Apr 24 2022

The Active Sun

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.

White light image of the Sun using Baader solar wedge and TV-85

Feb 6 2022

Extrasolar Planet Transits: A Proof of Concept

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!

Rc Magnitude vs Time (J.D.) for the transit and the check star.

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.

Jun 10 2021

10 June 2021 Annular Solar Eclipse

From NH this was a partial eclipse, but we had good weather and the opportunity to watch the sunrise with the eclipse already in progress. The choice location was one of many spots along the NH seacoast. We chose North Beach in Hampton which had easy to reach parking and plenty of locations to settle a tripod, telescope and camera.

Brought to the event was a Questar 3.5″ telescope with full aperture solar filter for visual use and a Nikon D810, 500mm telephoto and full aperture solar filter for video and images.

We arrived just after 4:15am EDT: nobody was there! Just us, the stars and the eerie red glow to the northeast. Jupiter and Saturn gave us wonderful pre-sunrise views through the telescope as we waited for the sun to get above the horizon. People started to arrive at about 5:00am. By 5:15am the lot was full. Clouds? Oh yes, there were clouds throughout the entire event, but we still had great chances to see and photograph the event. Here are some to enjoy:

Mar 5 2021

The Orion Nebula: Star Forming Region and Splendid Winter Target

The Orion nebula, also known as Messier 42 (M-42), is one of the most splendid winter deep sky targets for amateur astronomers. It can be seen as a faint fuzzy patch for those of us with excellent vision, just below the three belt stars of the constellation Orion.

In binoculars this patch of light shows some sweeping details and groups of stars surrounding the area. Through a modest telescope, the details do start to pop out, and if using a telescope of 16 or more inches in diameter, you will start to get hints of greenish color when viewing through an eyepiece. Unfortunately, the human eye is not the most sensitive to the red light that excited Hydrogen gas gives off (656.3nm), and the Orion Nebula outs out a lot of its light at this wavelength. As a bright nebula, it has become a favorite target for budding astrophotographers: even a small telescope and short exposures of a minute or so will show some very satisfying detail. Here is a color image of M-42 taken with the school’s Takahashi FC-125, a 125mm (5″) diameter refractor. The camera was a Nikon D-810a DSLR, their version of the D-810 but without their IR blocking filter. This allows a much higher sensitivity to the Hydrogen emission lines at 656.3nm. The “a” means astronomy in Nikon lingo. This image is constructed with three separate 60 second exposures, cleaned up by removing bias, dark and flat fields, then merged together to show the bright inner details along with the fainter outer regions of the nebulosity.

The nebula itself is some 1344 light-years from our Solar System and is about 24 light-years across. It is a well studied star forming region, with some of its young stars forming protoplanetary disks, the precursors to solar systems.

Dec 23 2020

Jupiter/Saturn Conjunction 21st December 2020

The date has come and gone, but the weather was the trickiest part of the event: we had a large cloudy set of systems across much of the northern portion of the USA, though we had almost exactly 30 minutes of clear skies here in Exeter, NH to see the conjunction in all its glory before the clouds then fog took over the evening.

Arrival at the observatory is something I just do, especially when there is an interesting or important event taking place. The day had been solidly overcast, but I was keeping watch on the NOAA GOES-East: Sector View site to see if any clear regions were headed our way. Sure enough, there was a parting in the clouds, about the width of Massachusetts, headed towards us from the southwest. I set up the camera and the telescope in the dome, pointing them both at the correct location… ready for that clear sky moment! Sure enough, the sky did clear!

Setup next to one of the observatory domes, the wide field view was lovely. With good vision, one could easily separate the two planets, Jupiter the brighter of the two, and Saturn the fainter. Here is a photo taken with Nikon D-810 and a AF-S Nikkor 1:3.5-5.6 28-300mm zoom lens, one of my favorite go-to travel lenses. The system was on a stable tripod and time-delay release was used on the shutter to prevent vibrations. The inset image is the telescopic view of the planet pair.

Moving inside the dome, I had the Takahashi FC-125 refractor setup with a Nikon D-810a at prime focus. This stem is very stable, driven on a Paramount Me and protected from the wind. Here are a couple of images taken through the telescope, one long exposure to see Jupiter’s and Saturn’s moons, and another to see some planetary detail. The seeing conditions were atrocious this evening, so no detail was really seen on Jupiter, alas. Saturn’s rings were readily visible, though.

Below is a long exposure image of the scene with all the objects labeled for identification. Those objects labeled “HIP #” are stars that happen to be in the field of view.

