Stories Wanted: Gemini is written entirely by our members, for our members. Gemini needs your stories: how you first became interested in astronomy, how your interest has evolved over the years, equipment you use, projects or activities you have worked on, star parties or events you’ve attended in this state and elsewhere, how you’ve encouraged others—especially young people—to get involved in this fascinating hobby. Submit your stories to gemini@mnastro.org

E-mail Update: If your e-mail address has recently changed, chances are your address used for MAS e-mail distribution lists is not current. Please inform the e-mail list administrator of your new e-mail address at mailman@lists.mnastro.org to update your address for the e-mail distribution lists. Also if your e-mail, phone number or street address has recently changed, please fill out the “Update Member Information” Web form at mnastro.org/update-member-information to update your contact information in the MAS member records.

August 2020Volume 46 Number 4a publication of the Minnesota Astronomical Society

In the pages of the Gemini

Astronomy in Chile

By Bill GlassChile’s connection to astronomy dates back to 1842, when the dying Bernado

O’Higgins (the hero of the War of Independence) expressed a desire that part of his estate be used to fund the installation of an astronomical observatory. Although apparently nothing came of this request, a few years later the United States chose to build Chile’s first observatory at the location recommended by O’Higgins. Over the years more observatories came into being, and the 1950s brought a rapid expansion when international astronomers became interested in the Atacama Desert region in northern Chile. The first of the observatories in that area was Cerro Tololo Inter-American Observatory. It was soon followed by the European Southern Observatory at La Silla.

With the boom in the number of scientific observatories came the realization that astronomy wasn’t just for the professionals; everyday people also had an interest. Soon some small observatories began to be created to provide educational and outreach programs to the general public. These were collectively called “tourist observatories” and were typically operated by amateur groups, universities, or local municipal governments—often with equipment donated by the major scientific observatories. Some of these observatories also included services targeted at more serious amateur astronomers that allowed them to rent time on telescopes or even host remotely-operated telescopes.

In June and July of 2019, I was a member of a tour group that went to Chile to see a total solar eclipse. The operator of the tour decided that since we all had an interest in astronomy, the tour would include visits to a half-dozen observatories scattered around the country. What follows is a brief description of those observatories.Observatorio Astronómico National de Chile

The National Astronomical Observatory of Chile (Observatorio Astronómico National de Chile or OAN) traces its roots back to an 1849 project of the United States Naval Observatory which was led by James Gilliss, the founder of the

Shooting for the MoonBy Theodore Sadler…Page 6

MAS Patron Members…Page 10

MAS Board Minutes for May/JuneBy Trena Johnson, secretary…Page 10

MAS 2020 Star Party Schedule…Page 11

2020 Camping with the StarsBy Merle Hiltner…Page 11

The nighttime view from the OAN. The city of Santiago has grown considerably since the observatory’s construction in 1962.

Minnesota Astronomical Society

GEMINI INFOEditorsBrian Litecky and Eugene Brown

WebmasterMAS Web Committee, chair Merle Hiltner, webteam@lists.mnastro.org

Forums AdministratorRuss Durkee

E-mail List AdministratorBob Brose

Monthly Meeting Presenter CoordinatorAhmed Reda

Astronomical League Coordinator (ALCOR)Jerry Jones

Outreach CoordinatorLilah Blinkman

Gemini is published 6 times annually by the Minnesota Astronomical Society.

Electronic submissions for Gemini may be sent to:gemini@mnastro.org

Hardcopy items should be sent to:Minnesota Astronomical Society

Attn: Gemini P.O. Box 14931

Minneapolis, MN 55414

MAS Board Members

President: Dave Falkner E-Mail: president@mnastro.org

Vice President: Valts Treibergs E-Mail: vice-president@mnastro.org

Treasurer: Matt Dunham E-Mail: treasurer@mnastro.org

Secretary: Trena Johnson E-Mail: secretary@mnastro.org

Board Member at Large: Gunnar Isberg E-Mail: boardmember1@mnastro.org.

Board Member at Large: Conrad Sanders E-Mail: boardmember2@mnastro.org

2GEMINI • www.mnastro.org

USNO. The Gilliss expedition’s mission was to establish an observatory in Chile to measure solar parallax and to observe Venus and Mars. Gilliss chose to build his observatory on Santa Lucia Hill, which is near Santiago. The expedition’s work was completed in 1852, at which time, Gilliss sold the buildings and equipment to the government of Chile. This became the national observatory.

Santa Lucia Hill is a remnant of an old volcano and is made of black basalt rock. The director of the observatory quickly discovered that daytime heating of the black rock caused the entire hill to shift slightly in position. By 1857, a new site a few miles away in Quinta Normal was selected, and the move was completed in 1862. This location proved to be very foggy, and by 1916 the observatory had moved again to Lo Esperjo, a few miles south of Santiago.

In 1927, ownership of the observatory was transferred to the Department of Astronomy of the University of Chile.

In 1956, the observatory began another move, this time to Cerro Calán, which is located in an eastern suburb of Santiago. The move was complete in 1962. Over the years, Santiago has expanded considerably, especially toward the east. The observatory’s site is now severely light polluted; this restricts its usefulness for serious research. Graduate students at the university are able to perform some photometric work to search for exo-planets as well as receive training in operating telescopes and designing observing sessions; more serious work is done at other observatories. Otherwise, the facilities at Cerro Calán are used primarily for outreach programs. The observatory holds two hour-long public events regularly except during the winter months; these include the opportunity to look through two of their telescopes.

The most modern telescope at the observatory is a 45cm Cassegrain reflector from Goto Corporation that was purchased in 2002 with a grant from the Japanese

The OAN’s 45cm reflector made by the Goto Corporation. It was purchased with a grant from the

Japanese government.

The OAN’s 28cm refractor built by Gustav Heyde (Dresden, Germany) in 1913.

