Comet C/2015 ER61 (PANSTARRS)
April 8, 2017
I went to Borton Landing
Road in Moorestown, NJ, on the morning of
April 8, 2017, hoping to get a picture of comet
C/2015 ER61 (PANSTARRS) while it was still in
outburst. The sky above the horizon looked hazy, astronomical twilight
began at 4:58 am EDT and the 92% illuminated moon set at 5:24 am. With
10x50 binoculars, I finally spotted comet
C/2017 E4 (Lovejoy)
at 5:00 am then PANSTARRS at 5:13 am. Both
were fairly faint in the haze and the early part of twilight with
residual moonlight. The picture above was captured at 5:19 am using a
Canon 6D digital SLR camera and a Canon 70 to
200 mm f/2.8L zoom lens (on a fixed tripod) set to 200 mm focal length
then cropped to a field 4.0° wide x 3.0° high.
It's a single frame exposed 2 seconds at f/4, ISO 3200. Quality is poor,
but PANSTARRS is visible. Mouseover for labels.
Binocular Comet Foursome
April 7, 2017
I headed back to Carranza
Field on the morning of
April 7, 2017, as it was the last day the waxing
gibbous moon (85% illuminated) would set before the start of
astronomical twilight (4:48 and 4:59 am EDT respectively) prior to full
moon on April 11. In addition to the recently observed comets mentioned
C/2015 ER61 (PANSTARRS), C/2017 E4 (Lovejoy)
41P/Tuttle-Giacobini-Kresak, I also wanted to
C/2015 V2 (Johnson) with binoculars. It was partly
cloudy when I arrived at 4:20 am, then cleared, but complete cloud cover
returned by 5 am. I had hoped to get a picture of PANSTARRS while still
in outburst, but the southeast direction was the last to clear and first
to cloud over again, so I was foiled. The snapshot above is Lovejoy
taken at 4:52 am with a Canon 6D digital SLR camera and a Canon 70 to
200 mm f/2.8L zoom lens (on a fixed tripod) set to 200 mm focal length.
It was exposed 4 seconds at f/4, ISO 6400. Mouseover for labels.
More importantly (to
four comets were ultimately seen with both 10x50 and 16x70 binoculars as
tabulated below with the initial sighting time.
C/2017 E4 (Lovejoy)
C/2015 ER61 (PANSTARRS)
C/2015 V2 (Johnson)
Lovejoy and PANSTARRS were
easy to see (at least once once the clouds over PANSTARRS cleared). In
all of my previous sightings, 41P was ghostly at best, but finally, in
the window between moonset and the start of astronomical twilight, it
was easy with the 16x70s and not difficult with the 10x50s. Johnson
wasn't too difficult with 16x70s in that window, when it was
finally visible with the 10x50s.
Another Binocular Comet
April 5, 2017
As noted on the comet
e-groups in recent days,
Comet C/2015 ER61 (PANSTARRS) has experienced an
outburst to the magnitude 6.x range, so it's an easy binocular object. I
saw it this morning,
April 5, 2017, with 16x70 binoculars from my
front yard a few minutes before the start of nautical twilight at 5:37
am EDT. It seemed a little brighter than nearby
C/2017 E4 (Lovejoy). Here's
Bob King's online article about it at Sky & Telescope.
Venus, the Morning Star
April 2, 2017
After sighting comet
C/2017 E4 (Lovejoy) on
April 2, 2017, as described below, twilight
brightened and the starry sky disappeared. However, I waited for
Venus to appear as a
"morning star" following inferior conjunction eight days before on March
25. It rose at 5:39 am EDT and was spotted with unaided eyes at 5:55 am
in the tree tops on the eastern end of
at 2.9° altitude. This picture was
captured at 6:01 am, 40 minutes before sunrise, when it was at 4°
altitude. Taken with a Canon 6D digital SLR
camera and a Canon 100 mm f/2.8L macro lens (on a fixed tripod), then
cropped to about 16° wide x 9° high.
Exposed 1/20 second at f/2.8, ISO 800, using auto white balance.
Unfortunately, it was heavily overcast on the morning of March 25, so I
didn't get to see Venus very close to the time of inferior conjunction.
Since then, my only Venus sighting had been mid-day on March 29.
Here's a summary of my Venus sightings near inferior conjunction.
