Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast – October 3-5, 2008

Greetings, fellow SkyWatchers! It’s Friiiiiiday… And time to head out to the Moon to begin some lunar exploration. Why not? This weekend commemorates Robert Goddard’s birthday! While we’re rocketing skyward, we’ll take a look at a great globular cluster that’s easy in both binoculars and telescopes, plus a few great stars you might or might not know about. For lucky viewers in South Africa and Australia? Head’s up for an Antares occultation! Are you ready? Then let’s head out into the night….

Friday, October 3, 2008 – Tonight we’ll begin on the lunar surface and go out on a limb – the southeastern limb – to have a look at an unusual crater. Named for the French agrochemist and botanist Jean-Baptiste Boussingault, this elliptical-appearing crater actually spans a handsome 71 kilometers. What makes Boussingault so unusual is that it is home to its own large interior crater – A. This double-ring formation gives it a unique stepped, concentric look that’s worth your time!

Now wait for the Moon to wester a bit and we’ll return to Pegasus and the incredible M15. Although skies are a bit bright, you can still have a very satisfactory look at M15 through any size binoculars or telescope.

You can find it easily just about two fingerwidths northwest of red Epsilon Pegasi – Enif (RA 21 29 58 Dec +12 10 00). Shining brightly at magnitude 6.4, low power users will find it a delightfully tight ball of stars, but scope users will find it unique. As resolution begins, sharp-eyed observers will note the presence of a planetary nebula – Pease 1. This famous X-ray source you have just seen with your eyes may have supernova remnants buried deep inside…

When we’re done? Let’s go have a look at Gamma Aquilae just for the heck of it. Just northwest of bright Altair, Gamma (RA 19 46 15 Dec +10 36 47) has the very cool name of Tarazed and is believed to be over 300 light-years away. This K3-type giant will show just a slight yellow coloration – but what really makes this one special is the low power field! Enjoy it in binoculars or drop in your favorite panoramic eyepiece and just relax… Sometimes there is peace and contentment in the light.

Saturday, October 4, 2008 – Today in 1957, the USSR’s Sputnik 1 made space history as it became the first manmade object to orbit the earth. The Earth’s first artificial satellite was tiny, roughly the size of a basketball, and weighed no more than the average man. Every 98 minutes it swung around Earth in its elliptical orbit…and changed everything. It was the beginning of the “Space Race.” Many of us old enough to remember Sputnik’s grand passes will also recall just how inspiring it was. Take the time with your children or grandchildren to check www.heavens-above.com for visible passes of the ISS, and think about how much our world has changed in just over half a century!

Do you remember the Professor Burg who discovered Antares’ companion during an occultation? Well, tonight we’re going to become a whole lot more familiar with the good professor, because it’s about to happen again! For almost all observers, at some time brilliant red Antares will be less than half a degree to the north of tonight’s crescent Moon. For South African and Australia, this will be a spectacular occultation, so be sure to check IOTA for precise times and locations on this universal date.

While we’re waiting on the event, let’s have a look at the crater named for Burg as we begin by using past study crater Posidonius as our guide. How many more of these craters can you identify?

If you walk along the terminator to the northwest, you’ll see the punctuation of 40 kilometer wide Burg just emerging from the shadows. While it doesn’t appear to be a grand crater like Posidonius, it has a redeeming feature: it’s deep – really deep. If Burg were filled with water here on Earth, it would require a deep submergence vehicle like ALVIN to reach its 3680 meter floor! This class II crater stands nearly alone on an expanse of lunarscape known as Lacus Mortis. If the terminator has advanced enough at your time of viewing, you may be able to see this walled-plain’s western boundary peeking out of the shadows.

Sunday, October 5, 2008 – Today marks the birthdate of Robert Goddard. Born in 1882, Goddard is known as the father of modern rocketry – and with good reason. In 1907, Goddard came into the public eye when a cloud of smoke erupted from the basement of the physics building in Worcester Polytechnic Institute, from which he had just fired a powder rocket. By 1914, he had patented the use of liquid rocket fuel, and the design of two- or three-stage solid fuel rockets. His work continued as he sought methods of lofting equipment ever higher, and by 1920 he had envisioned his rockets reaching the Moon. Among his many achievements, he proved that a rocket would work in a vacuum. By 1926 the first scientific equipment went along for the ride; by 1932, Goddard was guiding those flights; and by 1937 his motors were pivoting on gimbals and being controlled gyroscopically. His lifetime of work went pretty much unnoticed until the dawn of the Space Age, but in 1959 (14 years after his death) he received acclaim at last as NASA’s Goddard Space Flight Center was established in his memory.

Tonight let’s rocket to the Moon to explore a binocular curiosity located on the northeast shore of Mare Serenitatis. Look for the bright ring of Posidonius, which contains several equally bright points both around and within it. Now look at Mare Crisium and get a feel for its size. A little more than one Crisium’s length west of Posidonius you’ll meet Aristotle and Eudoxus. Drop a similar length south and you will be at the tiny, bright crater Linne on the expanse of Mare Serenitatis. So what’s so cool about this little white dot? With only binoculars you are resolving a crater that is one mile wide, in a seven mile wide patch of bright ejecta – from close to 400,000 kilometers away!

Tonight in 1923, Edwin Hubble was also busy as he discovered the first Cepheid variable in the Andromeda Galaxy. Hubble’s discovery was crucial in proving that the objects once classed as “spiral nebulae” were actually independent and external stellar systems like our own Milky Way.

While we’re out, let’s have a look at a Mira type variable, as we look about halfway between Beta and Gamma Cygni for Chi (RA 19 50 33 Dec +32 54 51).

Noted for being the second long-term variable discovered (by Gottfried Kirch in 1868), Chi is visible to the unaided eye when at maximum – but demands a telescope at minimum. Fluxing between magnitude 4 and 12, you’ll know if you’ve caught it at its lowest point when you can’t distinguish it from background stars! Of course, this is another wonderful cosmic joke on Bayer – for it was several years until the star he classed as visual returned to view. Maximum or minimum? Enjoy your own perceptions of this lovely red star!

Now, as the days pass… Watch as Jupiter and the Moon draw closer and then part company! It’s a lovely sight that doesn’t require any special equipment and makes for a relaxing evening of stargazing. Until next time, I wish you clear skies and a great weekend!

This week’s awesome images are: Crater Boussingault – Credit: Jim Mosher (LPOD), M15 – Credit: NOAO/AURA/NSF, Gamma Aquilae – Credit: Palomar Observatory, courtesy of Caltech, Sputnik 1 – Credit: NASA, 2005 Antares Occultation – Credit: John Chumack, Detail view of Posidonius – Credit: Greg Konkel, Robert Goddard – Credit: NASA, Crater Linne – Credit: Greg Konkel Annotations: Tammy Plotner and Chi Cygni at minimum (center of field) – Credit: Palomar Observatory, courtesy of Caltech. Many, many thanks! Each time we see these images it improves our understanding of what we look at and what we are looking for and their use is greatly appreciated!!

