SJAstro Page Index

Mars at Perihelic Opposition
July 27, 2018

I observed Mars on July 27, 2018, between 1:00 and 1:40 am EDT, from my Maple Shade, NJ, backyard with a Stellarvue 130 mm, f/7 apo refractor, mainly at 253x, using a Stellarvue Optimus 3.6 mm, 100° eyepiece. In particular, I was viewing Mars (in the scope plus a glance with unaided eyes) at 1:13 am EDT, the moment of opposition and the moment when it crossed the meridian for my location, essentially at 40°N-75°W. At the time, Mars was 24.3 arc seconds in apparent diameter and 24.7° altitude, somewhat low because of its -6.5° ecliptic latitude in southwest Capricornus.

Due to the global dust storm in progress on Mars (which may be subsiding slightly), surface detail was sparse. With patience at the eyepiece, I could make out a small, not-exactly-white spot representing the South Polar Cap and a slight whitish rim at the northern limb representing the Northern Polar Hood. There was also a vague, faint horizontal darkish band across the southern reaches of the disc, which did not show enough detail to match it to any of the Mars surface feature charts, although based on the date and time, those charts indicate it was mainly Mare Sirenum.

Update: It was pretty hazy on Wednesday night, August 15, 2018, and Mars wasn’t the brilliant beacon it’s been recently because of the haze, but I thought this might afford some decent seeing. So, I decided to get out my 80 mm, f/6 apo refractor for a quick look from the backyard around 11:30 pm EDT. Transit was at 11:35 pm and Mars was 23.3" apparent diameter. Using an Explore Scientific 4.7 mm, 82 deg eyepiece yielding 102x and a 48 arc minute true field of view, Mars looked steady (i.e., seeing was at least good, if not very good). I used a diagonal, so the view was correct vertically, reversed left-to-right.

Despite the relatively small aperture and low magnification, I quickly saw some detail. There was a darkish, inverted T-shaped feature just left (west) of the central meridian. The horizontal portion of the “T” was below the equator and below that, there was a disc-like area that was a bit lighter in color than the rest of the non-dark surface. Finally, there was a whitish patch along the bottom limb, a tad left of center. However, its visibility varied with the momentary seeing, and it periodically showed a dark rim at its upper edge. I’m not a Martian surface feature expert, but I suspected the darkish vertical extension was Syrtis Major, the lighter disc was Hellas, and of course, the South Polar Cap was at the bottom limb. So, it looks like the obscuring effect of the Martian dust storm is truly to diminishing. Next time, I’ll get out the 130 mm refractor and have a better view, before Mars drops below 20 arc seconds diameter after September 5.

When I opened WinJUPOS for Mars set to the time of observation and a refractor+diagonal orientation, I was pleasantly surprised to see a good match with my eyepiece view (see the WinJUPOS synthetic image below). It also corresponded with S&T’s Mars Profiler utility, which confirmed my suspected identities above. The Mars Profiler indicated Mare Tyrrhenum and Mare Serpentis formed the darkish horizontal band below Syrtis Major, perhaps extending to Sinus Sebaeus and Sinus Meridiani (the "pipe") towards the east (on the right like the eyepiece view).

This is a WinJUPOS-generated synthetic image of Mars on August 15, 2018, at 11:30 pm EDT, north up, east right (like a refractor+diagonal). The dashed vertical line is the central meridian, the dashed horizontal line is the equator. The small red circle is the sub-solar point.

Comet C/2017 S3 (PANSTARRS)
July 19, 2018

This image shows Comet C/2017 S3 (PANSTARRS), captured on July 19, 2018, at 2:51 am EDT from Carranza Field in Wharton State Forest, NJ. The comet is the small bluish-green spot in the bottom-left quadrant. It is next to the magnitude 7.4 star, HD 31779 in the constellation Camelopardalis, near the Auriga-Perseus border. Mouseover for labels. This comet experienced a couple of outbursts in July 2018 and is currently significantly brighter than originally predicted by the standard ephemeris. It was easily seen with 15x56 binoculars on the morning of July 19 at Carranza (under a clear, dark sky).

The image was taken with a Canon 6D digital SLR camera and a Canon 200 mm f/2.8L telephoto lens (on a fixed tripod). It was exposed 4 seconds at f/3.5, ISO 6400, 4000K white balance, and then cropped to about 57% of the original size for a field about 5.9° wide x 3.9° high. Otherwise, it's unprocessed.

