Comet 64P/Wirtanen

Comet Wirtanen has been giving us a moderate showing this time around the Sun. As it has been closer to Earth than it usually gets, we are enjoying a comet that might just get bright enough by December 16th to see without a pair of binoculars.  Last night we checked it out through the school’s 16″ telescope and took some images as well.

Comet 46P/Wirtanen: One is through the 16″, the other is a wider field view through a telephoto lens. The brilliant green color is striking and caused by the excited gases: cyanogen (CN)2 and diatomic carbon (C2).


20-21 January 2019: Total Lunar Eclipse

We have a splendid opportunity to see a total lunar eclipse this January. It will be taking place late on a Sunday night into the early hours of Monday morning. That Monday is also Martin Luther King, Jr. Day here in the USA, so many schools will not have classes that day. Eclipse timings are given in the above graphic, in Universal Time.  Converting that to the various USA time zones: 

Event Pacific Mountain Central Eastern
Partial eclipse starts 7:34 pm 8:34 pm 9:34 pm 10:34 pm
Total eclipse starts 8:41 pm 9:41 pm 10:41 pm 11:41 pm
Total eclipse ends 9:43 pm 10:43 pm 11:43 pm 12:43 am
Partial eclipse ends 10:51 pm 11:51 pm 12:51 am 1:51 am

Usually the real eclipse visibility starts to take place late in the penumbral phase approaching the first contact of the umbra. If you have not seen a lunar eclipse before, it is quite a special event. The moon will appear to have a charcoal chunk missing from it as the eclipse progresses.  Deeper into the eclipse, the moon will take on a rusty red hue caused by the sunlight passing through the earth’s atmosphere before arriving at the moon. Telescopes are not required, as one can see the whole event easily with the eye. Binoculars and telescopes will offer a nice closeup view.  Photography of the event is a relatively simple affair. A good tripod and telephoto lens will work well with the moderate shutter speeds required.  Tracking is not needed.  An example of a series of photos I took of the last total lunar eclipse is below. The camera was a Nikon D7000 with 200mm telephoto on a tripod. Click for a larger image.

The Annual Leonid Meteor Shower is Upon Us

It is that time of year again when we get to enjoy one of the best meteor showers, the Leonids. This one peaks mid-November and stems from the remains of Comet Tempel-Tuttle which has left its debris in a massive orbital path through which our planet passes yearly. This November the peak is on the mornings of November 17th and November 18th.  This is not likely to be a storm shower, as we have enjoyed in the past. This is more likely to produce anywhere between 10 to 15 meteors per hour. As with all meteor showers, you will see more if you are far away from city and town lights and have clear, transparent skies. Here in the state of New Hampshire, it will also be chilly, so you’ll want a coat, sleeping bag, and some warm food/drink to enjoy while looking up. The meteors will appear to stream out of the head of Leo, the Lion. This is the sky for those mornings (click to enlarge):

Looking southeast on the morning of November 17th: The Leonids will seem to originate from Leo's head.

Looking southeast on the morning of November 17th: The Leonids will seem to originate from Leo’s head.

A New and Potentially Bright Comet!

Don Machholz, Shigehisa Fujikawa and Masayuki Iwamoto have confirmed a new comet which might very well become bright enough to see without optical aid. Stand by for updates here in the coming days as the orbital elements and ephemeris are corrected. The comet has been designated:

MPEC 2018-V151: COMET C/2018 V1 (Machholz-Fujikawa-Iwamoto)

More information from the Minor Planet Center here:

A Winter Comet: 46P/Wirtanen

It appears that we might just have a bright comet for the end of 2018 and into the start of 2019: Comet 46P/Wirtanen. With a short period of just about 5.4 years, this time around the Sun, it will be very close to Earth (a mere 0.07AU or 11.6 million km) and enjoying its perihelion, too….. Predictions at this stage suggest a magnitude 3 object, well within the visibility range of the human eyeball.  When and where to look?  Here is an overall map of the comet’s path through December. Note that the perihelion date in December 16th, then the comet should be near its brightest:

Comet 46P/Wirtanen throughout December 2018.

