Twice as beautiful

Alcor and Mizar 

Alcor and Mizar. Pencil on white paper inverted in Photoshop. This is the first
sketch I’d been able to make, in my first observing session for months (due mainly
to bad weather and constant cloud cover). It was made on August 24th, 2007, using
my 4″ refractor, ideal for double star observations. The conditions were pretty
horrible – milky skies and a waxing, almost full Moon.
  Date: 24th August 2007
  Instrument: 4″ refractor
  Magnification: 42x
  Location: My backyard, Isle of Wight, England
  Conditions: Horrible! Waxing, almost full Moon, hazy skies. Not much use for
  ‘proper’ deep sky observing.
  NELM: 5.0
  Notes; A well-known double. A beautiful sight in the refractor

Faith Jordan

Multiple Stars – Split Personalities

Multiple stars 

Due to my newly found enthusiasm for observing, measuring and, of
course, sketching Double and Multiple Star Systems, I’ve decided to
present a selection of some of the most well-known star systems of that
kind.

Clockwise starting in the upper left corner, you will find Mizar and
Alkor in Ursa major, already known since ancient times. The upper right
corner shows Albireo, the indicator of late summer / early autumn and
for many observers one of the best double stars in the sky. The lower
right corner shows Epsilon lyrae, the famous double Double, I got the
proportions wrong there, nevertheless a fascinating sight. Finally, the
lower left corner is a drawing of Alamak in Andromeda, the “Autumn
Albireo”, as many call it, shining in the colors yellow and blue-green.
These four sketches represent the most well-known double stars,
basically any observer knows, however there are many other fantastic and
rewarding Double and Multiple Star Systems out there, so when you are
planning your next observing night, maybe you are going to visit one or two.

All sketches were made with a 6″ Newtonian f/5 at varying
magnifications, the conditions were good, around 6 mag, Bortle 4-5
skies, average seeing, pencil sketches, digitally re-worked.

Don’t forget to click on the sketch, which will take you to a larger
version and a better view!

Sebastian Lehner

Seeing double

Antares 

The goal of splitting the double star, Antares, had been tempting me for a while. I never seem to have the sort of seeing conditions that would make for a nice clean observation of this double. So I gave it a try on this less-than-perfect evening, and was successful in spotting the secondary star with my SkyView Pro 6LT (6″ f/8 Newtonian) at 240X.  Antares’ primary star flickered like a coppery flame in the jumping air currents, so I had to be patient and wait for the ripples of diffracted light to show me the way. The secondary began to coalesce as a consistent lump in the fluttering kidney beans of orange light near the position of the primary star’s second diffraction ring. It’s color was hard to pick up, but gradually, I perceived what looked like a yellow-green tint. To help keep myself honest, I had not checked data on the secondary’s current position angle ahead of time, and it looked to be at a PA of about 280 degrees. Checking Brian Workman’s 
double star calculator a couple days later gave a PA of 277° for 2007.5. The separation comes out to 2.18 arcseconds, which is fairly close for my ‘second diffraction ring’ sighting–that works out to 2.5 arcseconds in my scope.

When preparing my double star sketches for presentation online, I scan my original sketch to use as a template. Using that template, I then recreate the double star components using painting tools in Adobe Photoshop. See my Double Star Digitizing Tutorial for a detailed discussion of the process I use. After preparing that tutorial, I came up with a system for representing double star magnitudes consistently across all my sketches. A discussion of that system can be found at this link.  Although these methods give me a consistent way to present my double star observations, they don’t handle very close doubles well. The proportions compared to the eyepiece field of view are just too tight (a discussion about this issue can be found at this link. Based on suggestions from experienced observers such as Eric Graff and Ed Zarenski, I decided to supplement my sketches of close double stars with an inset graphic showing how the diffraction patterns of the double stars interacted.

This sketch of Antares shows the most extreme example to date of how I’ve tried to convey the highly magnified optical interaction between two closely paired stars. Presenting something this complex was quite a learning experience for me, but I think it does a fairly decent job of rendering what I saw. This can be seen in the detail portion of the sketch. You just have to imagine all of that jumping around and moving from moment to moment. You’ll notice that I was fortunate enough to have the spider vanes in a position that didn’t interfere with the secondary star.

