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!

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:

Feb 23 2020

First Light for the 0.7m!

First Light in astronomy is an old tradition filled with all sorts of interesting history. Some first light examples are not the best, while others are just tremendous. Ours was a little of both with the first exposure of the 0.7m telescope to the nighttime sky. Don’t worry! It all turned out just fine!

The vert first exposure of starlight to the telescope was last week: Conditions were good with a nice clear sky and freezing temperatures. The wind was calm. The telescope had never been focused before and had yet to have a pointing solution…. so it really had no idea where it was looking. We decided to aim it in the general direction of Orion and take the first images. Of course, they were blurry. The scope had never been focused before. At this point we got the CCD imager into automatic mode, making it take an image every second, non-stop so that we could run the focuser until we had the images nice and sharp…. out the focuser went, and the star images got smaller and smaller and smaller, then “kachunk!” The focuser had run out of travel, and the star images were not quite in focus yet! The imager was perhaps a few millimeters away from achieving a perfect focus. The good news was that this was more than enough to engage in the time consuming process of collimating the primary mirror. A few hours later we had aligned optics, but we had to order a small spacer ring to push the CCD imagers little further out.

The bright star Betelgeuse just slightly out of focus. Note the doubled diffraction rings around Betelgeuse. Those should be single spikes. The focuser didn’t have enough travel to bring the camera to the needed distance away from the scope. Time to order a part!

The interesting thing about this telescope’s control software is the building of a pointing model. By taking a series of images all over the sky, the software does an astrometric reduction on each image and measures the slight variations in the telescope’s true pointing versus where it thinks it is pointing. This takes care of all sorts of interesting issues: flexure in the pier, telescope and mount, mirror sag or flop (none here!) and general pointing. After some 20 images, we were able to point to any object in the sky and have it show in the images we took… just like that image of Betelgeuse above.

Once the spacer arrived this past Wednesday, we went out to install it and then wait for darkness to arrive. It was a nice clear and very cold night. The goal was to build a large pointing model and take some images of famous deep sky objects. I also wanted to test out a start-up and shut-down procedure that I had typed up earlier in the week. That evening, we started everything up: the dome was homed and set to track the telescope. The CCD imager was on and cooled to -30ºC. The telescope was on, homed and tracking. Would it reach focus! Absolutely! It was spot-on perfect. We then built a large pointing model with over 100 images. Now the telescope would find and center objects of our choosing, and it would track them for better than five minutes without needing any autoguider corrections. This is quite the telescope!

We chose some of the iconic late winter deep sky objects to share with you for official first light. These are all composites of four filters:

Luminance: a clear filter
J-C Rc: which was used as the red channel
J-C V: which was used as the green channel
J-C B: which was used as the blue channel.

The V, B, and Rc filters are Johnson-Cousins photometric filters used for photometry, the science of measuring brightnesses, which can lead to our understanding of an object’s surface temperature and size, among other things.

You might want to dim the room lights to see the details. Also, click on the images to see in a larger format. Enjoy!

The Orion Nebula, M-42, a star birth region about 1300 light-years away. This can be seen with binoculars and small telescopes easily. It was almost too bright for our CCD imager!

M-82, the Cigar Galaxy, a starburst galaxy about 12 million light-years distant.

M-81, Bode’s Galaxy, about 12 million light-years away. This resides very close to M-82.

This is the Crab Nebula, M-1 in Taurus. This is a supernova remnant from a star that exploded back in 1054 A.D.

The next phase of this telescope’s use will be to collect scientific data. We have already taken images of U Gem and V Ori to calibrate our photometry and to see if we can produce good data for scientific publication. It has passed with flying colors thus far!

Feb 18 2020

Telescope Installation

With the building complete, the time had come to install the telescope. Arriving early on a Wednesday morning, whole crews of people came to be a part of the event: the crane operator, the contractor, architect, videographers, students and more! It is not often that one gets to see such a large telescope lowered onto its pier using a crane. Below is a photo journal of that day’s events as well as the following day during which PlaneWave’s engineer, Matt Dieterich, and I spent the day wiring the systems and testing the electronics.

Brian Carmody and Matt Dieterich begin the initial inspection of the dome and pier prior to getting the installation started.

The CDK700 telescope arrives on a flatbed from the storage facility. The crane and operator has already arrived, so things are about to get busy!

The various telescope components were then uncrated while on the truck.

Tethering the telescope’s mount and primary mirror assembly to be hoisted. It was at about this point that everyone’s heart rate went up a little!

The telescope is now airborne, taking a short ride from the truck to the pier within the dome.

With some serious expertise, the telescope was guided gently to the dome.

The telescope being lowered through the dome’s shutter. While Matt (and everyone) looks on.

The sunrise continues while the telescope is gently lowered to the three bolts that will hold it onto the pier.

