December   2001

ACT, Inc. has been meeting continuously since 1937 and was incorporated in 1986. It is a nonprofit; tax deductible organization dedicated to promoting, to the public, the art of viewing and the scientific aspect of astronomy.


The Astronomy Club of Tulsa Club

Astro ArtistóRobert Daniels


Friday, December 7, 2001 at 7:30 PM


Room M1 inside Keplinger Hall, the Science & Engineering Building at TU. Enter the parking lot on the East Side of Keplinger Hall from Harvard and 5th Street. This will take you directly toward the staircase to enter the building. Room M1 is the first room on the left.

Notes from the President

Denny Mishler

Thank you for the opportunity to be the president of our club, the Astronomy Club of Tulsa. Ten years ago I became the president of another club, the 75 member Westminster Astronomical Society of Maryland. This was and is a very active club composed of amateurs and professionals (Hubble Space Telescope, Goddard Space Flight Center, Johns Hopkins Applied Physics Lab, etc). I learned many good things during the years I belonged to WAS, namely, enthusiasm plus effort makes this a great hobby. And with much clearer skies than in the East, the payoff is much more often here in the Heartland. As you get to know me, I hope to pass on my love of Astronomy.


Let's discuss the exciting and somewhat unusual meeting we have planned for you December 7th. Robert Daniels from Oklahoma City is a nationally known artist who paints Astro Art. He visits national art shows and conventions to present his popular paintings of star formations, nebulas, galaxies and otherly worlds. During his visit he will complete an Original Astro Painting and then provide it to the club for a drawing at $2 a chance. The club keeps the proceeds. This is a Win-Win situation, especially for the lucky club member or guest who wins the painting. Daniels will display a portion of his collection of prints, priced from $20 to $40, and originals starting at about $120. What an ideal meeting for bringing family members and friends to help pick out your Christmas gift or a gift for a budding Astronomer.

Most of us stayed in Tulsa for the Leonid Meteor shower and only if you were persistent and lucky were you able to experience a small portion of the meteor shower after the rain showers and clouds subsided. A group of our members traveled over 400 miles from Tulsa and experienced the Leonids in all their glory. Member David Stine and perhaps others in his group will give us a first hand account of their odyssey. Was it a full-blown meteor storm? Come and find out.

At the end of the meeting I will provide some refreshments, including my wife Barb's delicious chocolate chip cookies. You too are invited to bring your favorite goodies. We will need to leave the meeting room in its original clean condition.


How convenient that on Friday December 14th, the date of the monthly Star Party at our Mounds Observatory, we will be given a PARTIAL SOLAR ECLIPSE that afternoon from about 3 to 5pm. As the sun sets and the brightest stars begin to shine, myself or another club member will introduce the nighttime sky to those new to Astronomy. Just come and make yourself known and we will get started shortly after sunset (and the eclipse). Jupiter and Saturn should be spectacular all evening and a few Geminids may light up the sky from their maximum 1 day earlier. If these events aren't enough, let's throw in a near naked eye comet (called Linear of course). If you still aren't motivated to come out on the 14th then you need to add another hobby, like Alaskan SCUBA Diving (to wake you up).


If you missed the spectacular covering of Saturn by the moon (known as an occultation) on November 30th another one occurs December 28th. I don't know the times yet but we'll get them for you at the meeting.

What more could we ask for in December. Come out and enjoy the Hobby.

Clear Skies, Denny Mishler Club President


While enjoying our annual dinner meeting at Furr's Restaurant club members held the annual election of Officers and Board Members:

Election Results:

President - Denny Mishler

Board Members:

Vice President - Teresa Kincannon

Gerry Andries

Secretary - Aaron Coyner

Steve Chapman

Treasurer - Nick Pottorf

Hugh Selman

Co. Treasurer - John Land

Diana Williamson-Smith

Diana recently joined the club and comes to us from San Francisco where she was active in an Astronomy Club that viewed from a beautiful site overlooking the Bay Area. She is a writer of health, food and technology subjects and also teaches the bible. Even though new to the club, Diana has given helpful suggestions such as taking a club dinner photo and teaching the sky to those new to Astronomy. The other board members were previewed in the November Observer.