August 20203

government. Also in operation is a 28cm refractor from Gustav Heyde that was installed in 1913. There is also a 1.2m millimeter-wave radio telescope which is the twin of a radio telescope installed at Harvard. This instrument was originally installed at Cerro Tololo and moved to Cerro Calán in 2011. Finally, there is a 60cm refractor from Grubb in Newcastle, England, which has a rather unfortunate history.

The 60cm scope was ordered in 1909 and was supposed to be delivered in 1912, but delivery was delayed first by strikes and then by World War I. By the time the scope was again ready for delivery in 1923, prices for the scope and for shipping had increased and the government of Chile had to raise additional funds. The pieces arrived gradually, with the lens finally arriving in 1933. By then other problems had been discovered. The dome that had been built to house the telescope was too small, and no one in Chile had the experience to install a 35-foot-long scope. Attempts were made to modify the telescope, but it never performed satisfactorily and was eventually disassembled. Today it is still in pieces and the dome that was built for it is a glorified storage shed for the parts.La Silla

In the 1950s, all large astronomical telescopes were located in the northern hemisphere. Several European astronomers began talking about establishing a large observatory in the southern hemisphere. Initially it was assumed that this new observatory would be located in South Africa, where several European observatories were already located. However, astronomers were becoming aware of other places that offered some advantages. One of these regions was the Atacama Desert in northern Chile. In addition to being far from any light pollution and at reasonably high altitude, it also has very low humidity. Astronomers were interested in building telescopes designed for observing in infra-red light, and since infra-red is absorbed by water vapor, a site with low humidity was desirable. Average rainfall in the Atacama Desert is only 15mm per year; some weather stations have never received any rainfall. One of the people campaigning for building the new observatory in the Atacama was Federico Rutlant, the director of Chile’s National Observatory.

The ESO’s La Silla Observatory as seen from the approach road. From this angle, it’s easy to understand why the site was renamed “The Saddle.”

In 1962 the European Southern Observatory (ESO) organization was formed, and in 1963 it selected Chile as the location for the new observatory. A site-selection committee was formed, and in 1964 it selected a site known as Cinchado. The location had the advantage of being easily accessible and was already owned by the government. The site was renamed La Silla (“the saddle” in Spanish) and a road to the summit was completed in 1966. By 1968 three telescopes were in operation.

Today there are over a dozen telescopes onsite (some have been decommissioned) and two of them are open to public tours.

An aerial view of the La Silla Observatory. Photo courtesy of ESO.

The La Silla Observatory is open to the public for free tours every Saturday; advance registration is required. Just beyond the main gate is a parking area for visitors as well as rest rooms and a picnic area. Visitors’ vehicles are not permitted beyond the parking area. Because the summit road is single-lane at several points and some sections have non-standard right-of-way rules, only the observatory’s radio-equipped buses with their trained drivers are permitted access to the summit.

The building housing the New Technology Telescope.

Visitors are first taken to the visitors’ center, where there are some exhibits about the observatory and a short video about its history. Visitors can then walk to the New Technology Telescope and tour the inside of the building. After that they return to the buses for a short ride to the summit, where the ESO telescope is located. After a short tour of that telescope they return to the buses and go back to the parking area.

The New Technology Telescope (NTT) is a 3.58m Ritchey Chretien scope in an Alt-Az mount and was a pioneer in the use of active optics. It saw first light in March 1989. One interesting feature of the scope is a filtered air circulation system that is used during the day to cool the primary mirror to the temperature forecast for the upcoming evening. The main mirror is flexible; its shape is actively adjusted during observations by actuators.

4GEMINI • www.mnastro.org

The secondary mirror position is also actively adjusted in three directions. There are currently two instruments that are permanently installed on the scope. One is an infrared camera and spectrograph called SOFI and the other is a faint-object spectrograph called EFOSC2.

A view of a portion of the La Silla Observatory as seen from the ESO 3.6m telescope. The NTT is the building at the top of the ramp and the visitors’

center is in the lower left corner.

The ESO 3.6m is the largest telescope at La Silla and occupies the highest point of land on the site. It’s a Cassegrain scope in a conventional equatorial mount that saw first light in 1977. Since then it has been upgraded many times, including a new secondary mirror in 2004. For the last decade the only instrument on the scope has been HARPS—the High Accuracy Radial Velocity Planet Searcher. HARPS is a high-precision echelle spectrograph that is designed specifically for searching for exo-planets. HARPS discovered its first exo-planet in 2004 and to date has discovered more than 130.Observatorio Mamalluca

The Juan Francisco Cortes Building at the Mamalluca Observatory. Photo courtesy of Lonely Planet.

The Cerro Mamalluca Observatory was the first of the so-called tourist observatories (Observatorio Turistico) to be founded in Chile. It was started in 1994 when an amateur astronomy group (CASMIA) acquired some land in the hills north of the small town of Vicuña. With the help of the local municipality, the Chilean Ministry of Public Works and the Cerro

Tololo Observatory, Mamalluca was opened in 1998. The name Mamalluca is derived from the Quechan “wama” and “lluchka,” which roughly translates as “unusual blurry thing.”

Mamalluca consists of two buildings. The Juan Francisco Cortes Building was completed in 1995. It houses a 12'' Meade LX200 equipped for CCD digital imaging, and a meeting room. The rooftop patio provides space for three Orion 12'' Dobsonians. The second building is called the Nicolaus Copernicus and was completed in 2001. It includes a multi-media exhibition hall, a cafeteria, and an observation deck with four 16'' Orion Newtonians.

A view of the building housing the ESO 3.6m telescope (upper center). On the right, behind the bus, is the visitors’ center.

The main purpose of the observatory is to offer educational and tourist programs. The observatory has its main office in the center of Vicuña and offers four-hour-long tours (advance reservations are required) that include an opportunity to look through their telescopes. It is possible for larger groups to book the entire observatory for special events. The observatory will sometimes rent time on its telescopes to amateurs during times when tours are not being conducted.Observatorio Collowara

The Collowara Observatory Photo courtesy of the Collowara Observatory.