Slowly, slowly, slowly. Using tag lines, the telescope is kept from swaying or rotating as it is lowered into the dome.

The telescope had to be lowered onto the three pier bolts. Tolerances were to the millimeter!

The telescope’s mount holes aligned perfectly with the pier bolts. Everyone breathed a sigh of relief at the exact moment when the scope landed onto the levelling bolts.

Now it was time to repeat this whole process with the secondary mirror cage and assembly.

The secondary mirror arrives in place and is bolted to the telescope.

Next to install was the telescope’s control system which feeds power, reads encoders and sends commands back and forth through a neat intranet system.

The many components within the control box.

Using a laser mounted onto one of the two Nasmyth focal points, Matt begins initial collimation of the three mirrors. The corrected Dall-Kirkham optical design uses an elliptical primary, a spherical secondary and a flat tertiary mirror.

The many wires routed from the telescope’s interior, to the control box and to the control room computer.

Those same wires, this time a view from the base of the telescope mount. Within the mount are USB hubs, power supplies, and encoder systems. All must be wired correctly to allow proper control and to prevent twisting as the telescope moves in azimuth.

The pirmary CCD and filter wheel installed

The primary instrument will be an FLI CCD imager with a 10-place filter wheel, seen here at focal port #1 attached to the electronic focuser/de-rotator. All of these components are remotely controlled.

Brian, Matt and John: three happy and very tired telescope installers. The end of two days of work. Next steps? Clear skies to collimate and focus the telescope then build a pointing model.

Feb 3 2020

The 0.70m Imaging Train

The soon-to-be-installed 0.70m telescope will not have provision for eyepice viewing. Instead, telescopes of this size usually have an imaging system for collecting image data, among other instruments attached. This telescope will have tow primary instruments attached at its two focal points: an imaging CCD and a fiver-fed spectrograph.

The imaging CCD will be a Finger Lakes Instruments (FLI) PL16803 4096×4096 9μm pixel array (16.8 megapixel array) with an attached 10-place filter wheel system. The CCD is a non-antiblooming gate (NABG) system and is linear for most of its efficiency range. Below is a plot of its quantum efficiency. Given that it cooler can get 55ºC below ambient temperatures, we’ll be operating well below freezing every night, even in the summer. This means less thermal noise and clearer images with better data.

FLI CCD Imager right out of the box.

The filter wheel is a ten-place system, holding 10x50mm square filters for astronomical imaging. In this installation we’ll be using the system mostly for photometric and astrometric work, so the following filters have been installed:

Luminance: a clear filter.
Hα: Narrow band Hydrogen filter.
OIII: Oxygen narrow band filter.
SII: Sulfur narrowband filter.
g’2: The Sloan (SDSS) g photometric filter.
r’2: The Sloan r photometric filter.
B: Johnson/Cousins B photometric filter (Blue).
V: Johnson/Cousins V photometric filter (Green/Visual).
Rc: Johnson/Cousins Rc photometric filter (Red).
One empty filter position just in case 🙂

The FLI CFW-3-10 filter wheel ready to accept filters and the CCD imager.

The CCD bolts right onto the filter wheel, then the whole assembly is attached to the focal plane of the telescope. All of this is controlled remotely using imaging software, in this case MaxIm DL and ASCOM.

Installing all this requires good lighting, a relatively dust free environment, small tools and some time.

The color filters in their packaging, ready to be installed.

Equipment at the ready: it’s time to install the filters.

With clean-room gloves on, each filter is removed from its packaging, then placed into the correct slot with the filter wheel. Two small plastic retainers are then screwed into place to hold the filter wheel in place. The lovely part of this system’s design is that the filters can be installed without removing the filter wheel’s cover. Many others on the market require complete disassembly – not fun.

Should you be interested, some external Links:

Jan 18 2020

A Wide Field Orion Taking on Taurus

Winter is the Orion time…. time to get a wide field camera taking snaps of the winter sky. Here is a wide field frame of Orion with his nemesis, Taurus the Bull. This was a process-image of seven 15-second exposures at f/3.5 28mm, ISO10000, with automatic dark frame subtraction using a Nikon D810a on a tracking mount. Post processing was done in PixInsight to stack the images using median combine, flatten the background, correct color, then crop and save off as a JPG with the correct histogram. Some graininess was removed in Photoshop in the end.

This shows Orion with its definitely-fading Betelgeuse (upper left shoulder), the Orion Nebula, The Barnard Loop, The Rosette Nebula, Sh2-264 (Lamda Orionis Ring) and NGC2175 (upper left). Click on the image for full size.

Orion and Taurus Wide Field 2020-01-18

For an annotated picture:

ExeterAstro

Astronomy at Phillips Exeter Academy

Category astronomy