February 2017

Financials:

Balance Jan. 1 2017 $2276.27

2 new memberships $40.00

Ending balance Jan. 31 $2316.17

23 people attended the February club meeting.

Highlights from Abby's Astronomy News:

Cassini has taken detailed images of Saturn's rings with details as little as 0.3 miles across--i.e. the height of Earth's tallest building.

NASA's Dawn probe has sent stunning new images of Ceres, taken within 920 miles of the planet

SpaceX wins contract to launch satellite for NASA. Set for launch April 20-21 and will search for planets outside our solar system.

Hubble snapped a stunning image of the megamaser galaxy LEDA, which is centered on a low black hole mass.

Vera Rubin, who confirmed dark matter, has died at 88

Gene Cernan, the last man to walk on the Moon, has passed away at age 82

NASA released image taken by Hubble of the galaxy LEDA…

Abby's Pinterest site: youthbastro@gmail.com password Astronomy

BAS news updates:

Star party was held at Wah-Shah-She Jan 28. We had about a dozen people. Steve commented that the light at the parade grounds (where we were) was brighter than before. Apparently they recently switched the light bulb out.

Sooner Park might be a better location now for a star party since the Madison school has been torn down. And, Tri County Tech gets really dark at night.

We could have a star party for people in the community to bring scopes that they have and don't know how to work!

Upcoming projects in Tulsa, March 7 and April 15: Jerry will send out emails asking for volunteers and scopes for the March 7 event.

For the April 15 event, there will be a Russian Space Astronomy theme, and all we will need to provide is telescopes. They will have a lot of other activities, such as face painting.

Main Presentation--Contributing to Science by Observing Occultations by John Grismore

We can all participate in this! Jerry has done asteroid occultation work.

Citizen Science is defined as "scientific work undertaken by members of the general public, often in collaboration with or under the direction of professional scientists and scientific institutions". An academic paper written in 2015 (non-astronomical topic) estimated that citizen scientists contributed an average of $222, 068 for each of 7 projects. This involved 129,540 hours of unpaid work by 100,386 people. Citizen science is valuable!

Citizen science covers a broad range of topics across multiple scientific disciplines.

What is an occultation? It is the passage of one celestial body in front of another, thus hiding the other from view.

How can you have an occultation?

---A solar eclipse

---The Moon occulting a planet (as with Venus in 1978)

---The Moon occulting a star

---Planets occulting planets (last occurrence in 1818; next one Mars and Mercury Aug 11, 2079)

---Asteroids occulting stars

How do we observe occultations?

---Observe the target star

---Record the time of disappearance

---Record the time of reappearance

The "shadow path" marks the path of occultation of, for example, an asteroid occulting a star. John imagined what the scenario would likely have been if four of our group had done an observation of an asteroid occulting a star (which occurred with asteroid Selinur south of Bartlesville last December 6).

To do such an observation, you record the time the asteroid occults the star and the reappearance of the star and plot these as compared to the geographic location of the observer across the path of occultation. There will be positive and negative observations based on the distance of the observer from the center of the occultation and whether or not the observer is within the shadow path.

Clouds, birds and bats can interfere with measuring occultations.

Observation of asteroid occultations can also prove that an asteroid is actually two separate asteroids following the same orbital path. The Hercules Club is composted of observers who have been determined to have positioned themselves between the two shadows of a double asteroid, such that they observe an occultation by neither component.

What are contributions from occultations?

---Improved documentation of lunar orbit. Occultations were used during the Apollo period to document lunar features.

---Improved star locations

---Double star discovery and configuration

---Stellar diameters

---Improved asteroid orbits. This is especially important for near earth asteroids.

---Improved asteroid sizes and shapes, also very important for near earth asteroids

---Asteroid satellite discoveries (such as a satellite of Agamemnon on Jan 19, 2012)

There was a "golden age" of asteroid discoveries in the mid/late 1990s. "Stars that move".

John showed an image of the moon grazing Aldebaran near Oolagah July 29, 2016.

What do you need to observe an occultation?

The simplest tools would be a stop watch and notebook, but you can go much fancier than that with atomic clocks, tape recorders, astrovideo tools, camcorders and laptop hookups to a telescope. Can also use camcorders with binoculars. Meade makes a telescope with an automated video camera.

Coming up March 4: Moon occulting Aldebaran about 9:45 pm. Could perhaps have a public star party, weather permitting.

Coming up June 3: New Horizons going to MU69 in the Kuyper Belt for stellar occultation

The attached slide show of John's presentation has multiple links for more information about observing occultations.

And this from John, post-meeting:

Here’s a brief followup on the main message of the BAS program at the Monday meeting, that amateur astronomers are important contributors to science, and that amateur occultation observations provide important data for professional astronomers. An Astronomy & Astrophysics manuscript titled Volumes and bulk densities of forty asteroids from ADAM shape modeling was published on arxiv.org today (2/8/2017). There were 14 authors, of which about half were professional astronomers from several international universities, and the other half were amateur astronomers.

The following statement in the paper recognized the important contributions of amateurs:

Our high precision in the volume, thus consequently in the volume-equivalent diameter as well, was achieved mostly due to the usage of stellar occultations in the shape modeling. The ad- vantage of the occultations is that they essentially provide direct measurements of the size along the star path behind the aster- oid’s projection. … As a consequence, the size uncertainty is usually larger if we do not use stellar occultations in the shape modeling. We would like to stress that our results were only feasible due to the contribution of hundreds of observers that participated in the oc- cultation campaigns (see Tab. A.2).

Bold emphasis is mine.

Table A.2 includes 12 amateur observations from Oklahoma.

The paper can be viewed at https://arxiv.org/pdf/1702.01996.pdf .

BAS Public Website: http://sites.google.com/site/bartlesvilleastronomyclub/

BAS Yahoo Group: http://tech.groups.yahoo.com/group/BvilleAstro/

If you want to have your email address removed from the Bartlesville Astronomical Society mailing list, please send an email requesting removal to bvilleastro@gmail.com .