Wallpaper Wednesday

27 09 2012

Gemini North with Southern Star Trails. Image credit: Gemini Observatory

I completely forgot yesterday was Wednesday. Rather, I remembered, but only as “Today is Wednesday, the day I talk to my developmental editor,” not as “Today is Wednesday, the day I remember that I have a blog I’m supposed to update at least once a week.”

It’s just as well I missed my regularly scheduled update because now I can write about yesterday’s press release from Gemini Observatory. The observatory announced that its astronomers have produced the sharpest image yet made using ground-based (Earth-based) instruments of Pluto and its largest companion, Charon.

Speckle image reconstruction of Pluto and Charon obtained in visible light at 692 nanometers (red) with the Gemini North 8-meter telescope using the Differential Speckle Survey Instrument (DSSI). Image credit: Gemini Observatory/NSF/NASA/AURA

The pixelated image might not look like much, but as the press release noted, it’s “the first speckle reconstructed image for Pluto and Charon from which astronomers obtained not only the separation and position angle for Charon, but also the diameters of the two bodies.” That’s pretty exciting—if anyone has tried to sell you the diameter of Pluto recently, he or she should have prefaced the number with the word “about.” Astronomers have been setting upper limits on the diameter since Pluto’s discovery in the 1930s (the 1960s seemed to be a particularly fertile decade for arguments on the topic), but still qualify their assertions with “± 20km”. I’ve been looking forward to the New Horizons arrival at Pluto in 2015, but the Gemini announcement makes the wait a little less painful.

Of everything I’ve read today, the comment I enjoyed most was made by Elliott Horch, coauthor of the Gemini study:

This was a fantastic opportunity to bring DSSI to Gemini North this past July. In just a little over half an hour of Pluto observations, collecting light with the large Gemini mirror, we obtained the best resolution ever with the DSSI instrument—it was stunning![1]

First, you gotta love the enthusiasm. I recently heard an NPR story about the development of robotic intelligence. The claim was that one day, humans would stop experiencing the “A-ha!” moment because robots would do all our thinking for us. I’m guessing Elliott Horch wouldn’t agree with that premise.

Second, the comment about “just a little over half an hour” caught my attention. It’s a little misleading, of course. As Horch knows, since he was in charge of the project to develop the instrument, hours and hours and hours went into the design and installation of the Differential Speckle Survey Instrument (DSSI).[2] But then again, this is how contemporary astronomy works: you request a time slot on a popular instrument and pray the weather, the instrument, and everything else in the universe that can affect your project goes the way you want it to go. Sometimes you get an entire evening with an optical instrument, sometimes you get a few nights, sometimes you have to change your project because there’s no open time available at all. When everything works out, well, then  you see Charon and Pluto.

Today’s wallpaper celebrates the Gemini/DSSI/Korch team victory. Click on the observatory and star trails to reach the download page.


[1] Gemini Observatory Takes Sharpest Ground-Based Images Ever of Pluto and Charon (redOrbit.com)

[2] DSSI was installed temporarily at Gemini North last summer. It’s spent most of it’s observing life at Kitt Peak.

Wallpaper Wednesday

25 01 2012

LGS System on Mauna Kea Sky, Gemini Observatory. Photo credit: K. Pu'uohau-Pummill/Gemini Observatory

Today’s image of the Laser Guide Star of Gemini North makes a sweet wallpaper. Peeking in from behind the LGS system is the sky over the island of Hawaii and, yes, the moon! Click on the image above to connect to the wallpaper download page.

Wallpaper Wednesday

24 08 2011
Gemini North Waking Up

Gemini North Waking Up. Photo credit: Kairyu

Here’s a daytime photo, to complement one of my all-time favorite night-time images of Gemini North, Mauna Kea, Hawai’i. Click on the image to download the wallpaper in various sizes, including those meant for mobile devices as well as desktop computers.