David's Astro Corner


By David Stine

What would make a 16-year-old miss a concert and four adults' drive all the way across Oklahoma and into the Texas panhandle through rain and fog in one night? The answer, only the most exciting, grandest display of a meteor storm ever to be seen in their lives and possibly ever, the 2001 Leonid Meteor Storm. Before it was said and done we had traveled 846 miles round trip in 20 hrs and out of this 20 hrs only about 3 hrs was actual observing time. Just a little crazy you say, was it worth it? Just ask any of them, Ken Black, Teresa Kincannon, Steve Chapman, his daughter Susan and myself.

The adventure started out Saturday, November 17. All day long I kept a close watch on the weather for Tulsa as many members were planning on observing the Leonids at the club observatory. Jeff Lazalier informed me that Tulsa was a no go on Friday, but I kept hoping. I started calling people to see who was willing to travel out of Tulsa to clear skies. It was beginning to look like Eastern Arkansas or Western Tennessee would be our best bet. Ken Black and Teresa Kincannon offered to drive their vehicles, so we began to make plans. I put out an e-mail message to everyone on my list to see who was interested. Steve Chapman and his daughter accepted and were thrilled to be going. Everyone else seemed to think that it would be too far to travel and decided to stick it out in Tulsa. Wrong Decision.

We all gathered around the weather satellite display and I noticed a huge clearing in Amarillo. Arkansas looked very chancy. I called the meteorologist at an Amarillo TV station and he informed me of clear skies until possibly late Sunday morning with occasional fog. He assured me we would have clear skies for the best part of the meteor storm. This seemed to be our best choice. We gathered up our equipment and away we headed to the dark clear skies of the Texas panhandle in Ken's Durango.

It started raining on us not far from Tulsa. I think it was Susan that said we were like Tornado Chasers except we were the opposite, looking for clear skies instead of cloudy skies, so we declared ourselves Meteor Chasers. As we drove farther into western Oklahoma, the fog became intense and continued on into Texas. For a while we were beginning to get a little nervous that we might not be able to see anything. As we got closer to Amarillo, we started seeing stars again in and out of the fog. We had Steve's TV so we caught the 10 PM weathercast about 20 miles outside of Amarillo. They were talking about the meteor shower prospects and it looked good at least through sunrise. Our hopes just soared at that point. I remembered about a really dark sky in Palo Duro Canyon, which was about 20 miles south of Amarillo, so we headed there. To our amazement when we got there the canyon entrance gate was closed. We parked the Durango anyway and got out to take a look. BIG DISAPPOINTMENT! The sky was completely fogged over. It was time to head farther west. We only had to go about 10 miles west before we got into clear skies again. We stopped alongside of the road to check out the sky. It was oohs and ahs as we looked into what seemed a million stars. Then all of a sudden our first Leonid of the night went flashing by. This was about 12:30a.m. We decided to go farther south. We saw a sign that said Church Camp and assumed that it would be closed and might be a good location. The camp had too many lights so we found a little pull off by the side of the road. Now we could begin serious observing. It was perfectly clear and we started seeing the streaks about every 3-5 minutes. This was good as it was still only about 1:15a.m. and 3 hrs away from peak. After about 45 minutes and 40 meteors, clouds started intruding and we decided it was time to move even farther west. It was after 2a.m., so we knew we had about an hour before the big show would begin. We headed to Canyon, Texas where we stopped to gas up and ask some directions. Highway 60 would take us southwest toward Clovis, New Mexico. We started off again and it wasn't any time until I saw several Leonids out my side window. Then Steve and Susan began seeing them. Teresa was on the wrong side of the Durango but she started seeing Leonids on her side. When Ken saw them through his front window, we all agreed get this Durango off the road and parked. We took the next side country road which didn't look to traveled and found a spot and pulled over. As soon as we got out which was about 3:30a.m. a brilliant bolide flashed over our heads, then another meteor and another. We didn't even take time to get our chairs out of the Durango. We were only up to about 52 meteors in our count before getting to this location and within 15 minutes we were well over 200. It was just unbelievable. We were like little kids, oohing and ahing and laughing with delight as the meteors kept intensifying. Many times they would come from all over the sky. While I was yelling look at the NE, Ken would be saying one in the West, and Susan one, two, three, four in the South. There were so many you couldn't catch them all. You didn't have time to breathe or do anything.

