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Sunrise Solar Eclipse
June 10, 2021

There was an annular eclipse of the sun on June 10, 2021, but it was only a partial eclipse as viewed from the Delaware Valley. Several WAS members went to Laurel Run Park in Delran, NJ, to observe the event. This is a Green Acres site with a former agricultural field overlooking the Rancocas Creek. We set up just off Creek Rd on the southwest side of the park, so the distant tree line on the northeast side along the creek offered a low horizon to catch the already-eclipsed sun rising at 5:30 am EDT (maximum eclipse was at 5:32 am). However, clouds along the horizon obscured the sun until the first cusp of it emerged from the top of the clouds around 5:44 am, although a brilliant point of light (presumably the sun) momentarily shone through a fleeting small hole in the clouds a minute earlier.

All but the final picture were taken with a Canon EOS RP mirrorless digital camera and a Tamron 150 to 600 mm f/5.0 to 6.3 zoom lens on a Benro TMA38CL Mach 3 carbon fiber tripod with a Fotopro E-9H gimbal head (here's the rig in May 2021 aimed at the Lunar X); the focal length and exposure settings are noted in each caption.

Note on the Time: Because this is an ephemeral event, I paid extra attention to the picture times. Since the RP does not have an internal GPS to set the clock and it has a tendency to run a little fast, I set it manually on June 9. To calibrate the time of the eclipse images, I took a picture of the NIST web clock when I returned home from Laurel Run and compared the pictured time to the time in the EXIF data. The camera was one (1) second fast (NIST: 7:28:00 am, RP: 7:28:01 am), so a one-second correction was applied to the times in these eclipse pictures. Using SkyTools and the picture times, I obtained the respective solar altitudes (including atmospheric refraction), which are measured to the center of the sun's apparent 31.5 arc minute diameter disc (as opposed to rise time, which is when the refracted upper limb reaches the horizon). The moon was about 29.6 arc minutes diameter at the time.

 

The sun pillar…

While waiting for the eclipsed sun to emerge from the clouds, we saw a faint sun pillar extending above the obscured sun. Taken at 5:41 am EDT (sun at 1°23′ altitude) using 150 mm focal length, unfiltered. It was automatically exposed (minus 1 stop) for 1/160 second at f/5, ISO 100 and daylight white balance. It's unprocessed and uncropped for a field 13.6° wide x 9.2° high.

 

A cusp of the sun peeks out of the cloud…

The first recognizable bit of the sun to emerge from the clouds. Taken at 5:44:14 am EDT (sun at 1°53′ altitude) using 600 mm focal length, unfiltered. It was automatically exposed (minus 2 stops) for 1/640 second at f/9.0, ISO 200 and daylight white balance. It's unprocessed but cropped to 26% x 22% of the original linear dimensions (16:9 ratio) for a field 0.88° wide x 0.50° high.

 

The partially-eclipsed sun finally appears…

The entire extent of the eclipsed sun can now be seen. Taken at 5:51:37 am EDT (sun at 3°02′ altitude) using 600 mm focal length, unfiltered. It was automatically exposed (minus 3 stops) for 1/4000 second at f/22, ISO 100 and daylight white balance. Cropped to 58% of its original linear dimensions for a field 2.0° wide x 1.3° high, but otherwise unprocessed.

 

The foggy field in front of us…

Here's the now-weedy, uncultivated field between the observers and the distant tree line, enshrouded by some ground fog, which was low enough that it didn't impair our line of sight to the sun. Taken at 5:55:16 am EDT (sun at 3°38′ altitude) using 150 mm focal length, unfiltered. It was automatically exposed for 1/200 second at f/5.6, ISO 100 and daylight white balance. It's unprocessed, but cropped to 84% of the original height (yielding a 16:9 ratio) for a field 13.6° wide x 7.7° high.

    

The sun is now higher in a clearing sky, time for a filter…

After the sun escaped the bulk of the clouds and it was a bit higher in the sky, the increased brightness required filtration. Taken at 6:08:37 am EDT (sun at 5°51′ altitude) using 600 mm focal length and an ND-5 filter. It was manually exposed for 1/2000 second at f/8.0, ISO 1600 and daylight white balance. It's unprocessed, but cropped to 34% of the original linear dimensions for a field 1.2° wide x 0.8° high.

The ND-5 neutral density filter, a Marumi DHG ND-100000, provides 10⁵ (100,000x) attenuation of the incoming light without altering the color; the yellowish cast is due to selective absorption by the sunlight's longer path through the atmosphere at the low altitude. Note that the next two images were taken with the exact same equipment and exposure settings, but the sun is successively slightly brighter in them. That's due mainly to the sun's increasing altitude and correspondingly reduced atmospheric absorption, once it emerged from the cloud bank.

    

The sky around the sun is now mostly clear…

The sun continued to move higher in the sky, a little faster than the moon, so the lunar silhouette crept further off the northeastern limb of the sun. Taken at 6:19:40 am EDT (sun at 7°44′ altitude) using 600 mm focal length and an ND 5 filter. It was manually exposed for 1/2500 second at f/8.0, ISO 1600 and daylight white balance. It's unprocessed, but cropped to 34% of the original linear dimensions for a field 1.2° wide x 0.8° high.

 

The eclipse nears the end…

This is my final image of the eclipsed sun. Taken at 6:27:18 am EDT (sun at 9°04′ altitude) just before the camera's battery died (I decided to shut down rather than install a fresh backup battery since the eclipse would end at 6:30 am). Set to 600 mm focal length with an ND 5 filter. It was manually exposed for 1/2500 second at f/8.0, ISO 1600 and daylight white balance. It's unprocessed but cropped to 34% of the original linear dimensions for a field 1.2° wide x 0.8° high. Because of the still-low altitude, some atmospheric chromatic aberration (prismatic dispersion) is visible as lightly colored edges, bluish at the upper limb, reddish at the lower limb.

 

The observing site…

Here's an iPhone 11 snapshot at 5:59 am looking east-northeast towards the sun emerging from the clouds along the horizon. Steve M is on the left, my camera is at the center and Al M's camera is on the right. We set up here because the gate to the paved parking lot at the upper-right  corner of the frame wouldn't be opened by the ranger until after 6 am. Luckily, we weren't set up on the grass around that parking lot as lawn sprinklers over there erupted while we were safely observing from this spot. I didn't even know they had sprinklers!

 

 

Last Update: Sunday, November 07, 2021 at 02:03 PM Eastern Time