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Mercury Update - April 2018

Mercury has seven elongations in 2018. The initial sighting for each of these is tabulated below:

Sequence

Initial Sighting Date (2017/18)

Observing Location

Greatest Elongation (2018)

#1

December 24, 6:10 am EST Swede Run, Moorestown, NJ

January 1, western (morning)

#2

February 26, 5:56 pm EST Baseball Fields, Maple Shade, NJ

March 15, eastern (evening)

#3

April 22, 5:26 am EDT Old Mart Site, Pennsauken, NJ

April 29, western (morning)

#4

   

July 12, eastern (evening)

#5

   

August 26, western (morning)

#6

   

November 6, eastern (evening)

#7

    December 15, western (morning)

Click here for the sighting details of each elongation this year. The current sighting streak is now 47 elongations in a row, starting in January 2011, which includes seven complete calendar years of six or seven elongations each. The years 2011 and 2015 had seven (7) elongations each, while 2012, 2013, 2014, 2016 and 2017 had six (6) each. Click here for sightings from last year's elongations. This demonstrates that locating and seeing Mercury is not nearly as difficult as many suppose. It just takes some planning and a little effort.

 

 

The Crescent Moon in the Hyades
April 18, 2018

The two-day-old, 11% illuminated and earthshine-filled Crescent Moon was in the Hyades star cluster on April 18, 2018, when this image of them was captured from Maple Shade, NJ, at 8:54 pm EDT, 74 minutes after sunset in a hazy sky, soon to become cloudy. This is a single frame taken with a Canon 6D digital SLR camera and a Tamron 150 to 600 mm f/5-6.3 zoom lens (on a fixed tripod) set to 250 mm focal length, then cropped to about three-quarters of the original frame, producing a field 5.5 wide x 4.9 high. It was exposed 1.6 seconds at f/5.6, ISO 1600. Mouseover for labels. All of the stars here are in Taurus the Bull, so the labeled Bayer letter or Flamsteed number would be suffixed "Tauri." The labeled V-shape encompasses the Hyades and represents the face of the Bull. The horns would extend about 15 more-or-less vertically from Aldebaran (α) and Ain (ε) to Zeta (ζ) and Beta (β) Tauri respectively (β = Alnath).

Notice the magnitude 5.6 star, 63 Tauri, just above the moon. I saw it near the lunar limb on the camera's viewing screen during the session, and reviewing circumstances afterwards with SkyTools, saw that it was occulted by the moon at 9:08 pm (the moon is moving eastward, nominally to the upper-left in this view, about about its own half-degree diameter per hour). Looking through the images, the last one with 63 Tauri visible (below) was time-stamped 9:07 pm.

63 Tauri had vanished in the following frame that was time-stamped 9:08 pm (not shown). Taken with a Canon 6D digital SLR camera, which has an internal GPS that sets the clock, and a Tamron 150 to 600 mm f/5-6.3 zoom lens (on a fixed tripod) set to 205 mm focal length, then cropped to about one-quarter of the original frame, producing a field 2.7 wide x 1.8 high. It was exposed 1.3 seconds at f/5.6, ISO 800. Mouseover for labels.

 

 

Venus and Uranus
March 30, 2018

The planets Venus and Uranus were at conjunction on March 28, 2018, and less then 5 arc minutes apart after sunset. However, it was cloudy that night, as it was on the preceding and following nights, March 27 & 29, when they were little more than 1 apart. Finally, on March 30, 2018, despite rain in the afternoon and a poor weather forecast for the evening, it cleared out nicely shortly before sunset at 7:22 pm EDT. This picture of them was taken at 8:13 pm from the baseball field complex in Maple Shade, NJ, with a Canon 6D digital SLR camera and a Canon 200 mm f/2.8L lens (on a fixed tripod), then cropped to about half the original size for a field 5.0 wide x 3.7 high. It was exposed 0.8 second at f/8, ISO 1600.

In the picture, brilliant Venus is shining at magnitude -3.9, so it's overexposed and  shows a crown of diffraction spikes generated by the lens diaphragm. The magnitude +5.9 star HD 11257 is 15 arc minutes from Venus at the 1 o'clock position, the magnitude +4.3 star Omicron Piscium is 2.1 from Venus at the 7 o'clock position and barely-visible magnitude +5.9 Uranus is 2.3 from Venus at the 5 o'clock position (mouseover for labels). At the time of the picture, Venus was at 8.2 altitude and Uranus was at 6.0 altitude. Venus is moving eastward from the sun, and becoming higher in the evening sky, following superior conjunction on January 9, 2018. Uranus is dropping in the evening sky and will be at conjunction with the sun on April 18, 2018.

