On the Trail of Stars in Arizona

Arizona’s motto is the Canyon State – which is great. Canyons are cool. It’s also an astronomer’s dream. They sky is clear much of the year, and many areas are at a high elevation, too. Several prominent observatories are located in Arizona.

In May 2013 I took a week’s vacation in Arizona, with seeking out some astronomy opportunities high in mind. I will describe some of my other trip events in other posts. In this note, I thought I’d pass along results of my first couple of nights taking photos of the night sky near the wonderful Bed & Breakfast I stayed in, Down By The River. The B&B is in Cochise County, south and east of Tuscon, and as it’s in a rural area the sky is lovely there. The hosts, Mike and Angie, provided me with an amazing stay in their lovely inn. Highly recommended! http://downbytheriverbandb.com/

Here are a few of my early results.

A Couple of Individual Exposures

Scorpio rising over the BBQ. At the back of the Down By The River B&B, south of St. David, AZ.

On the evening of 29 May, 2013 three planets were in close alignment at sunset:

Mercury (top), Venus, and Jupiter together just after sunset on the evening of 29 May 2013. South of St. David, AZ.

A Stacked Star Trail Image

I love making star trail images. On the night of 29 May I was able to capture a fairly good series of 52 exposures, 30 seconds each, with the camera pointed just east of north:

A 27 minute star stack image taken from south of St. David, Arizona, on the evening of 29 May 2013. A total of 52 individual images, each 30 seconds long, were stacked together using StarStaX, a free program. Taken with a Nikon D800 and 24-120 mm lens at 24 mm, ISO 1000, f/3.5. I was having a little trouble getting the internal timer on the camera to work, so this series was taken by hand with a cable release. This copy is reduced down in size by about 90% in both directions. See below for a cropped portion at the original resolution.

The area around Polaris itself. Note that the centre of rotation is not right on the north star – the pole is a little less than one degree to one side of it. This section of the image above is cropped down to 800 pixels wide, showing the detail on the original image.

“Red, White, and Blue.” A little playing around with colours, brightness, and contrast on the image above. Sort of the Time Tunnel meets Van Gough.

I’ll post more as I’m able to catch up with things!

Copyright © 2013 David Allan Galbraith

Messier 27 – the Dumbbell Nebula

Space is full of interesting objects. We often think of stars and galaxies, but there are other kinds of distant objects that have been discovered over the past 250 years. In 1764 the French astronomer Charles Messier found a whole new class of objects. He was hunting for comets, and had started to create a list of things in the sky that might look a little like a comet, but which didn’t move. The list, now known as the Messier Objects, was originally intended to help him and others find comets by confirming which things viewed though telescopes weren’t actually comets.

Nearly 250 years ago, he turned his telescope to the sky and found something he catalogued as the 27th object in his list. For some time the telescopes available showed objects like M27 as looking a bit like the distant, outer planets in our own solar system, and they picked up the general name “Planetary Nebulae.” Just what they were wasn’t explained for another century, when William Huggins was able to look at the light from one of these fuzzy, roundish objects. Through spectroscopy he realized that he wasn’t looking at light being reflected from an object like a planet, or light from a hot luminous object like a star, but light being generated by excited gasses.

Planetary nebulae are now known to be the spectacular remnants of a star that is throwing off vast quantities of gas late in its life. Some of them appear to be shedding multiple shells of gas. In the case of Messier 27, also called the Dumbbell Nebula, researchers have estimated that the bright gas we can see with telescopes likely was emitted from a star in the centre of the object about 10,000 years ago.

In early May 2013 I decided to try using the University of Iowa’s Rigel telescope at the Winer Observatory, southeast of Tucson, Arizona (http://www.winer.org/) to image M27. This telescope can be used by anyone over the Internet on the Sierra Stars Observatory Network (http://www.sierrastars.com), and I’ve been experimenting with it for the past few weeks.

