A picture (or several) is worth a thousand words

I just returned from 3 nights attending to my favorite dark-sky astronomy activity...a new moon trip to Portal, AZ hosted by my good friend Jerry.  Accompanied by several other great friends- and most importantly my son, Ian, this trip was just what the doctor ordered  It had been a long time since we had a father-son trip and it fed my soul to be with him for just a few days.

Despite our best astronomical intentions, we only had one clear night (which was tremendous).  We were instead treated to some intense and dramatic monsoon storms for two days.  Below are several pictures from the trip- so instead of rambling on about spending time with my son and good friends, here are some pictures...

Thursday night thunderstorm- looking north

Same cell, a few minutes later!

After dark, cloud to cloud lightning illuminating the sky with stars in the background

Friday night, a pass of the International Space Station through a hold in the clouds

Clouds did clear somewhat late Friday night, allowing for this shot of the Milky Way

Milky Way at last!  Saturday night was our reward (Horizon is blurred due to tracking on stars)

Looking to the northeast Saturday night, lots of green airglow (which was noticeable to the eye)

 So that is the Portal roundup-  we observed many objects through several telescopes, but the best part was being with great people under desert skies.

Transit of Mercury

Yesterday saw the planet Mercury transit the face of the Sun from our unique perspective here on earth.  Slightly more common than a Venus transit which will not happen again in our lifetimes (see this post and this one as well), Mercury transits the Sun 12 or 13 times each century, always in May or November.  The apparent size of Mercury is rather small against the Sun, approximately 1/5 that of Venus.

We had a few programs running simultaneously yesterday for the transit-  up at the summit of Mount Lemmon the SkyCenter hosted a special program for visitors, and we also conducted an outreach event for students at Canyon View Elementary school.  The Sky School was hosting a group of 5th graders from Canyon View at our mountain based program, where I was operating the telescopes.  I set up at the Babad Do'Ag pullout approximately 2.5 miles up the Catalina Highway where we begin our Sky School programs with an exploration of the concept of a Sky Island.  Mercury began its transit prior to local sunrise and the transit is approximately a 7 hour event. I was all set by 5:30 AM and enjoyed watching the shadow profile of the Santa Catalina Mountains slowly creep across the Tucson basin as the Sun rose.  At left is the Coronado 90mm Hydrogen Alpha telescope we used for visual observation, as well as my 90mm Stellarvue triplet, 2x barlow and Canon 6D that I used to take pictures of the transit.  (Many folks ask about utility of the pink foam...it is simply to shade my camera in the Sun!)

Here are a few of the excited 5th graders observing the transit, I enjoyed the amazement of the student in the grey and red shirt exclaiming "It's so small!!"

I took a large number of images (approximately every 10 minutes until it was over) and processing them will require some time.  I did process one from near mid-transit and it is presented below.  As always, click the image to enlarge it and if your browser automatically re-sizes images you may need to click it again.

So there you have it- a fun and science filled day sharing the wonders of our Solar System with a group of our future scientists and leaders!

KPNO Sunset timelapse

Inspired by several time lapse videos that I have seen of astronomical events, (including this one by Dean Ketelsen made last week) I pieced together my version of the sunset which silhouetted Kitt Peak National Observatory yesterday evening.  See my previous post for more details...and it will look better if you watch it on YouTube and change the setting to 1080 HD...

Giant Magellan Telescope mirror 3

Image Credit Dean Ketelsen

Working in education and public outreach in the Department of Astronomy's Steward Observatory at the University of Arizona, I try to keep abreast of the remarkable work that happens at the department's Mirror Lab (or SOML as they call it).  The mirror lab is the only facility of its kind in the world, where we cast and polish mirrors for the worlds largest (such as the Large Binocular Telescope - LBT) and next generation telescopes (such as the Giant Magellan Telescope - GMT).  Currently the 3rd off-axis mirror for the GMT is in the oven, and the glass is approaching/passing melt-point as I write this.  (EDIT: Glass is now melted and smoothing.)  Each of the mirrors for the GMT is 8.4 meters across and in total seven mirrors will work together forming a single mirror over 25 meters in diameter!

After extremely careful inspection, the glass chunks were loaded into the oven a couple weeks ago around the custom built mold, and this past Monday the oven was turned on.  Long time SOML employee and the inspiration for this blog, Dean Ketelsen published a report documenting the casting preparations which I would recommend and can be seen here.  Temperatures have been ramping up over night and maximum temperature of 1165 degrees C will be between 10 and 11 PM local time tonight.  Already, the glass has melted, acquiring the consistency of honey and running down into the mold.  As the oven continues to heat up and rotate at almost 5 rpm the surface will slowly smooth out and the glass will become clear.  Early in the hours of Sunday morning the furnace will begin a slow cool down (continuing to rotate) and around Thanksgiving the mirror will be revealed.

There are several cameras inside the oven (remarkable in and of itself!) that are taking pictures in order that the process can be closely monitored.  Below are images from various temperatures which give you peek into the formation of the mirror, and the changes that occur at increasing temperatures.  You can see subtle changes even between the images from 892 degrees and 900 degrees C as the glass is noticeably transforming from its slumped state to melting.  I'll post a couple updates later today if I have time with pictures later in the process.

Camera 7 showing the edge of the mirror - click the images to enlarge them:

499 C

750 C

892 C

900 C

922 C

934 C

Shifting to camera 5 as the image is clearer...and the glass is now smoothing

990 C

Camera 3 showing a wide angle view at similar temps to above - click the images to enlarge them:

499 C

750 C

892 C

900 C

922 C

934 C

At this point the glass is now smoothing and you can see the reflection of the furnace top in the surface, as well as the very nice honeycomb structure of the mirror mold.

990 C

1012 C

At 1028 degrees C now, you can see the air bubbles that are rising up through the glass as it continues to smooth.

1028 C

UPDATE- 10:25 PM local time (MST) the furnace is now nearly at "high fire" maximum temperature.  You can see in both the edge view and wide view that the glass is clear and smooth.  At 1160 degrees Celsius, the furnace is only 5 degrees from its top temperature.

1160 C

1160 C

This is a short video I shot last year while the furnace was rotating during the high fire day for the second GMT mirror.