The Collowara Observatory is located in the town of Andacollo, a few miles from the city of La Serena, and is operated by the municipality of Andacollo. It is one of the newer tourist observatories, founded in 2002. The main building houses a 14'' Meade LX200, an auditorium and a small cafeteria. An

The interior of the building housing the ESO 3.6m telescope.

August 20205

outdoor viewing area has two Meade 10'' Newtonians and a Meade 16'' Dobsonian. The name Collowara comes from the Aymara language and roughly translates as “Land of Stars” or “Star Hill.” The sole purpose of the observatory is to offer educational and tourist programs, typically for small groups. Advance reservations are recommended.Cerro Mayu Observatory

The Cerro Mayu Observatory. Photo courtesy of Google.

The Cerro Mayu Observatory is located in the town of Quebrada de Talca, a few miles from the city of La Serena. The observatory traces its origins to 1970, when the Department of Astronomy at the Seminario Conciliar School of La Serena acquired its first telescope. Over the next few years the observatory expanded, and because of its association with the Cerro Tololo Observatory it acquired the nickname “Tololito.” In 2006 the observatory moved from La Serena to its current location about 15 miles away.

The observatory is a combination of science and the mystical, having a connection with the pre-Columbian culture of the area. The observatory has a 14'' Meade LX200 and a small auditorium for the use of scientific visitors. For those who are interested in the archaeology and cultural history of the area, there is a set of scientific statues, a ceremonial tower, a Sun gate, a water mirror and a solar calendar. These later structures are on a hill to the west of the main building. The purpose of the observatory is to offer educational and tourist programs. One unique program is that it is possible to access the observatory via a night-time trek on horseback.San Pedro de Atacama Celestial Explorations

The outdoor observing patio at S.P.A.C.E. with several of their telescopes. Photo courtesy of Alain Maury.

San Pedro de Atacama Celestial Explorations (S.P.A.C.E.) is located on the edge of the Atacama Desert near the small town of San Pedro de Atacama. It was founded in 2003 by Alain Maury,

an avid amateur astronomer from France who relocated to Chile. S.P.A.C.E. is very different from the other tourist observatories described earlier. Not only does it provide educational programs, but it also provides services aimed at amateur astronomers.

Almost every night, S.P.A.C.E. holds star tours for tourists staying nearby. A typical program lasts two hours and is attended by 20 to 30 people. It includes an introduction to the night sky, followed by an observing session using eight telescopes ranging between 20cm and 72cm in size. Alain is assisted by people wearing white lab coats so they can be easily found in the dark. Finally, the group is treated to a short astronomy-related talk along with some hot cocoa (the high desert can be quite chilly). Alain frequently hosts two or three groups each evening, so the facility is very busy.

In addition to the star tours, S.P.A.C.E. runs the onsite Atacama Lodge, which provides dormitory-style accommodations for visiting amateur astronomers. Each building provides a sleeping area, a common living area, and a kitchen/dining area. Those who stay at the lodge may bring their own telescopes or rent time on the scopes after each evening’s star tours are completed. S.P.A.C.E. also provides room for hosting a dozen remotely operated telescopes, although at this time all available slots are occupied.

The tour group I was traveling with split in two when we arrived in San Pedro de Atacama. About half the people stayed at the Atacama Lodge, while the other half (including me) stayed at a hotel in town. One evening I joined two friends and we hired a taxi to take us to the Atacoma Lodge so we could do some simple astrophotography. The three of us had a great time. We took our photographs and then Alain allowed us to join one of his star tours even though we weren’t paying customers. Alain’s outgoing nature definitely adds to the fun of his star tours. For example, I recall him giving us some instructions when we moved to the patio where the telescopes were located. “We don’t wait in organized lines here. We use the French system. Find a telescope with a short line, look through it for as long as you want, and when you’re done, look for another telescope with a short line.”

In many ways I was impressed with the views of the sky at S.P.A.C.E., but I was also disappointed. Perhaps I had expected too much from all the hype that I had read about the Atacoma skies. Yes, the sky is dark, but there is also a busy highway with auto lights about a mile away as well as a wind farm with its sea of red lights atop the wind turbines. I’ve been in places like Great Basin National Park in Nevada and Ayer’s Rock in Australia that had fewer local distractions.Other Observatories

In addition to the places described above, there are also many other observatories in Chile that are open to the public. For example, there are ALMA (Atacama Large Millimeter Array), Cerro Pachon, Cerro Parnal, Las Campanas, and Cerro Tololol Inter-American Observatory. Most are open only on weekends and some are open only once a month. All request advance registration. Some require four wheel drive vehicles with high clearance to access the site. There are also numerous tourist observatories. I have not found a complete list on any web site, but it’s quite likely that there are at least two dozen of them scattered around the country.

6GEMINI • www.mnastro.org

Shooting for the Moon

By Theodore Sadler Contributor to Getty Images, Iowa Outdoors Magazine, Town

Planner and Wisconsin DNR Magazine, as well as member of the Royal Photographic Society. (www.theodoresadlerphotography.com)

The Moon is our closest celestial neighbor as well as our most intriguing and regularly seen astronomical object that is available most days or nights. Compared to other targets of the night sky, with a little bit of patience, photographing the Moon can be as easy as 1, 2, 3.

• Planning, which includes weather, location, time and Moon phase

• Setup, such as camera settings, lenses and other accessories• Photographing and post-processing. When items one and

two are aligned, then three is a matter of capturing the best image possible and bringing out its best qualities.

The advent of digital photography has made different genres of astrophotography, once challenging, now approachable and extremely rewarding. Looking back on a hobby I’ve enjoyed for nearly 30 years, it is impressive how far it has come. From optics to tracking mounts to sophisticated software programs that make photo editing a snap, photography has come a long way. Yet as an easily recognizable subject, photographing the Moon can be a bit of a challenge. Here I’ll provide some helpful tips which will cover fun background information, camera gear, lenses, camera settings, software programs and more.

