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.
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 13th, 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.
- 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/]
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.
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.
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.
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:
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 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 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!
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.
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.
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 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.
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:
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.
For an annotated picture:
There has been a lot of buzz on the net about the star, Betelgeuse, Alpha Ori… the red supergiant in Orion’s shoulder (or armpit as people might prefer). It is a well known, bright red, supergiant, and it is a well known variable with a long period. Of late, it has been fading rather unusually for its regular patterns of ups and downs in brightness. This fading has everyone charged up…. you see, the star is old, near the end of its life. Stars of this high mass are supposed to supernova… BOOM! The trick is to know when. We have little idea on that, so any changes seen in stars like this make us get realllllly focused. Below is a snap of the latest observations of Betelgeuse’s brightness in V taken from the AAVSO. You can go see this data for yourself at http://www.aavso.org, and entering “Alfa Ori” sans quotes into the “Pick a star” field on the lower right of the page. Select plot light curve after that.
Orion with Betelgeuse as it would appear at 9:00pm from mid-northern latitudes tonight (January 15)
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!
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.
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.