ISON – Page 2 – A Darker View

Observing ISON through Perihelion

Plotted below is the path of comet ISON through perihelion. The image is zenith up on the morning of November 28th from the island of Hawai’i. The actual moment of perihelion will be Nov 28.77501UT (18:36UT or 08:36HST).

A few things are notable… The obvious one is how close the comet will get to the Sun. Not just in absolute terms, which is really close. But rather how close it will look to us. The comet will be under 30 arc-minutes from the center of the Sun, recalling that the Sun is about 30 arc-minutes across. The comet will not pass behind the Sun from our point of view. While we may not be able to see it while lost in the solar glare, it will remain in the view of those solar monitoring spacecraft that are near the Earth.

Separation will help in trying to spot the comet during the day. During the 27th, 28th and 29th the comet will be very close to the Sun. On the morning of the 29th the comet will be only 4.5° from the Sun. Best bet to attempt a daytime peek may be on the 30th or later, when the comet will again be more than 7.5° from the Sun. Look for the magnitude estimates and be prepared to give it a look.

ISON at Perihelion — The orbit of comet C/2012 S1 ISON as it passes through perihelion on November 28th, 2013

ISON, Mercury and Saturn in the Dawn

Not quite the dramatic comet in the dawn shot I was hoping for. The comet is just barely able to compete with the dawn glow. Still, a beautiful morning.

Waiting to see what fate holds in store for this dirty snowball as it travels through the hell of the solar corona. I will try another photo session after perihelion.

ISON in the Dawn — Comet C/2012 S1 ISON, Mercury and Saturn in the dawn over Hilo

Photographing Comets in the Moonlight

The Astrophoto Rig — The ZEQ25, TV-76mm and Canon 6D setup and taking photos of comet ISON under the light of a full Moon

Watching for ISON with Cloudcam

Wondering what comet C/2012 S1 ISON is looking like today? There is a very good camera aimed at the eastern horizon from the summit of Mauna Kea. Just what you need to take a look for yourself.

The CFHT Cloudcam is a DSLR camera that is programmed to take exposures constantly through the night. Used by the telescope operators to monitor oncoming weather, the camera shows the sky conditions over the eastern coast of the island and the city of Hilo. The images are live during the night, each morning you can load a timelapse video of the entire night.

The camera has quite a following, quite a few people check the camera constantly. This includes quite a few UFO consipracists. If anything odd shows up on the camera the video quickly shows up on YouTube and linked to postings on the UFO sites. When the launch of a missile from Vandenberg AFB in California created a glowing sphere of light these websites went into overdrive with wild speculation.

Most of the mornings this week have been too cloudy to see the comet. I have been checking the video each day. Currently at magnitude 5 the comet will be a small dot in the imagery. As the comet brightens it should appear nicely in Cloudcam.

Latest Cloudcam Image — The latest Cloudcam image

Comet C/2012 S1 ISON

Dispatch from the Summit – A Cloudy Mountian

Comet ISON is sinking rapidly into the dawn. I have been waiting for a chance to photograph it for a couple weeks now. The gear is ready to go. Any morning that I have had available has been awash with clouds. Not strictly my problem, Keck has lost quite a few nights to weather over the same time period.

Tonight looks to be no exception. We have a number of engineering tests planned for Keck 1, including the first night on sky for a system many of us have put a lot of work into, the TRICK infrared tip-tilt detector for Keck 1 AO. It does not look good.

Update: The night was a complete loss, the telescope never opened.

A Cloudy Mountain — Clouds obscure Mauna Kea on a late fall morning

Comet? Where?

There is one question we all have to ask when a beautiful comet graces the skies…

Comet C/2007 N3 Lulin on the evening of 26 Feb 2009

Where to look?

Like any other solar system object, comets move against the sky. Even worse, when close to the Earth or Sun they can be moving so quickly against the stars that coordinates quickly become out of date. Aiming a telescope using coordinates a day old, or sometimes even only an hour old will result in a view of empty sky. A few stars perhaps, but no comet.

You need a table of coordinated calculated for regular time intervals, an ephemeris. Alternately you need a set of coordinates calculated for the exact time you will be looking.

Continue reading “Comet? Where?”

Preparing for Comet C/2012 S1 ISON

Astronomers, professional and amateur alike, are getting ready for comet C/2012 S1 ISON, possibly the highlight of a year that has already seen several good comets.

Discovered in September 2012 by Vitali Nevski and Artyom Novichonok, of the ISON project, a group of telescopes dedicated to discovering and tracking solar system objects. The comet was then an 18th magnitude object in the outer solar system, an impressive find for a small telescope.

When astronomers first calculated the comet’s orbit they found a surprise. The comet will pass close to the Sun. Not just close, but extremely close! On November 28th the comet will pass perihelion, its closest approach to the Sun. At a mere 1,860,000km (1,150,000miles) this will be a close pass indeed. As perihelion is measured from center to center, the distance is even closer if you consider the 695,500km (432,200mile) radius of the Sun. Subtracting the solar radius you realize the comet will pass a mere 1,165,000km (724,000miles) above the surface of the Sun. At this distance the intensity of the solar radiation will be nineteen thousand times more intense than a sunny day on Earth.

The next surprise was hinted at by the orbital calculations. The orbital solution indicated a nearly hyperbolic path, suggesting that this was a new comet, one that had not visited the inner solar system before. This possibility was strengthened by later observations of the comet.

Continue reading “Preparing for Comet C/2012 S1 ISON”

ISON Webcast

We put it together in very short notice. Fortunately a webcast is pretty easy to put together.

Keck is hosting a sizable team of folks who are here to observe comet ISON. Astronomers from several institutions are participating in the NASA Comet ISON Observing Campaign. They have a total of 6½ nights, but only the last few hours of each night as the comet rises in the dawn. Comet C/2012 S1 ISON is starting to encounter significant publicity, we may as well take advantage of this.

It was a lot of fun. I particularly like the spot (41:00) where I made the mistake of saying spectra were not very pretty to look at in a room full of spectroscopists. These folks love spectra and quickly corrected me, leading to a nice discussion on why spectra are so valuable to astronomy, often more valuable than photos.

The video is embedded below. A lot of good information about comet ISON, indeed about comets in general. Nothing like having a room full of comet experts…

Waiting for ISON

I will probably make my first attempt to photograph C/2012 S1 ISON this coming weekend. A couple reasons for waiting… The bright Moon will have moved out of the morning sky by then. The comet, currently around magnitude ten, is brightening rapidly.

On the other hand the comet is plunging towards the Sun, rising later each day. Wait much longer and the photographic opportunity will slip away, at least until after Thanksgiving, when the comet will again appear after perihelion.

In the meantime, one of my favorite comet photos from years past…