los angeles astronomical society bulletin · warning —– at press time the new slide projectors...

6 LAAS BulletinLAAS Bulletin

For Sale Meade 12-inch LX-200. Extras include —– very nice cabinet, heavy-duty wedge, light extension shield, heavy duty tripod, canvas case, Meade l.p.i., Meade spotting scope.

If interested contact Tav at (818) 362 - 5092.

On the days and sunsets of Jan 12th and 13th, Comet McNaught was visible in the skies, the first daylight comet since Ikeya-Seki in 1965. I didn’t see it either day with the unaided eye in daylight, but it was plainly visible to the unaided eye hanging just over the horizon in strong twilight just after sunset. I did spot it through 50mm aperture binoculars in daylight, along with a tail I estimated to be 2 to 3 degrees long. Many of the visitors to Griffith saw it also. This was my first daylight comet, and the first I’ve seen in such strong twilight. On Jan 12th I also saw my first green flash.

This image was taken using a Nikon Coolpix 4300 digital camera and no telescope. But even though the comet was plainly visible with the unaided eye, it took a lot of enhancement of the image to show it, hence the dark disk around the comet.

David Nakamoto

Inside this issue

Feature Article: Fire Breathing Dragons ······························ 1,4-9 Contact Information ····························································· 2 Editor’s Message ·································································· 2 Mt Wilson Nights ································································· 3 Public Star Party News ························································· 3 LAAS Yahoo Group: How to Join ······································· 3 The Art of Observing: Web Camera Imaging ······················· 8-11, 13 Film: Journey to Palomar ····················································· 12 Monterey Park Observatory Map ········································· 12 Loaner Corner (David Sovereign) ········································ 14 Events Calendar ·································································· 15 Membership Information ····················································· 15 Image of Comet McNaught ·················································· 16 Telescope for Sale ································································ 16

Notes, corrections, questions, ideas, articles? All are welcome at: [email protected].

LOS ANGELES ASTRONOMICAL SOCIETY

BULLETIN volume 81, issue 2 February 2007

Page 1 LAAS BulletinLAAS Bulletin

Fire Breathing Dragons By Tim ThompsonBy Tim ThompsonBy Tim Thompson

By our own standards, our own sun is pretty impressive. It weighs in at 333,000 Earth masses, and is over a million times larger in volume. Its apparent temperature of nearly 10,000 degrees F (5800 Kelvins) is hot enough to melt & vaporize almost everything we know of (the single exception being that the sun’s temperature is

(Continued on page 4)

OUR 81th YEAR OF ASTRONOMY IN LOS ANGELES Los Angeles Astronomical Society

Griffith Observatory 2800 East Observatory Road

Los Angeles, CA 90027

Change of Address, Membership: Peter De Hoff, LAAS Secretary

LAAS Officers: President . . . . . . . . . . . . David Sovereign

(626) 794-0646 Vice President . . . . . . . . . . . Mary Brown

[email protected] Treasurer . . . . . . . . . . . . . Darrell Dooley

[email protected] Secretary (acting) . . . . . . . .Peter De Hoff

[email protected] Recording Secretary . . . . . PJ Goldfinger

[email protected] Volunteers: Library . . . . . . . . . . . . . . . . . Mary Brown

[email protected] Outreach . . . . . . . . . . . . . Don DeGregori

[email protected] Loaner Scopes . . . . . . . . Dave Sovereign

(626) 794-0646 Messier Program . . . . . . . . Norm Vargas

(626) 288-4397 New Members . . . . . . . . . . . Bob Redding

[email protected] Speakers Bureau . . . . . . . Tim Thompson

[email protected] Youth Liaison . . . . . . . . . . . . . .Brian Mok

[email protected] LAAS Bulletin Editor . . David Nakamoto

[email protected] Bulletin Printers and Web Site Managers

Peter De Hoff & Minghua Nie [email protected]

Contributing Editors . . . . . . . Mary Brown Tim Thompson Don DeGregori

David Sovereign

LAAS BulletinLAAS Bulletin

E d i t o r ’ s Message

C omet McNaught came and went so fast most of us probably didn’t get a chance to look at it.

Griffith also seemed to barely gotten the news, and this first daylight comet in almost 30 years hardly made a splash in the news. Nevertheless, those that managed to get the news were treated to a wonderful sight, the first such visitor since Ikeya-Seki in 1965. Many people couldn’t see it with the unaided eye in daylight due to the haze spreading out the glare of the sun, less than a dozen degrees away, but it was certainly a sight in binoculars. More on McNaught later in this issue.

The traditional Show and Tell meeting has been moved to February. One warning —– at press time the new slide projectors in the theater are not capable of focusing on the main screen, and there isn’t any solution other than to wait for the new lenses to come in. Please continue to read this column for more news on this, but I anticipate that the situation will clear up by the New Year. However, if it hasn’t, then we might consider moving the meeting to the adjoining classroom, which can only accommodate 30 to 40 people.

