Bonner Durchmusterung und Gaia

As our civilization and technology continue to evolve, it seems we take far too much for granted.  We neglect to consider how incredibly hard people used to work years ago to achieve results we today would pass off as almost trivial.  But history has many lessons to teach us, if only we would listen.

As an example, Prussian astronomer Friedrich Wilhelm August Argelander (1799-1875) at the age of 60 began publishing the most comprehensive star catalogue and atlas ever compiled, as of that date.  From 1852 to 1859, Argelander and his assistants carefully and accurately recorded the position and brightness of over 324,000 stars using a 3-inch (!) telescope in Bonn, Germany.  Employing the Earth’s rotation, star positions were measured as each star drifted across the eyepiece reticle in the stationary meridian telescope by carefully recording when each star crossed the line, and where along the line the crossing point was.

Stars Transiting in a Meridian Telescope

One person observed through the telescope and called off the star’s brightness as each star crossed the line, noting the exact position along the reticle on a pad with a cardboard template so that the numbers could be written down without looking away from the telescope.  A second person, the recorder, noted the exact time of reticle crossing and the brightness called out by the observer.  In this way, two people were able to record the position and brightness of every star.

Each star was observed at least twice so that any errors could be detected and corrected.  In some areas of the Milky Way, as many as 30 stars would cross the reticle each minute.  What stamina and dedication it must have taken Argelander and his staff to make over 700,000 observations in just seven years!  Argelander’s catalogue is called the Bonner Durchmusterung and is still used by astronomers even today.  It was the last major star catalogue to be produced without the aid of photography.

Like Argelander’s small meridian telescope, the European Space Agency’s Gaia astrometric space observatory is currently measuring tens of thousands of stars each minute (down to mv = 20) as they transit across a large CCD array—the modern day equivalent of an eyepiece reticle.  But instead of utilizing the Earth’s rotation period relative to the background stars of 23h56m04s, Gaia’s twin telescopes separated by exactly 106.5° sweep across the stars as Gaia rotates once every six hours.  A slight precession in Gaia’s orientation ensures that the field of view is shifted so that there is only a little overlap during the next six-hour rotation.

When Gaia completes its ongoing mission, it will have measured the positions, distances, and 3D space motions of around a billion stars, not just twice but 70 times!

Though electronic computers do most of the work these days, someone still has to program them.  Some 450 scientists and software experts are immersed in the challenging task of converting raw data into scientifically useful information.

I’d like to conclude this entry with a quotation from Albert Einstein (1879-1955), who was born and died exactly 80 years after Argelander.

Many times a day I realize how much of my outer and inner life is built upon the labors of my fellowmen, both living and dead, and how earnestly I must exert myself in order to give as much as I have received.

I love that quote.  Words to live by.

Outdoor Lighting Codes and Ordinances in Wisconsin

Last Updated: 5/22/2017

Here are all the outdoor lighting codes and ordinances in Wisconsin that I am aware of.  A big thank you to Scott Lind, PE, of Hollandale, Wisconsin for initially putting together this list in 2007!

Please post a comment or contact me via email if you have additions or updates to this list.

Blue Moundsmap
http://www.ecode360.com/27010348

Brookfieldmap
http://www.codepublishing.com/WI/Brookfield/html/Brookfield17/Brookfield17120.html#17.120.070

Chenequamap
http://chenequa.org/wp-content/themes/Chenequa/Documents/Ordinances/Chap5.pdf

Cloverlandmap
http://www.townofcloverland.org/Documents/Ordinances/Code%203.01%20Lighting.pdf

Delafieldmap
https://www.municode.com/library/wi/delafield/codes/code_of_ordinances?nodeId=CH17ZOCORERE411_GEPR_17.235OULIAM491

Delavanmap
http://ci.delavan.wi.us/download/departments/building-zoning/zoning-codes/zc_23-7perstand_code.pdf
See Section 23.707 Exterior Lighting Standards

Egg Harbormap
http://www.villageofeggharbor.org/vertical/sites/%7B569578EA-93E6-481F-B733-DF3296C08FEE%7D/uploads/%7B7B55219C-9B97-4628-AEF1-445C51A0BB09%7D.PDF

Fontana-on-Geneva Lakemap
https://www.municode.com/library/wi/fontana-on-geneva_lake/codes/code_of_ordinances?nodeId=PTIIMUCO_CH18ZO_ARTXDEST_S18-165EXLIST