Before we dive into all that I would suggest the following be taken into consideration, as many appear to enter into this hobby wanting to be the next Edward Weston of the night sky. First, have a tremendous reserve of patience (think of the volume of the Grand Canyon, then multiply that by five). Second, discipline goes a long way. Practice, practice, practice and learn from your mistakes. Lastly, and most importantly, have a sense of humor, have fun! Like the cyclist who is constantly “biking uphill and into the wind” lunar (astro) photography is a battle of the weather and elements, camera configurations, location, timing and more. Having the ability to laugh at yourself or the external factors helps tremendously and eases the pain of a terrible photo session. With these convictions firmly entrenched in your mind, let’s explore some interesting facts most people overlook.

The Full Moon amongst Trees at Twilight, Winter Study #2 2018. Minneapolis, MN. Sony a6000, 210 mm, ISO 100, f/11, 1/40 sec with polarizing lens.

Here are two fast facts regarding lunar photography that many may be unaware of, which you should know. One, optical illusion. The size of the Moon never changes from rise to set (same with the Sun, by the way). Unbelievable I know, but true. The great Moon illusion has been known since time immemorial. The size of the Moon photographed with a 50 mm lens is the

approximately correct size; it is how our minds interpret the Moon that is distorted. Second, many (most) Moon photographs that incorporate a cityscape or landscape at night with a large full Moon which is clearly well-defined are actually composites of two different images—one photographed at the correct lunar exposure (often with a telephoto lens to make it look much bigger) and the second at the correct subject exposure. Rarely does one exposure incorporate the correct metering for both the Moon and the subject-scape. This is one of many reasons why the Ansel Adams 1941 Moonrise, Hernandez photograph is so well admired and coveted.

Moonrise over Minneapolis, 2018. Minneapolis, MN. Sony a6000, 210 mm, ISO 100, f/6.3, 1/30 sec.

For the rest of our discussion of photographing the Moon, I’ll assume you know your camera well and understand many of its features already. Given the variety of cameras on the market today, it would be a lengthy tome to incorporate all the current digital camera models and features. Photographing the Moon can be viewed in two distinct phases. First is the technical step required of capturing a clear, crisp image of the lunar features of craters, mountain ranges and vast plains. Second is the post-processing to bring out the best of the image captured in the first phase. However, before diving into the technical aspect, it is important to understand and utilize the process of visualization—we picture in our mind’s eye what we wish to capture or convey with our photograph. Is it a feeling of what we think the Moon should look or feel like? Or is it a purely technical exercise of capturing the clearest, sharpest image we can imagine? If necessary, feel free to sketch in a notebook what you are trying to capture and perhaps note the feelings or emotions that go with it. This will help clarify the photographic settings needed to communicate such an impression.

Phase one. The technical aspect will cover pre-shooting assessment, photographing (camera gear, settings and more), and post-processing and correcting. Pre-shooting involves where and when to photograph the Moon. Is your intention to photograph the full Moon rising or a lunar-eclipse sequence? To capture both the light and dark side of the moon simultaneously, or grab a stunning image of the lunar mountain range? Summarized in Table 1 are some helpful photography applications available both for your smartphone and desktop computer. First is the Photographer’s Ephemeris. This handy program provides time, angles, elevations and location (with Google map) of the Sun and Moon. It is helpful for not only selecting possible locations to photograph from but also verifying where and when the

August 20207

Moon will rise or set. Following this would be determining sky conditions, readily available via Clear Sky Chart (CSC).

Working with up-to-date weather information, CSC provides critical details related to key atmospheric factors such as sky transparency, seeing and darkness (Bortle), along with additional factors that can impact image quality, such as wind and humidity. Once mastered, its value is priceless. Stellarium, provides back-up information related to astronomy targets, simulating the night sky and where objects will be throughout the night. These applications aside, another helpful tip is to check traffic conditions, especially if you will be driving far to a specific location. Nothing can be more frustrating than being delayed or missing a photographic shoot completely because of road work, traffic collisions or sporting events that can all snarl up the roadways.

Once the lunar phase, time, location and weather/sky conditions have all aligned, it’s time to prepare the camera and select the appropriate lens prior to getting to your chosen site. Summarized in Table 2 are the general camera settings used when photographing the full Moon, one of the most popular lunar subjects. Often known as “looney eleven,” this relates to the aperture setting (f/11) used in the days of film cameras to provide a crisp image of the Moon without blowing out the highlights.

To begin, consider film speed. For this, let’s refer to analog film measured in ASA and digital images in ISO. Digital cameras have ISO setting from low to high and analog film ranges from slow to fast. For reasons beyond the scope of this article, let us regard these as related but not precisely interchangeable. For analog cameras it is best to use a slower film, where the silver grains will be very fine, usually 50 to 125 ASA. While 25 ASA film is still sold, it is oftentimes not readily available, even via Internet stores. Regarding film, this brings up a key point—reciprocity. Film reciprocity is the bane of astrophotography. Essentially, film is manufactured for common lighting conditions, from low-lit to very bright sunny days; even very dimly lit subjects require exposures of no more than a second or two. However, when temperatures are cooler or minutes of exposure time are required for photographing deep-sky objects, this is where reciprocity begins: A film of 100 ASA with longer exposure times and/or colder temperatures (<4˚C/40˚F) behaves more like 25 ASA. Always consult the technical information about the film from the manufacture’s online resources or on the packet that came with the film. The film characteristics will be plotted among several helpful graphs. Look for the temperature and exposure time graph to determine the optimal exposure time for your situation.

Moonrise over Prairie, 2018. Bloomington, MN. Sony a6000, 204 mm, ISO 100, f/11, 1/13 sec.

With digital cameras, reciprocity is not an issue, but “noise” is. Digital noise increases with higher ISO values and becomes visibly noticeable above 1600; akin to visible grains from analog film, this appears as blotchy pixels. Most digital cameras have a base (lowest) ISO setting of 100; use this value to start. Other sources of noise from a digital image can be a bad sensor pixel, internal heat or other electronic emissions. Save your images in the RAW format to ensure that the most light information is captured. JPEG will work, but the amount of data used for optimizing the image during post-processing will be reduced. And set your digital camera’s white balance to “auto” or “AWB.”