One time out of the Leo radiant it looked like one of those pictures you see in Astronomy magazine showing people how meteors radiate out of the radiant with streaks coming out in a starburst. If we had of been in Afghanistan you would of thought the US was bombing again, with many of the meteors looking like missiles shot out of planes. Just an awesome sight. I had brought my camera and video camera, but the meteors were coming at such a rapid number that I didn't want to stop and set the equipment up. Every type of Leonid you could imagine was seen, point flashes, long earth grazers, doubles, triples, bolides that left trains that lasted for minutes, blue, red, green, gold, white and in between colors. By the time we had counted over 700 we were hoping for 1,000. What we didn't know was our goal would be shattered. There were several mini outbursts where we would see more than we could count at one time. Around 4:30a.m. there was this monster meteor that streaked across the sky from the East to the West lighting up the ground around us and leaving a train several minutes long. We would watch the other meteors then look back at the train and it would still be there like a jet's flume drifting in the heavens. We were like kids on Christmas morning. Our count kept getting larger and larger. When we went over 1900 we started playing a birth game, looking for the number meteor that would correlate with our birth date and hoping for a blazer. I think everyone got a blazer when the number fell on their date. By 5:15a.m. we were starting to get a few high clouds moving in, but we could still see the meteors flash behind these clouds making an unusual visual effect. We were up to 1990 meteors as more clouds started to move in. We had to get 2000. There was no way we were going to stop. When we stopped counting at 6a.m. we had counted 2011 meteors and probably missed another 2000. Our ZHR was figured by meteorsobs at approximately 3200/hr between 4a.m.-5a.m. and 2200/hr between 5a.m.-6a.m. ZHR is the number of meteors that you would have seen if you had been able to see every square foot of the sky. I hated to leave even though the activity had slowed down to about 1 every 30 seconds, but we all knew it was time to head back to Tulsa. It was an experience that we Meteor Chasers will never forget. What was it like elsewhere across the world? I have received over 300 reports from across the world and here are just a few excerpts from the best ones:

Barbara Wilson, Houston Texas from Louisiana- "a beautiful burst of 4-6 at once or maybe more out of the radiant that for a few seconds had trains that made the radiant appear as a sunburst." My count was up to 794 before I just stopped counting due to the increased activity. No matter what direction one looked they were falling."

Adam Marsh, Alice Springs Australia - "I have never seen a display like what I saw on that night. At the beginning a huge highlight, -5 split the sky and heralded what was to become an awesome display lasting over 3 hours. I reached a peak ZHR of around 3900/hr."

Constable Jack Kevin Andrews from just north of Salem, Alabama - "Very conservative estimate 3,600/hr. with 30-30% in the -4 to -6 mg. leaving extended trains. After viewing meteor showers for many years I have never seen anything like this before and probably never will again in my lifetime, it was truly a once in a lifetime event."

Jim Graham from New York City who had traveled about a 100 miles to darker skies-"It was a fabulous show, at one point we saw six at once, in about a second. Some seemed to have a punctuation mark at the end, with a little trail that blows up. We saw one that lit up a big piece of the sky and just exploded at the end."

Michael Mattiazzo from South Australia- "Awesome. The one word that could best describes the Leonid meteor storm of 2001. By peak time meteors were arriving one every 2-3 seconds. The highlights of the night were a burst of 5 meteors simultaneously emanating out of Leo in all directions, numerous 4 meteor outbursts, plus 3 memorable fireballs that lit up; the landscape like lightning, leaving a smoke trail visible for several minutes. Bright point meteors within Leo made the constellation appear to have "Stars of Bethlehem". Over 2,000 meteors were witnessed that morning."

Lew Gramer from China - ZHR rates were over 5,000/hr at times."

Gordon Pegue from Albuquerque, "Meteors were just raining down over the entire sky. Many possessed trains that were long and persistent resembling "Tinkerbell dust". My impression was of a ghostly sparkler trail that would fade...another interesting aspect of the rain of ancient solar system debris was the fair number of of meteors seen that were called "Anti-Leonids" that headed in the opposite direction and converged upon the radiant. The event was spectacular, remarkable, and quite enjoyable to all who attended and the chorus of wows, ooohhhs and aahhhs that followed each was music to this observer's ear.

Dean Salmon in Tucson (formerly ACT member) - "The south and west was clear and we saw so many I could not believe it. Many were as bright or brighter than Venus. There was so many it almost was like rain."

