Astronomy 110 Laboratory: Observing

To reach our observing site at Sandy Beach, you

1. Take the H1 EAST.
   
   
2. When the freeway ends, continue EAST on Kalanianaole Highway.
   
   
3. Continue on Kalanianaole Highway past Hawaii Kai, Hanauma Bay, Molokai Lookout, and Blowhole.
   
   
4. Turn RIGHT into the Sandy Beach park entrance.
   
   
5. Drive through the park to the far end, where you'll find a small parking area with a bathroom/shower building.
   
   
6. Look for a truck with a `University of Hawaii' sign and State of Hawaii seal.
   
   

Orientation featured Polaris, Summer triangle (Vega, Deneb, & Altair), rising and setting motions, celestial equator and ecliptic. Constellations seen included Ursa Minor & Ursa Major (both incomplete), Cygnus, Scorpius, and Sagittarius. Plotted position of Mars on star-chart, using 10×50 binoculars. Four 8 inch scopes, with 32 mm eyepieces (37.5×), 14 mm eyepieces (85.7×), and 10 mm eyepieces (120×), were used for telescopic observations. Moon: noted bright and dark areas (highlands and maria). Circular outlines of impact basins Mare Serenitatis (near terminator) and Mare Crisium (toward limb) evident. Mars: the South Polar Cap was visible as bright spot on limb of planet; some observers reported dark smudge near center which was probably Mare Erythraeum.

We set up all six telescopes. The Moon was observed using 32 mm eyepieces (37.5×) and moon filters. Students made sketches, concentrating on the overall pattern of highlands and maria and on the bright rays emanating from impact craters, including Tycho and Copernicus. Mars was observed and sketched using 14 mm eyepieces (85.7×) under good seeing conditions. Dark features visible on the surface include Syrtis Major and Sinus Sabaeus; Sinus Meridiani was also glimpsed after 22:00. Plotted position of Mars on star-chart, using 10×50 binoculars. Began sketching constellation of Scorpius.

Students sketched Scorpius, Sagittarius, and Cygnus, with some interruption due to passing clouds. At 21:00, we began observing Mars. Our six 8 in scopes each had a different eyepiece and filter combination: a 32 mm eyepiece (37.5×), a 14 mm eyepiece (85.7×), a 14 mm eyepiece with red filter, a 10 mm eyepiece (120×), a 10 mm eyepiece with red filter, a 10 mm eyepiece with blue plus LPF filters. We also set up a 10 in scope with a 2× barlow and a 12.5 mm eyepiece (200×). Good seeing conditions permitted a careful inspection of the planet. The red filter generally enhanced dark surface features, while the blue filter improved visibility of the South Polar Cap. Mare Tyrrhenum and Mare Cimmerium were apparent, creating the impression of a belt across the equator; by 22:00, the rotation of Mars had carried Syrtis Major into view. We plotted the position of Mars on the star-chart, using 10×50 binoculars. Finally, we estimated the brightness of Mars by comparing it with an artificial light source.

At the park, we had a clear view of the Milky Way stretching overhead from Cassiopeia in the north-east to Scorpius in the south-west; scanning it with binoculars, many students noticed ``fuzzy stars''. Class sketched Lyra to scale, and plotted the position of Mars. We then used all six 8 in scopes to examine different stages in the lives of stars. M8 (the ``Lagoon Nebula''), a star-forming region with a young star cluster, was viewed using two scopes with 32 mm eyepieces (37.5×); one scope had a Light-Pollution Filter which improved the view of the nebula. M11 (the ``Wild Duck Cluster''), a rich star cluster with a broad ``V'' shape, was sighted using a 14 mm eyepiece (85.7×). We also viewed another cluster, mistakenly identified as M18 but probably M25, using a 32 mm eyepiece. M57 (the ``Ring Nebula''), was viewed with a 10 mm eyepiece (120×); it was fairly easy to see the ring shape, but the central star was invisible. M27, (the ``Dumbbell Nebula''), was sighted with a 14 mm eyepiece and a Light-Pollution Filter; it appeared almost rectangular, with faint extensions above and below. We plotted the position of Mars on the star-chart, using 10×50 binoculars.

A cloud bank approaching from the northwest precluded any observations. Instead, the class met indoors, studied the formation images by a simple lens, built refracting telescopes from kits, and measured their magnification.

At the park, we set up six 8 inch scopes with lunar filters, reticles, and 25 mm eyepieces (48×). The class measured the apparent diameter of the Moon for the first time; subsequent observations will allow us to study the shape of its orbit. We then viewed Mars using the 14 mm eyepieces (85.7×); the planet is now in a waning gibbous phase, with the fully-illuminated side toward the west. Finally, we plotted the position of Mars on star-chart, using 10×50 binoculars.