Moon and Storm Clouds, 2018. Turtle Lake, WI. Sony a6000, 126mm, ISO 400, f/9, 1/6 sec.

Next, lens choices. As we know, how we perceive the Moon with the unaided eye and what we capture with a standard 50 mm lens is not the same. To obtain a large, frame-filling lunar photograph requires the reach of a telephoto lens, 135 mm or greater. Standard kit telephoto lenses sold with digital single-lens reflex (DSLR) cameras today are typically around 70-200 mm. A large, completely frame-filling image requires a minimum focal length of 500 mm. You may also use a telescope with a t-mount adapter to your camera body which fits into the eyepiece socket. For smartphones and some point-and-shoot cameras, use an afocal mount to photograph directly through the eyepiece.

What should be pointed out here is the quality of a good, fixed-focal-length prime lens. One I find extremely useful is the 135 mm. If you can purchase an apochromatic 135 mm prime lens, this will not only capture extremely crisp images of the Moon, but a fast lens design (< f/2.0) will make it a superb lens for photographing deep-sky objects such as galaxies, star clusters, nebulae, etc. While many zoom telephoto lenses are very good quality, they have a number of drawbacks compared to a prime lens. Due to the optical design of these lenses, the image may not be as sharp, overall speed is much slower (>f/3.5), chromatic aberrations are more prevalent (especially in the corners), and lenses up to and over 500 mm are very expensive.

Moving along to f-stops. For lunar photography, f/11 is an excellent starting point, especially for the full Moon. The reason for this is to increase the depth of field, which for an object so far away seems silly, but it does help, and to reduce the amount of light getting to the sensor (or film); this can improve the details captured. However, for focusing I would recommend having a shallow depth of field (faster f-stop) of around f/3.5 and once in focus changing to f/11. Additionally, understanding and knowing how to use a digital camera’s live-view mode and how to employ the focus magnifying feature is important to obtain critical focus of the lunar features of craters and mountains. During moonrise, especially from spring through autumn, thermal aberrations (i.e., heat) are more noticeable at the horizon than higher attitudes (>15˚) in the sky. Obtaining a critical focus during this time can be trying and a bit of patience is required. It is often helpful

8GEMINI • www.mnastro.org

to focus on the edge of the Moon or on features like craters or mountains. With many analog cameras, critical focus will rely on what can be obtained through the eyepiece, and if noted on the lens not going to the hyperfocal distance setting.

Regarding shutter speeds, given the combination of lens, f-stop and film selection, a good starting-point is 1/125 of a second. Typically, this will produce a dark background and a darkened lunar surface, depending on camera and conditions. From here feel free to bracket your speed from 1/20 to 1/125 of a second. If you are using a digital camera, use the playback button to review the image quality (focus, features, white and highlights not blown out, etc.). The phase of the Moon will determine the average shutter speed. Listed in Table 3 is a rough guide for different camera shutter speeds in accordance with lunar phases. If you have a mirrored camera, verify if it has a mirror lock-up option and use it. When the shutter button is activated, the mirror flips upward to allow light to fall upon the sensor or film. However, mirror flap can cause slight but noticeable movement, resulting in blurring of the image. This explains the development of the mirror lock-up feature and why mirrorless cameras are growing in the marketplace.

Before we go into the final accessories needed to capture a crisp, stable image of the Moon, let’s have a brief review of the use of filters. Traditionally, filters help improve contrast while at the same time helping to control the amount of light impinging upon the film or sensor. Without diving into too much detail, filters can be of different color values, different neutral density values (and/or gradients), or polarizing. Color filters in general lighten those that are the same value or adjacent values on a color wheel while darkening those of opposite values. Neutral density filters reduce the amount of light while not distorting it or its colors. Polarizing filters allow only light from one direction to pass through the filter and reject all other light. This allows the reduction or complete removal of light reflecting/scattering off surfaces and darkening it.

Under a Full Moon: Dog Walker, 2019. Minneapolis, MN. Sony a6000, 84mm, ISO 100, f/11, 1/13 sec.

The most popularly used filter for photographing the Moon is the 80A, a light-blue filter. It is great for black and white photography to improve contrast and equally helpful with color images, including digital. Another filter that can be helpful is a

polarizing filter, particularly during twilight or daytime settings where the sky needs to be darkened to allow the Moon to pop out. A rotating polarizing filter can greatly improve image sharpness. Last in the filter list would be a set of graduated neutral-density filters. These are not mandatory by any means but extremely helpful, especially when you want to capture both sky and foreground at twilight, which typically have different exposure values.

Moonset over the Countryside, Study #3 2018. Turtle Lake, WI. Sony a6000, 95mm, ISO 100, f/5.6, 6 sec.

To wrap-up our technical review, a discussion about tripods, shutter-release cables and intervalometers is in order. Without a doubt a sturdy tripod is a must when photographing the Moon or any celestial object. While a modern, well-built ball-head mount tripod may be ideal, a secondhand tripod from a garage sale or thrift shop will work equally well. I have used my grandfather’s tripod from the ’70s with great success. Whether analog or digital, a remote shutter release cable is invaluable for preventing camera shake. If a shutter-release cable is not at hand, use the camera’s timer function. Typically, this allows a 10-second window before the shutter is triggered, which permits enough time to stop most or all camera shake. While not necessary, a camera intervalometer for digital cameras is also very helpful, especially when you want to capture regularly timed exposures of the Moon as it moves across the sky. Many modern DSLR cameras have a built-in intervalometer, which can be programmed, or have an application that can be added. One can purchase an intervalometer from online stores for around $20.00

Once images are captured, phase two begins with post-processing of the images. For analog, this means either dropping the film off at a camera store for development or doing so at home and subsequently scanning the images into your computer for final adjustments. For digital photography, it’s a matter of loading the images into any number of different applications available. These include software from the camera’s manufacturer, software pre-loaded with your computer, or an off-the-shelf third-party application, such as Adobe’s Lightroom. Open the images into the application of choice.