The deadline for submitting bulletin material is the 10th of each month. Please submit electronically, if possible, to [email protected]. All other material may be sent to the address listed at the top of the column at left, but timely reception and publication cannot be guaranteed.

David Nakamoto

Membership Annual Dues: Youth $ 20.00 Regular (18-65) $ 35.00 Senior Citizen (65 and up) $ 20.00 Senior Family $ 30.00 Family $ 50.00 Group or Club $ 50.00 Life $ 500.00 Additional fees: Charter Star member $ 30.00 Star member, with pad $ 70.00 Star member, no pad $ 60.00 (Membership due date is indi-cated on the mailing label)

HANDY PHONE LIST LAAS Answering Machine ...... (213) 673-7355 Griffith Observatory Program .............................. (213) 473-0800 Offices ................................. Sky Report ...........................unavailable for

now Lockwood Site ........................ (661) 245-2106 (not answered, arrange time with caller. Outgoing calls – collect or calling card) Mt. Wilson Institute ................. (626) 793-3100

LAAS Home Page: http://www.laas.org LAAS Bulletin Online: http://www.laas.org/bulletin.html

Page 15 Vol 81, issue 2

EVENTS CALENDAR Date Event Location and Information

Feb 12th (Mon) General Meeting Griffith Observatory Show and Tell by members

Feb 17th (Sat) Dark Sky Night Lockwood Valley

Feb 24th (Sat) Public Star Party Griffith Observatory

Mar 12th (Mon) General Meeting Griffith Observatory Speaker TBD

Mar 17th (Sat) Dark Sky Night Lockwood Valley

Mar 24th (Sat) Public Star Party Griffith Observatory

The board meeting is held at 8pm on the Wednesday night prior to the general meeting, at Garvey Ranch Park. The Monday general meetings starts at 7:30 pm


This edition of the Loaner Corner will give a total rundown of the instruments and their status. All telescopes are fully equipped with three eyepieces and an accessory case. Reflectors also have a simple collimation tool. Refractors have a star diagonal. LAAS-1: 4.5” f/8 Celestron reflector on a Polaris mount – Checked out LAAS-2: 4.5: f/8 upgraded Tasco reflector on a driven Edmund mount – Available

LAAS-3: 8” f/8 reflector on a Dobsonian mount – checked out and overdue LAAS-4: 6” f/5 Telescopics reflector on a Dobsonian mount – checked out LAAS-5: 6” f/6 Parks reflector on a Polaris clone mount - Available LAAS-6: 10” f/4.5 Discovery reflector on a Dobsonian mount – Available LAAS-7: 80mm Meade refractor on an Orion Sky View equatorial mount – Checked out

LAAS-8: 80mm Selsi refractor on an equatorial mount – Checked out LAAS-9: 8” f/4.5 rebuilt Dobsonian mount. This mount is equipped with a Dob Driver II that is inoperable, but the telescope itself works well – Available For further information contact David Sovereign at (626) 794-0646

LOANER CORNER

LAAS-4

LAAS-2

Vol 81, issue 2

There are currently no more Mount Wilson 60” nights scheduled. Please send any suggestions for possible future nights to [email protected]

Mt Wilson 60” Nights

LAAS Yahoo Group Some have asked me how to join the LAAS Yahoo group. The group is private, and therefore does not come up in a search. You can join by sending email to: [email protected] with your full name so the moderator can verify your membership in the LAAS. Your full name is necessary so we can check our records to see if you really are a member of the LAAS. If approved, you will receive further instructions via email.

Public Star Party News If members want to attend an event at Griffith as a member of the LAAS and get the parking on the hill, the LAAS Secretary needs to have their name on a list so it can be passed on to Griffith Observatory. This does not include general meetings as everyone is already on that list. But it does include public star parties. If you want to bring someone who is not a member of the LAAS to any LAAS event, including general meetings, then the Secretary also needs their name. Contact Peter De Hoff, the LAAS Secretary, at

[email protected]

if you have questions or wish to add names to the list. It is hoped that these rules will be relaxed or modified once the newer staff at GO gets more used to the LAAS.


below the vaporization temperature of Osmium, not that the sun is famous for having lot of Osmium in it). But the sun is a wimp. Way up at the high end of stardom is an exclusive type of star called a Luminous Blue Variable, or LBV. Millions of stars have been cataloged in the Milky Way, but of all those millions, only a dozen are known to be LBV stars, and there are a couple dozen more


Eta Carinae & the Homunculus Nebula, as imaged by the Hubble Space Telescope. The nebula was born in the Great Eruption, which began in 1837

and lasted 20 years.


the artifacts along the upper edge and lower left corner are due to the stacking technique. The clarity of the image, like the one on page 11, is due as much to using a wavelet filter as to the stacking technique, but care has to be taken that artifacts are not introduced that are due to noise, seeing, and stacking errors. A good general rule of thumb is less is more.

David Nakamoto


10 Freeway

Valley Blvd

Garvey Ave

Graves Ave

Gar

field

A

ve

Alh

ambr

a A

ve

New

A

ve

Del

Mar

A

ve

San

Gab

riel

Blv

d

Atla

ntic

B

lvd

Garvey RanchPark Observatory

Ora

nge

Ave

N

(The place to build your telescope)(The place to build your telescope)(The place to build your telescope) Map to Monterey Park Observatory

Film—Journey to Palomar Special Screenings

At this year’s RTMC, Robin and Todd Mason spoke about their new documentary, The Journey to Palomar, about the life of George Ellery Hale who built Yerkes, Mount Wilson and Palomar Observatories. Robin and Todd are now screening the completed documentary at special fundraising events, to raise funds towards getting the film on PBS and to raise awareness among those who are most passionate about the subject.

More information on the two available screenings of The Journey to Palomar coming up can be found at:

<http://www.journeytopalomar.org/screening_july_21a.html>http://www.journeytopalomar.org/screening_july_21a.html

http://www.journeytopalomar.org/screening_july_27a.html

The venues are special but small so seating is very limited. Questions should be directed to Mike Simmons at [email protected]

Vol 81, issue 2

candidates. It’s an exclusive group. They are the fire-breathing dragons of the Milky Way, and the king of the dragons is the peculiar variable star Eta Carinae.

Edmund Halley first unambiguously cataloged the star we now call Eta Carinae in 1677, under the name Eta Roboris Caroli, for the constellation Robur Carolinum (Charles’ Oak), a constellation invented by Halley. Eta Carinae is not found in Ptolemy’s Almagest (AD 132), which means it was likely not in the lost catalog of Hipparchus (circa 130 BC) either. It is not found in the later catalog of Abd al-Rahman Al-Sufi (AD 964) and was too far south to be seen from


Eta Carina as imaged by the Chandra X-ray telescope. The field of view of the HST picture is confined to the blue area at the center of the image. The diffuse red horseshoe shaped region is about 2 light years across, and shows gas heated to about 3 million Kelvins. The inner blue region is about 3 light months across

and shows gas heated to 30 – 60 million Kelvins. The gas is heated by ultraviolet emission from Eta Carinae.


Samarkand by the early 15th century astronomer Ulugh Beg. Neither is the star to be found in the catalogs made by 15th & 16th century Dutch & Portuguese mariners. Either the star was too faint for them to see, or not bright enough to be cataloged. It could not have been as bright as it was when Halley cataloged it at 4th magnitude in 1677 (his 4th magnitude would be 3rd magnitude by today’s standards). The first accurate measure of its magnitude are due to John Herschel, who put it at magnitude 1.2, and made note of the fact that it had become considerably brighter than it had been in the past.

Until the close of 1837, Eta Carinae was just another star. But then it began its Great Eruption; in about 2 weeks it brightened by a full magnitude, and then continued to brighten until it reached an apparent visual magnitude of -1, and was the second brightest star in the sky, behind Sirius. In 1857 it began the long decline to obscurity, and by 1870 it was a 7th magnitude star, below the naked eye limit. Steadily increasing in brightness ever since, it now sits at about 5th magnitude, but is highly variable.

Eta Carinae lies about 7700 light years away in the constellation Carina (which is one of the pieces of the older constellation Argo Navis), and is associated with the Carina Nebula star forming region, and the massive young star cluster Trumpler 16. Anything that can shine with an apparent magnitude of -1, from 7700 light years away (almost 1000 times farther away than Sirius) has to be really, really bright. So what is Eta Carinae? It was long thought to be a single, supermassive star, carrying as much as 120 solar masses. But it is now known that Eta Carinae is in fact a close binary. We know it is a binary from periodic variations in brightness connected to the orbital period of the companion star. And, recent observations from the Far Ultraviolet Survey Explorer (FUSE) have directly detected the UV emission from the companion star. One study models the system with a gargantuan primary star of 120 solar masses, with a somewhat evolved, O class companion star that wimps out at a mere 30 solar masses. Another study cuts the primary mass back to 90 solar masses. In any case, we do know that we have two very massive stars. The companion’s orbit is very eccentric, but not very large, with a semi-major axis about 17 AU with a closest approach (periastron) distance just under 2 AU. Since stars that size are as big as a half AU in radius, their periastron passage brings them almost into contact. A 30 solar mass O star will have an effective temperature about 40,000 Kelvins (compared to the sun’s 5800), and both stars will emit ferocious stellar winds. Stars that massive shine brighter than the Eddington Limit. That means the starlight is so bright that radiation pressure alone will accelerate some of the material in the outer layers of the star beyond escape velocity. The star literally blows itself apart. So this becomes a colliding winds binary system, where the shock from the powerful colliding winds generates copious X-ray emission. Together, the Eta Carinae binary shines several million times brighter than the sun, about as bright as it is possible for any star to shine. It may well be that this is the brightest & most massive binary system in the galaxy. It may well be that



This image of the moon shows Copernicus, the large crater to the lower right, Mare Imbrium to its left, and Mare Serentatis above Mare Imbrium. By processing the images in black and white, the fuzziness of the images due to using a two-element refractor are reduced, and stacking can eliminate most of the seeing. Artifacts of the stacking process are visible on the left edge of the moon, and in the upper right corner.

On page 13, the image shows the crater Tycho in the lower right quadrant. Again,



greater than the noise, so if the noise averaged 50, the nebula was no greater than 60! Keep in mind that although the nebula itself is visible to the unaided eye, the average surface brightness, the brightness per unit area, is a lot fainter, so this seems to confirm the findings using Titan, that the limit for this equipment is around 8th magnitude. The horizontal bands running across the image are due to readout noise in the camera and are normally not visible, but they’re visible due to the faintness of the details.


Vol 81, issue 2

The VINCI/VLT & CONICA infrared instruments of the European Southern Observatory peer through the dust to reveal the immediate environment of the

stars of Eta Carinae. The image shows an elongated cloud, the long axis of which is coaligned with the axis of the larger double lobed Homunculus nebula.


The Art of Observing

Limits of Web Cameras

By David Nakamoto

February 2007

the primary alone is the most massive single star in the galaxy. There are only a few rivals.

The HST image of Eta Carina shows that the stars themselves are invisible, buried deep inside the double lobed dust cloud called the Homunculus Nebula. The clouds of dust are made from gas that was ejected during the great eruption that began in 1837. As the gas cooled & condensed into dust, the growing dust cloud enshrouded the stars, and that explains how Eta Carinae dimmed by nearly 9 magnitudes in the years after 1857. Since then, the stars have brightened about 4 magnitudes as cracks open in the expanding dust shell and reveal the hidden stars. That’s how FUSE was able to see the UV emission from the companion star. That’s how the VINCI/VLTI interferometer of the European Southern Observatory was able to map the region around the stars, with milliarcsecond resolution. As time goes by, and the Homunculus opens, we will be able to peer into the heart of the fire-breathing dragon.

One more thing: Stars that massive don’t last long. The age of the system is probably 2-3 million years, and the great eruption probably marks the final departure from the main sequence for the Eta Carinae system. In the next few tens of thousands of years, the system will host a supernova. Not just any supernova, but a gamma ray burst (GRB) generating hypernova. The shape of the Homunculus Nebula indicates that the rotational axis of the system points away from us, and physical models of GRBs indicate that the burst is aligned with that axis. That’s good, because a GRB that close could lead to massive devastation on Earth. But somebody down the line of history is going to see a really big celestial show.

Web cameras can be used on more than planets and the moon, and it’s interesting to see what they’re capable of. The following series of images were taken at the December 30th 2006 Griffith public star party. For each, hundreds of images were collected by a web camera attached to a 5-inch aperture f/5 refractor, not the best instrument to use, not only because of the low magnification, but also because of color dispersion that spreads the images out. As a consequence, every object had its light spread out, especially in the blue and red wavelengths, blurring details. Some of this can be compensated for by processing the images in black and white, but using a Newtonian or Maksutov



would have been better.

This image of Sirius to the left is an enlargement of a small region from the original image, and printed as a negative to help see details; the eye is better at seeing black on white, rather than the other way around. The actual image of Sirius is spread out despite the stacking of the i ma ge s t h r o u gh R e g i s t a x . Nevertheless, there appears to be a bump on the south side of Sirius,

perhaps the companion, although I have not located a web resource that gives the position of the companion. This is an enlargement of the original image. The arcs to either side of Sirius are artifacts of the stacking process.

The image to the left is of the star Rigil in Orion, again printed a s negative to help see details. Rigil has two companions that are visible in even small telescopes, but the terrible seeing that night prevents a sharp image from being formed, even with image stacking. Nevertheless, there does appear to be a bump on the left side of the main star image, perhaps one

of the companions, although once again web sources do not specify the position of either companion. The arcs surrounding the star are once again artifacts of seeing and stacking. As with the image of Sirius, this is an enlargement from the original image.

So there is some use for web cameras for double star imaging, especially the brighter ones, and the images can be processed in color. However, some cares needs to be heeded. For color, Newtonians, Maksutovs, and SCTs help to prevent colors from spreading. Aperture still counts on fainter objects, and steady skies are also a big plus.

