The news is, of course, old to those who have been following the Sun’s activity of late: things are getting more exciting. There are more spots, more flares and more CMEs as we approach solar maximum. Solar Cycle 25 is off to a good start, and interestingly, there are websites which post that it will be weaker than 24… while others show that it will be more active. Official news can be found here: https://spaceweatherarchive.com/2022/01/09/solar-cycle-25-update/
Right now the sunspot counts are higher than the predictions for the cycle. Read into that as you will, as solar physics is still a burgeoning field. The current prediction is for the cycle to reach maximum in mid-2025. With that amateur radio enthusiasts and astronomers will enjoy the changes to the Sun and ionosphere. With the activity, changes to our solar observing practices have been made, so that it can be shared safely with students & adults, and the data collected to send to the AAVSO Solar Group. While all but the 0.7m have solar filters, the results of using a Herschel wedge from Baader along with a 10mm Radian and polarizer on a TV-85 have been amazing. It’s small, light weight, easily transported and will also hold a Nikon D-810 for imaging. Attached are a couple of photos from earlier this week, all taken in gusty wind conditions. Note that if you are intending to get new solar observing gear, the lead times on ordering gear are now long… and solar maximum is coming. Images are below: be sure to click to see full size. The spots are impressive! Clear skies to all.
With this winter term’s Selected Topics in Astronomy class, we chose to give the new 0.7m telescope a workout and see if it could produce results fine enough to detect extrasolar planets using the transit method. The transit method focuses on the slight apparent brightness changes in a star when one of its planets orbits in front of it from our viewpoint here on Earth. Many planets have been discovered this way: The Kepler Mission has over 2800 candidates and 2600 confirmed. The TESS mission has over 2600 candidates and 122 confirmed exoplanet discoveries. So, where to start?
We chose a well-known exoplanet, visible to us in the northern hemisphere, with a predicted brightness change that should be readily visible to our equipment. The predicted transit times needed to be well established and had to start and end during nighttime, so that we could detect the entire transit event. WASP-43b became the primary target. It has a 0.81 day orbit (FAST!) and is a large planet orbiting a small diameter star (spectral type K7 V), making for large changes in brightness. All we needed was a clear night when one of its transits was taking place. Using the Swarthmore exoplanet transit search site (https://astro.swarthmore.edu/transits/transits.cgi) we found a perfectly good transit opportunity on the night of 26 January. The goal was to start photometric observation an hour before the transit started, observe through the entire transit, then end an hour after the event. The goal was achieved!
Images were taken in rapid cadence, one minute integrations each, through an Rc filter to minimize the Earth’s atmospheric effects.
The image above shows the results of the data capture: two plots. The upper plot shows the magnitude of WASP-43 changing through the transit period in J-C Rc magnitudes. X: Time in J.D. Y: Rc observed magnitudes. The bottom plot is of a check star used to validate the data set. We used reference and check star Rc magnitudes from the AAVSO for this study. Note the error bars are small: these represent systemic errors in the measurements based on signal-to-noise values of the individual images. The variances in magnitudes, which are on the order of 0.010 mag, are caused by atmospheric changes and seeing conditions. Exeter, NH is very close to sea level, so we have a lot of air mass to observe through. With these conditions the dip of about 0.040 magnitude in WASP-43’s brightness was easily seen: a success!
This is also an indicator of the observatory’s capabilities. We now know that a typical winter observing run can expect 0.010 magnitude fluctuations in seeing conditions and that a star with m=12, we can expect an excellent signal-to-noise ratio. What’s next? To work on assisting scientists with solidifying the orbital periods of other less known exoplanet systems.
