The gorgeous Full Moon rose behind Mount Hamilton, as viewed from a well chosen location at sunset, east of San Jose, California on March 7. The lunar disk frames historic Lick Observatory perched on the mountain’s 4,200 foot summit. Photographer Rick Baldridge
Both Moon and observatory echo the warm color of sunlight (moonlight is reflected sunlight) filtered by a long path through the atmosphere. Substantial atmospheric refraction contributes the Moon‘s ragged, green rim. Of course, the March Full Moon is also known as the Full Worm Moon.
LICK OBSERVATORY MOONRISE
by Rick Baldridge
I’ve had many questions regarding the photo of the Full Moon coming up over Lick Observatory,
so I thought I’d write a brief story of how this all came about.
The PHOTOGRAPHIC technique is not at all difficult – basically a telephoto lens (in this case
telescope) properly focused with the correct exposure. That’s really it. Digital Single Lens
Reflex (DSLR) cameras help a great deal with exposure and getting the correct focus.
EQUIPMENT USED: Canon Rebel XTi DSLR body attached to a StellarVue 80mm ED
refractor 560mm focal length (f7.0) with a 2” adaptor and T-ring to mount the Canon DSLR.
Nothing else. No filters. Used a tripod mount only. I do use a Canon Angle Finder C, which
gives a 1.25x and 2.5x enlargement of the optical viewer to help get better focus. Used Mirror
Lock-up feature and an electronic cable release to reduce vibration. For the record, the
exposure was 1/100 sec, f7.0, ISO 200. White balance was set to “Sunlight”. (Auto White
balance is OK, but does take correcting the colors on the master to make them look natural.)
Telescope and HD video camera captures the Moonrise.
Photos courtesy Paul Mortfield
The HD video turned out pretty well, too! Just turn it on, set the focus and exposure, and let it
Considerable planning for the correct location is the trickiest part of this endeavor. I have a
program called SKYMAP by Rob Matson, an old DOS-based program (used for satellite
tracking) which is simple but very accurate. Many years ago, I wrote the land feature file that
shows a wire-frame model of the Mt. Hamilton topography and the Lick dome locations, and it
has proven very accurate. (See example next page.) This helps me to compute locations where
the Lick domes and the center of the Moon line up on the Earth’s surface — like a “Center Line”
of a Solar Eclipse so to speak. I compute the proper Latitude needed for a span of Longitudes
every 0.05° — i.e -122.00°, -121.95°, -121.90, etc. and draw those points in Google Earth to get
my own “center line” for a Moonrise event. I’m sure there are other programs / resources out
there to help a would-be observer to calculate a proper observing location.
The Lick building is about 400 feet long, so you have to be about that close to the “Center Line”
to have the domes/building silhouetted against the Moon. Proper location is certainly the most
important part of getting a photo like the APOD shot. The closer you are to the subject, the more
accurate you have to be. The APOD shot was taken 14.6 statute miles from Lick Observatory.
Graphic output of SKYMAP program with land feature wire frame model of Lick Domes and Mount
Hamilton topography. Moonrise was exactly as shown – MARCH 7th, 2012 at 18:08:20pm PST.
Lick HAMCAM shots taken at exact time of ADOP shot.
One final note – another aspect of getting a good shot like this is the foreground illumination.
Unless you want a completely dark foreground where the Lick domes would be totally black and
only form a silhouette on the Moon, you must have a Moonrise about 1 day BEFORE actual Full
Moon – elongation about 6° – 10° less than 180° is best. In this particular case, I calculated the
Moon would rise behind Lick when the Sun was JUST setting. In fact, the Moon’s CENTER was
actually below the horizon – with only about 1/3 of the Sun’s disk above the Pacific Ocean. This
gave the nice pinkish cast to the Lick domes and buildings, just about 30 seconds before they
got MUCH darker after the Sun set!
Also for the record, the photo in APOD was cropped, and very slightly corrected for contrast. A
very, very slight amount of un-sharp masking was used in PHOTOSHOP. Below is a FULL
FRAME sample to show you what the 560mm focal length lens (telescope) produces. In this
shot, you can see many of the other Lick domes, including the large 120” Shane Reflector dome
left of the Moon. As you can see, I cropped in the APOD shot about 3x – about 1/3 the given
field of the original.
I hope this write-up answered your questions. Thank you for your interest in the photo. It’s
always very exciting to see an event like this!
Special thanks to Paul Mortfield and Bryan Murahashi who joined me for this event.
Campbell, CA USA