The image on the next page is currently the faintest object I’ve been able to image using the equipment described on the previous pages. It’s M42, the Orion Nebula. North is to the left, and the image is once again printed as a negative to help see details. The data for the nebula in the original image was only +10



The Art of Observing

Limits of Web Cameras

By David Nakamoto

February 2007

the primary alone is the most massive single star in the galaxy. There are only a few rivals.

The HST image of Eta Carina shows that the stars themselves are invisible, buried deep inside the double lobed dust cloud called the Homunculus Nebula. The clouds of dust are made from gas that was ejected during the great eruption that began in 1837. As the gas cooled & condensed into dust, the growing dust cloud enshrouded the stars, and that explains how Eta Carinae dimmed by nearly 9 magnitudes in the years after 1857. Since then, the stars have brightened about 4 magnitudes as cracks open in the expanding dust shell and reveal the hidden stars. That’s how FUSE was able to see the UV emission from the companion star. That’s how the VINCI/VLTI interferometer of the European Southern Observatory was able to map the region around the stars, with milliarcsecond resolution. As time goes by, and the Homunculus opens, we will be able to peer into the heart of the fire-breathing dragon.

One more thing: Stars that massive don’t last long. The age of the system is probably 2-3 million years, and the great eruption probably marks the final departure from the main sequence for the Eta Carinae system. In the next few tens of thousands of years, the system will host a supernova. Not just any supernova, but a gamma ray burst (GRB) generating hypernova. The shape of the Homunculus Nebula indicates that the rotational axis of the system points away from us, and physical models of GRBs indicate that the burst is aligned with that axis. That’s good, because a GRB that close could lead to massive devastation on Earth. But somebody down the line of history is going to see a really big celestial show.

Web cameras can be used on more than planets and the moon, and it’s interesting to see what they’re capable of. The following series of images were taken at the December 30th 2006 Griffith public star party. For each, hundreds of images were collected by a web camera attached to a 5-inch aperture f/5 refractor, not the best instrument to use, not only because of the low magnification, but also because of color dispersion that spreads the images out. As a consequence, every object had its light spread out, especially in the blue and red wavelengths, blurring details. Some of this can be compensated for by processing the images in black and white, but using a Newtonian or Maksutov


Vol 81, issue 2

would have been better.

This image of Sirius to the left is an enlargement of a small region from the original image, and printed as a negative to help see details; the eye is better at seeing black on white, rather than the other way around. The actual image of Sirius is spread out despite the stacking of the i ma ge s t h r o u gh R e g i s t a x . Nevertheless, there appears to be a bump on the south side of Sirius,

perhaps the companion, although I have not located a web resource that gives the position of the companion. This is an enlargement of the original image. The arcs to either side of Sirius are artifacts of the stacking process.

The image to the left is of the star Rigil in Orion, again printed a s negative to help see details. Rigil has two companions that are visible in even small telescopes, but the terrible seeing that night prevents a sharp image from being formed, even with image stacking. Nevertheless, there does appear to be a bump on the left side of the main star image, perhaps one

of the companions, although once again web sources do not specify the position of either companion. The arcs surrounding the star are once again artifacts of seeing and stacking. As with the image of Sirius, this is an enlargement from the original image.

So there is some use for web cameras for double star imaging, especially the brighter ones, and the images can be processed in color. However, some cares needs to be heeded. For color, Newtonians, Maksutovs, and SCTs help to prevent colors from spreading. Aperture still counts on fainter objects, and steady skies are also a big plus.

The image on the next page is currently the faintest object I’ve been able to image using the equipment described on the previous pages. It’s M42, the Orion Nebula. North is to the left, and the image is once again printed as a negative to help see details. The data for the nebula in the original image was only +10



greater than the noise, so if the noise averaged 50, the nebula was no greater than 60! Keep in mind that although the nebula itself is visible to the unaided eye, the average surface brightness, the brightness per unit area, is a lot fainter, so this seems to confirm the findings using Titan, that the limit for this equipment is around 8th magnitude. The horizontal bands running across the image are due to readout noise in the camera and are normally not visible, but they’re visible due to the faintness of the details.



The VINCI/VLT & CONICA infrared instruments of the European Southern Observatory peer through the dust to reveal the immediate environment of the

stars of Eta Carinae. The image shows an elongated cloud, the long axis of which is coaligned with the axis of the larger double lobed Homunculus nebula.


Samarkand by the early 15th century astronomer Ulugh Beg. Neither is the star to be found in the catalogs made by 15th & 16th century Dutch & Portuguese mariners. Either the star was too faint for them to see, or not bright enough to be cataloged. It could not have been as bright as it was when Halley cataloged it at 4th magnitude in 1677 (his 4th magnitude would be 3rd magnitude by today’s standards). The first accurate measure of its magnitude are due to John Herschel, who put it at magnitude 1.2, and made note of the fact that it had become considerably brighter than it had been in the past.

Until the close of 1837, Eta Carinae was just another star. But then it began its Great Eruption; in about 2 weeks it brightened by a full magnitude, and then continued to brighten until it reached an apparent visual magnitude of -1, and was the second brightest star in the sky, behind Sirius. In 1857 it began the long decline to obscurity, and by 1870 it was a 7th magnitude star, below the naked eye limit. Steadily increasing in brightness ever since, it now sits at about 5th magnitude, but is highly variable.

Eta Carinae lies about 7700 light years away in the constellation Carina (which is one of the pieces of the older constellation Argo Navis), and is associated with the Carina Nebula star forming region, and the massive young star cluster Trumpler 16. Anything that can shine with an apparent magnitude of -1, from 7700 light years away (almost 1000 times farther away than Sirius) has to be really, really bright. So what is Eta Carinae? It was long thought to be a single, supermassive star, carrying as much as 120 solar masses. But it is now known that Eta Carinae is in fact a close binary. We know it is a binary from periodic variations in brightness connected to the orbital period of the companion star. And, recent observations from the Far Ultraviolet Survey Explorer (FUSE) have directly detected the UV emission from the companion star. One study models the system with a gargantuan primary star of 120 solar masses, with a somewhat evolved, O class companion star that wimps out at a mere 30 solar masses. Another study cuts the primary mass back to 90 solar masses. In any case, we do know that we have two very massive stars. The companion’s orbit is very eccentric, but not very large, with a semi-major axis about 17 AU with a closest approach (periastron) distance just under 2 AU. Since stars that size are as big as a half AU in radius, their periastron passage brings them almost into contact. A 30 solar mass O star will have an effective temperature about 40,000 Kelvins (compared to the sun’s 5800), and both stars will emit ferocious stellar winds. Stars that massive shine brighter than the Eddington Limit. That means the starlight is so bright that radiation pressure alone will accelerate some of the material in the outer layers of the star beyond escape velocity. The star literally blows itself apart. So this becomes a colliding winds binary system, where the shock from the powerful colliding winds generates copious X-ray emission. Together, the Eta Carinae binary shines several million times brighter than the sun, about as bright as it is possible for any star to shine. It may well be that this is the brightest & most massive binary system in the galaxy. It may well be that


Vol 81, issue 2

This image of the moon shows Copernicus, the large crater to the lower right, Mare Imbrium to its left, and Mare Serentatis above Mare Imbrium. By processing the images in black and white, the fuzziness of the images due to using a two-element refractor are reduced, and stacking can eliminate most of the seeing. Artifacts of the stacking process are visible on the left edge of the moon, and in the upper right corner.

On page 13, the image shows the crater Tycho in the lower right quadrant. Again,



10 Freeway

Valley Blvd

Garvey Ave

Graves Ave

Gar

field

A

ve

Alh

ambr

a A

ve

New

A

ve

Del

Mar

A

ve

San

Gab

riel

Blv

d

Atla

ntic

B

lvd

Garvey RanchPark Observatory

Ora

nge

Ave

N

(The place to build your telescope)(The place to build your telescope)(The place to build your telescope) Map to Monterey Park Observatory

Film—Journey to Palomar Special Screenings

At this year’s RTMC, Robin and Todd Mason spoke about their new documentary, The Journey to Palomar, about the life of George Ellery Hale who built Yerkes, Mount Wilson and Palomar Observatories. Robin and Todd are now screening the completed documentary at special fundraising events, to raise funds towards getting the film on PBS and to raise awareness among those who are most passionate about the subject.

More information on the two available screenings of The Journey to Palomar coming up can be found at:

<http://www.journeytopalomar.org/screening_july_21a.html>http://www.journeytopalomar.org/screening_july_21a.html

http://www.journeytopalomar.org/screening_july_27a.html

The venues are special but small so seating is very limited. Questions should be directed to Mike Simmons at [email protected]


candidates. It’s an exclusive group. They are the fire-breathing dragons of the Milky Way, and the king of the dragons is the peculiar variable star Eta Carinae.

Edmund Halley first unambiguously cataloged the star we now call Eta Carinae in 1677, under the name Eta Roboris Caroli, for the constellation Robur Carolinum (Charles’ Oak), a constellation invented by Halley. Eta Carinae is not found in Ptolemy’s Almagest (AD 132), which means it was likely not in the lost catalog of Hipparchus (circa 130 BC) either. It is not found in the later catalog of Abd al-Rahman Al-Sufi (AD 964) and was too far south to be seen from


Eta Carina as imaged by the Chandra X-ray telescope. The field of view of the HST picture is confined to the blue area at the center of the image. The diffuse red horseshoe shaped region is about 2 light years across, and shows gas heated to about 3 million Kelvins. The inner blue region is about 3 light months across

and shows gas heated to 30 – 60 million Kelvins. The gas is heated by ultraviolet emission from Eta Carinae.


below the vaporization temperature of Osmium, not that the sun is famous for having lot of Osmium in it). But the sun is a wimp. Way up at the high end of stardom is an exclusive type of star called a Luminous Blue Variable, or LBV. Millions of stars have been cataloged in the Milky Way, but of all those millions, only a dozen are known to be LBV stars, and there are a couple dozen more


Eta Carinae & the Homunculus Nebula, as imaged by the Hubble Space Telescope. The nebula was born in the Great Eruption, which began in 1837

and lasted 20 years.

Vol 81, issue 2

the artifacts along the upper edge and lower left corner are due to the stacking technique. The clarity of the image, like the one on page 11, is due as much to using a wavelet filter as to the stacking technique, but care has to be taken that artifacts are not introduced that are due to noise, seeing, and stacking errors. A good general rule of thumb is less is more.

David Nakamoto


This edition of the Loaner Corner will give a total rundown of the instruments and their status. All telescopes are fully equipped with three eyepieces and an accessory case. Reflectors also have a simple collimation tool. Refractors have a star diagonal. LAAS-1: 4.5” f/8 Celestron reflector on a Polaris mount – Checked out LAAS-2: 4.5: f/8 upgraded Tasco reflector on a driven Edmund mount – Available

LAAS-3: 8” f/8 reflector on a Dobsonian mount – checked out and overdue LAAS-4: 6” f/5 Telescopics reflector on a Dobsonian mount – checked out LAAS-5: 6” f/6 Parks reflector on a Polaris clone mount - Available LAAS-6: 10” f/4.5 Discovery reflector on a Dobsonian mount – Available LAAS-7: 80mm Meade refractor on an Orion Sky View equatorial mount – Checked out

LAAS-8: 80mm Selsi refractor on an equatorial mount – Checked out LAAS-9: 8” f/4.5 rebuilt Dobsonian mount. This mount is equipped with a Dob Driver II that is inoperable, but the telescope itself works well – Available For further information contact David Sovereign at (626) 794-0646

LOANER CORNER

LAAS-4

LAAS-2


There are currently no more Mount Wilson 60” nights scheduled. Please send any suggestions for possible future nights to [email protected]

Mt Wilson 60” Nights

LAAS Yahoo Group Some have asked me how to join the LAAS Yahoo group. The group is private, and therefore does not come up in a search. You can join by sending email to: [email protected] with your full name so the moderator can verify your membership in the LAAS. Your full name is necessary so we can check our records to see if you really are a member of the LAAS. If approved, you will receive further instructions via email.

Public Star Party News If members want to attend an event at Griffith as a member of the LAAS and get the parking on the hill, the LAAS Secretary needs to have their name on a list so it can be passed on to Griffith Observatory. This does not include general meetings as everyone is already on that list. But it does include public star parties. If you want to bring someone who is not a member of the LAAS to any LAAS event, including general meetings, then the Secretary also needs their name. Contact Peter De Hoff, the LAAS Secretary, at

[email protected]

if you have questions or wish to add names to the list. It is hoped that these rules will be relaxed or modified once the newer staff at GO gets more used to the LAAS.

OUR 81th YEAR OF ASTRONOMY IN LOS ANGELES Los Angeles Astronomical Society

Griffith Observatory 2800 East Observatory Road

Los Angeles, CA 90027

Change of Address, Membership: Peter De Hoff, LAAS Secretary

LAAS Officers: President . . . . . . . . . . . . David Sovereign

(626) 794-0646 Vice President . . . . . . . . . . . Mary Brown

[email protected] Treasurer . . . . . . . . . . . . . Darrell Dooley

[email protected] Secretary (acting) . . . . . . . .Peter De Hoff

[email protected] Recording Secretary . . . . . PJ Goldfinger

[email protected] Volunteers: Library . . . . . . . . . . . . . . . . . Mary Brown

[email protected] Outreach . . . . . . . . . . . . . Don DeGregori

[email protected] Loaner Scopes . . . . . . . . Dave Sovereign

(626) 794-0646 Messier Program . . . . . . . . Norm Vargas

(626) 288-4397 New Members . . . . . . . . . . . Bob Redding

[email protected] Speakers Bureau . . . . . . . Tim Thompson

[email protected] Youth Liaison . . . . . . . . . . . . . .Brian Mok

[email protected] LAAS Bulletin Editor . . David Nakamoto

[email protected] Bulletin Printers and Web Site Managers

Peter De Hoff & Minghua Nie [email protected]

Contributing Editors . . . . . . . Mary Brown Tim Thompson Don DeGregori

David Sovereign


E d i t o r ’ s Message

C omet McNaught came and went so fast most of us probably didn’t get a chance to look at it.

