___ _ _ __ __ _ __ __ __ _ _ _ ___ _ _ _ __ __
| |_| |_ |_ | | \ |_ |_\ | /_\ | | | |\/| |_ |_
| | | |_ __| | |_/ |_ | \ | | | |_ | | | | |_ __|
_______________________________________________________________
VOL. XIII NO.6 June 1995
_______________________________________________________________
A PUBLICATION OF THE APL ASTRONOMY CLUB
_______________________________________________________________
FROM THE EDITOR
Membership in the APL Astronomy Club is open to all JHU/APL
Recreation members. The Club frequently sponsors astronomical
activities and has a Celestron 11-inch telescope with Nikon
camera, an 8-inch Tinsley telescope, an Astroscan 4.5-inch
telescope, and a pair of 16X80mm binoculars available for use by
members on a weekly basis. The Club also maintains a library of
astronomical literature in room 7-54 which includes a current
subscription to Astronomy magazine. Anyone wishing to join the
Club should contact any member.
Contributions to this Newsletter should be submitted to the
Editor (Rm 6-247, internet e-mail: gef@aplcomm.jhuapl.edu) by the
15th of the month prior to the month in which publication is
desired.
CLUB OFFICERS
President ................ Marty Pittinger .. X8588
Vice President ........... Tom Potyraj ...... X6598
Secretary/ST Editor ...... Gary Frishkorn ... X6825
Treasurer ................ Bernard Kluga .... X7257
Librarian ................ Ray Sterner ...... X3032
EQUIPMENT CUSTODIANS
C-11, Tinsley ............ Bernard Kluga .... X7257
16X80mm Binoculars ....... Tom Potyraj ...... X6598
Questar .................. Gary Frishkorn ... X6825
__________________________________________________________________
CLUB NEWS
Last month s astronomy club meeting included an
interesting smorgasbord of topics. Ray Sterner showed
some stereographic starfields which were viewed using
red-blue glasses. He also brought a stereo viewer
which was used to view stereo images of the first-
quarter moon taken by Gary Frishkorn. David Dunham
showed a video he made last month of an interesting
lunar graze which included eight events. Nick Beser
brought some digitized images of the Palomar Sky
Survey plates now available on the net. Thanks to
everyone who contributed.
----------------------------------------------------
Watching Pluto and Artificial Satellites
The promise of some interesting solar system sights
lured me out of bed before 3:00 A.M. last May 6. First,
I hadn t seen Jupiter since it disappeared into the
evening twilight last Fall. Reports were that the new
belt created by the impact of comet Shoemaker-Levy was
still visible and I wanted to see it for myself. Then
there was Saturn whose ring system was nearing the edge-
on angle as viewed from earth. I intended to follow
Saturn for the next few weeks to see how long the rings
would remain visible before the actual crossing.
It was a very clear night but turbulence made for less
than perfect seeing. Jupiter was just passing the
meridian by the time my homemade 8 inch dobsonian had
cooled down. Turbulence rendered all but the equatorial
belts invisible 80 percent of the time but brief
intervals of good seeing were enough to provide a
glimpse of the comet impact belt. It appeared as a
uniform narrow stripe in the southern hemisphere, only a
shade darker than the surrounding cloud belts. Ten
months ago the belt had been the most visible feature on
the planet; now it was a real challenge to detect and I
felt very fortunate to have witnessed this particular
part of the big planet s history.
By 3:45 Jupiter s visibility was deteriorating as it
sank lower in the southwest and Saturn had not yet
risen. I needed something to fill in the time so I
pulled out a finder chart for Pluto which showed that it
was still high in the sky and decided to try and locate
it. I had seen Pluto with my scope in the past and knew
that it required excellent conditions to reliably
detect from my back yard. Given the amount of
turbulence I was not very confident of success this
time. I star-hopped to the position indicated in the
chart and watched for a glint of light. Nothing. Even
averted vision didn t seem to show anything. Finally a
brief point-like flicker ... and then another. Probably
the turbulence was declining a bit. As I continued to
watch the object s visibility continued to improve until
it finally remained visible with averted vision most of
the time. I continued following for a while and double
checked the chart to make sure that no stars equal to
Pluto s brightness were near the observed spot.
Suddenly, ahead of Pluto, I saw a very faint star that I
had not noticed before. It appeared a magnitude or so
brighter than Pluto and I was surprised I had not seen
it earlier. Just as I was about to refer to the chart
it became apparent why it had remained invisible. It
was a very slow moving artificial satellite drifting
toward Pluto! Within a few tens of seconds it skimmed
to within only an arc minute or two of Pluto and then
proceeded to move away. Because of the slow speed it
was apparent that the satellite must be in a very high
orbit. Suddenly it dawned on me that it might be a
geosynchronous satellite and that there was an easy way
to find out. I quit tracking the stars and Pluto and
watched to see if the satellite would remain stationary
in the field of my undriven scope. Sure enough! The
satellite just sat there while all of the stars
drifted slowly across the field! I continued to watch
the satellite for several minutes and noted that it was
also changing brightness in an irregular way. During a
few instances it brightened considerably, probably
reaching 11th magnitude, or so, only to fade and
disappear completely at other times. Eventually it
faded and never reappeared. Evidently I (and Pluto) had
stumbled across it during a favorable period of sun
angle illumination. From what I remembered reading
about geosynchronous satellites they usually appear
extremely faint (generally around 13 - 14th magnitude)
so I had never imagined I would see one in my 8 scope.
As most amateurs come to realize, it s the unexpected
discoveries that often turn out to be the most
enjoyable.
The next day I dug out a back issue of Sky & Telescope
that related to photographing the geosynchronous
satellites. (September 1990 page 319) The article
described how these satellites are spaced out above the
earth s equator, and that depending on the observer s
latitude, they would appear either above or below the
celestial equator due to parallax. Pluto had been
at -6.5 degrees declination when it passed the
satellite, which gives about the right amount of
parallax for my observing site at 39 degrees North.
Since Pluto does not change its declination much over
the course of a year it should continue to be in the
realm of the geosynchronous satellites for some time;
passing by each one as it courses across the sky every
night. The article also mentioned that the satellites
often have slightly inclined orbits which cause them to
appear to drift by small amounts above and below their
positions over the equator. This fact suggests that it
would probably take more precise orbital predictions to
determine whether Pluto will actually be within the same
field of view as a particular satellite. Even without
such predictions, however, anyone observing Pluto this
year from a few degrees of either side of 39 North,
probably has a reasonable chance of running into one of
these satellites; so if you decide to visit Pluto this
summer, don t forget to keep and eye out.
So far it hadn t been a bad haul for one hour s worth of
observing: a glimpse of the comet riddled clouds of
Jupiter, the most distant planet in the solar system,
and, in the same field as the latter, the most distant
artificial satellite I had ever seen. Yep, and I hadn t
even started looking at Saturn yet!
-- Gary Frishkorn
*****************************************
Telescope Training Available at Bloomberg Observatory.
To get training on the 20" Cassigrain Telescope @ Bloomberg,
Please send your request to train to: Ryan Newcomer's E-Mail
address or call the observatory at 1-410-516-6525
ryan.newcomer@pha.jhu.edu
******************************************