Posted on by Tammy Plotner

Reflections of The Soul – IC 1848 by Ken Crawford

IC 1848 by Ken Crawford

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If we want to be technical, Lynds Bright Nebula 667 is the designation and it’s also known as Sharpless 2-199. Captured here is Collinder open clusters 34, 632 and 634 and small emission nebula 670 and 669 along with the entire cluster designation known as IC 1848. However, let’s forsake science for just a few moments and take a look at what it’s more commonly known as…. The “Soul Nebula”.

Situated along the Perseus arm of the Milky Way galaxy, the “Soul Nebula” reflects true inner beauty as well as a generous portion of hard science. Just this year, this giant cloud of molecular gas was the target study for triggered star formation. According to the work of Thompson (et al); “We have carried out an in-depth study of three bright-rimmed clouds SFO 11, SFO 11NE and SFO 11E associated with the HII region IC 1848, using observations carried out at the James Clerk Maxwell Telescope (JCMT) and the Nordic Optical Telescope (NOT), plus archival data from IRAS, 2MASS and the NVSS. We show that the overall morphology of the clouds is reasonably consistent with that of radiative-driven implosion (RDI) models developed to predict the evolution of cometary globules. There is evidence for a photoevaporated flow from the surface of each cloud and, based upon the morphology and pressure balance of the clouds, it is possible that D-critical ionisation fronts are propagating into the molecular gas. The primary O star responsible for ionising the surfaces of the clouds is the 06V star HD 17505. Each cloud is associated with either recent or ongoing star formation: we have detected 8 sub-mm cores which possess the hallmarks of protostellar cores and identify YSO candidates from 2MASS data. We infer the past and future evolution of the clouds and demonstrate via a simple pressure-based argument that the UV illumination may have induced the collapse of the dense molecular cores found at the head of SFO 11 and SFO 11E.”

With an estimated age of 1 Myr, IC 1848 is home to seventy-four sources of young stellar objects and all of them increase from outside of the rim to the center of the molecular cloud. The bright rim is an ionization front – the barrier between between the hot ionized gas of the HII region and the cold dense material of the molecular cloud where high mass stars are forming. Why is reflecting on the “Soul” so important? Probably because recent studies of meteorites have shown Fe isotopes present in the early solar nebula – suggesting our Sun was given birth in a region on high-mass star formation that experienced a supernova event. Bright-rimmed clouds like IC1848 replicate those conditions.

According to the work of J. Lett: “A bright IR source has been detected within a bright-rimmed dust cloud at the edge of the IC 1848 H II region. The source appears to be an early-type star with a circumstellar dust shell typical of protostars. This star is associated with the position of greatest CO excitation in a dense molecular cloud. The contours of CO emission correspond to those of the bright-rimmed dust cloud, showing that the star formed within the bright rim. Formaldehyde observations at 6 cm, 2 cm, and 2 mm are used to determine the density of the layer between the star and the ionized gas of the bright H..cap alpha.. rim. The location of this star, with respect to the dense molecular cloud which is subject to the external pressure of HII region, indicates the possible role of the expansion of IC 1848 in triggering star formation in dense regions at the perimeter of the H II region. The observed CO emission is used to determine the required luminosity of the embedded star. An early-type star of this luminosity should be detectable as a compact continuum source.”

Indeed, NGC 1848 is in the earliest stages of massive star birth, but it’s hidden behind its dust. According to Murry (et al): “We have completed a multiband (ultraviolet, optical, and near-infrared) study of the interstellar extinction properties of nine massive stars in IC 1805 and IC 1848, which are both part of Cas OB6 in the Perseus spiral arm. Our analysis includes determination of absolute extinction over the wavelength range from 3 ?m to 1250 Å. We have attempted to distinguish between foreground dust and dust local to Cas OB6. This is done by quantitatively comparing extinction laws of the least reddened sightlines (sampling mostly foreground dust) versus the most reddened sightlines (sampling a larger fraction of the dust in the Cas OB6 region). We have combined previous investigations to better understand the evolution of the interstellar medium in this active star forming region. We found no variation of extinction curve behavior between moderately reddened and heavily reddened Cas OB6 stars”.

Shrouded in mystery yet home to Globulettes – the seeds of brown dwarfs and free-floating planetary-mass objects. From the work of G. F. Gahm (et al): “Some H II regions surrounding young stellar clusters contain tiny dusty clouds, which on photos look like dark spots or teardrops against a background of nebular emission which we call “globulettes,” since they are much smaller than normal globules and form a distinct class of objects. Many globulettes are quite isolated and located far from the molecular shells and elephant trunks associated with the regions. Others are attached to the trunks (or shells), suggesting that globulettes may form as a consequence of erosion of these larger structures. Since the globulettes are not screened from stellar light by dust clouds farther in, one would expect photoevaporation to dissolve the objects. However, surprisingly few objects show bright rims or teardrop forms. We calculate the expected lifetimes against photoevaporation. These lifetimes scatter around 4 × 106 yr, much longer than estimated in previous studies and also much longer than the free-fall time. We conclude that a large number of our globulettes have time to form central low-mass objects long before the ionization front, driven by the impinging Lyman photons, has penetrated far into the globulette. Hence, the globulettes may be one source in the formation of brown dwarfs and free-floating planetary-mass objects in the galaxy.”

Apparently there’s a lot to contemplate when you look into the “Soul”….

Many thanks to AORAIA member Ken Crawford for this hugely inspiring image!

Posted on by Tammy Plotner

Celestron Optics Kit – One Heck Of A Teaching Tool!

Are you ready for one very sweet and complete optics package? For anyone who does astronomy outreach work, is interested in practicing binocular astronomy or is just looking for a great teaching tool, I’ve got something you really need to take a look at… the Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit.

When I first spied the Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit I was researching for inexpensive binoculars to supply to our guests at the Observatory. It is not uncommon during a public night or an outreach program to have a hundred or more guests and one or two pairs of binoculars doesn’t go very far. My goal was to find something a non-profit organization could afford, priced so that we could get several pairs, and geared towards performance so our guests weren’t disappointed with the view and our binocular astronomy program. Since the introduction of the green laser pointer a few years ago, I quickly learned that even a novice (right down to my four and five year old grandchildren) can follow the visible beam to where you target it, to its end with binoculars. Then the beam is switched off and the object is in the binoculars! With a mind for safety, it’s a simple and fun way to teach anyone to use binoculars for deep sky observing.