Fox Crossingmap
http://www.town-menasha.com/departments/clerks-office/ordinances/
Click on section Chapter 29 Development Ordinance and search for “lighting”

Fox Pointmap
http://www.ecode360.com/14717677

Genevamap
http://www.townofgenevawi.com/uploads/documents/ORDIN-59%20Regulate%20Outdoor%20Lighting%20&%20Advertising%20Signs.pdf

Green Lake Countymap
http://ecode360.com/9770791

Hollandmap
https://drive.google.com/file/d/0B1qD1hgbbNz-bWRSWmlkN2o0eEU/view

Kenoshamap
https://www.kenosha.org/images/GENORD.pdf
See Section 4.07 Artificial Light and Glare

Koshkonongmap
http://koshkonongwi.com/download/outdoor-lighting-ordinance/

Madisonmap
http://www.cityofmadison.com/attorney/ordinances/documents/chapter%2010%20-%20streets,%20alleys,%20sidewalks,%20and%20gutters.pdf
See Section 10.085 Outdoor Lighting

Mequonmap
https://www.municode.com/library/wi/mequon/codes/code_of_ordinances?nodeId=PTIICOOR_CH58PLDERE_ARTVSISTDECR_DIV2COINPAINMUMIREDE_S58-567OULIIN

Middletonmap
http://www.ci.middleton.wi.us/DocumentCenter/View/43

Mineral Pointmap
http://skythisweek.info/mineralpointlighting.pdf
Is this lighting ordinance still in effect?  I cannot find it on the Mineral Point website.

Mukwonagomap
https://www.municode.com/library/wi/mukwonago/codes/code_of_ordinances?nodeId=PTIICOOR_CH100ZO_ARTIXSIPLRE_S100-601SIPLARRESTALNOMIPR
See Section e Lighting Standards

New Glarusmap
http://www.newglarusvillage.com/__media/pdfs/ordinances/LightingLandscape.pdf
See Article XVIII Exterior Lighting Plans and Standards

Oconomowoc Lakemap
http://www.oconlake.com/Documents/ord178.html

Richfieldmap
http://ecode360.com/16178580

Shorewood Hillsmap
http://www.shorewood-hills.org/vertical/sites/%7B00D5AF3F-ADFE-4173-AF3A-FC0C1A78DA4B%7D/uploads/Ch_22_Dark_Sky.pdf

Springdalemap
http://www.townofspringdale.org/site_files/editor_files/image/file/Ordinance/031714_pdf_Final_Dark_Sky_Lighting_Ordinance.pdf

Springfieldmap
http://www.town.springfield.wi.us/ordinances/chapter-9/
See sections 9.02(7) Exterior Lighting, and 9.04(7) Exterior Lighting Plan

Sturgeon Baymap
https://www.municode.com/library/wi/sturgeon_bay/codes/code_of_ordinances?nodeId=CO_CH20ZOCO_20.12USREDI
See Section 20.12.(1)(b)12

Sussexmap
http://www.villagesussex.org/vertical/sites/%7B1FD3B636-3BF9-4496-900E-EAA7FFADF5E8%7D/uploads/17.0600_Traffic_Loading_Parking_Access_Storage_and_Lighting-01-2016.pdf
See Section 17.0608 Lighting

Westportmap
http://www.townofwestport.org/Ordinances/Title%209/Title%209%20Chapter%207.pdf

Whitefish Baymap
http://www.ecode360.com/documents/WH3817/WH3817-016.pdf
See Section 16.31 III A2

Williams Baymap
http://www.williamsbay.org/images/doc/Chapter%2015.pdf
See Section 15.03 Outdoor Lighting and Advertising Signs

Winneconnemap
http://ecode360.com/14487227?highlight=260#14487227

The Wisconsin State Law Library maintains a comprehensive list of Wisconsin Ordinances and Codes.  This will be a good resource for us to find additional outdoor lighting codes and ordinances to be added to this list, as well as to check your local government’s codes and ordinances in general.

It is interesting to note that nearly two-thirds of these ordinances are for suburban communities in very light-polluted metro areas.  Another four ordinances are no doubt in place to help protect the Yerkes Observatory (Williams Bay, Geneva, Fontana-on-Geneva Lake, and Delavan).  Where are the rural ordinances and dark sky preserves?  Since there are very few remaining locations in Wisconsin where the night sky is truly dark, shouldn’t we be aggressively protecting those areas?  Wouldn’t it be easier to save a pristine area than to restore an almost hopelessly polluted one? Another interesting point is that upscale suburban communities are much more likely to have a lighting ordinance than more affordable communities.  Some subdivisions even exclude streetlights, but these are almost never places where most of us can afford to live.