This can get really complex, and, as you imagined, very expensive. There is this sudden realization that good scopes are pricey, and the less expensive ones are, well, to be honest, not worth the cash. They end up in closets or basements. For a first time telescope, especially for kids, I always recommend a really good pair of 8×50 or 10×60 binoculars. These get good use at night, AND during the day… bird, scenic views and the like. If we are talking seriously into astronomy and telescope are the only choice, then go for the most scope you can afford: one with a quality heavy mount and large aperture. My close friend Ed Ting has made a wonderful page with a load of buying tips here: http://scopereviews.com/begin.html Do start there and work through it. At all costs avoid the department store telescopes. They are a plague in our science with their cheap, shaky mounts and promises of ridiculously high powers 😉
Coupled with a telescope purchase is the inevitable need for some accessories. I’ll list a few here to consider:
A wide range of good eyepieces. These get expensive but will last a very long time. I recommend three to start, one for low, medium and high magnification. Magnification can be found by dividing the telescope’s focal length by the focal length of the eyepiece. Typical low power magnifications are on the order of 25-30x. Medium: 75-150x. High: 200-300x. One rarely uses the high magnification. Honest!
A good sky atlas. Good ones can be used for eyes, binoculars and small telescopes like these options: Sky & Telescope’s Pocket Sky Atlas – Jumbo Edition and the Sky & Telescope’s Pocket Sky Atlas.
A red-light flashlight. A simple regular flashlight with red cellophane covering is good.
Maybe even a subscription to Sky & Telescope Magazine or Astronomy Magazine. These help the newcomer by projecting what good targets will be available in future months.
Those looking up at the sky through late November to late December are in for a real treat, a close conjunction of Jupiter and Saturn. This is quite an event! It will be easily visible to those with or without optical aid. It takes place early in the evening, so even those who go to bed early can enjoy. All you need is a clear early evening and a low horizon to the southwest. Here’s a short video to show you more. Enjoy!
Last night’s target now processed… stage 1…. the initial offering. Sometimes I remain happy with the first edit, sometimes not. This is NGC6888, the Crescent Nebula in Cygnus. The central star is known as a Wolf-Rayet star, WF 136, which is massive and rapidly shedding its outer laters into the surrounding interstellar medium. This whole system is about 5000 light-years distant and about 25 light years across. This image was taken with our 0.7m telescope through several filters: Luminance is a combination of one hour of clear plus one hour of Ha. The color data was taken using Ha, SII, and OIII narrowband filters.
Yesterday the concrete for the telescope’s pier was poured. What an exciting moment in this telescope’s history. The contractors used a very large Sonotube held rigidly in place with a temporary framework of wood and cables. Internally there is quite the framework of rebar to help reinforce the pier’s strength. A few conduits were also placed inside for electrical and data lines which will drive the telescope. Images (click on them to enlarge):
A view of the building’s site with the framework around the Sonotube for the pier.
A closeup of the pier near the completion of the pour.
This will likely be a series of posts involving some very exciting news here at the observatory: We are adding a new observatory building complete with dome and telescope! Very much exciting times! The new structure will be 16’25’ in dimension with a 16′ diameter dome on the south side. The interior will be divided into two sections: the telescope/equipment room and the control room. A wall with large glass window will separate the two so that people can work with low-level red lighting while keeping the telescope and its sensitive instrumentation in the dark and away from the heat of humans which can cause disturbing air currents.
Artists Impression of the 0.7m Telescope Dome.
The telescope is a PlaneWave 0.70m diameter modified Dall-Kirkham optical system with two ports. One port will hold a CCD imager with filter wheel. The other will attach to a fiber-fed echelle spectrograph. It is difficult to imagine the scale of such an instrument. The telescope alone weighs over 1500 pounds! For a comparison here I am standing besides the same model of instrument at a recent American Astronomical Society meeting.
Ground breaking started a couple of weeks ago. Concrete pouring started today for the pier footing and the footing for the building’s foundation. This will help give a sense of scale the final structure.
The boundaries of the structure have been posted here with wooden stakes. The ground is being prepped to dig for the base level foundation.
The gravel base for the concrete has been laid here. Looking closely you can see the inset region in the gravel where the pier for the telescope will rest.
The initial concrete pour which took place today. The central region is the base for the telescope pier. The surrounding is the base for the building’s foundation.
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).
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:
Partial eclipse starts
Total eclipse starts
Total eclipse ends
Partial eclipse ends
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.
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: