Thanks to Bruce and the SPOC committee for the Ealing focuser upgrade and maintenance on the digital setting circle measuring rotors. I used the Ealing last evening for about an hour to practice galaxy targeting but ending up staying on M65 and M66 under high-humdity water-vapor-obscured moderate-to-poor seeing. A stream of about six children and five adults cycled through the Ealing. The new focuser has a profile where the focusing tube is much closer to the Ealing base. Although kids still tended to try and put weight on the focuser, due to the focuser's lower horizontal profile, they could not get as much leverage in the second that it takes for an operator to wave them off. The fine focuser knob makes for smooth quick adjustment to a crisp image. One general public visitor commented that he did not understand why the 16 inch Ealing had such a better image than the larger Grim scope. But I suspect that, as a glasses wearer, he was able to get the Ealing into proper focus with the fine focusing knob but could not do so with the Grim. On setup, I aligned the Skywizard on Arcturus and did a Skywizard Find to Denebola - a 35 degree slew through a meridian swap. The Skywizard targeted to within 3/4 of a degree. After synching the Skywizard on Denebola (ST419), a 7 degree slew to M65 was within 1/2 degree - just on the edge of a 1/3 degree TFOV. I was unable to speed calibrate the Astrophysics controller. I believe this may be because the Ealing feels more unbalanced than I recall being in previous years, particularly on the declination axis. I understand from the SLAS board meeting this week that there was discussion of replacing another key component in quick-accurate targeting of the Ealing - the 4.25 inch Mak. My experience with the Mak was the same as on prior sessions. The TLM of 4.25 inch aperture is critical to accurate targeting of the Ealing. With 4.25 inches of aperture, most galaxy and globular faint fuzzies can just be seen in the Mak's 1.25 deg TFOV. If you center both the Ealing eyepiece and the Mak on a bright star (like Denebola) and then do a short slew to a target, seeing the faintly target in the 4.25 inch Mak is essential to quickly getting the target in the Ealing's 1/3 degree eyepiece field-of-view. In the other smaller aperture finders, their TLM is too low to see most galaxies or globulars. The problem with the Mak is that there is no way to smoothly and quickly make a finder centering adjustment by using a bright star to co-align it with the Ealing eyepiece. IMHO, if the proposal is to replace the Mak with a fixed refractor, maintaining the 4.25 inches of aperture with its higher TLM is essential along with the ability to smoothly recenter the 4.25 inch finder after a meridian swap. IMHO, having a seamless and smooth method of recentering the 4.25 inch finder is the higher priority fix than changing the Mak - which has an inherent mirror flop targeting error - to a refractor - which has no mirror flop error. Thanks to Dave B. for directing targets on the Grim and to Daniel T. for a quick galaxy and comet tour on his 16 inch DOB. Clear Skies - Kurt
Last night was a good example of the seeing determining maximum usable aperture. I noticed that the 100mm refractor was showing a more crisp view of Saturn than the Bogdan (and other scopes with twice the aperture), even though it was appreciably dimmer in the smaller scope. On 5/16/10, Canopus56 <canopus56@yahoo.com> wrote:
One general public visitor commented that he did not understand why the 16 inch Ealing had such a better image than the larger Grim scope. But I suspect that, as a glasses wearer, he was able to get the Ealing into proper focus with the fine focusing knob but could not do so with the Grim.
That was what I noticed when looking at saturn. Both were very sharp and free of chromatic "inhancement" , but conditions allowed the smaller refractor to use more magnification. Long tubes need perfect conditions and are affected more in average seeing.
That is a great little refractor Chuck (not to mention the modest cost), I saw a nice double through it also, it is a great scope for double stars also. I think this can also be true for solar observing. Last night was a good example of the seeing determining maximum usable
aperture. I noticed that the 100mm refractor was showing a more crisp view of Saturn than the Bogdan (and other scopes with twice the aperture), even though it was appreciably dimmer in the smaller scope.
