flight to the airport, i found the google satellite image of my hotel somewhat disconcerting:

Hotel not yet built in google maps images

needless to say i paid triple that rate at eclipse time.

so what gives?

north view from hotel:

Casper's Eternal Flame and cloud cover...

locals informed me, Casper is a boom or bust town, currently driven by natural gas,  not booming at present.

so i had a brand new hotel with brand new shopping malls at the edge of town designed for expansion that wasn't happening.  so much for the crowds. 

i had allowed 3 hours for the 20 minute ride to the airport after the eclipse...

and made it in 15 minutes.  all the traffic was north south after the eclipse, not east west to the airport.

that being said, folks that attempted to drive north to the eclipse track on the morning of the event were basically stuck on the freeway, unable to make it. 

spent one late night stargazing up in casper mountain.  the views were stunning, but no pics (another story):

Sunset, Casper Mountain Wyoming

Casper Mountain Panorama
click for full size

despite long term predictions, and near term forecasts for clear skies, i came very close to being clouded out. 

after a beautifully clear morning, here's the sky to the northeast 15 minutes before totality:

weather radar from eclipse day:

note thin line of clouds moving right over Casper
Thanks to Dave Kodama for the image

I actually viewed and imaged the eclipse through clouds:

Great American Eclipse
8/21/17

overexposed, but you can see a hint of the corona's triangular spikes, and of course the thin clouds.
i think scattered light from the clouds kept the sky lighter than most eclipse accounts. 

by 4th contact (end of partial eclipse)
the sun was completely obscured by clouds:

4th Contact

More to follow...

Image details:
cell phone Droid Turbo ;)
Casper Wyoming
42,50.9694N 106,15.5688W
8/21/2017
Casper Mountain
8/18/2017

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.  Skywatcher star adventurer tracking mount.  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

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.  Skywatcher star adventurer tracking mount.  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