Find the tools which allow for adjustment of brightness, contrast, highlights, shadows and blackpoint, as well as sharpness and saturation. Begin by increasing the contrast slightly. At this point the image will darken. Have the shadows and lunar features sharpened? Do they look pleasing to your eyes? Do they look as

August 20209

you have visualized them? If yes, then move on to highlight and white values, including brightness. Typically, these need to be reduced ever so slightly. Do so until you see whites of different values across the lunar surface or until pleasing to your eyes. If necessary, increase the brightness value to achieve a bright Moon with distinct white-shaded features. At this point examine your photograph. Does it look visually pleasing? Are the features distinct and not washed out? Continue to make minor adjustment until the image of the Moon and the composition as a whole appears as you visualized it. Save a separate copy from the original RAW file in case you want to make further adjustments.

I trust that this quick tutorial has enlightened you and helped in the process of taking more satisfying pictures of the Moon

and then being able to make post-processing adjustments that communicate what you initially visualized. I don’t know about you, but every time I go out to photograph the Moon, I cannot help but think (hum) Dean Martin’s classic song That’s Amore.

“When the Moon hits you eye like a big pizza pie, that’s amore…”

Photographing the Moon, whether full or crescent, is a fantastic challenge and target to master. I’ve enjoyed this hobby for many years, and I hope I’ve provided a condensed version of that knowledge for your enjoyment and education. The night sky is full of wonders, so get out there and enjoy it!

Continued on page 12

Table 1. Summary of helpful applications for determining Moon phase, location, timing and sky conditions when planning to photograph the Moon or other astronomy objects. Additional helpful websites are listed below that I have consulted over the years; I have found them invaluable.

Name Description URL

Photographer’s Ephemeris

Application (desktop and smartphone) for planning where the Moon (and Sun) will rise and set at your locale

www.photoephemeris.com

Clear Sky Chart Wonderfully helpful tool to help plan astronomy photography and estimate sky conditions

www.cleardarksky.com/csk/

Stellarium Powerful 3-D star map for identifying location and timing https://stellarium-web.org/

Moon Exposure Cal-culator

Developed by Xavier Jubier, this website provides impressive camera information for photographing the Moon. This is a must to review.

http://xjubier.free.fr/en/site_pages/astronomy/Moon-ExposureCalculator.html

Lunar Eclipse Expo-sure Guide

Developed by Fred Espenak, it provides very detailed infor-mation on photographing a lunar-eclipse sequence.

http://mreclipse.com/LEphoto/LEphoto.html

Moon Photogra-phy—A How-to Guide

An older website that provides useful lunar photography information. Developed by Keith Cooley.

http://home.hiwaay.net/~krcool/Astro/moon/howto-photo/

Table 2. Summary of general camera settings for photographing the full Moon, also known as “looney eleven.”

Setting Analog Digital

Mode (camera) (manual) M(anual) or A(perture priority)

Film Speeda (ASA or ISO)

50 or 100 100

Lensb (mm) >135mm >135mm

f/stop f/11 f/11

Shutter Speedc (sec.)

1/125 1/125

Filterd 80A 80A

Tripod Yes Yes

Shutter Release Yes Yes

Live View Yes Yes

Mirror Lock-up Yes Yes

a. Note for film cameras: Reciprocity becomes an issue with colder temperature and/or longer exposure times. Be sure to review film information to know the correct exposure time.

b. If given a choice, prime lenses are the way to go because of the optical performance they can deliver. Zoom lenses are amazingly convenient, but due to their necessary and optical train they lose performance compared to the fixed-focal-length of a prime lens.

c. This is a starting point, depending on sky conditions, time of day, etc. Shutter speed may need to be either increased or decreased.

d. This is often overlooked but is incredibly important. A good 80A filter provides improved contrast and helps reduce the light that comes from a full Moon. It is especially helpful for black and white photography.

e. A shutter release or intervalometer is your best friend. It minimizes camera shake and any excessive noise that can develop in the final image.

10GEMINI • www.mnastro.org

MAS Patron Members

Patron memberships are available to those who wish to contribute a little extra to support MAS activities. Patron memberships are established by constitution at 2-1/2 times the Regular membership rate—currently $65 annually for a patron membership. The $39 additional contribution is tax deductible. Patron memberships help fund equipment acquisitions, facility improvements, outreach activities and more. We would like to thank the following patron members as of July 11.

Femi AbodunrinTom and Arlene AlmScott AndersonJack AtkinsSteve BaranskiGreg BarilBradley BeiselDenise BeusenScott BilleadeauKatie BloomeWayne BolineRev. Eugene BrownJay BrueschStephanie BueJonathan BurkhardtJeff BurrowsEarl ByeWilliam BynumKen CarlsonKurt CasbyStuart ChastainCara ClarkDeane ClarkBruce ColemanMark ConnollyMichael DanielsGary DavisMary Beth Smith & Ted DeMattiesDavid DennisThomas DillonTony DuBoisMolly DuffinMatt DunhamDave EckbladWilliam Eggers

Steven EmertDennis FaithDavid FalknerRobert FarrellCody FeigumPatricia FlugaurRobert FoucaultAndrew FraserRobert FriedleinAlan FullerPaul GadeJim GerrityGregory GibbonsWilliam GlassMartin GodfreyBradley GordonMartin GormansonSteven GrabarkiewiczZdenko GrajcarAntone GregoryJere Gwin-LenthDale HagertEric HallBrandon HamilJames HannonRyan HansonAndrew HarwoodDustin HaskinsGreg HaubrichMichael HaydockJonathan HaymanVictor HeinerAngela Heins FamilyBrian HendricksJohn HillMerle Hiltner