To take an image of Messier 27 I first programmed the telescope to take a single shot of the nebula for 150 seconds, to get a feeling for exposures, which the telescope captured early on the morning of 7 May 2013. M27 is quite a bright object, and many people have fun finding it with a small telescope. It has a magnitude of 7.5, meaning that it’s just below the limit of objects you can expect to see on a dark sky with your eyes, but it’s well within the expected range of objects to see with a modest amateur telescope or binoculars.  It’s in the Vulpecula constellation (“the little fox”) just south of Cygnus, the swan. The 150 second exposure wasn’t overexposed for the nebula, and in fact looked a bit faint, so I decided to take a series of 300 second images. I set the telescope to take two 300 second exposures with no filter, and two more 300 second exposures with each of the red, green, and blue filters on the system. The images were captured early on the morning of Thursday 9 May 2013. Here’s the result, after combining the “black and white” frames first (“Luminance”) and then preparing the colour information (“RGB”), using free software called Fitswork4:

Messier 27, the Dumbbell Nebular, imaged with the 37 cm Rigel telescope owned by the University of Iowa, located in Arizona (the “Iowa Robotic Telescope Facility” or IRTF). The image was prepared from a series of monochrome pictures taken through colour filters (the “LRGB” process). combined with Fitswork4 and adjusted a bit with Adobe Photoshop Elements.

The Dumbbell Nebula sits about 1,360 light years away from earth, and is about one light-year across. It’s also notable because of the star that remains at its centre: it’s the largest-known white dwarf star.

This first try at M27 is encouraging, but I wasn’t able to get good registration, or alignment, of the red, green, and blue frames. As a result the colours I was able to produce in the combined image are a bit off. If I can improve the registration process the image should be a bit better. I need to do some more work on my “workflow” to process image files once I have them.

For more information on M27, check out Wikipedia: http://en.wikipedia.org/wiki/Messier_27

Copyright © 2013 David Allan Galbraith

A Quick Look At 1 Ceres

Is it a giant asteroid? Is it a dwarf planet? Is there a difference?

1 Ceres has been classified as both. Ceres is the largest object in the Asteroid Belt between Mars and Jupiter – something like 900 km across. We will get our first really good look at it in about 2 years when NASA’s Dawn spacecraft arrives in its orbit. It was in fact the first “asteroid” discovered, in 1801. It ranges from magnitude 7 to 9, so is almost never visible to the unaided eye, but it’s also pretty easy to find with most telescopes.

I thought I’d take a look using the University of Iowa’s Rigel telescope in Arizona, using the web-based Sierra Stars Observatory Network. Here’s a shot of 1 Ceres captured during the night of 1 May 2013. Ceres is the bright “star” in the middle of the frame. It’s so bright (around magnitude 8) that it’s actually quite overexposed on this cropped image. The image here was made by stacking three 150 second exposures.

The dwarf planet 1 Ceres photographed early on the morning of 1 May 2013 using the University of Iowa Rigel Telescope in Arizona. Ceres is the brightest object in this image, in the centre of the frame. It’s so bright compared to the many background stars that it’s actually over-exposed here. A composite of three stacked 150 second exposures without filters taken with the 31 cm robotic telescope, over the Sierra Stars Observatory Network.

The particulars from the FITS file of the first of three images taken by Rigel:
DATE-OBS= '2013-05-01T03:25:00.311' / UTC, start of exposure
LST     = '10:39:31'           / Local sidereal time at exposure start
POSANGLE= '  70:48:39'         / Position angle, degrees, +W
LATITUDE= ' 31:39:56'          / Site Latitude, degrees +N
LONGITUD= '-110:36:05'         / Site Longitude, degrees +E
ELEVATIO= ' 38:22:26'          / Degrees above horizon
AZIMUTH = '283:31:10'          / Degrees E of N
OBJRA   = '  6:39:18.3'        / Target center J2000 RA
OBJDEC  = ' 28:48:59.6'        / Target center J2000 Dec

 

Copyright © 2013 David Allan Galbraith