The Hidden Universe

We continue our series of excerpts (and discussion) from the outstanding survey paper by George F. R. Ellis, Issues in the Philosophy of Cosmology.

Thesis B6: Observational horizons limit our ability to observationally determine the very large scale geometry of the universe.
We can only see back to the time of decoupling of matter and radiation, and so have no direct information about earlier times; and unless we live in a “small universe”, most of the matter in the universe is hidden behind the visual horizon.  Conjectures as to its geometry on larger scales cannot be observationally tested.  The situation is completely different in the small universe case: then we can see everything there is in the universe, including our own galaxy at earlier times.

What an intriguing idea.  If the entire universe (or the self-contained section we find ourselves in) is substantially smaller than the distance light has traveled since the universe became transparent to radiation (“decoupling”, about 380,000 years after the Big Bang), we might be able to see our Milky Way galaxy (and other galaxies) at various points in the past.

The key point here is that unless we live in a small universe, the universe itself is much bigger than the observable universe.  There are many galaxies—perhaps an infinite number—at a greater distance than the horizon, that we cannot observe by any electromagnetic radiation.  Furthermore, no causal influence can reach us from matter more distant than our particle horizon—the distance light can have travelled since the creation of the universe, so this is the furthest matter with which we can have had any causal connection.  We can hope to obtain information on matter lying between the visual horizon and the particle horizon by neutrino or gravitational radiation observatories; but we can obtain no reliable information whatever about what lies beyond the particle horizon.  We can in principle feel the gravitational effect of matter beyond the horizon because of the force it exerts (for example, matter beyond the horizon may influence velocities of matter within the horizon, even though we cannot see it).  This is possible because of the constraint equations of general relativity theory, which are in effect instantaneous equations valid on spacelike surfaces.  However we cannot uniquely decode that signal to determine what matter distribution outside the horizon caused it: a particular velocity field might be caused by a relatively small mass near the horizon, or a much larger mass much further away.  Claims about what conditions are like on very large scales—that is, much bigger than the Hubble scale—are unverifiable, for we have no observational evidence as to what conditions are like far beyond the visual horizon.  The situation is like that of an ant surveying the world from the top of a sand dune in the Sahara desert.  Her world model will be a world composed only of sand dunes—despite the existence of cities, oceans, forests, tundra, mountains, and so on beyond her horizon.

Let us now define some terms that Ellis uses above.

visual horizon – the distance beyond which the universe was still opaque to photons due to high temperature and density

particle horizon – the distance beyond which light has not yet had time to reach us in all the time since the Big Bang; our particle horizon is, therefore, farther away than our visual horizon

spacelike surface – a three-dimensional surface in four-dimensional space-time where no event on the surface lies in the past or future of any other event on that surface; every point on the surface as it exists at one instant of time

Hubble scale – a cosmological distance unit equal to the reciprocal of the Hubble constant times the speed of light; see derivation below

A reasonable value for the Hubble constant H0 is 70 km/s/Mpc.  A galaxy one megaparsec distant has a cosmological recession velocity of 70 km/s, two megaparsecs distant 140 km/s, and so on.

You may notice that there are two units of distance in H0: kilometers and megaparsecs.  We can thus rewrite H0 in units of s-1 (reciprocal seconds of time) as follows:

The Hubble time is defined as the inverse of the Hubble constant:

Converting this into more convenient units of years, we get

The Hubble scale is now simply the Hubble time multiplied by the speed of light.

Converting this into more convenient distance units of light years, and then parsecs, we get

As Ellis says, we are like ants in the Sahara desert that cannot see their Earth-universe beyond the sand dunes.  Like the ant, is there a limit to our intellect as well?

References
Ellis, G. F. R. 2006, Issues in the Philosophy of Cosmology, Philosophy of Physics (Handbook of the Philosophy of Science), Ed. J. Butterfield and J. Earman (Elsevier, 2006), 1183-1285.
[http://arxiv.org/abs/astro-ph/0602280]

Evening Planets

The most convenient time for most of us to observe the planets is in the early evening.  With that in mind, I’ve prepared an ephemeris of favorable evening times to view each of the eight major planets of the solar system over the next ten years.  Some interesting patterns emerge, which I will comment on.