Quasars, ESO VLT, UKIDSS, and more

4 07 2011
Paranal Platform, home of the ESO's VLT

Paranal Platform, home of the ESO's VLT. Photo credit: ESO/H. H. Heyer

The FORS2 instrument on ESO’s Very Large Telescope (VLT). Gemini North. UKIDSS. Astronomers in Germany. Astronomers in the United Kingdom. Astronomers in Hawaii. A quasar with a mass two million times that of our Sun. That’s the short version of the story. The slightly longer version runs something like this:

The European Southern Observatory is home to the VLT and its array of (mostly) optical instruments. Among those instruments is FORS2 (FOcal Reducer and Spectrograph), a visible-spectrum imager and low-resolution spectrograph.* For the past five years, German astronomers working through the ESO have been searching for a quasar with a redshift higher than 6.5. The higher the redshift, the more distant the object; the more distant the object, the closer the object to the originary moment of the universe. Until recently, the most distant quasars we’ve observed have had redshifts of approximately 6.4.** This means we’re seeing these objects as they were about 870 million years after the Big Bang. We know there are more distant objects out there, but they can’t be viewed with instruments tuned to the visible spectrum. They’re simply too far away; by the time the radiation from these objects reaches us, it’s been so stretched by the expansion of the universe, it can only be detected in the infrared.

Enter the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS). As its name implies, UKIDSS is a consortium of astronomers working together to conduct infrared surveys of the sky using the Wide Field Infrared Camera (WFCAM) on the UKIRT on Mauna Kea. Imagine the celebration when the team discovered a quasar with a redshift of 7 (actually, 7.085±0.003). Now known as ULAS J1120+0641, this new quasar shows us the universe only 770 million years after the Big Bang—100 million years earlier than previously measured quasars. If those numbers aren’t big enough to give you pause, here’s another one to consider:  it took 12.9 billion years for the light from ULAS J1120+0641 to reach us. That definitely qualifies as far, far away.

But the story’s not quite over yet. Before announcing the quasar’s discovery in the journal Nature last week, the research team conducted some follow-up observations at the VLT and Gemini North to confirm the object’s distance from us. I could type for ten more minutes, but that still wouldn’t give me enough time to list all the groups and countries contributing to the VLT and Gemini Telescopes (and my typing speed is quick). I know I’m supposed to be in a state of sadness over the end of the U.S. space shuttle program, and I am, but I’m also heartened daily by the incredible successes of these multi-national, multi-agency, multi-interest projects.

The ESO has made the letter describing the discovery available in .pdf form in its public archives.

* The design of FORS2 and its now-retired twin, FORS1, happened by joint effort of ESO, Landessternwarte HeidelbergUniversity Observatory Göttingen and University Observatory Munich.

**The quasar CFHQS J0210045613 has a redshift of 6.44; SDSS 1148+52513, a redshift of 6.42; and CFHQS J2329+030114, a redshift of 6:42.

Wallpaper Wednesday

29 06 2011
Laser and Star Trails over North Gemini

Laser and Star Trails over Gemini North. Photo credit: Gemini Observatory/Joy Pollard

Today’s wallpaper features Gemini North, the Mauna Kea branch of the Gemini Observatory.  Like Gemini South on the summit of Cerro Pachon in Chile, the observatory at Gemini North houses an 8.1-meter diameter optical/infrared telescope. Together, North and South are capable of surveying the entire night sky with an array of instruments.

In addition to star trails, the image above shows the trace the Laser Guide Star (the LGS creates an “artificial star” which is used as a reference source for the  adaptive optics systems of the telescope’s various instruments) created on May 21, 2010.  If you’re looking at the high-res wallpaper, you can see a similar LGS trace from the W. M. Keck Observatory in the lower left hand corner of the photo. The bright, wide streak at the far left of the image is the moon’s trail. Several other Mauna Kea observatories and telescopes are also visible in the high-res image.  From left to right, they are: the Subaru Telescope (looks like a tube set on end), Keck (the twin domes), NASA IRTF (behind which can be seen the peak of Haleakalā on Maui, rising from the clouds), and CFHT (just behind Gemini North).

Observatories and Instruments