Comet 46P/Wirtanen throughout December 2018. (click to enlarge)

On the night of 16 December for mid-latitude northern observers, looking south, this is what you should see…a lovely view of Orion and surrounding constellations. The comet should be near the Pleiades, making for a fine photographic opportunity.

Looking south of 16 December.

Looking south of 16 December. (click to enlarge)

Orionid Meteors 2018

A good meteor shower to watch is the annual Orionids. This one originates from the famous comet:  1P/Halley – yep, that one!  As the comet orbits the Sun, little particles are left behind all over the place along the path.  When our planet orbits through this debris, we see a meteor shower. This year, the peak night will be October 21-22, 2018… some time around 2:00am will be when the shower radiant is high in the sky. All you need is a good dark sky to view from. No optical gear is needed. Suggestions for those nearing winter:  A sleeping bag, hot drinks, and some snacks. The image below shows that evening at about 1:30am local time with Orion rising in the southeast. The small red circle is the radiant from which the Orionid meteors will seem to emanate.

Orionid radiant

Looking southeast at 1:30am local time to see Orion and the Orionids radiant (red circle).


Cleaning Time!

Every observatory needs basic maintenance, and those here at PEA are no different. I usually cringe at the thought, but cleaning is a part of the requirement… not that I dislike cleaning. I actually really find it meditative, and a clean observatory dome makes me smile. The cringe-feeling comes from the prospect of kicking up a ton of dust, pollen, cob webs, and such… all of which will have to come to rest some place: Hopefully not on any optics! EEEK! Scheduling the cleaning is a whole other game to play, as well. School ends in early June. A few weeks later, the summer school program begins, and then runs for 5 more weeks. Grass is growing and getting cut throughout June and summer, so, why clean if it’s going to get even more dusty and grassy and pollen-dusty…? So… I wait until the end of summer, when there is a cool, dry, sunny day, like today!

Step – one – cover the optics. Then cover the telescope tubes and mounts with trash bags. Open the dome and aperture.

Two – Vacuum the whole place from top to bottom. We have open studs, so there are a lot of nooks and crannies to work through.

Three – Damp wipe of surfaces, and then a scrub of the floor.

Four – wipe down the ladder and other step-stool devices used by observers throughout the year.

Five – wait for everything to be dry. A light breeze and sunny, dry weather help here. Today was a perfect day.

The result? A clean observatory with a bunch of displaced spiders and no more wasp nests. Webs are gone. Pollen and dust are gone. Happiness!


A clean machine!

A Meeting of Jupiter and the Moon

A nice photo opportunity will be taking place on August 17th just after sunset. Head outside and look to the southwest for the crescent moon. Just a little to the lower right (southwest) from the moon will be brilliant Jupiter. Heading more to the west, Venus will be lighting up the sky. Enjoy!

Screenshot 2018-08-16 09.36.12

The Moon, Jupiter and Venus just after sunset on August 17th.

The Annual Perseid Meteor Shower

Each August, the Earth passes through a stream of comet debris from Comet 109P/Swift-Tuttle.  The comet will not be back our way until 2126… so… I wouldn’t wait up for that one.  Along the orbital path, the comet has left behind small bits and pieces, most no bigger than a grain of sand. These run into our planet’s atmosphere and burn up due to friction. The result of this friction-filled reentry is a meteor, a rapid streak of light through the sky.  This shower usually gives us about 60 meteors per hour at peak, and many fireballs: bright meteors that can even be bright enough to cast a shadow.  How to see it?

  • Pick a clear night closest to the peak, which is on August 12th/13th.
  • Go to a dark sky site: avoid lights and cities. The darker, the better.
  • Bring something comfortable to lie down on: sleeping bags are good.
  • Bring food, drink, and bug spray if needed for your location.
  • Spend the night time hours looking up at the sky! No optics required other than your eyeballs.
  • Avoid lights!  No cell phones. No flashlights. Your eyes take between 30-60 minutes to become dark adapted, and you lose that dark adaptation instantly if you see a light. Avoid lights!
  • The shower appears to come from a spot in the sky in the constellation Perseus. This rises just before midnight, so best observing will be after that, into the morning hours.
  • Have fun!