And from Donner Summit in California, Gregg Pasterick -"I have been watching meteor showers since 1975. I have suffered relentless cloud cover and rejoiced in crystal clear skies. I've counted 100 Geminids per hour, been blinded by fireballs, and watched Perseids tumble across a dance floor of northern lights, but never, not in my wildest meteor shower fantasies, have I had to forgo my usual hourly tallies in favor of five minute counts, counts that resulted in numbers typical of hourly totals.........this was 12 Leonids streaking across the stars every minute...this was the frequent strobe of flash bulbs behind us as Leonids burst like paparazzi photographing a celebrity...this was the cheer of a crowd a quarter-mile down the road as one Leonid exploded in a blinding flash, leaving a train that lasted for more than 7 minutes.... Yes this was the BIG ONE, and I was invited to the party. My five-minute rates hovered in the vicinity of 45-50 meteors. Leaving the remains of the night and the marvelous Leonid meteors for whomever else was left among the rocky slopes of Donner Summit, I drifted off to bed like a ghost satisfied with the life it had just departed..."

And a very unusual reported close encounter..."Laura Yuran and her 11 year old son Jonathan wrote... about halfway into observing they began hearing what sounded like hail, then a short time later hail like objects started pelting them. As Laura went to get her husband a large piece fell where she had been standing. Jim Seevers, an astronomer from Chicago's Adler Planetarium said the rocks are most likely meteorites from the Leonid meteor storm, but the pieces collected will need to be analyzed. Laura said until the rocks are analyzed, she's trying to play hostess to the excited neighborhood. Eventually she hopes to put the objects in a display case. We really enjoyed watching the Leonids, with the blue lights and long tails..."(This would be a first if the story pans out)

It is really hard to describe what we all saw in Amarillo, but I hope you get the idea. I can assure you it was worth every mile we traveled as Meteor Chasers. Would we do it again if Tulsa conditions look grim next year... without a doubt. So was this our last chance, not exactly. The moon will be full next year during the shower which will result in many dim meteors not being seen, however it will only be 10 or 15 degrees high in the west at the peak time of 4:37a.m.CST. The preliminary prediction from Asher and McNaught is an unheard of 30,000/hr for Tulsa and all of North America. Even at 10% of this that's still 3,000/hr. So for those who were clouded out this year there may still be hope for you. Mark your calendars now and this time if you are assured of clouds don't take the chance of another miss, instead become Meteor Chasers and go wherever the clear dark skies await you.

My personal thanks to Ken Black for volunteering his vehicle for the trip, and to Teresa, Steve and Susan for joining us in a once in a lifetime experience.

For the best pictures, video and stories on this year's Leonid Meteor Storm go to There are some amazing photos and time-lapse video, which will give you an idea of the intensity of this year's storm.

Coming up in December:

Comet Linear C/2000 WM1 - The comet should be possibly as bright as 4th Mg. by the week of Dec. 10-16 about 25 degrees in altitude in the south in the constellation Sculptor between 7 PM and 11 PM. Here are some coordinates for that time period.

12/12 - 00 07.49 RA -29 13.7 DEC

12/14 - 23 53.76 RA -33 26.9 DEC

12/16 - 23 40.71 RA -37 02.8 DEC

Don't forget the Dec. 14th partial annular eclipse of the Sun at 5 PM and on Dec. 28th, the moon will occult Saturn.

And one last thing, the annual Geminid Meteor Shower peaks on the night of December 13th at 10 PM. This is a very dependable shower and in a dark sky you can usually see at least one meteor a minute during the night. This shower is long lasting and is not a brief outburst like the Leonids. The meteors are slow and bright yellow and the best thing is you don't have to get up in the early morning hours like most showers. The radiant is already high in the East by 9 PM. Just remember to bundle up and hope for better skies than was in Tulsa for the Leonids.

That's it from my Astro Corner this month. .