With the exception of Mercury, what follows is a range of dates when each planet is at least 10° above the horizon at the end of evening twilight at latitude 43° N.  Mercury, however, is never even above the horizon at the end of evening twilight.

Mercury’s Maximum
Altitude at 43° N
Solar Depression
Angle
End of
Twilight
13°
Civil
12°
Nautical
below horizon
18°
Astronomical

Here is a list of dates when Mercury is highest above the western horizon at the end of evening civil twilight.

Mercury

Dates – Highest Above
Evening Horizon
Altitude
Constellation
July 18, 2017
Leo
November 28, 2017
Sgr
March 15, 2018
12°
Psc
July 2, 2018
Cnc
November 10, 2018
Oph
February 27, 2019
11°
Psc
June 16, 2019
10°
Gem
October 20, 2019
Lib
February 11, 2020
11°
Aqr
May 30, 2020
12°
Gem
September 25, 2020
Vir
January 25, 2021
10°
Cap
May 14, 2021
13°
Tau
September 2, 2021
Vir
January 9, 2022
Cap
April 28, 2022
13°
Tau
August 14, 2022
Leo
December 24, 2022
Sgr
April 11, 2023
13°
Ari
July 28, 2023
Leo
December 8, 2023
Sgr
March 24, 2024
12°
Psc
July 11, 2024
Cnc
November 20, 2024
Oph
March 8, 2025
12°
Psc
June 25, 2025
Cnc
November 1, 2025
Sco
February 20, 2026
11°
Psc
June 9, 2026
11°
Gem
October 10, 2026
Lib
February 4, 2027
11°
Aqr
May 24, 2027
13°
Tau
September 15, 2027
Vir

Mercury, the innermost planet, whips around the Sun every 88 days (116 days relative to the Earth—its synodic period).  It never strays more than 28° from the Sun.

As you can see in the graph below, Mercury is presently highest above our evening twilight horizon when it reaches greatest eastern elongation in April, and lowest in October.

Similarly, greatest eastern elongations that occur in the constellations Taurus and Aries present Mercury highest above our evening twilight horizon, and Libra, the lowest.

Now, let us turn to Venus.  Unlike Mercury, Venus usually spends a considerable number of days well above the horizon near greatest elongation.  This occurs because Venus orbits further from the Sun—reaching a maximum angular separation of 47°— and because its orbital period is only 140.6 days shorter than the Earth’s: the Earth “keeps up” with Venus reasonably well as the two planets orbit the Sun (the synodic period of Venus is 583.9 days), so it is a long time between successive elongations.  In the next ten years, we will see Venus high above the evening horizon during only three intervals, though for a generous three or four months each time.

Venus

Dates – At Least 10° Above the Horizon
at the End of Evening Twilight
Constellation
January 2, 2020 – May 7, 2020
Cap – Tau
February 26, 2023 – June 3, 2023
Cet – Cnc
November 30, 2024 – March 2, 2025
Sgr – Psc

Now, we turn to the superior planets: Mars, Jupiter, Saturn, Uranus, and Neptune.  These planets are visible in our evening sky during and after opposition.

Mars has the longest synodic period of all the major planets—780 days—so it takes an unusually long period of time for the orbital positions of Mars and the Earth to change relative to one another.  Approximately every two years we get the opportunity to see Mars at least 10° above the horizon at the end of evening twilight.  The number of evenings Mars is visible varies quite a lot (due to its significant orbital eccentricity): 293 evenings during the 2018 perihelic opposition of Mars, down to 145 evenings during the aphelic opposition of Mars in 2027.  In any event, Mars spends a considerable amount of time during these intervals very far away from Earth and therefore disappointingly small in our telescopes.  The best time to observe Mars is during the early weeks of the intervals listed below when Mars is at or near opposition.

Mars

Dates – At Least 10° Above the Horizon
at the End of Evening Twilight
Constellation
July 21, 2018 – May 10, 2019
Cap – Tau
October 5, 2020 – May 27, 2021
Psc – Gem
November 28, 2022 – June 11, 2023
Tau – Cnc
January 7, 2025 – June 22, 2025
Cnc – Leo
February 12, 2027 – July 7, 2027
Leo – Vir

Jupiter orbits the Sun every 11.9 years, so it is easy to see why it is in a different constellation along the zodiac each year.

