Wednesday, March 13, 2013

Group Portrait!

Today was the big day - Comet PanSTARRS (C/2011 L4), newly seen above our northern hemisphere horizon, was being passed by the crescent moon, making an interesting photo opportunity.  I've found that the best way to do a composition like this is to add something of interest to the celestial sights.  Hmmm, let's see, what is to the west of Tucson???  Oh yea, where did I start work over 3 decades ago when coming to town, and where do I continue part time???  Yea - Kitt Peak National Observatory!  Since the comet/Moon conjunction would happen during twilight, having a silhouette of the Observatory might be pretty cool!  The plan was to head west of Tucson on Ajo Way, highway 86, then head south from Three Points towards Mexico on 286.  About 12 miles should put me directly East of Kitt Peak, about the right spot.  Because the highway is mostly north-south, once the targets were spotted, I could adjust my position as needed for perfect alignment.  The road is pretty desolate, only used by a little ranch traffic, and a Border Patrol truck every 5 minutes it seemed.  They even stopped to see what I was up to - waiting for a marijuana drop?  Naw - just lookin' for a comet!  The mountain in the distance is Baboquivari, located about 15 miles south of Kitt Peak.
Arriving well before sunset to scout out a spot (lots of wide spots from Border Patrol trucks doing quick U-turns!) I had time to set up the William Optics 11cm triplet scope to do a panorama of the Observatory profile.  Since the sun was setting nearly behind it, I had to wait for the sun to dip behind the Quinlans to cut out the glare.  The panorama shown at left, the profile pretty matching the orientation as seen from Tucson - the solar scopes at left, the 4-meter at far right with the U of A's 90" in the valley just below it to the left.  A shot of the setup with Melinda's camera is at right, zoomed into the image of the Solar Telescope.
Finally the sun sank below the mountainous horizon and eventually the Moon popped out.  Oops - a bit too far north, so headed south a bit more, another stop and look, and moved back a bit to split the difference.  To catch the Moon, Comet and Observatory, the 70-200 zoom seemed about perfect, and ended up shooting all of the conjunction with that setup on the ole' Byers Cam-Trak, the little 80's vintage equatorial mount for tracking, in case I needed to expose more than a couple seconds.  Finally it was showtime!  Shooting against the twilight with the background changing in brightness as it got darker made life difficult, so with the ISO at 400, I started at 1 second at F/4, finally getting down to 2 seconds wide open at F/2.8 before the pair set.  I took some data sets that can be made into a time-lapse if I want to do the work - we'll see.  The photo at right was taken w/Melinda's camera and semi-normal lens as my camera was working.
Already tonight I've seen about a dozen pictures of the Comet/Moon conjunction, if not more, but what no one has mentioned is that there is another bystander in the group shot - Uranus!  I noticed on some of the comet positional maps that besides the Moon, it would also pass the gas giant Uranus, and while you might spot it in the left picture above, it tends to get lost when resolution is reduced to fit on a monitor page.  At left here is a full resolution crop from the above picture - Uranus is easily visible below and right of the comet, right between it and solar scope!  And to make sure you don't think I'm pulling your leg, at right is a stack of a dozen (!) frames, stretched to show not only Uranus, but another field star, plotted next to a map of the comet from Heavens-above for the appropriate observation time, rotated to match approximate orientation.  I drew the lines to help you match the pattern.
The Earth keeps on turning, and it wasn't long until the Comet/Moon show came to an end, but taking a picture every 6 seconds, there are lots to chose from!  The image at left is about the last one before the comet sank behind the Observatory.  A few seconds later, the bright nucleus set, but the tail makes it look like a bright searchlight is being used atop the Mountain.
I needed to hustle in to work, so put the gear away in a hurry, but then, after not being under a dark sky in so long, how could I pass up a couple snapshots of the brilliant Winter Milky Way?!  The first shot was at left - the Zodiacal light seemingly to come out of Kitt Peak on the horizon, extending up to the Pleiades and beyond to brilliant Jupiter.  Then at right is the sweep of stars across the southern sky from Sirius and Canis Major to lower left, through Orion near the center, up to the V-shaped Hyades cluster, and on to Jupiter and the Pleiades again.  Both of these are only 30 second tripod shots with a Nikon 16mm fisheye wide open at F/2.8.  Gotta enjoy it while you can!  So I was a few minutes late to work...


John Dolby said...

Dean, that's an incredible piece of work! The universe seems to smile on your amazing talent, brilliant planning, and quality work. Love you, man!

Matthew Parker said...

Beautiful work. Thank you.

Dean said...

Thanks John, Matthew! When complimented at work, I told him that I got lucky. His response: "Luck rewards the well-prepared!". Seems appropriate, somehow... -Dean

Astroweis said...

Hi Dean,

it is so wonderful! Wish, I was back in Arizona for some while. Seems like weather is way better than here.

Keep up your great work!


Unknown said...

Beautiful video sequences of the comet!!!