But the green laser wasn’t what I was after… It was the binoculars, wasn’t it?

Another aspect of the binocular astronomy classes we give is providing a monthly star chart to our guests that highlights a few objects for them to locate on their own. It’s just a simple handout – one I print out at home before any program and we stand around in the dark and share a red flashlight as I teach them how to read it and point out the marker stars with the green laser. Yep. We share the red flashlight… A simple tool that should be in the hands of every single person that even remotely takes an interest in reading an astronomy chart outside at night… And one that I just don’t happen to have ten extra to pass around.

But the red flashlights wasn’t what I was after… It was the binoculars, wasn’t it?

So, back to basics. I needed multiple pairs of binoculars that could withstand hard use and perform well. After many years, and many pairs of personal binoculars, I’d love to put Nikon, Oberwerk or Fujinons in every one’s hands, but the reality check is not every one’s hands are ready for these types of binoculars. What I needed was something I knew from experience that could withstand being dropped, was water-proofed and provided an excellent view. In that case, experience tells me Celestron and are great all-purpose astronomy binoculars 10×50.

So, here I am… Staring at the Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit for $59 and then the reality check really comes home. For this price I can order five… And get five pairs of binoculars, five green laser pointers and five red flashlights… All for about what five pairs of binoculars would cost! Click. Ordered.

After they arrived, it was time to put them to the test, eh? And now we’re not just talking the “Tammy Test” we’re talking about the multi-person, multi-use, how long will these kits hold up type of test. Here’s my first group – the Ohio Military Police. There wasn’t just three of them either – there were over three hundred. Needless to say, not one of them had a problem using the binoculars or with focusing them. Out of all of them that I interviewed, no one had issues with astigmatism on any of the binoculars and the lasers pointers and flashlights all performed equally well. These tests were carried out over two days and those binoculars were used hard, folks… No wimpy care, here.

On we go, eh? How about your average scout troop? Now we’re talking young hands… Hands that can’t be trusted on their own with the green lasers, but the leaders can. In this case, we can easily do a presentation where we can point out constellations with the green lasers and responsible adults can also assist in the program by pointing out particular stars or objects for us to name. By having several flashlights available, small groups of kids can work together with charts and adults at the same time to learn constellations on their own. When it’s time to practice astronomy, we use the same “follow the beam” trick, they learn and have a great time!

Still more? Then try thirty plus groups a year that look like this. Wild teens and sometimes sedate adults who come here to learn about astronomy. Telescopes are great and we share those, too. But nothing takes the cake like having your own pair of binoculars in hand – or having a green laser to point at something when you have a question. So, how did the Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit perform in all of these situations? The binoculars are still going strong, folks. After all that use, not one single pair of them has shown any signs of a problem. The red flashlights are all still working on the original batteries and so are the green lasers. However, the green lasers are not extremely powerful and not very bright during situations like dusk or full Moon. At the same time, compared to other lasers in my possession, they do a fine job and should not be discounted. After all, the laser and flashlight are almost like getting them for free when you buy the binoculars!

In the long run the Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit is an exceptional bargain at $59 and one I highly recommend. As a matter of a fact, I recommend it so much that OPT is even going to give one to a lucky Universe Today reader to keep so you can test it out yourself! From now until October 7, 2008 at 12:00 pm PDT you can send an email with the title of this review in the subject line and your name in the body of the email and Universe Today will randomly choose a winner to get your own Celestron Green Laser Pointer Optics Kit for free! No matter where you live…

Put ’em to the test and see if you don’t agree. The Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit is an exceptionally rugged and good performing astronomy binocular and having a red flashlight and green laser is a huge bonus.

The Celestron 10X50 UpClose Binoculars and Green Laser Pointer Optics Kit were purchased for this review from OPT and a free kit will be provided to a randomly chosen winner by Oceanside Photo and Telescope.

Posted on by Tammy Plotner

Russian “Space Junk” – Caught In The Act

Fireball over Adelaide - Doug Robertson

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While imaging the Large Magellanic Cloud, astrophotographer Doug Robertson got a real surprise when he went to process his data…. He’d accidentally recorded the uncontrolled return of the intermediate stage of a recent Russian rocket launch that just put three GLOSNASS satellites into orbit.

Eyewitnesses in Adelaide, Australia were astounded when a huge fireball lit up the skies shortly after midnight local time. The initial response was believed to be attributed to meteoric activity, but the 45 second event broke into several pieces and traveled along a parallel trajectory. Hearing the news, Robertson checked his photographic data and sure enough, during the time stamp of 12:12:38am, he’d caught the event. Like all good astronomers, the initial reaction is to immediately report and wait for an answer.

According to the Publicity Officer of the Astronomical Society of South Australia, Tony Beresford: “Last night at around 00:18CST sept 27 or 14:48 UT Sept. 26, an intermediate stage of a recent Russian launch that put 3 GLOSNASS satellites into orbit, re-entered the atmosphere and became visible travelling N-S over Adelaide. I had a full report from a person who saw the pass from Hallett Cove immediately after the event. It was an expected uncontrolled re-entry. The rocket stage had broken into several pieces. This aspect seems similar to other re-entries reported to me over the years. It took nearly a minute to pass over. A Sunday Mail reporter who rang this morning said they had a least a dozen reports. Some of the reports incorrectly used the term “meteor shower” to describe what they saw. Some meteors could give the same phenomena of multiple bodies on parallel paths, but that is not a meteor shower!!”

Is returning “space junk” a problem? You bet. In a very comprehensive article done by Nancy a few months ago called Space Debris Illustrated: The Problem in Pictures, she clearly illustrated how spent booster stages and discards from spacecraft could turn into a serious problem for future spaceflight if left unmonitored and uncontrolled. While the Russian return was expected, it’s still just another indicator of a mounting problem – inactive space hardware in orbit around the Earth .

According to NASA Shuttle program director John Shannon, “Next month’s shuttle flight to the Hubble Space Telescope faces an increased risk of getting hit by space junk because it will be in a higher, more littered orbit than usual. New number-crunching puts the odds of a catastrophic strike by orbital debris including bits of space junk at about 1-in-185 during Atlantis’ upcoming mission to Hubble. That compares to 1-in-300 odds for a shuttle flight to the International Space Station.”

Thankfully for everyone concerned there was no impact on the Shenzhou-7 mission – just a little late night excitement. Said Robertson, “Unfortunately I didn’t witness this naked eye. But as you see that main fragment/track looks extremely bright. Although rough, the crop clearly shows the number of fragments/debris surrounding the brighter tracks – reminded me off the shuttle disaster a few years ago. Glad it wasn’t anything to do with the manned Chinese mission. Wish I had put down my coffee and stepped outside a bit earlier to see it!”

Many thanks to AORAIA member, Doug Roberston for this fine catch!

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast – September 26-28, 2008

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Greetings, fellow SkyWatchers! It’s a dark sky weekend and a great opportunity to really get to know some unusual deep sky objects – like brilliant open clusters and tiny compact galaxy groups. Even if you just sit outside and stargaze, you might catch a member of the Alpha Aurigid meteor shower! Are you ready? Then get out your binoculars and telescopes and let’s head out for adventure…

Friday, September 26, 2008 – Tonight we’ll begin our adventures with Vulpecula – it’s time to go fox hunting. What we’re after requires dark skies – but can be seen in both binoculars and a small telescope. Once you’ve found Alpha begin about two fingerwidths southeast and right on the galactic equator for NGC 6823 (RA 19 43 10 Dec +23 17 54).

The first thing you will note is a fairly large, somewhat concentrated, magnitude 7 open cluster. Resolved in larger telescopes, the viewer may note these stars are the hot, blue-white variety. For good reason… NGC 6823 only formed about two million years ago.

Although it is some 6000 light-years away and occupies about 50 light-years of space, it’s sharing the field with something more – a very faint and very large emission/reflection nebula called NGC 6820.

In the outer reaches of the star cluster, new stars are being formed in masses of gas and dust as hot radiation is shed from the brightest of the stellar members of this pair. Fueled by emission, NGC 6820 isn’t always an easy visual object – it’s faint and covers almost four times as much area as the cluster and using a filter helps. But, trace the edges very carefully, since the borders are much more illuminated than the region of the central cluster. It’s like a whisper against your eyes. Take the time to really observe this one! The processes going on are very much like those occurring in the Trapezium area of the Orion nebula.

Be sure to mark your observing notes. NGC 6823 is Herschel VII.18; and NGC 6820 is also known as Marth 401!

Saturday, September 27, 2008 – Today we celebrate the 1814 birth of Daniel Kirkwood. In 1866, this American astronomer was the first to publish his discovery of gaps in the distances of asteroids from the Sun – “Kirkwood Gaps.” Not only did he study the orbits of asteroids, but he was the first to suggest that meteor showers were caused by orbiting debris from comets. Known as “the American Kepler,” Kirkwood went on to author 129 publications, including three books.

Tonight it’s time to break out the muscle and challenge big telescope users to hone their skills. It’s galaxy hunting time and our destination for tonight is Hickson Compact Group 87 (RA 20 48 11 Dec -19 50 24)…

Several billion years ago, on the ecliptic plane about four degrees west-southwest of Theta Capricorni, and around 400 million light-years from our solar system, a galactic association decided to form their own “Local Group.” Orbiting around a common center about every 100 million years, their mutual gravity is pulling each of them apart – creating starbursts and feeding their active galactic nuclei. Small wonder they’re shredding each other… They’re only 170,000 light-years apart! One day they may even form a single elliptical galaxy bright enough for the average telescope to see – because as they are now, this group isn’t going to be seen with anything less than 20″ in aperture.

So, shall we try something a little more within the realm of reality? Then go ahead and drop about eight degrees south of Theta and try picking up on the NGC 7016/17/18 group (RA 21 07 20 Dec -25 29 15). Are they faint? Of course! It wouldn’t be a challenge if they were easy, would it? With an average magnitude of 14, this tight trio known as Leavenworth 1 is around 600 million light-years away. They’re very small, and not very easy to locate… But for those who like something a bit different?

I dare you…

Sunday, September 28, 2008 – As your starry mission this evening, we’ll continue our studies in Vulpecula with a spectacular open cluster – NGC 6940 (RA 20 34 24 Dec +28 17 00). At close to magnitude 6, you’ll find this unsung symphony of stars around three fingerwidths southwest of Epsilon Cygni.

Discovered by Sir William Herschel in 1784 and logged as H VIII.23, this intermediate-aged galactic cluster will blow your mind in large aperture.

Although visible in binoculars, as aperture increases the field explodes into about 100 stars in a highly compressed, rich cloud. Although not visited often, NGC 6940 is on many observing challenge lists. Use low power to get the full effect of this stunning starfield!

Now, move on to Aquila and look at the hot central star of an interesting planetary nebula – NGC 6804 (RA 19 31 35 Dec +09 13 32). You’ll find it almost four degrees due west of Altair. Discovered by Herschel and classed as open cluster H VI.38, it wasn’t until Pease took a closer look that its planetary nature was discovered. Interacting with clouds of interstellar dust and gases, NGC 6804 is a planetary in decline, with its outer shell around magnitude 12 and the central star at about magnitude 13. While only larger telescopes will get a glimpse of the central star, it’s one of the hottest objects in space – with a temperature of about 30,000 K!

While you’re out under the stars, be sure to keep an eye open for the fast moving members of the Alpha Aurigid meteor shower whose radiant is in the northeast near Capella. Activity started just two days ago and will last through the next week. Here’s wishing you clear skies and a great weekend!!

This week’s awesome images are: NGC 6823/6820 – Credit: Palomar Observatory, courtesy of Caltech, Hickson Compact Group 87 – Credit: Palomar Observatory, courtesy of Caltech, NGC 7016/17/18 – Credit: Palomar Observatory, courtesy of Caltech, and NGC 6940 and NGC 6804 – Credit: Palomar Observatory, both courtesy of Caltech.

Posted on by Tammy Plotner

Observing Alert: Outburst of GK Persei

GK Persei Prior To Outburst...

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Wake up, all you variable star observers!! According to AAVSO Alert Notice 384 released just minutes ago, the cataclysmic variable star – GK Persei – is beginning to wake up and appears to be entering another outburst.

According to Matthew Templeton: “As reported in AAVSO Special Notice #125, the cataclysmic variable GK Persei appears to be entering another outburst. The object began a slow rise on or about 2008 September 10 UT (JD 2454719.5), rising nearly one magnitude above its typical quiescent level of m(vis) = 13, to near m(vis) = 12.2 at present (2008 September 24 UT, JD 2454733.5). This rate of brightening is typical of past outbursts, and suggests a rise to full outburst may occur soon. However, this activity comes much sooner than expected based on past intervals between outbursts, and the last outburst (2006 December 5, JD 2454075) reached a much fainter maximum than normal — about m(vis)=11.5, more than one magnitude fainter than the typical m(vis)=10.5-10.0.

Locator Chart (AAVSO)
Locator Chart (AAVSO)
Observers are asked to closely follow GK Persei at all wavelengths during the current outburst, however it may evolve. Both visual and filtered CCD photometry are strongly encouraged.

The most recent visual (M. Komorous) and V-band CCD (D. Lane) made around 2008 September 24.2 UT (JD 2454733.7) have GK Persei around m(vis) = 12.2 to 12.3. GK Persei (AUID 000-BBG-044) is located at the following J2000 coordinates: RA: 03 31 12.00 , Dec +43 54 15.0

Charts for GK Per may be plotted using VSP

Please promptly submit all observations to the AAVSO via WebObs. Thanks to all observers who have reported GK Per in outburst and who have submitted observations thus far!”

Clear skies, good luck and good observing….

Posted on by Tammy Plotner

Deep Inside a Giant: Part 2 – Centaurus A by Mike Sidonio

Centaurus A Dustlane - Mike Sidonio

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Our first glimpse into the intricacies of Centaurus A was the big picture. We soon found out that not only was the first photograph a deep study, but the study of NGC 5128 was going to go deeper as well. One of the most obvious of all features is the central dust lane which positively crackles to the eye photographically. Let’s be mindful of the radiation and get just a little closer….

In every visual representation of Centaurus A, one of the most dramatic of all features is the central dustlane. To the human eye, the dust is an obstruction – blocking the starlight and what lay beyond. But, to the camera, shifting to redder wavelengths allows us a glimpse at what lay beyond. Through carefully controlled exposures and filtering, red emission from ionized gas at the H-alpha line appears, and blue regions of star formation along the dust lane spring to life – where blue giant stars are being formed. According to 2000 study done by Wild and Eckart; “The interstellar medium of Centaurus A (NGC 5128) has been studied extensively in recent years, using mostly molecular lines tracing low to medium density gas. The amount and distribution of the dense molecular gas was largely unknown. Here we present new millimeter data of the rotational transitions and obtained spectra of the emission which traces dense molecular gas at the center and along the prominent dust lane at offset positions. We find that Centaurus A and the Milky Way are comparable in their line luminosity. However, towards the nucleus the fraction of dense molecular gas measured via the line luminosity ratio, as well as the star formation efficiency, is comparable to ultra-luminous infrared galaxies (ULIRGs). Within the off-nuclear dust lane and for Centaurus A as a whole these quantities are between those of ULIRGs and normal and infrared luminous galaxies. This suggests that most of the FIR luminosity of Centaurus A originates in regions of very dense molecular gas and high star formation efficiency.”

A highly efficient star forming region… Yes, indeed. Those brilliant blue regions you see along the edges are brand new star clusters. Merger induced star formation…

Do you see now why the dustlane in Centaurus A appears to scream? Normally star formation occurs in the dense parts of molecular clouds… collapsing themselves into a ball of plasma to form a star. But, according the work of Martig and Bournaud; “Star formation in galaxies is for a part driven by galaxy mergers. At low redshift, star formation activity is low in high-density environments like groups and clusters, and the star formation activity of galaxies increases with their isolation. This star formation-density relation is observed to be reversed at z~1, which is not explained by theoretical models so far. We study the influence of the tidal field of a galaxy group or cluster on the star formation activity of merging galaxies, using N-body simulations including gas dynamics and star formation. We find that the merger-driven star formation is significantly more active in the vicinity of such cosmological structures compared to mergers in the field. The large-scale tidal field can thus enhance the activity of galaxies in dense cosmic structures, and should be particularly efficient at high redshift before quenching processes take effect in the densest regions.”

But… But, what happens if you have a galaxy that happens to be tidally triggered into star formation and then it just happens to merge with another galaxy at the same time? Aaaaah…. You’re beginning to see the light aren’t you? The galaxy that merged with NGC 5128 was triggered into a burst of star formation, then it combined with Centaurus A and a whole new thing happened. Let’s take a look at the work of Peng and Ford: “Stellar streams in galaxy halos are the natural consequence of a history of merging and accretion. We present evidence for a blue tidal stream of young stars in the nearest giant elliptical galaxy, NGC 5128 (Centaurus A). Using optical UBVR color maps, unsharp masking, and adaptive histogram equalization, we detect a blue arc in the northwest portion of the galaxy that traces a partial ellipse with an apocenter of 8 kpc. We also report the discovery of numerous young star clusters that are associated with the arc. The brightest of these clusters is spectroscopically confirmed, has an age of 350 Myr, and may be a protoglobular cluster. It is likely that this arc, which is distinct from the surrounding shell system and the young jet-related stars in the northeast, is a tidally disrupted stellar stream orbiting the galaxy. Both the age derived from the integrated optical colors of the stream and its dynamical disruption timescale have values of 200-400 Myr. We propose that this stream of young stars was formed when a dwarf irregular galaxy, or similar-sized gas fragment, underwent a tidally triggered burst of star formation as it fell into NGC 5128 and was disrupted 300 Myr ago. The stars and star clusters in this stream will eventually disperse and become part of the main body of NGC 5128, suggesting that the infall of gas-rich dwarfs plays a role in the building of stellar halos and globular cluster systems.”

Needless to say, the developments in Centaurus A are a little shocking, aren’t they? And shocked gas is what it’s all about. Says John Graham; “Observational evidence for shock-induced star formation is found in the northeast radio lobe of the nearby radio galaxy Centaurus A (NGC 5128). A gas cloud, recently detected in H i, is impacted by the adjacent radio jet to the extent that cloud collapse is triggered and loose chains of blue supergiant stars are formed. Diffuse clouds and filaments of ionized gas have been observed near the interface of the H i cloud and the radio jet. These show velocities that cover a range of more than 550 km s−1. Line intensities in their spectra are characteristic of a shock-related origin with strong [N ii] and [S ii] relative to Hα. The [O iii]/Hα line ratio indicates a large range in excitation that is not correlated with velocity. Distinct from this component is a group of four apparently normal H ii regions that are excited by embedded young stars and whose velocities are very close to that of the H i cloud. Star formation will continue for as long as the gas cloud remains close to the radio jet. The loose chains of blue stars in the area are resolved only because NGC 5128 is so close. The reported faint blue extensions and plumes in more distant analogs probably have similar origins.”

So now we have all kinds of things we’ve learned deep inside this giant. Is there anything else we should know before we leave this part and go on? Oh, you know it… A supermassive black hole 200 million times the mass of our own Sun.

Using the infrared vision of Hubble, astronomers can now see a hot gas disk is tilted in a different direction from the orientation of the jet – the indicator of the black hole. It’s believed this may be because the merger is so recent and the disk has not yet aligned to the spin, or the galaxies may still be playing tug of war. According to Ethan Schrier of STSCI, “This black hole is doing its own thing. Aside from receiving fresh fuel from a devoured galaxy, it may be oblivious to the rest of the galaxy and the collision. We have found a complicated situation of a disk within a disk within a disk, all pointing in different directions.” The most astounding part of all is the black hole itself may possible be a merger of two independent black holes! Is this why there is core-dominated radio-loud quasars here as well? As a radio galaxy it releases 1000 times the radio energy of the Milky Way in the form of large bi-directional radio lobes that extend some 800,000 light years into intergalactic space. Well, guess what… There’s theories on that, too.

According, to Saxton, Sutherland and Bicknell, that radio source may just be a plasma bubble: “We model the northern middle radio lobe of Centaurus A (NGC 5128) as a buoyant bubble of plasma deposited by an intermittently active jet. The extent of the rise of the bubble and its morphology imply that the ratio of its density to that of the surrounding ISM is less than 10^{-2}, consistent with our knowledge of extragalactic jets and minimal entrainment into the precursor radio lobe. Using the morphology of the lobe to date the beginning of its rise through the atmosphere of Centaurus A, we conclude that the bubble has been rising for approximately 140Myr. This time scale is consistent with that proposed by Quillen et al. (1993) for the settling of post-merger gas into the presently observed large scale disk in NGC 5128, suggesting a strong connection between the delayed re-establishment of radio emission and the merger of NGC 5128 with a small gas-rich galaxy. This suggests a connection, for radio galaxies in general, between mergers and the delayed onset of radio emission. In our model, the elongated X-ray emission region discovered by Feigelson et al. (1981), part of which coincides with the northern middle lobe, is thermal gas that originates from the ISM below the bubble and that has been uplifted and compressed. The “large-scale jet” appearing in the radio images of Morganti et al. (1999) may be the result of the same pressure gradients that cause the uplift of the thermal gas, acting on much lighter plasma, or may represent a jet that did not turn off completely when the northern middle lobe started to buoyantly rise. We propose that the adjacent emission line knots (the “outer filaments”) and star-forming regions result from the disturbance, in particular the thermal trunk, caused by the bubble moving through the extended atmosphere of NGC 5128.”

And now you know just a little bit more about what’s deep inside a giant…

Many thanks to AORAIA member, Mike “Strongman” Sidonio for the use of this incredible image.

Posted on by Tammy Plotner

Deep Inside a Giant – Centaurus A by Mike Sidonio

Centaurus A - Ultra-Deep by Mike Sidonio

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Before you dismiss this as just another photo of Centaurus A, you better look again. It’s way deeper… First discovered by James Dunlop on August 4, 1826 this incredible galaxy known as Centaurus A (NGC 5128) has been tickling the imagination of astronomers since John Herschel described it as “two semi-ovals of elliptically formed nebula appearing to be cut asunder and separated by a broad obscure band parallel to the larger axis of the nebula, in the midst of which a faint streak of light parallel to the sides of the cut appears.” in 1847. What makes this incredible galaxy tick? Step inside and let’s find out…

Regardless of the fact that J. Herschel pointed out NGC 5128’s unusual characteristics, it would be 102 years before astronomy really took this galaxy seriously – not because the science didn’t progress – but because there just wasn’t any large optical telescopes located in the southern hemisphere. However, things were about to change drastically in 1949 when the 80-foot radio antenna at Dover Heights, Australia went on-line. There astronomers John Bolton, G. Stanley, and Bruce Slee were the first to identify Centaurus A as a powerful radio galaxy – the first source to be linked to an extra-galactic hot spot.

But just how hot is it? Try a study done in July 2008 by Cuoco and Hannestad searching for ultrahigh energy neutrinos from Centaurus A and the Auger hot spot. “The Pierre Auger Collaboration has reported a correlation between ultrahigh energy cosmic rays (UHECR) and nearby active galactic nuclei (AGN) within Ëœ75Mpc. Two of these events fall within 3 degrees from Centaurus A (Cen A), the nearest AGN, clearly suggesting that this object is a strong UHECR emitter. Here we pursue this hypothesis and forecast the expected rate of ultrahigh energy neutrinos in detectors like IceCube. In our baseline model we find a rate of Ëœ0.4–0.6yr-1 events above a threshold of 100 TeV, the uncertainty of which is mainly related to the poor knowledge of the physical parameters of the source and details of the model. This situation will improve with detailed high energy gamma ray measurements of Cen A by the upcoming Gamma Ray Large Area Space Telescope (GLAST) satellite. This would make Cen A the first example where the potential of high energy multi messenger astronomy is finally realized.”

Now, let’s go back in time… Back to 1954 at Palomar Observatory’s twin telescopes with Walter Baade and Rudolph Minkowski. It was then the first proposal was made that the bar of dark dust bisecting the galaxy was the result of a merger between two galaxies – a giant elliptical and a small spiral. “The radio source Cygnus A is an extragalactic object, two galaxies in actual collision.” This simple observation was again confirmed in 2005 by Karataeva (et al); “We present the results of stellar photometry in eight fields of NGC 5128 (Cen A), a candidate polar-ring galaxy, obtained by reducing images from the Hubble Space Telescope archive. In all cases, the color-magnitude diagrams reached the red-giant region, and the distance to the galaxy was determined from the position of the tip of the red-giant branch (4.1 Mpc), in agreement with previous estimates. Comparison of the diagrams with theoretical isochrones indicates that the red supergiants in the dark lane region are metal-rich, which is atypical of the polar rings. Our results are consistent with the assumption made by several authors that the absorption of a less massive spiral galaxy by a more massive one is observed in NGC 5128.”

But, that’s not all that’s coming off Centaurus A. Massive amounts of X-rays have been detected as well, with the very first picked up in 1970 with the use of a sounding rocket and then confirmed by the UHURU satellite. The emission was very localized, but it wasn’t steady, it changed in intensities. Again, scientific curiosity was aroused and again, an answer was found – a black hole. According to the work of Marconi (et al): “We present new HST Space Telescope Imaging Spectrograph observations of the nearby radio galaxy NGC 5128 (Centaurus A). The bright emission line with longest wavelength accessible from HST was used to study the kinematics of the ionized gas in the nuclear region. The STIS data were analized in conjunction with the ground-based near-infrared Very Large Telescope ISAAC spectra to infer the presence of a supermassive black hole and measure its mass. We performed a detailed analysis of the effects on MBH of the intrinsic surface brightness distribution of the emission line, a crucial ingredient in the gas kinematical analysis. The observed velocity dispersion in our spectra can be matched with a circularly rotating disk and also the observed line profiles and the higher order moments in the Hermite expansion of the line profiles, h3 and h4, are consistent with emission from such a disk. To our knowledge, Centaurus A is the first external galaxy for which reliable BH mass measurements from gas and stellar dynamics are available and, as in the case of the Galactic Center, the MBH gas kinematical estimate is in good agreement with that from stellar dynamics. Thus Centaurus A ranks among the best cases for supermassive Black Holes in galactic nuclei.”

