The current sunspot is large enough to show motion when viewed visually. In only a ten-minute period, a small "tail" on the eastern (trailing) edge of the spot went from a gentle curve, to a sharp kink, then a branch forked-out forming a crude "Y". Little intrustions, or "bays", of the penumbra scallop-out the edge of the umbra. This spot is a good candidate to see a white-light flare, if you are lucky enough to be at the eyepiece at the right time. Use at least 100X, more if your local seeing will permit it. Don't set-up on or near pavement if it can be helped. A driven scope will make following the spot easier, but 100X isn't too bad for hand-tracking. Just watch the spot carefully, and you'll notice changes within a few minutes. I find the motion much more difficult to see with my glass TO glass filter, than the Baader material, which provides a white solar image and better contrast. C. __________________________________________________ Do you Yahoo!? Yahoo! Web Hosting - establish your business online http://webhosting.yahoo.com
I just picked up some #13 Welder's glass. The spot is very easily seen naked eye. I need to get a solar filter for one of my scopes. Greg --- Chuck Hards <chuckhards@yahoo.com> wrote:
The current sunspot is large enough to show motion when viewed visually. In only a ten-minute period, a small "tail" on the eastern (trailing) edge of the spot went from a gentle curve, to a sharp kink, then a branch forked-out forming a crude "Y". Little intrustions, or "bays", of the penumbra scallop-out the edge of the umbra. This spot is a good candidate to see a white-light flare, if you are lucky enough to be at the eyepiece at the right time. Use at least 100X, more if your local seeing will permit it. Don't set-up on or near pavement if it can be helped. A driven scope will make following the spot easier, but 100X isn't too bad for hand-tracking. Just watch the spot carefully, and you'll notice changes within a few minutes. I find the motion much more difficult to see with my glass TO glass filter, than the Baader material, which provides a white solar image and better contrast.
C.
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An interesting phenomenon: Looking at the sun with my 50mm f/9 refractor at about 28X, I thought I could see a tiny white dot near the edge of the umbra. At 100X in my 70mm f/10 refractor, there is no sign of the white spot. Must be a contrast artifact of my eye, related to the "black drop" effect of Mercury during a transit. This spot would be a good candidate for a time-lapse movie if someone felt like imaging all-day long! Greg, I highly recommend the Baader mylar solar filter material. The view is superior to that given by any other white-light filter material I've ever used, including evaporated metal-on-glass. It's also inexpensive enough to make a full-aperture filter for a larger scope. C. --- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
I just picked up some #13 Welder's glass. The spot is very easily seen naked eye. I need to get a solar filter for one of my scopes.
Greg
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I was planning on using Baader film, I looked through a number of different filters during last June's eclipse, and Baader film was by far the best, hands down.
Greg, I highly recommend the Baader mylar solar filter material. The view is superior to that given by any other white-light filter material I've ever used, including evaporated metal-on-glass. It's also inexpensive enough to make a full-aperture filter for a larger scope.
C.
--- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
I just picked up some #13 Welder's glass. The spot is very easily seen naked eye. I need to get a solar filter for one of my scopes.
Greg
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Greg Taylor wrote:
I just picked up some #13 Welder's glass. The spot is very easily seen naked eye. I need to get a solar filter for one of my scopes.
I don't know that a #13 is safe. #14 is the only one I've heard is safe. http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/eclipsePhoto.html#Safety Patrick
S&T Says that it is. --- Patrick Wiggins <paw@trilobyte.net> wrote:
Greg Taylor wrote:
I just picked up some #13 Welder's glass. The spot
is
very easily seen naked eye. I need to get a solar filter for one of my scopes.
I don't know that a #13 is safe. #14 is the only one I've heard is safe.
http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/eclipsePhoto.html#Safety
Patrick
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Never fear anyway, I found the solar image through the #13 to be a hair too bright for comfort, so I'm getting some darker stuff tomorrow. Greg --- Patrick Wiggins <paw@trilobyte.net> wrote:
Greg Taylor wrote:
I just picked up some #13 Welder's glass. The spot
is
very easily seen naked eye. I need to get a solar filter for one of my scopes.
I don't know that a #13 is safe. #14 is the only one I've heard is safe.
http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/eclipsePhoto.html#Safety
Patrick
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Elsewher one their site I found: Filter Transmittance The luminous transmittance of the filter, when determined as described in clause 6 of EN167, shall not exceed 0.0032%. Filter transmittance in the waveband 280 to 380 nm (ultraviolet radiation) shall not exceed 0.003% at any wavelength. Transmittance in the near infrared waveband (780 to 1400 nm) shall not exceed 0.027% at any wavelength. Filters with luminous transmittance (in the waveband 380 to 780 nm) equivalent to scale number 12 to 16 as specified in Table 1 of EN169:1992 are considered suitable for direct observation of the sun. It should be noted that many observers will find the solar image uncomfortably bright when filters with scale numbers of 12 or 13 are used. --- Patrick Wiggins <paw@trilobyte.net> wrote:
Greg Taylor wrote:
I just picked up some #13 Welder's glass. The spot
is
very easily seen naked eye. I need to get a solar filter for one of my scopes.
I don't know that a #13 is safe. #14 is the only one I've heard is safe.
http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/eclipsePhoto.html#Safety
Patrick
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Greg, you've done your research. Well done. I recall a similar report stating that #12 & up were "safe". Welder's glass filters are great for inexpensive, non-magnified views of the sun, but the contrast is so poor that they should be considered only if no other proper filters are available. C. --- Greg Taylor <astronomus_maximus@yahoo.com> wrote:
Elsewher one their site I found:
Filter Transmittance
The luminous transmittance of the filter, when determined as described in clause 6 of EN167, shall not exceed 0.0032%. Filter transmittance in the waveband 280 to 380 nm (ultraviolet radiation) shall not exceed 0.003% at any wavelength. Transmittance in the near infrared waveband (780 to 1400 nm) shall not exceed 0.027% at any wavelength. Filters with luminous transmittance (in the waveband 380 to 780 nm) equivalent to scale number 12 to 16 as specified in Table 1 of EN169:1992 are considered suitable for direct observation of the sun. It should be noted that many observers will find the solar image uncomfortably bright when filters with scale numbers of 12 or 13 are used.
--- Patrick Wiggins <paw@trilobyte.net> wrote:
Greg Taylor wrote:
I just picked up some #13 Welder's glass. The
spot is
very easily seen naked eye. I need to get a solar filter for one of my scopes.
I don't know that a #13 is safe. #14 is the only one I've heard is safe.
http://sunearth.gsfc.nasa.gov/eclipse/SEhelp/eclipsePhoto.html#Safety
Patrick
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I've found that #14 is more comfortable to use than #13. If one then views the sun at an oblique, say 45*, angle through the filter, it is even better. The best part about it though is that the #14 welder's glass is sold for less than $2 for a 2x4 plate at Praxair 1884 S. 300 W. SLC. Greg __________________________________________________ Do you Yahoo!? Yahoo! Web Hosting - establish your business online http://webhosting.yahoo.com
participants (3)
-
Chuck Hards -
Greg Taylor -
Patrick Wiggins