Jupiter

Dates – At Least 10° Above the Horizon
at the End of Evening Twilight
Constellation
March 30, 2017 – July 24, 2017
Vir
April 29, 2018 – August 29, 2018
Lib
May 28, 2019 – October 19, 2019
Oph
June 26, 2020 – December 10, 2020
Sgr
July 30, 2021 – January 22, 2022
Aqr
September 10, 2022 – March 1, 2023
Psc
October 21, 2023 – April 5, 2024
Ari
November 28, 2024 – May 5, 2025
Tau
January 1, 2026 – May 28, 2026
Gem
February 2, 2027 – June 16, 2027
Leo

The orbital periods of Saturn, Uranus, and Neptune are 29.5, 84.0, and 164.8 years, respectively, so we can see why they take a successively longer amount of time to traverse their circle of constellations.  You’ll also notice that the interval of visibility shifts later each year, but the shift is less with increasing orbital distance.  The synodic periods of Saturn, Uranus, and Neptune are 378.1, 369.7, and 367.5 days, respectively.

Saturn

Dates – At Least 10° Above the Horizon
at the End of Evening Twilight
Constellation
May 31, 2017 – October 25, 2017 Oph
June 10, 2018 – November 11, 2018 Sgr
June 20, 2019 – November 28, 2019 Sgr
June 30, 2020 – December 12, 2020 Cap – Sgr
July 12, 2021 – December 27, 2021 Cap
July 24, 2022 – January 9, 2023 Cap
August 7, 2023 – January 23, 2024 Aqr
August 21, 2024 – February 4, 2025 Aqr
September 5, 2025 – February 17, 2026 Psc
September 20, 2026 – March 2, 2027 Cet – Psc

Uranus

Dates – At Least 10° Above the Horizon
at the End of Evening Twilight
Constellation
October 2, 2017 – March 16, 2018
Psc
October 7, 2018 – March 20, 2019
Ari
October 12, 2019 – March 23, 2020
Ari
October 15, 2020 – March 27, 2021
Ari
October 20, 2021 – March 31, 2022
Ari
October 25, 2022 – April 4, 2023
Ari
October 30, 2023 – April 7, 2024
Ari
November 3, 2024 – April 12, 2025
Tau
November 8, 2025 – April 16, 2026
Tau
November 13, 2026 – April 20, 2027
Tau

Neptune

Dates – At Least 10° Above the Horizon
at the End of Evening Twilight
Constellation
August 13, 2017 – January 30, 2018
Aqr
August 16, 2018 – February 2, 2019
Aqr
August 19, 2019 – February 4, 2020
Aqr
August 21, 2020 – February 6, 2021
Aqr
August 24, 2021 – February 8, 2022
Aqr
August 27, 2022 – February 11, 2023
Aqr
August 30, 2023 – February 13, 2024
Psc
September 1, 2024 – February 15, 2025
Psc
September 4, 2025 – February 17, 2026
Psc
September 7, 2026 – February 17, 2027
Psc

Two Paths to Low Mass

A brown dwarf (also known as an infrared dwarf) is, in a way, a failed star.  Early in their lives, these ultra-low-mass stars (13+ MJ) fuse deuterium into helium-3, and in the highest mass brown dwarfs (65-80 MJ) lithium is depleted into helium-4, as shown below.

But the mass is too low for fusion to be sustained (the temperature and pressure in the core aren’t high enough), and soon the fusion reactions peter out.  Then, only the slow process of thermal contraction provides a source of heat for the wanna-be star.

There is another, very different, path to a brown dwarf star.  A cataclysmic variable usually consists of a white dwarf and a normal star in a close binary system.  As material is pulled off the “donor star” (as the normal star is called) onto the white dwarf, the donor star can eventually lose so much mass that it can no longer sustain fusion in its core, and it becomes a brown dwarf star.

When we see a white dwarf / brown dwarf binary system, how do we know that the brown dwarf wasn’t always a brown dwarf?  Strong X-ray and ultraviolet emission provides evidence of an accretion disk around the white dwarf, and astronomers can calculate the rate of mass transfer between the two stars.  Often, this is billions of tons per second!  Using other techniques to estimate the age of the binary system, we sometimes find that the donor star must have started out as a normal star with much more mass than we see today.

Homogeneity and Isotropy

We continue our series of excerpts (and discussion) from the outstanding survey paper by George F. R. Ellis, Issues in the Philosophy of Cosmology.