I made three different pencil sketches at the eyepiece, trying to describe how the secondary appeared within the jumping glare of its orange primary. These raw sketches can be seen below (note that they are shown prior to rotating the sketch to my usual position of North up):

Pencil sketches 

When creating this part of the digital sketch, I used a semi-soft paintbrush to plot the position of the primary star’s diffraction disc. I then used the circle selection tool to stroke progressively fainter rings around the primary. I have been using the excellent information from Ed Zarenski’s article “Understanding Resolution” to help me better proportion the position of these rings to the size of the primary star’s diffraction disc. After plotting these rings, I used a soft eraser tool to erase gaps in them to mimic what I had drawn in my sketches. I then came back with a small, soft paintbrush to slightly brighten up the second diffraction ring where I had noted the position of the secondary star. I then used coloring techniques described in the tutorial above to colorize the image.

It really was a beautiful and challenging sight. Watching the colorful light from a distant star give up it’s wave properties as it passes through the telescope and then tempt you to dissect its secrets is an enjoyable task. Give it a try sometime and see if you can identify the secondary in that bubbling mass of starlight. Someday I hope to observe and sketch this duo under much smoother seeing. Full details about the observation can be found here.

Jeremy Perez

Standing On The Shoulders of Giants

Mu Cephei 

µ Cephei: Red Supergiant

µ Cephei, was first discovered by William Herschel and called Garnet
Star, because it appears to shine in garnet red due to its spectral
class of M2Ia. It is the reddest star visible with the naked eye and may
be one of the brightest and largest stars in our whole Galaxy.
It is a Red Supergiant in the last phase of its life, fusing helium into
carbon. Its radius is 1425 times the radius of the sun and it is 38000
times brighter – only thinking about those numbers can do your head in.
Sketching it was easy, however, more than once interrupted by passing
clouds.

Date: November 18, 2006
Location: Erbendorf, Bavaria, Germany
Instrument: Dobsonian 8″ f/6
Constellation: Cepheus
Seeing: II-III of VI
Transparency: III-IV of VI
NELM: 5m0
Magnification: 80x
Technique: pencil on white paper, digitally enhanced in Photoshop

Sebastian Lehner

Little Man Big

Homunculus Nebula 

The Homunculus Nebula is one of my personal favorites when it comes to southern
hemisphere deep sky objects. I was favored with good seeing conditions one evening
and attempted a sketch using a soft lead pencil.

The Homunculus (Latin for “little man”) surrounds the notoriously variable star Eta
Carinae. Using a 4mm Plossl with a twelve inch f/10 Schmidt-Cassegrain (~760X), this
peculiar reflection nebula resembled a pale yellow bipolar planetary nebula. At
times, I thought the bipolar lobes appeared as a weak reddish color but I could
never hold the sight long enough to be certain. The disc was quite irregular in
shape and displayed much subtle detail. Eta Carinae was also of a subtle yellowish
tint. Indeed, Eta is included in the list of “red” stars compiled by George Chambers
back in the late 19th century.

The ASOD drawing was copied from the original sketch using Photoshop. The airbrush,
blurring and dodging tools were used.

Dave Riddle
Smyrna, Georgia USA

A star in the guise of a comet

Hubble’s Variable nebula

Here is a sketch of NGC 2261, the Hubble’s variable nebula.

Some informations :

– Telescope : Dobson Lukehurst 495/2032, Pentax XW 7 mm (x290), no filter.
– Date : 30/10/06, 04:00 UT.
– Place : Nailly, Yonne, France.
– Sky : not transparent (lim. magnitude about 5,0) but with very good seeing.

A draft was made during the observation, then I made two sketches : one with the stars, the other with the nebula (on a white paper and with a lead pencil). Then, I scanned the two sketches and saved negative pictures. The picture with the nebula was colored in a light green. And finally, I added the two images.  The sketch is not perfect : the east side of the nebula was more luminous than the west side – it is not obvious in the sketch. But the color of the nebula seems (to me) well shown.

Bruno Salque

Here’s a link to a archived post on Astronomy Picture of the Day that discusses some of the fascinating aspects of Hubble’s variable nebula.