Griffith also seemed to barely gotten the news, and this first daylight comet in almost 30 years hardly made a splash in the news. Nevertheless, those that managed to get the news were treated to a wonderful sight, the first such visitor since Ikeya-Seki in 1965. Many people couldn’t see it with the unaided eye in daylight due to the haze spreading out the glare of the sun, less than a dozen degrees away, but it was certainly a sight in binoculars. More on McNaught later in this issue.

The traditional Show and Tell meeting has been moved to February. One warning —– at press time the new slide projectors in the theater are not capable of focusing on the main screen, and there isn’t any solution other than to wait for the new lenses to come in. Please continue to read this column for more news on this, but I anticipate that the situation will clear up by the New Year. However, if it hasn’t, then we might consider moving the meeting to the adjoining classroom, which can only accommodate 30 to 40 people.

The deadline for submitting bulletin material is the 10th of each month. Please submit electronically, if possible, to [email protected]. All other material may be sent to the address listed at the top of the column at left, but timely reception and publication cannot be guaranteed.

David Nakamoto

Membership Annual Dues: Youth $ 20.00 Regular (18-65) $ 35.00 Senior Citizen (65 and up) $ 20.00 Senior Family $ 30.00 Family $ 50.00 Group or Club $ 50.00 Life $ 500.00 Additional fees: Charter Star member $ 30.00 Star member, with pad $ 70.00 Star member, no pad $ 60.00 (Membership due date is indi-cated on the mailing label)

HANDY PHONE LIST LAAS Answering Machine ...... (213) 673-7355 Griffith Observatory Program .............................. (213) 473-0800 Offices ................................. Sky Report ...........................unavailable for

now Lockwood Site ........................ (661) 245-2106 (not answered, arrange time with caller. Outgoing calls – collect or calling card) Mt. Wilson Institute ................. (626) 793-3100

LAAS Home Page: http://www.laas.org LAAS Bulletin Online: http://www.laas.org/bulletin.html

Vol 81, issue 2

EVENTS CALENDAR Date Event Location and Information

Feb 12th (Mon) General Meeting Griffith Observatory Show and Tell by members

Feb 17th (Sat) Dark Sky Night Lockwood Valley

Feb 24th (Sat) Public Star Party Griffith Observatory

Mar 12th (Mon) General Meeting Griffith Observatory Speaker TBD

Mar 17th (Sat) Dark Sky Night Lockwood Valley

Mar 24th (Sat) Public Star Party Griffith Observatory

The board meeting is held at 8pm on the Wednesday night prior to the general meeting, at Garvey Ranch Park. The Monday general meetings starts at 7:30 pm


For Sale Meade 12-inch LX-200. Extras include —– very nice cabinet, heavy-duty wedge, light extension shield, heavy duty tripod, canvas case, Meade l.p.i., Meade spotting scope.

If interested contact Tav at (818) 362 - 5092.

On the days and sunsets of Jan 12th and 13th, Comet McNaught was visible in the skies, the first daylight comet since Ikeya-Seki in 1965. I didn’t see it either day with the unaided eye in daylight, but it was plainly visible to the unaided eye hanging just over the horizon in strong twilight just after sunset. I did spot it through 50mm aperture binoculars in daylight, along with a tail I estimated to be 2 to 3 degrees long. Many of the visitors to Griffith saw it also. This was my first daylight comet, and the first I’ve seen in such strong twilight. On Jan 12th I also saw my first green flash.

This image was taken using a Nikon Coolpix 4300 digital camera and no telescope. But even though the comet was plainly visible with the unaided eye, it took a lot of enhancement of the image to show it, hence the dark disk around the comet.

David Nakamoto

Inside this issue

Feature Article: Fire Breathing Dragons ······························ 1,4-9 Contact Information ····························································· 2 Editor’s Message ·································································· 2 Mt Wilson Nights ································································· 3 Public Star Party News ························································· 3 LAAS Yahoo Group: How to Join ······································· 3 The Art of Observing: Web Camera Imaging ······················· 8-11, 13 Film: Journey to Palomar ····················································· 12 Monterey Park Observatory Map ········································· 12 Loaner Corner (David Sovereign) ········································ 14 Events Calendar ·································································· 15 Membership Information ····················································· 15 Image of Comet McNaught ·················································· 16 Telescope for Sale ································································ 16

Notes, corrections, questions, ideas, articles? All are welcome at: [email protected].

LOS ANGELES ASTRONOMICAL SOCIETY

BULLETIN volume 81, issue 2 February 2007


Fire Breathing Dragons By Tim ThompsonBy Tim ThompsonBy Tim Thompson

By our own standards, our own sun is pretty impressive. It weighs in at 333,000 Earth masses, and is over a million times larger in volume. Its apparent temperature of nearly 10,000 degrees F (5800 Kelvins) is hot enough to melt & vaporize almost everything we know of (the single exception being that the sun’s temperature is


los angeles astronomical society bulletin · warning —– at press time the new slide projectors...

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