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Posts from the ‘News’ Category

25
Jul

The July Comet C/2020 F3 NEOWISE: Quite a Show!

Comet C/2020 F3 NEOWISE was definitely the comet of the year, one of the best in a couple of decades. Hovering low in the morning sky before dawn, then, later in July making its evening appearance low in the northwest sky after sunset, it provided hauntingly beautiful views of the night sky. Not much impresses more than a comet with a visible tail.

By July 20th, the comet was easily seen without optical aid, about 25 degrees above the northwest horizon just after sunset when the stars started to come out. It sported a long dust tail: to my eyes it appeared some 5 degrees long, but others were calling for longer, even up to 15 degrees. In either case, it was impressive. In binoculars it gave an even more stunning view. Below is a wide field photo I took of the comet on July 20 taken with a tripod-mounted Nikon D-810 and a 28-300mm Nikkor zoom wide open for 10 seconds at iso 1000. No tracking was used. Click on it for larger image.

Comet C/2020 F3 NEOWISE 20 July 2020

This wide field show is a 10s exposure with 28-300mm lens on Nikon D810 iso 1000.

Desiring a closer look at the details in the comet’s tails, I needed to use a tracking system with higher focal length for better image scale. The best bet for such a large object is a wide field astrograph. I grabbed the Takahashi FSQ-106ED4X, a splendid modified Petzval refractor telescope, and placed it on a portable Losmandy G-8 mount, battery operated, for the field. Attached to this was a Nikon D-810a, the modified version of the 810, allowing more H-alpha light to shine through. Nikon made this camera deliberately for astro-imagers, but this comet doesn’t have a whole lot of H-alpha light to speak of.  I set the system to tracking the stars and had the comet imaged for 1-minute exposures throughout the night at iso 1000, f/5, FL-530mm. By the end of the evening, all the gear was coated in dew except the heated objective lens (phew!) and I had some 30GB of images to deal with.

Once home and slept, the arduous task of slewing through all the images began. There were so many! I culled off the ones that had interference from automobile lights, lasers from people nearby shining them at the comet, kids with flashlights, and airplanes passing through the field. I kept the rest, some 30 near-perfect images. An example here, an unedited 1-minute exposure:

Comet C/2020 F3 NEOWISE 20 July 2020

Unedited 1-minute exposure of the comet.

It’s a very nice image!  The issue is that there is still some vignetting to deal with and some image noise from the heat and readout of the camera’s chip. There is always inherent noise to any digital system, and the solution? Stacking those images together in a median and getting a much cleaner and sharper image. The process is time consuming and CPU intensive, but well worth the effort. Stacking also gets rid of any one-time events like satellite passes (keep reading for more) which streak across the frames throughout the night. Surprisingly there are many. The end result of all the processing is this image below. It pretty much presents a fine portrait of Comet NEOWISE. The dust tail certainly spreads widely throughout the frame, and the blue ion tail is more than evident.

Comet C/2020 F3 NEOWISE 20 July 2020

This was taken through a Takahashi FSQ-106ED4X telescope at f/5. iso 1000 with Nikon D-810a. This is a stack of 30, 1 minute exposures.

What about those satellites? Just how many are flying through all those images? Watch this video to see!

So many satellites!  If you go through this video frame by frame you will also see one frame that has two streaks from a nearby green laser pointer. Alas.

11
Jul

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 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.

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/]

Comet C/2020 F3 NEOWISE Comet C/2020 F3 NEOWISE Comet C/2020 F3 NEOWISE Comet C/2020 F3 NEOWISE Comet C/2020 F3 NEOWISE Comet C/2020 F3 NEOWISE

15
Jan

Betelgeuse is Fading

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 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.

AAVSO V filter light curve of Betelgeuse

AAVSO V filter light curve of Betelgeuse

Where is Betelgeuse located? Here’s a chart as seen from mid northern latitudes tonight at 9:00pm

Orion

Orion with Betelgeuse as it would appear at 9:00pm from mid-northern latitudes tonight (January 15)

3
Dec
2019 Geminid Shower

2019 Geminid Meteor Shower

One of the best meteor showers of the year is rapidly approaching. Peaking on the night of December 13/14, the Geminids put on a good show with peaks averaging at 120 meteors per hour. Now, with the moon being just past full that night, many of the fainter meteors will be drowned out by moonlight. Don’t be discouraged, though: we still expect to see some 30 meteors per hour. The best time to watch? After midnight, usually around 2:00am is best, but you can start seeing them after 10pm easily enough. Gemini will be high in the sky, and the night time side of Earth will be heading into the meteor stream.

The source of these meteors is from asteroid 3200 Phaethon, named after the son of Helios… Phaeton swings very close to the Sun in its orbit, being one of the Apollo asteroid members. Does it pose a threat to Earth? Not for the next 400 years or so, which is as far as our high-level orbital analysis shows. The asteroid has a 30 year orbit… so maybe in the distant future we might have to worry about this one.

2019 Geminid Shower

Looking east at about 9pm local time, the constellations Orion and Gemini will be well above the horizon. Alas, the moon will also be in Gemini and just past full phase. Rather than looking at the moon-lit Gemini, look straight up and all around in the sky for the Geminid meteors.

1
Aug

The 2019 Perseid Meteor Shower is Here!

The Annual Perseid Meteor Shower

Each August, the Earth passes through a stream of comet debris from Comet 109P/Swift-Tuttle.  The comet will not be back our way until 2126… so… I wouldn’t wait up for that one.  Along the orbital path, the comet has left behind small bits and pieces, most no bigger than a grain of sand. These run into our planet’s atmosphere and burn up due to friction. The result of this friction-filled reentry is a meteor, a rapid streak of light through the sky.  This shower usually gives us about 60 meteors per hour at peak, and many fireballs: bright meteors that can even be bright enough to cast a shadow.  How to see it?

  • Pick a clear night closest to the peak, which is on August 11th/12th/13th.
  • Go to a dark sky site: avoid lights and cities. The darker, the better.
  • Bring something comfortable to lie down on: sleeping bags are good.
  • Bring food, drink, and bug spray if needed for your location.
  • Spend the night time hours looking up at the sky! No optics required other than your eyeballs.
  • Avoid lights!  No cell phones. No flashlights. Your eyes take between 30-60 minutes to become dark adapted, and you lose that dark adaptation instantly if you see a light. Avoid lights!
  • The shower appears to come from a spot in the sky in the constellation Perseus. This rises just before midnight, so best observing will be after that, into the morning hours.
  • Have fun!