Below is an image from within the dome, a view looking along the telescope out the dome aperture where the conjunction was easily seen. This photo was taken with an iPhone. The insert is the telescope’s view. You can also see the incoming clouds from the southwest which were headed to interfere with our observing plan in the very near future.

Not some 10 minutes later, this is what the observatory site looked like: a foggy mess. Only the first quarter moon was visible through the fog and clouds.

Nov 28 2020

Telescope buying?! Wonderful!

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.

Stay well and enjoy clear skies!

Nov 25 2020

Jupiter and Saturn’s Big Month Together: 2020 December

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!

https://youtu.be/rKwFqnVdKiM

Oct 18 2020

NGC 6888: The Crescent Nebula

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.

Jul 11 2020

Comet C/2020 F3 NEOWISE the July 2020 Surprise

This has been quite a year. Now, add to this a bright new comet, and it gets a little better, yes? Comet C/2020 F3 NEOWISE: Named after the Wide Field Infrared Survey Explorer’s asteroid hunting mission [https://neowise.ipac.caltech.edu/], this comet has become visible to the unaided eye, and, for now, is a morning object rising just before the Sun in the northeast sky. By the week of July 13^th, the comet will be more of an early evening object, and it should also be getting fainter as it heads both away from Earth and the Sun.

Weather here in New Hampshire is not forgiving to astronomers. In July we typically have high humidity and heat. Add to that some vertical temperature instability, and thunderstorms will be the rule followed by wet foggy mornings once dew point is reached. We did have one clear morning this week, and that allowed for some quick imaging of comet NEOWISE. Be sure to click on the images to see in larger format.

Equipment used:

Nikon D-810a with 28-300mm zoom lens at 150mm at f/3.5 and Optolong L-Pro light pollution reduction filter.
Nikon D-810 with 300mm telephoto at f/4.
Tripods with slow motion controls: untracked.

Those looking to spot the comet should bring with them a pair of binoculars and the information provided in this article from Sky & Telescope. Be sure to find a viewing location away from ground fog, and with a low horizon. A Bright New Visitor: How to Spot Comet NEOWISE [https://skyandtelescope.org/press-releases/new-bright-visitor-comet-neowise/]

Mar 28 2020

Spring is a Time for Galaxies

As the winter milky way begins to set in the west, the spring time constellations bring views into the deeper universe, much more distant than the local open clusters and nebulosity of winter skies. Last night was particularly clear and offered an opportunity to visit Leo and Virgo to see some of the brighter galactic neighbors and also something much more distant. Here are some of the images taken with the 0.7m telescope, including shots of the most distant objects we have imaged to date. To view these images well, you might elect to reduce your room lighting and adjust your monitor to see fainter shades. All the images are monochrome luminance shots. No color this time.

M-65. A spiral galaxy 35 million light-years away. Part of the Leo Triplet with M-66 and NGC 3628.

NGC 3628, an edge on spiral galaxy in Leo about 3 million light-years away.

Barred spiral galaxy M-95. This is about 33 million light-years away and was discovered by Pierre Méchain in 1781.

M-96, a spiral galaxy in Leo some 31 million light-years away.

A galaxy trio: M-105, NGC 3384 and NGC 3389., all about 35 million light-years distant.

What follows is a two-image focus on Messier 87, a large elliptical galaxy in Virgo. This one has been in the news quite a bit for the recent work done with the Event Horizon Telescope to image the region immediately surrounding M-87’s central supermassive black hole. This black hole also is the cause for a large apparent superluminal jet (relativistic jet) of material being ejected from the galaxy at very high speeds. The first image is a wide field view. There are many other galaxies in the image, all part of the Virgo Cluster of galaxies. The second image is a close-up of M-87 showing the relativistic jet radiating out to the lower right of the galaxy’s core.

Wide field view of M-87 and surrounding galactic neighbors.

M-87 detail showing the relativistic jet.

Would you enjoy an annotated edition of the M-87 Region? Here it is! As many galaxies as could be ID’ed have been labeled.

M-87 Annotated Region: Click to see in larger format.

3C_273 (star like object left-most of the central triangle of objects): one of the brighter nearby quasars in Virgo, this object holds the record for most distant object yet seen by the 0.7m telescope. It resides some 2.4 billion light years! As it is so luminous, it is not a difficult object to image, even with small telescopes, but is it fun to note that we are seeing such ancient light from the immediate surroundings of a black hole 2.4 billion light-years away!Can’t find it? Here it is again with markers:

ExeterAstro

Astronomy at Phillips Exeter Academy