North America Nebula
April 2, 2017
After taking comet
pictures at Carranza Field
April 2, 2017 (scroll down for those), I noticed
the Summer Triangle was high high in the northeast, so I took some shots around the
first magnitude star Deneb
and the North America Nebula
(NGC 7000). I finally got around to looking at the non-comet pictures
more closely, and posted the selected picture above on May 2. It's a single frame taken
at 5:02 am EDT (two minutes before the start of astronomical twilight) with a Canon 6D digital SLR
camera and a Canon 100 mm f/2.8L macro lens (on a fixed tripod), then
cropped to about 14° wide x 10.5° high. Exposed 4 seconds at f/3.5, ISO
12800, using 3600K white balance. Mouseover for labels.
Cygni is particularly interesting in that it was the first star to
have its parallax reliably measured.
Comet C/2017 E4 (Lovejoy)
April 2, 2017
My first sighting of
Comet C/2017 E4 (Lovejoy) was accomplished with
16x70 binoculars on
April 2, 2017, at 4:35 am EDT from Carranza Field
in Wharton State Forest, NJ. This picture of it near Enif (Epsilon
Pegasi, the nose of the Winged Horse) and the globular cluster Messier
15 was captured at 4:52 am when the comet at 17° altitude in the east.
Taken with a Canon 6D digital SLR
camera and a Canon 100 mm f/2.8L macro lens (on a fixed tripod). It was
cropped to about 8.6° wide x 6.2°
This is a single frame exposed 4 seconds at f/3.5, ISO 8000, using
tungsten white balance. Mouseover for labels.
The comet was easy to see
with the 16x70s, in contrast to comet 41P/Tuttle-Giacobini-Kresak that
was spotted a minute before in Draco. The latter had a diffuse coma with
low surface brightness while E4 was condensed with relatively high
surface brightness. In the 16x70s, E4 looked similar to M15, but perhaps
slightly dimmer. No tail or coma elongation was evident, and unlike its
appearance in this image, E4 did not look greenish visually. It was not
seen with unaided eyes. Bob King has an
online article at Sky & Telescope about observing C/2017 E4
The picture below
shows Comet 41P/Tuttle-Giacobini-Kresak
in Draco, across from the handle of the Big Dipper, at 4:58 am EDT, when
it was at 55° altitude in the northwest. Taken with a Canon 6D digital
SLR camera and a Canon 100 mm f/2.8L macro lens (on a fixed tripod). It
was cropped to about 16.5° wide x 9.3°
This is a single frame exposed 5 seconds at f/3.5, ISO 8000, using
tungsten white balance. Mouseover for labels. 41P was
previously seen in the bowl of the Big Dipper on March 22 at Belleplain
State Forest with an 80 mm refractor and 10x50 binoculars.
The Crescent Moon and Mercury
March 29, 2017
Crescent Moon was about 45 hours old and 5.4% illuminated when
it joined the planet Mercury
in this picture captured on
March 29, 2017, at 8:09 pm EDT. Taken from the
old Collins Farm site in Maple Shade, NJ, with a Canon 6D digital SLR
camera and a Canon 100 mm f/2.8L macro lens (on a fixed tripod) plus a
Kenko 1.4x teleconvertor, providing an effective focal length of 140 mm.
Exposed 1/3 second at f/4, ISO 1600. This is the best evening elongation
of the year for Mercury because of the current steep angle of the
ecliptic in the west after sunset. During the picture-taking session,
Mercury (in Pisces) was easily visible with unaided eyes about 9½° from the moon,
which was 5° south of the ecliptic in Cetus. The faint star off the
upper-right limb of the moon is magnitude 4.3 Xi Ceti.
Venus Nears Inferior Conjunction
March 12, 2017
Venus was less than two weeks from
conjunction (March 25, 2017, at 6:17 am EDT) when this picture of the
6.3% illuminated disc was captured at 7:45 pm EDT on
March 12, 2017, from Maple Shade, NJ. Taken with a Canon 7D Mk II digital SLR camera and a Canon
f/5.6L telephoto lens (on a fixed tripod), plus a 1.4x Kenko teleconvertor, for an effective focal
length of 560 mm. It was then cropped to about 16% of the horizontal
dimension x 18% of the vertical direction of the
yielding a field 0.36° wide x 0.27° high. This single frame was exposed
1/8000 second at f/8, ISO 1600 (about one-third stop less than the "sunny sixteen rule"
for earthbound subjects)
using daylight white balance. Besides cropping and resizing, no
processing was applied.
The image below is a more
severe crop, roughly 2.5% of the original, providing a field about 3.5 x
2.6 arc minutes (and it magnifies the effects of imperfect seeing).
Since Venus was 55.3 arc seconds apparent diameter at the time, the 560
mm focal length projected a 0.15 mm wide image onto the sensor, which is
equivalent to 37 pixels at 4.09 μm per pixel for the 7D Mk II. Also note the coloring
at the upper and lower edges of the crescent due to
atmospheric chromatic aberration. At 7:45 pm, Venus was just 12° altitude
(with a solar elongation of 20.6°). Finally, note that the cusps of the
crescent point nearly straight up, perhaps tilted slightly to the right.
Since the ecliptic is tilted a little left of vertical after sunset now,
we might expect the cusps to be tilted a little left. However, the
ecliptic latitude of Venus was +8.1°, so it's actually a little right of
a vertical line from the sun perpendicular to the horizon (the horizontal edges
of the frame were parallel to the horizon; the zenith is up).
March 16, 2017, I went to the Maple Shade,
NJ, baseball field complex to look at Venus after sunset again (the same
session that I spotted Mercury for the first time of the second 2017
elongation). I initially saw Venus at 7:13 pm EDT with unaided eyes,
shortly after arrival and shortly after sunset at 7:08 pm. The crescent
was not visible with my unaided eyes, but easily seen with 16x70 and
10x50 binoculars. In both cases, it looked similar to the picture above,
i.e., decidedly thicker than its 3.6% illumination would suggest
(probably due to a combination of the great brilliance and the imperfect
seeing at its 13° altitude). I was out again the following afternoon,
March 17, and spotted Venus at 1:49
pm with 7x42 binoculars (the crescent was visible), but I could not
see it with unaided eyes. At the time, Venus was about 15° from the sun
at the 11 o'clock position (so I blocked the sun with my neighbor's
house) and was at 61½° altitude, 185° azimuth. The
Astronomy Picture of the Day for March 17, 2017, has an excellent
illustration of Venus' changing phases.
March 20, there were streaky clouds
along the western horizon, but I went to the Maple Shade baseball field
complex for a look anyway. I spotted the slim crescent of Venus at 7:10
pm EDT (two minutes before sunset) with 10x50 binoculars through thin patchy
clouds, then lost it at 7:15 pm in a rising bank of thicker clouds. I
was unable to find nearby Mercury, mainly because of the clouds. On
March 21, I went back to the Maple
Shade baseball field complex after noticing some clearing to the west at
7:30 pm. I found Venus in the tree tops at 7:40 pm with 10x50 binoculars
and the crescent was easily visible. I then looked with unaided eyes and
could see Venus, but no crescent. Next, I picked up Mercury at 7:44 with
the 10x50s, then saw it with unaided eyes between scattered, streaky
March 22, I initially spotted Venus at 1:07
pm EDT with 10x50 binoculars, 9½° directly above the sun, which was
blocked by my neighbors house. Later in the day, viewing from the
eastern side of the athletic field at Belleplain State Forest, NJ, I found
Venus in my 80 mm apo refractor at 6:50 pm (24 minutes before sunset)
not far above the tree tops on the western side of the field (I
was there for a college student field trip). The slender crescent was
quite lovely in the scope. The western tree line at Belleplain was around 6°
apparent height, so Venus disappeared in the trees not long after 7 pm. It had not
been seen with unaided eyes in the bright, whitish sky near the sun at
the horizon. In
contrast, higher Mercury was easily visible with unaided eyes when I
looked for it at 7:45 pm. On
March 23, I made my first morning
observation of this Venus elongation. I went to the old Mart site in
Pennsauken, NJ, and sweeping the horizon with 10x50 binoculars, I
spotted Venus at 6:40 am, shortly after arrival. The crescent was
distinct, although somewhat bloated by the low altitude, about 2¼° when
found. I was subsequently able to glimpse Venus with unaided eyes in the
brightening twilight (sunrise at 6:58 am). Therefore, I was able to see
Venus at either end of the night of March 22/23 (at sunset and then
again at the subsequent sunrise), thanks to its +8.4° ecliptic latitude.
Unfortunately, on the morning of March 25
when inferior conjunction occurred at the same time as Venus rose (6:17
am EDT for 40°N-75°W), it was heavily overcast.
