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!

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:

Dec 27 2019

The Dome Works!

Not a surprise at all, but we now have a rotating, opening and closing dome! Next steps are to putty in the weather seal along edges, and it will be complete. The interior of the building is getting walls and paint soon. Lighting and network cabling come next followed by the installation of the telescope by end of January! Stay tuned!

A wide angle look at the dome interior with the lower shutter open.

Exterior view with the lower shutter open and the dome rotated to point north.

All three of the observatory’s domes visible for comparison.

Below: Two short movies of the dome shutter being opened. This is a two-part process with the top shutter opened first followed by the lower shutter which tilts out. The top shutter’s lower edge overlaps the bottom shutter thus preventing weather from getting inside.

Dec 21 2019

There is a Roof and a Dome

Progress has been swift on the construction of the new building. Roofers have installed the waterproof roof layer and sealed around the dome’s base structure (framing). The dome has been built in place, and the shutter also installed. Interior work now progresses with the installation of the walls, trim, lights and such. Remember that for any of the images below, just click on them for a larger view.

Prior to pouring the concrete walkway we were expecting both rain then snow and freezing temperatures. Heating pads were placed to prevent frost on the ground before pouring the cement.

One wall has siding in this image, and the dome opening has been covered to protect the interior from rainfall.

All four exterior walls now have been sided, ventilation louvers have been installed, and the roofers are working on the rubberized layer on top the structure and around the dome, base frame.

Inside the control room, the base bearings of the dome have been unpacked for inspection and comprehension! So many parts are in this package, that it is a little mystifying.

The view of the telescope room through the framed wall of the control room. The window casement has been installed along with initial conduit for electrical. network and telescope control lines.

The dome is almost complete in this image taken at 6:30am with the sun rising. The dome’s motion is smooth and has that familiar rumble to it as it rotates in azimuth on its well-aligned and level bearings.

A wide-field image of the dome interior. Note that edges are a little warped in this image due to the camera’s odd stitching of the frames. You can see the top of the pier and the orange power line system for dome operations which make the system effectively wireless. No wires will be dangling down from above to control the dome’s motion.

Roof is complete. Dome is complete. Door has been installed.

Nov 17 2019

The Structure Takes Shape

This has been an exciting couple of weeks. As we have seen our first frost of the season (no snow just yet!), we have been putting up the frame and the structure of the building. Click on images for full size.

The corners of the building have been placed and the first wall frame goes up.

Work on the wall frames continues. Soon after this they will be sheathed with plywood.

The four walls are up, and the roof’s lower layers have been installed. There is also a ring for the dome.

The entrance to the observatory. Note the walls inside have yet to receive their plywood, and the floor needs to have concrete poured.

A view of the dome base framework from the rooftop. Imagine a large telescope on the pier with a 16′ dome surrounding it. The roof has a slight pitch to allow water and snow to run off to the north.

Another view from the roof. Where is that dome? Here it is! It’s the bundle of materials on the pallet. Some assembly is required. The black mats are covering what will be the walkway to the building.

Oct 31 2019

The Pier is Poured

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.

A wide field view of the site.

Oct 24 2019

0.7m Telescope Observatory Construction Begins

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.

ExeterAstro

Astronomy at Phillips Exeter Academy

Category Tech