On 5/16/10, Canopus56 <canopus56@yahoo.com> wrote:
One general public visitor commented that he did not understand why the 16 inch Ealing had such a better image than the larger Grim scope. But I suspect that, as a glasses wearer, he was able to get the Ealing into proper focus with the fine focusing knob but could not do so with the Grim.
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Chuck: On Friday night I took Alan MacRoberts article in S&T with me to SPOC. Using the chart for the elongations of Mimas I was able to see the see this tiny moon next to the glow of the nearly edge on rings. I was using 17.5 inches of aperture and I needed to wait for the mirror to cool down and then had to catch a moment of excellent seeing in the variable seeing of the night. Alan and others have seen this with 12 inches of aperture. Now I'll be looking for Iapetus and Hyperion which are supposed to be easier. On Friday and Saturday I picked up two comets. The transparency wasn't very good on either night but these still came through as easily as a Messier eliptical galaxy. DT --- On Sun, 5/16/10, Chuck Hards <chuck.hards@gmail.com> wrote:
From: Chuck Hards <chuck.hards@gmail.com> Subject: Re: [Utah-astronomy] Thank you on Ealing upgrades and repairs To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, May 16, 2010, 12:06 PM Last night was a good example of the seeing determining maximum usable aperture. I noticed that the 100mm refractor was showing a more crisp view of Saturn than the Bogdan (and other scopes with twice the aperture), even though it was appreciably dimmer in the smaller scope.
On 5/16/10, Canopus56 <canopus56@yahoo.com> wrote:
One general public visitor commented that he did not understand why the 16 inch Ealing had such a better image than the larger Grim scope. But I suspect that, as a glasses wearer, he was able to get the Ealing into proper focus with the fine focusing knob but could not do so with the Grim.
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Daniel, if you are interested in adding a fan(s) to blow across the front of your mirror, I would be willing to help. Per Bryan Greer's breakthrough article in S&T some years ago, and verified by Alan Adler, where he proved that breaking-up the air currents above the mirror's surface is more important than cooling the mirror to ambient temperature, I would love to help engineer and fabricate such a simple system for your (or anybody's) reflector. The results are remarkable. I use a modified version of this on my 6" Newtonian and you can see instant results as soon as you flip the fan switch on. Hours before the mirror itself has cooled. Increased aperture is always better, as long as you arent' hobbled by other factors. On 5/16/10, daniel turner <outwest112@yahoo.com> wrote:
Chuck:
On Friday night I took Alan MacRoberts article in S&T with me to SPOC. Using the chart for the elongations of Mimas I was able to see the see this tiny moon next to the glow of the nearly edge on rings. I was using 17.5 inches of aperture and I needed to wait for the mirror to cool down and then had to catch a moment of excellent seeing in the variable seeing of the night. Alan and others have seen this with 12 inches of aperture. Now I'll be looking for Iapetus and Hyperion which are supposed to be easier.
On Friday and Saturday I picked up two comets. The transparency wasn't very good on either night but these still came through as easily as a Messier eliptical galaxy.
Chuck: My experience with large mirrors is that waiting an hour works better than a fan. I just spend the time walking around talking to others and looking through their telescopes. I'm also trying to come up with a good picture that represents the event well. I put my camera on a monopod and hold it up in the air for a longer perspective of the entire ground. The only problem seems to be that people want to look up and point at the camera. http://www.slas.us/gallery2/main.php?g2_itemId=3428 DT --- On Sun, 5/16/10, Chuck Hards <chuck.hards@gmail.com> wrote:
From: Chuck Hards <chuck.hards@gmail.com> Subject: Re: [Utah-astronomy] Thank you on Ealing upgrades and repairs To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, May 16, 2010, 3:37 PM Daniel, if you are interested in adding a fan(s) to blow across the front of your mirror, I would be willing to help.
Per Bryan Greer's breakthrough article in S&T some years ago, and verified by Alan Adler, where he proved that breaking-up the air currents above the mirror's surface is more important than cooling the mirror to ambient temperature, I would love to help engineer and fabricate such a simple system for your (or anybody's) reflector.
The results are remarkable. I use a modified version of this on my 6" Newtonian and you can see instant results as soon as you flip the fan switch on. Hours before the mirror itself has cooled.