Yet, is that all there is? No. As early as 1972, gamma ray emissions from NGC 5128 were being explored. Which, according to the work of Ozernoy and Aharonian, may very well be tied to the black hole itself. “An analysis of the experimental data on nuclear gamma-ray lines from Cen A reveals essential energetic difficulties, associated with the usual interpretation of these lines as a result of interactions of subcosmic rays with interstellar gas; since the necessary instantaneous energy loss rate of the cosmic rays should reach tremendous values. These difficulties are eliminated if the gamma rays are produced in the relativistic non-isothermal plasma near a compact source of activity — such as a massive black hole or a magnetoid (spinar).”

But don’t stop there. By the late 1970, John Graham had also discovered an outer gas shell from the galactic merger – a shell which was studied again in 2008 by Stickel (et al): “Deep far-infrared (FIR) imaging data detected the thermal emission from cold dust in the northern shell region of NGC5128 (Centaurus A), where previously neutral hydrogen and molecular gas has been found. These observations are in agreement with recent theoretical considerations that in galaxy interactions leading to stellar shell structures the less dissipative clumpy component of the ISM from the captured galaxy can lead to gaseous shells. Alternatively, the outlying gas and dust could be a rotating ring structure resulting from an interaction or even late infall of tidal material of a merger in the distant past. With all three components (atomic gas, molecular gas, dust) of the ISM present in the northern shell region, local star formation may account for the chains of young blue stars surrounding the region to the east and north. The dust cloud may also be involved in the disruption of the large scale radio jet before entering the brighter region of the northern radio lobe.”

But, let’s get down here. The photo at the top of this page wasn’t taken with the Hubble. It didn’t go through Chandra. It was taken by a very dedicated amateur astronomer named Mike Sidonio who understood exactly what needed to be done to capture all the true beauty of this too-often photographed sky gem. Says Mike; “This unique and extremely deep colour image, compiled from nearly 20 hours of exposure with just a 6” telescope, was taken from a very dark sky in remote Australia. The image reveals the full outer halo of the peculiar radio galaxy Centaurus A (NGC 5128) in Centaurus including faint polar extensions extending from the top and bottom of the galaxy running diagonally. Also evident in this image is the extensive but extremely faint Milky Way nebulosity and dust known as “Galactic Cirrus” or “Integrated Flux” that permeates this entire region. Galactic Cirrus material lies just above the plane of our galaxy and is lit by the light of The Milky Way as a whole but due to its extreme faintness at 27mag/sq arc sec, is seldom seen in images, it is visible as faint patches of dusty looking nebulosity all over the image. The Cirrus nebulosity around Centaurus A is some of the faintest in the sky and is well below the natural sky brightness. Countless distant background galaxies of all shapes and sizes can be found scattered all over the field of view as well.”

But Mike isn’t just any astrophotographer. He’s won numerous Malin awards and Astro Awards. His work has been featured in magazines such as Sky & Telescope and Astronomy, as well as Astronomy Picture of the Day, and this single Centaurus A image is only a small fraction of the study Mr. Sidonio did on this subject. For those of you who are curious, I would highly suggest visiting Mike Sidonio’s Centaurus A Pages, where each individual image takes you on an ever deeper visual journey into this fascinating galaxy.

Many thanks to AORAIA member, Mike “Strongman” Sidonio for the use of this incredible image.

Posted on by Tammy Plotner

Pentax Eyepieces – Observatory Quality

Back awhile ago I did a review on plossl eyepieces. In that article I was trying to reach for the average individual looking for a high quality eyepiece on a limited budget. This time I asked for an example of observatory quality eyepieces that I know some of our readers own and enjoy. Is there a difference between how a very expensive eyepiece behaves in average equipment as opposed to an average eyepiece? Is there a difference in how it behaves in observatory class equipment? Step inside and let’s take a look…

The reputation of certain eyepieces sometimes precedes itself and the case is certainly true when it comes to Pentax Eyepieces. Known widely for delivering superb color correction and outstanding contrast, I was very anxious for these beauties to arrive and put them to the test. In this case, I have asked for the Pentax XW series, which would put it in the Erfle category – alongside such popular brands as the Nagler, the Panoptic, the Ultima LX and the QX series. In dollar amounts, the Pentax figures roughly in the same category as the first two aforementioned products, and roughly three times more expensive than the last two. But is the performance worth the price?

High dispersion, low refraction lanthanum glass… These are great words, but nothing can match the precision machined quality of the outward appearance of a Pentax eyepiece. Absolutely nothing in its construction appears to be left to chance and I very much approved not only of how the body of the eyepieces appears to be “sealed”, but the fact that they have very positive grip surfaces and little safety grooves cut right into the barrel so they can’t accidentally fall out of the focuser. I can also see from examination that the insides are blackened to reduce internal reflections and that the eyepieces are fully threaded for filters… But how do they perform?

The last of the three eyepieces I asked to test was the Pentax 40mm XW 2″ Eyepiece. If you are looking for a true observatory quality eyepiece, look no further. Combined with aperture, the 40mm delivers a wide, true field that only marginally suffers from vignetting around the edges with fast focal ratio telescopes and virtually disappears as the focal length increases. Once again, we are talking about an eyepiece that was made to perform with eye sight limitations and with just a few minor adjustments, a total pinpoint panorama of stars can be yours. While I’ve used a lot of Erfle design eyepieces, this is perhaps the first low power, wide field Erfle that I’ve used that didn’t require me to hold my head just right to take in the view. With or without glasses…

My next step was to take this eyepiece arrangement and put them to the test in a true observatory telescope – a 31″ f/7. Eyepiece after eyepiece… Outstanding performance, perfect color correction and incredible eye relief. Is seeing believing? Yes and no. In my mind to deem something “observatory quality”, it has to measure up to the bar that I set for it – and that means the durability of use that an observatory eyepiece will go through in years of service. While I can field test an eyepiece for performance qualities, what I can’t tell you is what will happen to it ten years down the road. So… I investigated.

There’s a good reason why I admired the construction of the Pentax eyepieces when I first examined them – they are weather-proof. While you would not want to drop them in a bucket of water, these eyepieces are all rated JIS Class 4. Just what does that mean? It means that dust and particles sized 1.0mm in diameter or more cannot infiltrate. It means water splashed against the enclosure from any direction shall have no harmful effects. It means that by Pentax standards they actually sprayed these eyepieces down with a stream of water for 10 minutes and nothing reached the internal lenses. It means Pentax guarantees these eyepieces for life.

In the long run, Pentax eyepieces are an investment – a worthy investment in observatory quality.

The Pentax Eyepieces provided for this review were supplied by Oceanside Photo and Telescope.

Posted on by Tammy Plotner

Weekend SkyWatcher’s Forecast – September 19-21, 2008

Greetings, fellow SkyWatchers! Are you psyched up for tonight’s Pleiades occultation? I am! While the Moon often passes near the ancient cluster, it’s not often we get to enjoy such a great event so well placed at a comfortable time of the year. This weekend we’ll be watching for ISS passes, reaching for the “Ring”, visiting Andromeda, and taking on two new Herschel 400 studies. Time to get out your telescopes, spotting scopes and binoculars and head out into the night because…. Here’s what’s up!

Friday, September 19, 2008 – On this day in 1848, William Boyd was watching Saturn – and discovered its moon Hyperion. Also today in 1988, Israel launched its first satellite. And don’t forget…t his evening will feature possibly the best occultation of the Pleiades by the Moon this year, so be sure to check with IOTA for details!

How long has it been since you’ve watched the ISS pass overhead, or seen an Iridium flare? Both are terrific events that don’t require any special equipment to be seen – even in the daytime! Be sure to check with www.heavens-above.com for accurate times in your location – and enjoy. While you’re out SkyWatching, be sure to have a look for Spica on the southwestern horizon after sunset. You just might discover a few planets joining the show!

When skies are dark, it’s time for us to head directly between the two southernmost stars in the constellation of Lyra and grab the “Ring.” What summer would be complete without it?

Discovered by French astronomer Antoine Darquier in 1779, the Ring Nebula was cataloged later that year by Charles Messier as M57 (RA 18 53 35 Dec +33 01 45). In binoculars the Ring will appear as slightly larger than a star, yet it cannot be focused to a sharp point. To a modest telescope at even low power, M57 turns into a glowing donut against a wonderful stellar backdrop. The accepted distance to this unusual structure is about 1,400 light-years, and how you see the Ring on any given night is highly dependent on conditions. As aperture and power increase, so do details, and it is not impossible to see braiding in the nebula’s structure with scopes as small as 8″ on a fine night, or to pick up the star caught on the edge in even smaller apertures.

Like all planetary nebulae, seeing the central star is considered the ultimate achievement in viewing. The central itself is a peculiar bluish dwarf which gives off a continuous spectrum, and might very well be a variable. At times, this shy, near 15th magnitude star can be seen with ease with a 12.5″ telescope, yet be elusive to even 31″ in aperture weeks later. No matter what details you may see, reach for the “Ring” tonight. You’ll be glad you did.

Saturday, September 20, 2008 – On this night in 1948, the 48″ Schmidt telescope at Mt. Palomar was busy taking pictures. Its very first photographic plate was being exposed by the same man who ground and polished the corrector plate for this scope – Don Hendricks. His object of choice was reproduced as panel 18 in the Hubble Atlas of Galaxies, and tonight we’ll join his vision as we take a look at the fantastic M31, the Andromeda Galaxy.

Seasoned amateur astronomers can literally point to the sky and show you the location of M31, but perhaps you have never tried to find it. Believe it or not, this is an easy galaxy to spot even under the moonlight. Simply identify the large diamond-shaped pattern of stars that is the Great Square of Pegasus. The northernmost star is Alpha, and it is here we will begin our hop. Stay with the northern chain of stars and look four fingerwidths away from Alpha for an easily seen star. The next along the chain is about three more fingerwidths away… And we’re almost there. Two more fingerwidths to the north and you will see a dimmer star that looks like it has something smudgy nearby. Point your binoculars there, because that’s no cloud – it’s the Andromeda Galaxy!

Now aim your binoculars or small telescope its way… Perhaps one of the most outstanding of all galaxies to the novice observer, M31 spans so much sky that it takes up several fields of view in a larger telescope, and even contains its own clusters and nebulae with New General Catalog designations. If you have a slightly larger telescope, you may also be able to pick up M31’s two companions – M32 and M110. Even with no scope or binoculars, it’s pretty amazing that we can see something – anything! – that is over two million light-years away!

Sunday, September 21, 2008 – On this date in 2003, the Galileo spacecraft bravely entered the atmosphere of Jupiter as it completed its final mission. Launched in 1989 and orbiting the giant planet since 1995, the hugely successful Galileo taught us much about Jupiter’s lethal radiation belts, magnetic field, atmosphere, and moons – but it had one last command to execute: self-destruction. Although it was still performing flawlessly (despite its lack of fuel and with its instrumentation badly scarred by radiation), scientists feared it might contaminate other possible life-sustaining moons such as Europa, and the decision was made to aim it into Jupiter’s certain oblivion. We salute its final moments!

And what was Sir William Herschel doing on this date a couple of centuries ago? You can bet he was out telescoping; and his discoveries on this night were many. How about if we take a look at two logged on September 21 which made the Herschel “400” list?

Our first stop is northern Cygnus for NGC 7086 (RA 21 30 30 Dec +51 35 00). Located on the galactic equator about five degrees west of Beta Cephei, our target is an open cluster. At magnitude 8.4, this loose collection will be difficult for the smaller scope, and show as not much more than an arrow-like asterism. However, larger scopes will be able to resolve many more stars, arrayed in long loops and chains around the brighter members. Although it’s sparse, NGC 7086 has been studied for metal abundance, galactic distance, membership richness, and its luminosity function. Be sure to mark your notes for H VI.32, logged by Herschel in 1788.

Now hop on over to Andromeda for NGC 752 (RA 01 57 41 Dec +37 47 06). You’ll find it just a few degrees south of Gamma and in the field north of star 56. Located 1300 light-years away, there’s a strong possibility this cluster was noted first by Hodierna before being cataloged by Herschel on this night (1786). At near magnitude 5, this “400” object is both large and bright enough to be seen in binoculars or small telescopes, and people have often wondered why Messier did not discover it. The star-studded field containing about 70 members of various magnitudes belong to H VII.32 – a very old cluster which has more recently been studied for its metallicity and the variations in the magnetic fields of its members. Enjoy them both tonight! Sir William did…

Until next week, I will you clear skies and happy hunting!

This week’s awesome images are: M57 “Ring Nebula” – Credit: NOAO/AURA/NSF, 48″ Schmidt Scope (Drawing by Russell Porter) – Credit: Palomar Observatory courtesy of Caltech, The Andromeda Galaxy – Credit: Anonymous, Artist’s concept of Galileo – Credit: NASA, NGC 7086 – Credit: Palomar Observatory, courtesy of Caltech and NGC 752 – Credit: Palomar Observatory, courtesy of Caltech. Our many thanks!