Diana Williamson-Smith is looking for a telescope in the $300-$400 range that would be suitable for a newcomer to study deep sky objects. So, if you are looking to sell that scope that you no longer use, contact her at < Diana Williamson-Smith e-mail >


December 2001 Skies

By John Land

This December the skies are full of treasurers for those hardy souls willing to brave the winter chill to do some observing. You have to do some planning to get ready for winter observing. Since your body loses up to 50% of its heat through the head area, a warm hat or hood are essential to observing comfort. Your feet need to be insulated from cold ground temperatures so thick soled shoes and double socks will keep your toes nice and cozy. Layers are best for the rest of the body holding a nice warm blanket of air between the layers. Besides keeping your body warm you have to let your telescope adjust to the outdoor temperatures. Before observing you need to set your telescope outdoors for at least an hour to let its mirrors or lenses cool down. Until the telescope cools to ambient temperatures the image will be blurred as the sir and glass try to contract. Avoid observing over rooftops, roads or driveways, which give off heat absorbed during the day. Large grassy areas are ideal for observing.

December sky events include:

Geminid meteor shower peaks on the night of Dec 13 and 14. This is one of the best annual showers displaying 50 to 70 meteors per hour. Unlike the recent Leonid shower, you should be able to see a nice display of meteors 2 or 3 days before and after the peak. Since Gemini is already up in early evening you can start watching as soon as it gets dark. Gemini is easy to find this year. Look for the very bright planet Jupiter rising in the ENE. The Gemini stars Pollux and Castor are to the left of Jupiter. The radiant for this shower is near the upper star, Castor. To watch for meteors a dark open sky view is best. No special equipment is needed. You just need to stay out for at least a half-hour to have time to observe several meteors. Keep a record of all the meteors you count, and the number of very bright ones you see along with their directions.

Partial Solar Eclipse - Friday Dec 14 3:00 PM to 4:50 PM

There will be about a 25% partial eclipse of the sun on Friday Dec 14.

To observe the eclipse you must have a safe solar filter. The eclipse glasses we sold for the Dec 200 will work nicely for the unaided eye. To do telescope observation you need a solar filter in front of your telescope to absorb or reflect the excessive harmful light of the sun. This would be a good opportunity to do some observing with a school or scout group near you home. Or just get the boss to let his staff off early to enjoy the event. We hope to have the observatory open before the eclipse if you want to come out and then stay for observing that night.

Saturn Occultation Dec 28 2:45 AM Disappearance 3:50 AM reappearance

You really have to be dedicated to observe this event. Saturn passes behind the Moon about 2:45 AM and reappears about 3:50 AM. These times are for Broken Arrow so if your actually observed times may differ slightly. Although this one can be seen without a telescope, a magnification of 100 power or more will let you watch as the moon swallows up the rings.

Comet Linear WM 1 is also putting on a good show. It was an easy binocular object in Aires over Thanksgiving and may just reach naked eye observing levels by Christmas. The asteroid Vest may also be found in the Hyades cluster of Taurus. For more information on these events go to

Am I hearing things?


November 26, 2001: All at once there was a eye-squinting flash of light and a strange crackling noise. Puzzled sky watchers looked at one another ... and confessed: "Yes, I heard it, too."

Hearing meteors? It could happen -- and indeed it did, plenty of times during this month's Leonid meteor storm.

"I am sure I could hear several of the meteors," recalled Karen Newcombe, a Leonid watcher from San Francisco -- one of many who reported meteor sounds to Science@NASA on Nov. 18th. "Several times when a Leonid with a persistent debris train flew directly overhead, I heard a faint fizzing noise [instantly]." There was no delay between the sight and the sound.

"How is that possible when the meteor was so many miles above my head?" she wondered.

The same question has bedeviled some of history's greatest scientists. For example, in 1719 astronomer Edmund Halley collected accounts of a widely-observed fireball over England. Many witnesses, wrote Halley, "[heard] it hiss as it went along, as if it had been very near at hand." Yet his own research proved the meteor was at least "60 English miles" high. Sound takes about five minutes to travel such a distance, while light can do it in a fraction of a millisecond. Halley could think of no way for sky watchers to simultaneously hear and see the meteor.

Baffled, he finally dismissed the reports as "pure fantasy" -- a view that held sway for centuries.

Yet just last weekend scores of people little inclined to fantasy heard the Leonids. The sounds weren't rumbling sonic booms or the loud crack of a distant explosion arriving long after the meteor's flash had come and gone. Rather, these were exotic, delicate noises, heard while the meteor was in full view. Scientists call them "electrophonic meteor sounds."