4.2.2 Indirect determination: justifying a Friedmann-Lemaître geometry
Considered on a large enough angular scale, astronomical observations are very nearly isotropic about us, both as regards source observations and background radiation; indeed the latter is spectacularly isotropic, better than one part in 104 after a dipole anisotropy, understood as resulting from our motion relative to the rest frame of the universe, has been removed.

No matter what direction we look, the universe looks statistically the same at a scale of hundreds of millions of light years.  We call this property isotropy.  Case in point: when compared one to the other, the Hubble Deep Fields look remarkably similar, even though they are about 135° apart in the sky.

Hubble eXtreme Deep Field in the constellation Fornax
Hubble Deep Field in the constellation Ursa Major

Taken individually, both of these deep fields also exhibit homogeneity, that is, they generally show a fairly uniform distribution of galaxies across the field.

Does the dipole anisotropy in the cosmic background radiation (CBR), due to our motion with respect the rest frame of the universe, indicate an absolute frame of reference?  Not at all.  Though the rest frame of the universe is the preferred frame for cosmology, it is not a particularly good frame of reference to use, for example, in describing the motion of the planets in our solar system.  The laws of physics are the same in all inertial (unaccelerated) reference frames, so none of them can be “special”—or absolute.  An absolute frame of reference would be one in which the laws of physics would be different—indeed simpler—but no such reference frame exists.  And any non-inertial (accelerated) reference frame indicates there is an external force outside the system acting on the system, so it can never be used as an absolute frame of reference.

We’re moving toward Leo and away from Aquarius, relative to the cosmic background radiation
Top: CBR with nothing subtracted; Middle: CBR with dipole anisotropy subtracted; Bottom: CBR with both dipole anisotropy and galactic emission subtracted
Cosmic Background Radiation from the Planck spacecraft with anisotropies removed

If all observers see an isotropic universe, then spatial homogeneity follows; indeed homogeneity follows if only three spatially separated observers see isotropy.  Now we cannot observe the universe from any other point, so we cannot observationally establish that far distant observers see an isotropic universe.  Hence the standard argument is to assume a Copernican Principle: that we are not privileged observers.  This is plausible in that all observable regions of the universe look alike: we see no major changes in conditions anywhere we look.  Combined with the isotropy we see about ourselves, this implies that all observers see an isotropic universe.

The Copernican principle states that we are not privileged observers of the universe.  Any observer elsewhere in the universe will see the same universe that we do.  The laws of physics, chemistry, and biology are truly universal.  The Copernican principle is a good example of the application of Occam’s razor: unless there is evidence to the contrary, the simplest explanation that fits all the known facts is probably the correct one.

References
Ellis, G. F. R. 2006, Issues in the Philosophy of Cosmology, Philosophy of Physics (Handbook of the Philosophy of Science), Ed. J. Butterfield and J. Earman (Elsevier, 2006), 1183-1285.
[http://arxiv.org/abs/astro-ph/0602280]

Designated Night Sky Viewing Areas

Governor Dodge State Park was established in 1955 and is the fourth largest state park in Wisconsin.  It offers several excellent locations for astronomical observation, most notably the large open grassy area just east of the Twin Valley Lake picnic area, and the paved parking lot for the backpack campsites.  The latter location is the furthest away from the urban skyglow of Dodgeville that offers a good view of nearly the entire night sky.

State park regulations require everyone to leave the park by 11:00 p.m., with some exceptions made for overnight campers, fishing, and public programs in progress (such as public star parties).  Since most stargazing can only be done after 11:00 p.m. (especially during the warm months of the year), this rule greatly diminishes access to our state parks for astronomical activities.  I would like to see one designated area of Governor Dodge State Park—the Twin Valley Lake picnic area site—open all night long for astronomical activities.  So, we would add an additional exception to the 11:00 p.m. curfew:

7. Registered stargazers may at the designated observing site during closed hours.

A “registered” stargazer would be anyone who has a current annual state park pass and has registered with the park as an amateur astronomer / stargazer.  Whenever possible, those planning to visit the designated observing site after hours should notify park staff that day before the park office closes, but this should not be required as sometimes the sky unexpectedly clears or a northern lights display commences after hours that cannot be anticipated beforehand.

Here’s another idea.  The Wisconsin DNR could issue an extra-fee annual astronomy sticker which would allow registrants 24-7 access to designated astronomy areas in participating state parks.  This is an attractive idea because it would be another revenue source for our cash-strapped state park system.  Administration and site maintenance costs would be minimal.