Gary HoaglundMichael HobbsLauren HoenGreg HokansonMichael HopfenspirgerAnton JachimDick JacobsonGale JallenLen JannuschMark JobJulie A. Y. JohnsonKurt JohnsonTrena JohnsonJerry JonesMichael KauperKenneth KerrickSam KhoroosiMichael KibatMichael KnowlenJim KnudsenBill KockenDavid KockenParke KunkleGreg LarsonChristine LaughlinLouis LeichterPaul LiederClayton LindseyShawn LovettWalid MaalouliEdward MalinkaJohn MarchettiVanessa McCahonBruce McDonaldDuane McDonnellJavier Medrano

Rebecca MesserMatt & Jessica MeyerBeverly MillerGerald MillerRobert MillerScott MorganPat NassefBradley NassetBrian NelsonDouglas NelsonJacquelyn NelsonDoug NevermanKenneth NichollsTracy NiebelingAlan NootDouglas OinesThor OlsonChristopher PaolaGary PedersonMark PetchenikJJ PludeBecky PollackAhmed RedaMichael RegouskiKirby RichterStephen RiendlLuigi RomoloJohn RosenbergJames RowanDaniel RuhJack SandbergRoy Cameron SarverJames SchenzRonald SchmitSteven SchmittAnna Schoeneberger

Loren SchoenzeitDavid SchultzJon SeilkopKristopher SetnesMike ShawJeff ShlosbergBernie SimmonsDavid SiskindDavid SjogrenDennis SjogrenEric SmestadAndrew SmithKatherine SprollKegan StewartBernie StingerJack StormsPeter SullivanDavid SwymelerDavid TostesonValts TreibergsSteve UlrichBob VangenPaul VanNormanLawrence WaitePaul WalkerLeilani Wayt-MuellerSarah WeaverCraig WeinertMark WicklundMary WilliamsNeil WorthinghamRobin WrightGene YatesJohn ZimitschMark ZimitschNeal Zimmerman

MAS Board Meeting Minutes for May/June

By Trena Johnson, secretaryMay

Attendance: Dave F, Valts T., Matt D., Trena J., Conrad S., Steve E., Vic H., Merle H., Lilah B. Our current membership is at 524. Amazon Smile YTD $14.22. Thank you. Site Reports: JJC/Metcalf: Belwin is not open to the general public yet. Keyholders can use it with one person in the observatory and two on the plaza. ELO: The observatory can be used with two or three persons inside Onan and one in Sylvia, with 10 people maximum for the entire site with good distance on the upper and lower plaza. CGO: The outhouse design is complete. Specialized items have been ordered; we are waiting on construction materials. We discussed trees vs. fencing. Fencing is needed for this year with trees added in the fall or next spring. LLCC: Trees have been removed. LLCC members are looking for new members as others are wanting to rotate out or retire. Please see the forum for all updated Stay Safe guidelines.June

Attendance: Dave F, Valts T., Matt D., Trena J., Gunnar I., Conrad S., Deane C., and Ahmed R. Our

current membership is at 515. Please consider nominating MAS when buying through Amazon Smile program. Your donation is appreciated. Site Reports: JJC/Metcalf: Per Jon H., the site is in good shape. The Ash Dome is planning to be out the second week of July. Coordination between MAS and Belwin for interior scaffolding to be put up and telescopes to be removed. Watch the forums for more information. Merle and Jon are getting SimpliSafe cameras installed in and around the observatory. LLCC: Also in good condition. Site is closed. ELO: We received a bid from CRC but are awaiting additional bids. Site is in good condition with members only allowed at the observatory. CGO: Facilities are open to a small number of members. Check the forum for current restrictions for all sites. North end light fence is awaiting approval by the counties. Sign up on the forum if you can help assist in the building. Loaner Scope Program: It is resuming with safety protocols in place. Constitution Committee: We are awaiting updates. Star Parties: These are resuming via reservation only. See the forum postings. CWTS/NNSF: Camping with the Stars and Northern Nights Star Fest are tentative.

11 August 2020

Minnesota Astronomical Society 2020 Star Party Schedule Twilight Completely dark Moon % ELO Public Cherry LLCC Friday Date Sunset ends: from: to: Illuminated Night (Saturday) Grove Weekend Notes Saturday 8/8 8:28 PM 10:22 PM 10:22 PM 11:04 PM 78% x

August 14 8:19 PM 10:09 PM 10:09 PM 2:09 AM 20% x x

August 21 8:08 PM 9:54 PM 9:57 PM 4:35 AM 9% x (22nd) x x NNSF weekend: 18-23

Saturday 9/5 7:42 PM 9:21 PM 9:21 PM 9:28 PM 89% x

September 11 7:31 PM 9:08 PM 9:08 PM 12:49 AM 36% x x

September 18 7:18 PM 8:53 PM 8:53 PM 5:18 AM 2% x(19th) x x x

Saturday 9/26 7:03 PM 8:37 PM 2:30 AM 5:28 AM 75% x Fall A-Day

October 09 6:39 PM 8:13 PM 8:13 PM 11:33 PM 50% x(10th) x Opposition of Mars – Fri/Sat at ELO

October 16 6:27 PM 8:01 PM 8:01 PM 5:53 AM 0% x x 4M

October 23 6:14 PM 7:49 PM 1:26 AM 6:03 AM 61% x(24th) x

November 06 4:57 PM 6:33 PM 6:33 PM 9:24 PM 68% x(7th) x

November 13 4:49 PM 6:26 PM 6:26 PM 5:26 AM 3% x x

November 20 4:43 PM 6:21 PM 10:13 PM 5:34 AM 34% x

Saturday12/19 4:38 PM 6:20 PM 10:10 PM 5:58 AM 27% x Jupiter-Saturn conj. 13'

2020 Camping with the Stars

By Merle HiltnerEagle Lake Observatory Facility Manager

This year’s Camping with the Stars (CWTS) was a unique event. With restrictions for attendance and social distancing taken into account, we had a scaled-down event that eliminated speaker presentations on Friday, the pot-luck picnic on Saturday, and all of Sunday’s activities, including the morning brunch and what has turned out to be the annual viewing of Galaxy Quest.