A Visit to SALT: The South African Large Telescope

During the last week of June 2018, I was in South Africa working with a school as they brought focus to their interests in students-centered, discussion-based learning. My host, Shaun Hudson-Bennett, a member of their Maths Department is a wonderful person and shared an interest in visiting the South African Large Telescope. We were based in the town of Somerset just east of Cape Town… about a 4 hour drive south of SALT. SALT is located in the town of Sutherland in a region that is largely rolling hills and flat open terrain reminiscent of what we would call “high chaparral” here in the American West. Sandy and silty soil is mixed in with scrubby shrubs and prickly plants that all struggle to get water to survive. The geology of the area is lovely to behold: layered metamorphic and sedimentary mountains, and one can even find a volcano remnant. Much of the area is a fossil lover’s dream-scape.


Heading out of Cape Town, one must first get through some of the mountainous regions. It is very colorful, even in winter, with grape arbors and other fields planted.


Headed into the high chaparral nearing SALT. The rods are very straight for a good length of time.


Entering the town of Sutherland. Lots of eateries and dark sky observing sites are available here.


Some of the smaller domes on the summit.

SALT itself is surrounded by what I call dark sky country: there are dark sky reserves in the area, and most businesses in the town of Sutherland are very much aware of the value of their dark sky commodity.  Small bed-and-breakfasts are spotted throughout the town, each advertising their private star-gazing pads and fields. Climbing the road out of Sutherland, one arrives at the summit region of the South African Astronomical Observatory, home to SALT and quite a few other facilities owned both by South Africa and a number of other foreign consortiums (Japan and Russia to name but two). At 1798 m (5899 ft), SALT is well placed for its work, primarily spectroscopy. The air is not too thin, and walking around was easy enough.


The SALT dome and alignment tower.

SALT Facts:

  • Location: Sutherland, South Africa in the semi-desert region named the Karoo.
    • Latitude: 32°22′34″S
    • Longitude: 20°48′38″E
  • Altitude: 1798 meters (5899 feet).
  • Optical Design: Optical with a total of 91 hexagonal 1m diameter mirrors making a composite 11m diameter hexagonal primary.
  • First Light in September 2005.
  • Primary Science: Spectroscopy, polarimetry, imaging:
    • Robert Stobie Spectrograph (RSS) (née Prime Focus Imaging Spectrograph).
    • The Berkeley Visible Image Tube camera (BVIT).
    • Fiber-fed High Resolution Spectrograph (HRS).
  • Website:


My host, Shaun (right), Frigid (the Penguin) and myself in front of the SALT primary mirror. The mirrors are very thin and lightweight. Combined they equate to an 11m diameter primary.


The instrument payload package at prime focus (black painted objects). These move for tracking in both RA and Dec by sliding on rails.

The optics of the telescope are most interesting. The system has a fixed altitude for the primary, so pointing and tracking are not done by moving the primary and all attached equipment, as is done with most other systems. At SALT, tracking is accomplished by moving the equipment package at primary focus. So, to image, the camera system is slewed across the top of the observatory as the target moves through the field. The telescope can be rotated in azimuth to view other regions of the sky. Each segment of the primary is adjustable using remotely controllable actuators. This allows the system to be aligned rapidly. Alignment is accomplished using what I call a collimation tower, an interesting structure that looms high on the outside of the dome. Essentially the telescope is rotated until the tower-top is at the center of curvature for the primary. Each of the 91 mirrors of the primary are then tipped and/or tilted until they are precisely aligned to form a spherical primary system using lasers sent from the tower to each mirror on the primary.  To maintain alignment, the whole structure is air-conditioned to maintain conditions as close to ambient as possible. The interior was pretty chilly the day we arrived, as it was winter there (in June).


The whole telescope can rotate in azimuth on air-bearings like this one. Once aimed, the bearings are deflated and the telescope remains static throughout integrations. Only the instrument payload set moves during data capture.


Another view of the massive primary assembly.

Visiting?  They do allow visitors during daylight hours, twice daily (at this time), and reservations are very highly recommended. More information may be found on the SALT website: