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):
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: https://www.minorplanetcenter.net/mpec/K18/K18VF1.html?fbclid=IwAR2ZmjuWzNVq4QQb4mZNGeVtJdyEhnjZEgmyj08SsUtCcTL_NFqkq5bRUFc
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:
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.
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.
Ever watched footage of the Mercury, Gemini or Apollo space projects? When Houston talks to the astronauts, there is a beep, then some talking then another beep? Yep – those beeps are Quindar Tones. If you listen carefully, the tones are not the same pitch: there are two distinct tones, one at 2525Hz and the other at 2475Hz. They are both 250ms in length…. like these:
What are these tones for? What’s going on? Why the beeps? Well, it all boils down to older technology. Back when they were shooting astronauts into space on top of missiles (some more controlled than others), eventually they got people into orbit. As astronauts orbited the Earth, they needed some way to talk to them, even when their space capsules were not within the line of sight of Mission Control in Houston, Texas. Communications centers and tracking stations were built around the world, each with the ability to talk directly to the space capsule as it orbited on by. Mission Control then had telephone lines to each of these stations around the world. These lines were dedicated lines, and expensive. The tones were used as a method to control when the remotely located transmitter was transmitting, and used the phone lines to send these remote control tones as audible beeps. Both tones originated at Mission Control…. like this:
- Mission control needs to say something to the astronauts in space. They push the push-to-talk switch.
- This send a 2525Hz intro tone to the system.
- The remote communications station receives the intro tone, and turns on the transmitter to the radio antenna aimed at the space capsule.
- Voice communications takes place.
- When done, Mission control releases the PTT switch, and the 2475Hz outro tone is sent, thus turning off the system. The remote transmitter is off.
An example for you is below. Note that the Quindar tones only take place just before and after Mission Control speaks. The astronauts do not initiate any of the tones. They make all radio calls into the “blind” so to speak, hoping that some ground tracking station is picking them up.
Now, you might wonder about the issues here. If an astronaut were to also talk at the same time, they might pick up a Quindar tone on their audio and retransmit it back to the ground and cause all sorts of troubles down on the Earth side of things. Yep – that was a problem(!) so engineers made their best effort to prevent the tones from even reaching the astronauts by placing a filter into the stream of all uplinked audio sent to the capsule. These filters were simple notch filters centered on the tone frequencies…. not perfect, by any means, but it worked, generally.
The name “Quindar”? That came from the organization that invented the system, Quindar Electronics. You can visit their site at: http://www.qeiinc.com/History.aspx to see some of their excellent history.
What now? Quindar tones were used from the early flights of Merucry through the Space Shuttle program. With new methods of telecommunications (i.e. fiber optics, satellite feeds, etc), sending command and control statements to remotely located transmitter sites is a lot easier. There is no need for audible tones these days.
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 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!
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!
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.
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.
- Location: Sutherland, South Africa in the semi-desert region named the Karoo.
- 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: http://www.salt.ac.za/
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).
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: https://www.salt.ac.za/
Back in the early 1900s, heliochronometers were all the rage for those seeking some extraordinary piece for their garden or other vista-filled location. This particular instrument was built by the Pilkington & Gibbs company of London. Only about 1000 of these were made by the company – sadly much of the brass was melted down to support the war effort and the making of artillery shells. This unit is not only intact, but is in 100% working condition, another rarity, as many of these were left exposed to the elements where they would slowly get coated by a green oxidation patina.
Using these instruments was quite simple once it had been properly installed. Installation requires that their primary rotation axis be parallel to the rotation axis of the Earth, aimed at true north and with the correct angle to account for one’s latitude. I accomplished this easily enough with the gentle use of a wrench, a screw driver and compass, being sure to dial in first the correct magnetic variation for the compass for our location.
In use, one first sets the calendrical date on the smaller inner dial: June 16th. This slides the gnomon back and forth to account for the equation of time(!): quite a remarkable design!
One then rotates the larger dial to project the dot of sunlight cast through a hole in the gnomon (sight vane) onto the opposing vertical line on the center of the screen vane. One then reads the hour and minute on the brass gauge on the outer edge of the main dial. Simple and accurate! In this case, it was within two minutes, likely because I have yet to adjust the minute readout-scale to its proper position for our longitude within the time zone.