Although clouds covered much of the sky, the class was able to view and sketch two constellations: Pegasus and Cassiopeia. We also succeeded in plotting the position of Mars on the star-chart, using 10×50 binoculars. Uranus was visible a few degrees to the northwest of Mars's position.

The class began charting the constellation of Cepheus; the red color of the Garnet Star (mu Cephei) was evident. Shortly thereafter, we were treated to a brief but rather heavy shower, which effectively ended telescopic observation for the evening. After the shower passed, we made our first measurements of the magnitudes of the variable stars beta Lyrae and delta Cephei. Clearing to the east allowed us to view the Pleiades (M45) and the bright star Capella (alpha Aurigae). We plotted the position of Mars using 10×50 binoculars.

We viewed the Sun using an 8 inch scope with a full-aperture solar filter and a specialized Halpha scope. A large sunspot group was visible near the center of the Sun's disk. Using a reticle on the 8 inch scope, we estimated the size of the spot group at almost 10% of the Sun's diameter; in round numbers, this is about 100,000 miles, or roughly the size of Jupiter! Another sunspot group was visible on the edge of the Sun's disk; as the Sun rotates, this group will be well-placed for observation by early next week. The Halpha scope revealed several prominences, some associated with the spot group on the edge of the disk.

Although the crescent Moon was faintly visible at time, clouds blocked any attempt to measure its apparent diameter. Instead, we discussed the technique for measuring distances via parallax, and measured the distance to an observing flashlight on a tripod, using streetlights on the other side of the park as background reference points.

After setting up all six 8 inch scopes with lunar filters, reticles, and 25 mm eyepieces (48×), we measured the apparent diameter of the Moon. We then switched to 14 mm (85.7×) and 10 mm (120×) eyepieces to observe double stars, including epsilon Lyrae, beta Lyrae, beta Cygni, 61 Cygni, epsilon Pegasi, delta Cephei, eta Cassiopeiae, and iota Cassiopeiae. We also used these eyepieces to view and sketch Mars; few surface features were visible, but the planet is now distinctly gibbous. We plotted the position of Mars using 10×50 binoculars and found that it had moved a good distance to the east-northeast since our last observation.

Unstable weather foiled plans to go to Sandy Beach and view galaxies. Instead, we stayed indoors, built simple grating spectroscopes, and used them to view spectral lines of various elements. During the break, we were able to observe and estimate magnitudes for the variable stars beta Lyrae and delta Cephei.

A slab of broken cloud initially blocked our view of most of the sky. Clearing began near the zenith; once Mars was visible, we began plotting its position and estimating its brightness. Shortly after 19:00 the Moon was sighted low in the west; we used two 8 inch scopes with reticles and 25 mm eyepieces (48×) to measure its apparent diameter. Finally, despite returning clouds, we estimated magnitudes for the variable stars beta Lyrae and delta Cephei.

At the park, we set up four 8 inch scopes and one 10 inch scope. Despite the bright Moon, a number of new constellations were visible, including Andromeda, Perseus; Orion rose later in the evening. We estimated magnitudes for the variable stars delta Cephei and beta Lyrae; the latter was near minimum. Students practiced finding and viewing objects using the telescopes; objects observed include the Moon, the planet Mars, the Andromeda Galaxy (M31), the Pleiades star cluster (M45), and the Orion Nebula (M42). A narrow-band light pollution filter and 12.5 mm eyepiece (100×) on the 10 inch scope gave the best views of M42. After the break, the planet Saturn was observed; several of its moons, including Titan were also visible. Later, we attached spectroscopes to two telescopes and observed the spectra of Fomalhaut, an A3V star showing two lines of hydrogen, and Betelgeuse, an M2I star showing a number of molecular bands. We also viewed Rigel and M45 through an 8 inch scope with a piece of window-screen held in front to illustrate diffraction. A few people stayed late enough to view the spectrum of Sirius, an A1V star and the brightest in the sky; it showed four lines of hydrogen, and another line was glimpsed in the orange.

The final meeting of the course was fairly brief. We discussed some aspects of the lab on the Shape of the Moon's Orbit; see the link under REPORTS for details. Binoculars were returned and observing log books collected.

REPORTS

Report: Shape of The Moon's Orbit. In October and November 2003 we measured the Moon's apparent diameter and used the results to study the shape of the Moon's orbit. This page summarizes the results.

Last modified: December 18, 2003
http://www.ifa.hawaii.edu/~barnes/ASTR110L_F03/observing.html