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One Great Outreach

Discussion in 'Star Parties, Clubs, and Outreach Events' started by Jim O'Connor, Nov 13, 2016.

One Great Outreach

Started by Jim O'Connor on Nov 13, 2016 at 10:07 PM

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  1. Jim O'Connor

    Jim O'Connor Active Member

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    Last Saturday, four of us from Tucson Amateur Astronomy Association (Stephen Ferris, Chuck Hendricks, Bernie Stinger, and myself) supported Pima County Natural Resources Parks and Recreation Department with their periodic night under the stars in Tucson Mountain Park's Ironwood Picnic Area. PCNR has increased the frequency of these events, and when the weather cooperates, they become active, productive sessions of educational inquiry and exploration of the night sky. This was one of them. It was also a personal highlight for several reasons I'll detail.

    Since the moon, 2 days from full, would rise an hour prior to sunset, I arrived very early since I wanted to do some trial runs with various focal reduction configurations. If you don't like techie stuff, skip this paragraph. For public events, I use a 10" Meade SCT mounted on an Orion Atlas EQ-G equatorial mount and tripod, with a Mallincam Xterminator live video camera feeding into a 19" QFX monitor. The camera performs as an equivalent 8mm Plossl eyepiece with 50 degrees apparent field of view. If I operated the SCT at its native f/10, the magnification would be too high, field of view too tight, and exit pupil not optimum for Deep Sky Objects. I needed to reduce the focal ratio to under f/5 for best performance. Usually I've been using a 2" 50% focal reducer, but while the resulting 1270mm effective focal length works well with some deep sky objects, for the sun, moon, and most open clusters and emission/reflection nebulae the image is larger than the monitor. My early pre-sunset goal was to try to mix and match a Celestron f/6.3 reducer with either my 1 1/4" or 2" 50% reducers without inducing coma or vignetting. My experience was that with the f/6.3 reducer/field flattener installed, the 2" 50% reducer greatly shrunk the field of view, but I did not have enough focuser travel to achieve focus. However, with a 2" to 1 1/4" adapter and the 1 1/4" reducer, the shorter nose piece allowed focus although with a larger image that just fit on the monitor.

    When I got the right combination of focal reducers, it turned out that the nearly full moon was far too bright for the system; even at 1/12000 second shutter speed and gamma adjustments, the majority of the moon was a bright blur. I was able to add a polarizing filter at 40% to the optical train and it got a great view of Luna.

    The first thing that made this a great outreach was that, in the first group of visitors to arrive, I got a chance to meet Anne Wilson, a National Park Service Ranger at Agate Fossil Beds National Monument in Nebraska. Next year, for the Great American Eclipse, my wife Susan and I will be supporting public activities at Agate. Anne was in town with one of her sons, visiting a friend from high school, and she came to the event with her son, her friend, and her friend's mother. It was great to meet Anne and the rest of the gang. We went over the lunar history, the various cultural artifacts like the Lunar Poodle, the Chinese Lunar Rabbit and their lunar calendar, Lady in the Moon, and other various topics. As soon as it was dark enough to get Polaris, I did a quick polar alignment and started hunting objects. More visitors had arrived, and I aligned on Schedar in Cassiopeia and started with The Owl Cluster, NGC457. With the extra focal reduction it easily fit on the monitor. Visitors generally like this object, and it's a good one to introduce stellar formation and evolution Since many of the stars are very large, they are young but will reach the end of their lives soon. With too long an integration time (I started at the maximum SENSE UP, about 2.1 seconds), so many stars are shown that it is hard to see the Owl in the rest of the star field. I eventually reduced the integration and the Owl jumps out. Back to the longer integration, I could point out a few of the red giants in the mix; although the cluster is only about 22 million years old, a lot of the stars have already progressed to end stage development. Lots of teaching can go on with this cluster.

    I then hopped over to the Double Cluster, NGC869 and NGC884. Each cluster filled the monitor by itself, so we could point out a lot of features. Even in an eyepiece, the colorful stars are notable, but with the video, there is a higher intensity to the colors. While we were in the area, we talked about Persius and the Cassiopeia/Andromeda story along with Persius' prize; he went off to slay the Medusa, and he has brought the head back. This is a fairly short period variable star, and the fact that the variability is notable over about a 3 day period caused Semitic peoples to name it Satan, the Devil, or the spectre of a ghost, The Ghoul, or Al Ghoul, later becoming Algol.

    In among the cluster show, we also explored some other cultural stories regarding elements of the Milky Way (Via Galacticos, leading to now calling all stellar island universes Galaxies), how the Zodiac came about, Cygnus versus Niska the Goose, and more.

    I learned a bit of the effect of atmosphere conditions on the camera image. We had scattered cirrus around, and moisture at altitude that was just below cloud formation. But the moisture and clouds have an effect on urban lights, with the red component being reflected from these layers such that there is a strong red highlight to the image needing a blocking filter like IR or Ultrablock to knock down the interference. I got surprised by the effect of the moon. There was a constant red splotchy nature on the monitor when not pointed at the moon due to the lunar light's red and longer wavelengths maintaining their presence while the shorter wavelengths being scattered. The moon, when off-axis, was also providing a lighted circle brightening to the side of the center. I was able to remove the light and atmospheric effects by altering the brightness and contrast settings on the monitor, although I should have used a blocking filter.

    We had a group of seven or eight deaf young folks with a signing interpreter visit, and were really enjoying the clusters. I tried to modify my usual ramblings to make the discussion easier to follow. It was extremely enjoyable to work with the group, and another element that made this a great outreach.

    At the end of our cluster show and tell, Anne and her party headed out, while I went for more eye candy. I shifted over to The Ring Nebula, M57. With the new reducer configuration shrinking the exit pupil, the image was a bit smaller than I usually get (a nickel instead of a quarter) but the colors were more intense and brighter. Lots of excitement over the double white dwarf artifact and the cosmic diamonds. Then I shifted over to M27, the Dumbbell, and although a bit smaller than earlier times, it was still over a quarter of the screen with a diaphanous blue-green central element and bright red caps at the ends . The integration times on both nebulae were significantly shorter than without the double focal reducers. I was able to discuss the stellar evolution process again, this time with two examples of our sun's likely demise.

    All good things come to an end, and the visitors and we left Ironwood after an enjoyable evening.
     
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