Increased aperture is always better, as long as you arent' hobbled by other factors.
On 5/16/10, daniel turner <outwest112@yahoo.com> wrote:
Chuck:
On Friday night I took Alan MacRoberts article in S&T with me to SPOC. Using the chart for the elongations of Mimas I was able to see the see this tiny moon next to the glow of the nearly edge on rings. I was using 17.5 inches of aperture and I needed to wait for the mirror to cool down and then had to catch a moment of excellent seeing in the variable seeing of the night. Alan and others have seen this with 12 inches of aperture. Now I'll be looking for Iapetus and Hyperion which are supposed to be easier.
On Friday and Saturday I picked up two comets. The transparency wasn't very good on either night but these still came through as easily as a Messier eliptical galaxy.
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Daniel, you are obviously not familiar with Bryan Greer's work on this subject. (Incidentally, Bryan is the owner of Protostar). Alan Adler validated his findings and published his working systems- on a Bill Kelley-style flexed mirror telescope, come to think of it. He doesn't cool the mirror, he breaks-up the boundary layer of slow-moving, warm air immediately in front of it. The effect is striking. You flip on the fan, blowing over a warm mirror, and the image snaps into near perfection- instantly. His ground-breaking work has been all but forgotten by amateurs. They still think in terms of "cooling" the mirror. Their loss. On 5/16/10, daniel turner <outwest112@yahoo.com> wrote:
Chuck:
My experience with large mirrors is that waiting an hour works better than a fan. I just spend the time walking around talking to others and looking through their telescopes.
I have not seen the camera in the air but I have seen you poking sticks at people with refractors. :)
Date: Sun, 16 May 2010 16:27:19 -0700 From: outwest112@yahoo.com To: utah-astronomy@mailman.xmission.com Subject: Re: [Utah-astronomy] Thank you on Ealing upgrades and repairs
Chuck:
My experience with large mirrors is that waiting an hour works better than a fan. I just spend the time walking around talking to others and looking through their telescopes. I'm also trying to come up with a good picture that represents the event well. I put my camera on a monopod and hold it up in the air for a longer perspective of the entire ground. The only problem seems to be that people want to look up and point at the camera.
http://www.slas.us/gallery2/main.php?g2_itemId=3428
DT
--- On Sun, 5/16/10, Chuck Hards <chuck.hards@gmail.com> wrote:
From: Chuck Hards <chuck.hards@gmail.com> Subject: Re: [Utah-astronomy] Thank you on Ealing upgrades and repairs To: "Utah Astronomy" <utah-astronomy@mailman.xmission.com> Date: Sunday, May 16, 2010, 3:37 PM Daniel, if you are interested in adding a fan(s) to blow across the front of your mirror, I would be willing to help.
Per Bryan Greer's breakthrough article in S&T some years ago, and verified by Alan Adler, where he proved that breaking-up the air currents above the mirror's surface is more important than cooling the mirror to ambient temperature, I would love to help engineer and fabricate such a simple system for your (or anybody's) reflector.
The results are remarkable. I use a modified version of this on my 6" Newtonian and you can see instant results as soon as you flip the fan switch on. Hours before the mirror itself has cooled.
Increased aperture is always better, as long as you arent' hobbled by other factors.
On 5/16/10, daniel turner <outwest112@yahoo.com> wrote:
Chuck:
On Friday night I took Alan MacRoberts article in S&T with me to SPOC. Using the chart for the elongations of Mimas I was able to see the see this tiny moon next to the glow of the nearly edge on rings. I was using 17.5 inches of aperture and I needed to wait for the mirror to cool down and then had to catch a moment of excellent seeing in the variable seeing of the night. Alan and others have seen this with 12 inches of aperture. Now I'll be looking for Iapetus and Hyperion which are supposed to be easier.
On Friday and Saturday I picked up two comets. The transparency wasn't very good on either night but these still came through as easily as a Messier eliptical galaxy.
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participants (5)
-
Canopus56 -
Chuck Hards -
daniel turner -
erikhansen＠thebluezone.net -
Steve FISHER