Here's a summary table of these sighting dates and times.
Mars and Uranus
February 26, 2017
The "Red Planet"
Mars (magnitude 1.3)
passed close to greenish-blue Uranus
February 26, 2017 (although the colors aren't
very saturated in this non-processed image). The two planets were only
34 arc minutes apart when this image was captured at 6:44 pm EST from
Maple Shade, NJ. At the time, Mars was at 30° altitude in the west-southwest during
astronomical twilight. Taken with a Canon 7D Mark II digital SLR camera at the prime focus of a
William Optics 80 mm, f/6 apo refractor on a fixed tripod. It was exposed 1
second at ISO 3200. The field is approximately 2.7° x 1.8°. Mouseover
for labels. In the clear sky, Mars was easy to see with unaided
eyes about 11° above-left of brilliant Venus, then Uranus was easy to
see next to Mars with 10x50 binoculars.
February 20, 2017
This image of the area
around, and including,
was captured at 12:18 am EST on
February 20, 2017, from Carranza Field in Wharton
State Forest, NJ. It's a single frame taken with a Canon 6D digital SLR
camera and a Canon 100 mm f/2.8L macro lens on a fixed tripod. Exposed 4
seconds at f/3.5, ISO 20,000. Mouseover for labels.
After several unsuccessful
attempts to spot 45P from the suburban area around my home in Maple
Shade, NJ, last week (after its closest approach to earth on February
11, 2017, and the subsiding full moon of February 10), I finally got to
see it again after last spotting it after sunset around New Year's Day
2017 (see below). In my 85 mm spotting scope, I picked it up at 11:55 pm
EST on February 19. It was just a dim glow at lowest power (27x) and it
almost faded away at maximum power (60x). There seemed to be some
elongation in a roughly ENE-WSW direction, but no tail was evident. The
galaxy NGC 4414 (magnitude 11) was a visible smudge within the coma of
45P, roughly SSW of the comet's apparent center, which is only an arc
minute from the borderline between Canes Venatici and Coma Berenices.
NGC 4414 is about 6 arc minutes on the other side of the border.
The image below is an
nominal 57% crop of the original image above to better show the comet,
the galaxy and a short green line indicating the approximate elongation
(mouseover for labels). It spans about 11.6° x 7.8° (vs. 20.3°
x 13.6° for the original). Since it was exposed at a relatively high ISO
20,000 (necessitated by the comet's low surface brightness), there's a
very noticeable amount of noise in this single frame. The greenish color
of the coma as seen in better images is absent here, and it was not
detected visually either.
The Crescent Moon, Venus and a Comet Open the New Year
January 1, 2017
Crescent Moon was 13% illuminated when this
picture of it was captured at 5:54 pm EST on
January 1, 2017, from Maple Shade, NJ. Of course,
we see the whole disc since the remainder is illuminated by earthshine
(and the illuminated portion is greatly overexposed to bring out the
earthshine, as well as the field stars). The planet Venus is 56% illuminated
as it nears Greatest Eastern Elongation on January 12th, but it too is
greatly overexposed, and too small at this scale, to show its gibbous
shape. Taken with a Canon 7D Mk II digital SLR camera and a Canon 100 mm
f/2.8L macro lens, then cropped to about 85% of the original size for a
field 10.6° wide x 7.4° high. Exposed 1 second at f/4, ISO 1600.
Mouseover for labels.
Comet 45P/Honda-Mrkos-Pajdusakova was about 11°
from the Crescent Moon at the 5 o'clock position when this picture was
captured at 6:07 pm EST on
January 1, 2017, from Maple Shade, NJ. The comet
was in the 7.x magnitude range, which is relatively bright as far as
typical comets go, but because of its low altitude (just under 11° at
the time), a little moon glow plus suburban light pollution (this site
is 8 miles east of center-city Philadelphia), it was still a
quarter-hour before the end of astronomical twilight and that the
atmosphere was slightly hazy meant the comet presented low contrast in
the sky. It was just a vaguely visible smudge both visually with 16x70
binoculars and in this image. Taken with a Canon 7D Mk II digital SLR
camera and a Canon 100 mm f/2.8L macro lens, then cropped to about 50%
of the original size for a field 6° wide x 4° high. Exposed 1 second at
f/4, ISO 1600. Mouseover for labels.
for some older images.