I've also labeled the position where the comet was seen with the 15x56s on the morning of July 18 from Maple Shade, NJ, although with much more difficulty under partially cloudy, light-polluted suburban skies. Update: I saw C/2017 S3 (PANSTARRS) again on the morning of July 20 from Swede Run in Moorestown, NJ. It was picked up at 2:26 am with 15x56 binoculars and then subsequently with an 85 mm spotting scope. It did not appear as bright as it did the previous morning at Carranza Field, but Swede Run is essentially a suburban location, and on top of the that, fog and haze were developing, reducing the transparency. It was certainly brighter than July 18 in Maple Shade. Update: As of July 21, reports on the comet e-groups indicate C/2017 S3 is starting to fade again. Is this a temporary bump in the road, or the beginning of the end? This comet has already been surprising, so we'll just have to wait and see what happens as it approaches perihelion on August 15.

The Crescent Moon and Venus
July 15, 2018

The 2.9-day-old, 12.3% illuminated Crescent Moon was 2.66° from the planet Venus (center to center) when this image of them was captured at 8:48 pm EDT on July  15, 2018, from the baseball field complex in Maple Shade, NJ. This is a single frame taken with a Canon 6D digital SLR camera and a Canon 400 mm f/5.6L telephoto lens (on a fixed tripod), then cropped vertically to a 16:9 ratio for a field about 5.1° wide x 2.9° high. It was exposed 1/400 second at f/6.3, ISO 3200 and daylight white balance. Since it was only 21 minutes after sunset, the sky was still fairly blue. The image below was taken 25 minutes later in a darker sky.

The Crescent Moon was 2.44° from the planet Venus (center to center) when this image of them was captured at 9:13 pm EDT on July  15, 2018, from the baseball field complex in Maple Shade, NJ. This is a single frame taken with a Canon 6D digital SLR camera and a Canon 400 mm f/5.6L telephoto lens (on a fixed tripod), then cropped vertically to a 16:9 ratio for a field about 5.1° wide x 2.9° high. It was exposed 1/2 second at f/5.6, ISO 1600 and daylight white balance. This is an additional 7 stops of exposure compared to the first image. It was now 46 minutes after sunset, and some blue remained in the sky. Unfortunately, the sky was also somewhat cloudy and hazy, so the longer exposure in a darker sky shows glowing halos around them, as well as earthshine on the Moon. Magnitude +3.9 Rho Leonis is faintly visible below-left of magnitude -4.1 Venus, which is 8 magnitudes, or 1,600x brighter than Rho. Mouseover for labels.

Here's a snapshot of the photo setup for these Moon+Venus images. It was taken with my iPhone 5s at 8:52 pm. Exposed 1/24 second at f/2.2, ISO 320. The Canon 6D camera is attached to a white Canon 400 mm telephoto lens, the tripod foot of which is attached, via an Arca-Swiss style plate, to a Acratech GP ball head (in the gimbal position) on top of a Benro carbon fiber tripod. I use an infrared remote to trigger the shutter, so there's no cord dangling down. I meant to move onto the grass after setting up, but I forgot. Mouseover for labels. I've also indicated the spot where Mercury was subsequently spotted with 10x50 binoculars.

The Crescent Moon and Aldebaran
July 10, 2018

The 26.5-day-old, 11.2% illuminated and earthshine-filled Crescent Moon was exiting the Hyades star cluster on July  10, 2018, when this image of them was captured from Swede Run in Moorestown, NJ, at 4:25 am EDT, 75 minutes before sunrise, and 2.77 days before the next new moon on July 12 at 10:48 pm. 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 600 mm focal length, then cropped to 90% of the original frame, producing a field about 3° wide x 2° high. It was exposed 0.8 seconds at f/6.3, ISO 3200, 4200K white balance. The moon passed about 4 arc minutes from the first-magnitude star Aldebaran, which is just off the southern cusp in this image (one needed to be farther north to see an occultation). Mouseover for labels.

The image below is a much-shorter exposure that shows some detail in the illuminated crescent at the expense of not showing the earthshine. Aldebaran, below the southern cusp of the Moon, shows a reddish color, some intrinsic but certainly some red contributed by the atmosphere at the low altitude, about 9.5° at the time.

This is a single frame taken at 4:17 am 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 600 mm focal length, then cropped to 38% x 56% of the original frame, producing a field about 1.3° square. It was exposed 1/125 second at f/6.3, ISO 3200 (100x less exposure than the previous image at 0.8, or 1/1.25 seconds), 3600K white balance.

Click here for the previous page.

Click here for an index to previous SJAstro pages.