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OBSERVING SATURN WITH THE ALPO OBSERVING SATURN WITH THE ALPO OBSERVING SATURN WITH THE ALPO OBSERVING SATURN WITH THE ALPO Julius L. Benton, Jr. Coordinator ALPO Saturn Section


  1. OBSERVING SATURN WITH THE ALPO OBSERVING SATURN WITH THE ALPO OBSERVING SATURN WITH THE ALPO OBSERVING SATURN WITH THE ALPO Julius L. Benton, Jr. Coordinator ALPO Saturn Section ������� ��������������� �������� ����������������������������� ��������������� ������������������������������������������� !"� ���������������������������������������������������������������������������������� ������!������������!������������� ��"���� ���#������������������������������������ ��������������������������$������������"� ������������������"������������������������������������������������������������������������%�����������������%������� ����������%��������������#��������������������������������$ � ������������� �������������������

  2. Guiding Principle of the ALPO Guiding Principle of the ALPO Guiding Principle of the ALPO Guiding Principle of the ALPO Encourage and coordinate regular, systematic investigations of our solar system with instrumentation readily available to amateur astronomers. � ������������� �������������������

  3. INTRODUCTION INTRODUCTION INTRODUCTION INTRODUCTION ������������� ������������������� &

  4. Value of Amateur Planetary Observations Value of Amateur Planetary Observations Value of Amateur Planetary Observations Value of Amateur Planetary Observations • Freedom to observe at leisure for extended periods of time. • Systematic observations provide long-term records for further study by professional astronomers. • Observations of changing atmospheric features on Saturn are used to alert professionals in selecting targets for high- resolution spacecraft imaging. • Skilled observers routinely produce excellent digital images at different wavelengths that are useful to professional astronomers. • Amateurs have actively participated in the Cassini mission. ' ������������� �������������������

  5. Some Achievements by Amateur Observers Some Achievements by Amateur Observers Some Achievements by Amateur Observers Some Achievements by Amateur Observers • Long-term visual work confirmed that distinct belts and zones are not just occasionally seen on Saturn’s globe. • Cassini's and Encke's divisions are not the only “gaps” in the rings (ripples or “intensity minima” were routinely seen prior to Voyager ). • Ring C can be seen and imaged with small-to-moderate apertures. • Long-term studies show a recurring pattern for atmospheric storms. • CM data reveal variations in rotation rates for the SEB and NEB. • Intensity estimates of belts and zones show a subtle seasonal effect. • The tenuous Ring E external to Ring A was seen prior to Voyager . • Dusky radial "spokes" were reported in Ring B prior to Voyager . • The bicolored aspect of the rings and brightness asymmetries around Ring A have been seen visually and successfully imaged. � ������������� �������������������

  6. Suggested Suggested Suggested Suggested Equipment for Equipment for Equipment for Observing Saturn Equipment for Observing Saturn Observing Saturn Observing Saturn • Minimum aperture recommendations: � 10.2 cm ( 4.0 in ) for refractors. � 15.2 cm (6.0 in) for Newtonians and Catadioptrics. • Equatorial mount with slow-motion controls and a clock-drive. • Color filters of known wavelength transmission. • A printed or on-line ephemeris (e.g., Astronomical Almanac, WinJupos, WIMP ). • Digital imager and a laptop with software to process images. ( ������������� �������������������

  7. Some Keys Some Keys to Meaningful Results Some Keys Some Keys to Meaningful Results to Meaningful Results to Meaningful Results • Saturn apparitions last about 378 days between conjunctions. � Plan your observations well ahead of the observing season. � Start observing early when Saturn is just visible before sunrise. � Continue monitoring Saturn through opposition to conjunction. � Keep accurate records (e.g. date & time, location, telescope, magnifications, filters, etc.). • Use standard observing forms for reporting data (available on ALPO Website). • Submit all observations on a regular basis via e-mail or s-mail). • Strive for simultaneous observations (i.e., two or more observers viewing at the same time on the same date). ) ������������� �������������������

  8. ALPO Saturn Observing Programs ALPO Saturn Observing Programs ALPO Saturn Observing Programs ALPO Saturn Observing Programs • Visual numerical relative intensity estimates. • Full-disc drawings of Saturn using ALPO observing blanks. • Regular digital imaging of Saturn at various wavelengths. • Central meridian (CM) transit timings of features on the globe. • Visual estimates and measurements of belt and zone latitudes. • Visual monitoring and imaging of "intensity minima“ in the rings. • Studies of the bicolored aspect and brightness asymmetries around the circumference of Ring A. • Accurate timing and imaging of stellar occultations by Saturn. • Specialized studies at small or edgewise ring inclinations (e.g., transits of satellites and their shadows across the globe). • Visual observations and magnitude estimates of Saturn’s satellites. * ������������� �������������������

  9. Sample ALPO Sample ALPO Sample ALPO Sample ALPO Saturn Drawing Saturn Drawing Saturn Drawing Saturn Drawing Blank Blank Blank Blank Although regular digital imaging of Saturn is very important, observers should not neglect to make routine visual numerical relative intensity estimates of globe and ring features. + ������������� �������������������

  10. Saturn’s Changing Ring Tilt Since 2009 Saturn’s Changing Ring Tilt Since 2009 Saturn’s Changing Ring Tilt Since 2009 Saturn’s Changing Ring Tilt Since 2009 • Saturn’s rings attain a maximum tilt of +27 o toward Earth in October 2017. • Summer solstice is approaching in Saturn’s Northern Hemisphere. • Next edgewise ring presentations occur in 2025 (unfavorable) and 2039. ������������� ������������������� ��

  11. Standard Nomenclature for Saturn Standard Nomenclature for Saturn Standard Nomenclature for Saturn Standard Nomenclature for Saturn ������������������� ������������� ��

  12. Geocentric Phenomena for 2014 Geocentric Phenomena for 2014- Geocentric Phenomena for 2014 Geocentric Phenomena for 2014 - -15 Apparition - 15 Apparition 15 Apparition 15 Apparition 2014 Nov 18 d UT • Conjunction 2015 May 23 d • Opposition 2015 Nov 30 d • Conjunction Opposition Data Equatorial Diameter Globe 18.5 ″ Polar Diameter Globe 16.5 ″ Major Axis of Rings 41.9 ″ Minor Axis of Rings 17.2 ″ Visual Magnitude (m v ) +0.0m v +24.2 o B = − 18.3 o Declination �� ������������� �������������������

  13. SOME INTERESTING PAST SOME INTERESTING PAST SOME INTERESTING PAST SOME INTERESTING PAST AND AND AND AND RECENT OBSERVATIONS RECENT OBSERVATIONS RECENT OBSERVATIONS RECENT OBSERVATIONS ������������� ������������������� �&

  14. The Memorable Great White Storm of 2010 The Memorable Great White Storm of 2010- The Memorable Great White Storm of 2010 The Memorable Great White Storm of 2010 -11 - - 11 11 11 • First imaged by Cassini at 23:26UT on December 5, 2010 at 35 ° N Saturnigraphic latitude. • By late February 2011 the massive storm widened by 15,000km encircling the globe between Saturnigraphic latitude 35 ° N and 40 ° N. Images courtesy of NASA‘s Cassini Mission • White spots arise as columns of material break through the upper NH 4 -ice cloud deck and spread out. • The NTrZ storm illustrates how shifting seasons and insolation can help stir up weather on Saturn. �' ������������� �������������������

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