The 9.8 magnitude difference between Venus and Uranus is equivalent to a difference of 8,300 times in brightness, or 13 photo stops, hence the difficulty in showing them both with a single exposure and no localized processing to enhance Uranus. In addition, the difference in the already-low altitude causes greater atmospheric extinction of Uranus, and the noticeable twilight gradient also diminishes Uranus' visibility in the photo. Uranus and Omicron Piscium could not be seen with 16x70 binoculars during the March 30 session from 8:00 and 8:30 pm. My last visual sighting of Uranus (using an 80 mm apo refractor at 72x) was on March 26 when it was about 2.4 above Venus. It was not easy to see.

 

 

The Crescent Moon, Venus and Mercury
March 18, 2018

The 1.5-day-old Crescent Moon joined the planets Venus and Mercury in this view captured on March 18, 2018, from Swede Run in Moorestown, NJ, at 8:01 pm EDT, 51 minutes after sunset. The Moon was at 4.3 altitude and 2.5% illuminated. Venus, 3.9 from the moon, was at 5.3 altitude and magnitude -3.9. Mercury, 3.8 from Venus, was at 7.2 altitude and magnitude +0.4. It's a single uncropped frame taken with a Canon 6D digital SLR camera and a Canon 200 mm f/2.8L lens (on a fixed tripod). It was exposed 1/10 second at f/2.8, ISO 1600, daylight white balance. Mouseover for labels. Here's my 2018 Mercury sighting page.

 

 

Venus and Mercury
March 3, 4 & 5, 2018

In early March 2018, both Venus and Mercury were in eastern elongation and were visible low in the west after sunset. At time, Mercury was moving eastward more rapidly than Venus and passed it, reaching conjunction in geocentric right ascension on March 5 at 1 pm EST. Their appulse (closest approach) for an observer at 40N-75W, only a few miles from Maple Shade and Moorestown, NJ, would be on March 4 at 1 am EST. The closest visible approach was on the evening of March 3 when they were 1 05' apart at 6:30 pm EST. On March 4, they were 1 09' apart and on March 5, they were 1 29' apart at 6:30 pm. During these three days, Venus was at magnitude -3.9 while Mercury was at magnitude -1.2 on March 3 & 4, magnitude -1.1 on March 5. Venus was seen with unaided eyes on all three dates, but obvious on the clear evenings of March 4 & 5. Mercury was also readily visible with unaided eyes on March 4 & 5. Of particular note on March 5, both were seen with 10x50 binoculars at 5:52 pm, 4 minutes before sunset, when Mercury was at 13.5 altitude. Check the Mercury 2018 page for more details about visual observations on these dates, under Elongation #2.

The pictures below show Venus and Mercury on March 3, 4 & 5, 2018. The scale varies a little between them, but they clearly show Mercury (on the right) increasing in altitude relative to Venus on successive evenings. Mouseover for labels.

March 3, 2018, at 6:36 pm EST (42 minutes after sunset) from the baseball field complex in Maple Shade, NJ. Canon 6D digital SLR camera (on a fixed tripod) and a Sigma 70 to 300 mm, f/4-5.6 zoom lens set to 300 mm focal length, then cropped to about 60% of the original size (and a 16:9 ratio), which yielded a field about 4.6 wide x 2.6 high. It was exposed 1/6 second at f/5.6, ISO 800.

 

March 4, 2018, at 6:37 pm EST (42 minutes after sunset) from Swede Run in Moorestown, NJ. Canon 6D digital SLR camera and a Canon 70 to 200 mm, f/2.8L zoom lens (on a fixed tripod) set to 190 mm focal length, then cropped to about 65% of the original size (and a 16:9 ratio), which yielded a field about 7.5 wide x 4.3 high. It was exposed 1/20 second at f/2.8, ISO 800.

 

March 5, 2018, at 6:40 pm EST (44 minutes after sunset) from the baseball field complex in Maple Shade, NJ. Canon 6D digital SLR camera and a Tamron 150 to 600 mm f/5-6.3 zoom lens (on a fixed tripod) set to 329 mm focal length, then cropped to about 84% of the original height (for a 16:9 ratio), which yielded a field about 6.2 wide x 3.5 high. It was exposed 1/4 second at f/5.6, ISO 1600.

 

 

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Last Update: Sunday, April 22, 2018 at 03:49 PM Eastern Time