Meteor listeners have long been reluctant to report their experiences -- a result of Halley-esque skepticism. But hearing a meteor doesn't mean you're crazy. Indeed, modern researchers are increasingly convinced that the electrophonic sounds are real.

Colin Keay, a physicist at the University of Newcastle in Australia, not only believes in electrophonic meteors, he's also figured out what causes them. According to Keay, glowing meteor trails give off not only visible light, but also very low frequency (VLF) radio signals. Such radio waves, which oscillate at audio frequencies between a few kHz and 30 kHz, travel to the ground at the speed of light -- solving the vexing problem of simultaneity.

Of course, human ears can't directly sense radio signals. If Keay is right, something on the ground -- a "transducer" -- must be converting radio waves into sound waves. In laboratory tests, Keay finds that suitable transducers are surprisingly common. Simple materials like aluminum foil, thin wires, pine needles -- even dry or frizzy hair -- can intercept and respond to a VLF field.

Here's how it works: Radio waves induce currents in electrical conductors. "Strong, low-frequency currents can literally shake ordinary objects," explains Dennis Gallagher, a space physicist at the NASA Marshall Space Flight Center. "When things shake, they launch vibrations into the air, which is what we hear."

Higher-frequency radio waves, like TV transmissions or FM radio broadcasts, oscillate much too fast (hundreds of millions of times per second) to substantially shake conductors. Even if they did, we couldn't hear the resulting MHz-frequency sound waves, which are far above the frequency range of a human ear.

But VLF waves can do the job. Keay discovered that even a pair of glasses could be made to vibrate slightly. Perhaps that explains the experience of Erich in Troy, New York: "When I was out [viewing the Leonids on Nov. 18th]," he reported, "I had my head back on the ground and heard a sizzling sound. My head was close to grass and leaves and I wear wire frame glasses as well. The sound was definitely simultaneous with the observation of a rather large streak."

But how do meteors generate VLF radio signals?

"It was a knotty problem," recalls Keay. When he began his work on electrophonic meteors in the 1970's, physicists had no idea how VLF waves might emerge from a meteor's ionized trail. "Some new mechanism had to be found."

"[I was inspired by] Fred Hoyle's sunspot theory in which energy is trapped in twisted magnetic fields," he says. Magnetic fields that suddenly untangle -- snapping back like stretched rubber bands -- can trigger solar flares: violent blasts of electromagnetic radiation and energetic particles.

Perhaps, thought Keay, magnetic fields in the glowing trail of a meteor might do something similar.... only on a much less energetic scale.

When a meteoroid races through Earth's atmosphere, the air around it becomes a plasma -- that is, a cloud of ionized gas. Plasmas have a curious property: Lines of magnetic force that permeate them become trapped. Wherever the plasma goes, the magnetic field follows. If a magnetized plasma becomes turbulent, the magnetic fields inside it become twisted and tangled as well.

The plasma tails of certain meteors do become turbulent, says Keay, and they are permeated by a magnetic field: Earth's. "The plasma is swirling so fast that the magnetic field can be scrambled up like spaghetti." And therein lies a source of energy for VLF waves.

Keay continues: Eventually the plasma cools. Electrons return to the atoms from which they were earlier ripped, and the gas becomes neutral again. Magnetic fields find themselves suddenly free to straighten out. That abrupt rebound is what produces the low frequency radiation.

It's a plausible theory, says Gallagher: "It's easy to understand and is supported by Keay's laboratory work."

Gallagher added, "I think what makes this exciting is that we're talking about a phenomenon that has been experienced by people for perhaps thousands of years. Even in modern times folks who reported hearing such sounds were ridiculed. It was only about 25 years ago that Keay was able to do the research and legitimize the experiences of all those generations of people."

"It shows there are still wonders in nature yet to be recognized and understood. We should take this experience with meteors as reason to open our minds to what may yet be learned."

2002 Calendar of events

at TU
Jan 11 Jan 25
Feb 08 Feb 22
Mar 08 Mar 22
Apr 12 Apr 26
May 10 May 24


Astronomy Club of Tulsa, 918.688.MARS

President: Dennis Mishler

Vice President: Teresa Kincannon

Treasurer: Nick Pottorf

Assistant Treasurer: John Land

Secretary:Aaron Coyner

RMCC Observatory Manager: Gerry Andries

Observing Chairman: David Stine

Web Master: Tom McDonough

New Membership: Dennis Mishler