In spite of the limitations we still had a great time. Friday was filled to capacity, as we limited attendance to 35. We started with mostly clear skies with a line of high clouds and haze encroaching slowly from the west. We began with viewing Jupiter and Saturn, both near opposition, and a crescent Moon as well as Comet NEOWISE (C2020/F3) that looked fantastic on the video setup. Thankfully, everyone was able to view the comet, which is what all wanted to see, before it was obscured by the haze later in the evening. It is unusual that we had both Jupiter and Saturn at their best, but neither was the center of attention. We also gave the guests views of the Ring Nebula (M51) and a globular cluster or two before the sky fully hazed over by about 11:30 p.m.

On Saturday we opened up at 2:00 p.m. to almost completely overcast skies and a temperature of nearly 90º with 100º heat index. During the mid-afternoon we had brief views of the Sun with one small sunspot as well as Venus.

There were two speaker presentations in the afternoon. Our “Mad Scientist,” Colin Kilbane, had tables set up on the plaza and had attending guests build model rockets that were later launched. Our second presentation was by Brad Nasset; his was a demonstration of the solar system—how the planets are aligned and where to find them.

After a break for supper, the sky had gotten a little darker and we were in a light rain. This was shortly after 6:00 p.m. and we still had one speaker scheduled. I contacted Jake Hairrell and we decided to cancel the 7:00 p.m. presentation—although I am looking forward to his “Astronomy Trivia Contest” at Fall Astronomy Day.

Eternally optimistic, I was still holding out hope that the rain would hold off and we could have our final event, the door prize drawing. Between 7:00 p.m. and 8:00 p.m. we had a downpour that lasted five or six minutes, and then we were back to very light to no rain. By a little after 8:00 p.m. the rain had passed. Eight or nine hearty souls were still there. With so few guests I decided it was pointless to have a door prize drawing; instead, we laid out a dozen prizes on a table and had each remaining guest take an item.

This concluded the scheduled events for the 2020 CWTS, but before we were done we were treated to a spectacular double rainbow as the setting Sun emerged from the clouds. It was a reminder that things always seem to work out.

Thank you to everyone who helped out and who gave presentations during the weekend: Bob Benson, John Zimitsch, Dave Johnson, Don Gazdik, Colin Kilbane and Brad Nasset. Double thanks to John Z. for helping me on Saturday and special thanks to Lilah, our observatory program director, for donating several MAS merchandise items. These were passed on to a number of young guests during the weekend.

Comet NEOWISE (C2020/F3)

How to pay your dues June 2020 Volume 46 Number 3Your MAS membership expires at the beginning of the month shown on your membership card. You will be notified of your renewal

by e-mail two months prior to expiration and by USPS mail the month of your expiration. You may renew by mail or online using PayPal. By mail: Send your payment to the MAS membership coordinator at: Minnesota Astronomical Society, Attn. Membership coordinator, P.O. Box 14931, Minneapolis, MN 55414. Make checks payable to MAS. Current annual membership rates when paying by check are: $26 regular, $13 student, and $65 for patron memberships. You may renew for one year or for two years at a time. Online using PayPal: PayPal charges a fee, so MAS includes a voluntary contribution in the PayPal membership rates to offset that fee. Membership rates us-ing PayPal are $27.50 regular, $13.75 student and $67.25 patron. The membership form and the procedure for joining or renewing using PayPal may be found at www.mnastro.org/members/join/.

Sky and Telescope and Astronomy Magazine Subscriptions

MAS members are offered subscriptions to these magazines at an astronomy club discount.

The Sky & Telescope discount subscription is $32.95 for one year or $62.95 for two years. You may call Sky & Telescope at 1-800-253-0245 to subscribe at the astronomy club discount rate, paying using your credit card. You must identify yourself as a member of the Minnesota Astronomical Society and provide the discount code of 4CLB13. If you do not wish to pay using a credit card, preferring to pay with a check, you may go to skyandtelescope.com/clubrenew for subscription renewals or www.skyandtelescope.com/clubspecial for new subscriptions. You will be presented with a form you can print, fill out and mail in with your payment check.

The Astronomy magazine discount subscription is $34 for one year, $60 for two years, or $83 for three years. You may call Astron-omy magazine at 1-877-246-4835 to subscribe at the astronomy club discount rate, paying using your credit card. You must identify yourself as a member of the Minnesota Astronomical Society and provide the society’s Club ID number of 37-2921-23389. If you do not wish to pay using a credit card, preferring to pay with a check, you may call Astronomy magazine at 1-877-246-4835 and request a re-newal notice to be mailed to you. The renewal notice will be preprinted with the MAS Club ID number and the astronomy club discount subscription rates. You may then return it to Astronomy magazine Customer Service through the mail with the accompanying payment check.

How To Subscribe to MAS E-Mail Distribution Lists and Join MAS Discussion Forums:

The MAS uses Web discussion forums and e-mail distribution lists for timely communications. We highly recommend that you sub-scribe to both the Web forums and the MAS general distribution e-mail list. To join the MAS Web discussion forums, visit mnastro.org/Explore/Discussion Forum and click Register and complete the online registration form. To subscribe to the MAS e-mail list, visit lists.mnastro.org and click on the MAS list link and follow the subscription instructions. There is a general list (MAS), an outreach list and lists for other special purposes.

MN ASTRONOMICAL SOCIETYP.O. Box 14931 Minneapolis, MN 55414

a publication of the Minnesota Astronomical Society

Table 3. Assuming all other camera configurations remain constant, the following provides a working range of shutter speeds for photographing different Moon phases.

Moon phase

Camera Settingsa Full Quarter 3/4 Crescent Eclipseb

Shutter Speed 1/125 – 1 s 1/25 – 1/80 1/13 – 1/50 1/10 – 1/20 1s – 1/125

a. Assuming the following has already been pre-set: lens > 135 mm, ASA 50 – 125, f/stop f/11, filter 80Ab. Due to the constant change in lighting conditions brought about by a lunar eclipse, the shutter speed will vary.

Continued from page 9