The introduction of the mercury vapor lamp for general lighting in the 1930s probably marked the beginning of significant light pollution. Lighting levels have increased slowly, year-to-year, with sky brightness levels increasing only slowly on timescales of a year; no measurement protocols or instruments existed to quantify this increase. However, on timescales of 10--20 years, or on generational timescales, the increases in night sky levels, particularly in urban areas, have been dramatic. Younger people speak with their parents or grandparents who remark how beautiful the sky used to be, and how many stars they could see when they when they were younger. Older people can themselves remember how many stars were visible in the sky when they were younger. Whole generations of children now grow up without ever seeing the Milky Way.

Society has not had tools to easily measure sky brightness, and monitoring from space has only recently become available. A subtle increase of 10% sky brightness per year, for example, is not noticeable to the human eye on the time scale of a year, and has been tolerated by society. But such an increase compounds to an increase of a factor 2.6 in 10 years, 6.7 in 20 years, and a factor 45 in 40 years, corresponding to a dramatic increase in sky brightness, an almost complete loss in ability to see faint objects in the night sky, and rendering the sky unusable for most forms of astronomy. The most striking examples are the urban observatories found in many major cities that can no longer be used.

Session 2 was primarily focused on measurement of light at night, with an emphasis on measurement of light pollution. It comprised of 6 papers that are summarized below. Over the last decade, our ability to measure light pollution has grown tremendously, and the instrumentation needed to produce reliable quantitative measurements has become much more affordable, and now includes consumer grade digital cameras and even smart phones. During this same time period, light pollution has continued to grow. The widespread changes from mostly high-pressure sodium lighting to LED lighting that are now occurring make continued monitoring and measurement of light pollution particularly important into the future.

Complete presentations may be viewed at: http://www.noao.edu/education/IAUGA2015FM21

The two Pan-STARRS telescopes, located on Haleakala, Maui, Hawaii, are 1.8-meter diameter telescopes equipped with 1.4 Gigapixel cameras that deliver 7 square degree fields-of-view. The first of these telescopes, Pan-STARRS1, is conducting a search for Near Earth Objects, and is currently the leading discoverer of Near Earth Objects. The second telescope, Pan-STARRS2, is nearing the end of its commissioning, and is becoming more productive.

Pan-STARRS has become the leading survey for Near Earth Objects, responsible for approximately half of the NEO discoveries to date in 2015. Pan-STARRS is also the leading discoverer of new comets.

We use a WISE-2MASS-Pan-STARRS1 galaxy catalog to search for a supervoid in the direction of the Cosmic Microwave Background Cold Spot. We obtain photometric redshifts using our multicolor data set to create a tomographic map of the galaxy distribution. The radial density profile centred on the Cold Spot shows a large low density region, extending over 10's of degrees. Motivated by previous Cosmic Microwave Background results, we test for underdensities within two angular radii, 5°, and 15°. Our data, combined with an earlier measurement by Granett et al. 2010, are consistent with a large Rvoid=(192 ± 15)h−1 Mpc (2σ) supervoid with δ ≃ −0.13 ± 0.03 centered at z=0.22 ± 0.01. Such a supervoid, constituting a ∼3.5 σ fluctuation in the ΛCDM model, is a plausible cause for the Cold Spot.

The activities of the Commission have continued to focus on controlling unwanted light and radio emissions at observatory sites, monitoring of conditions at observatory sites, and education and outreach. Commission members have been active in securing new legislation in several locations to further the protection of observatory sites as well as in the international regulation of the use of the radio spectrum and the protection of radio astronomical observations.

Brief meetings were held to confirm the elections of the incoming Division President, Francoise Genova and Vice President, Ray Norris along with the Organizing Committee which will consist of the incoming Presidents of the 7 Commissions (5,6,14,41,46,50 and 55) plus additional nominated members. The incoming Organizing Committee will thus consist of:

The past President of Division XII, Malcolm Smith, took the chair of the business meeting of C50, in the absence of the past President of C50, Richard Wainscoat. He described the procedure of the election in 2006 of the then-time vice-president of C50, Richard Wainscoat, as President of C50, after the untimely deatch of the then-time C50 President, Hugo Schwarz. He also described the procedure for electing the incoming OC members and officers.

What follows is a short report on the Business Meeting of the Astronomy and World Heritage Working Group held on Thursday August 6, 2009. This was the first formal Business Meeting of the Working Group since its formation following the signing of the Memorandum of Understanding between the IAU and UNESCO on Astronomy and World Heritage in October 2008.

The view of the night sky from most of the populated regions of Earth is now seriously compromised by light pollution. An entire generation of citizens is now growing up without ever having the opportunity to gaze upon the magnificent night sky from a dark location. Much of modern astronomy involves study of faint objects, often with brightnesses similar to or fainter than the night sky. Astronomers are therefore extremely vulnerable to increases in sky brightness from light pollution. Despite their remote locations, the dark night skies over the major optical observatories are increasingly threatened by growth of artificial light at night.

The activities of the Commission have continued to focus on controlling unwanted light and radio emissions at observatory sites, monitoring of conditions at observatory sites, and education and outreach. Commission members have been active in securing new legislation in several locations to further the protection of observatory sites.

Division XII consists of Commissions that formerly were organized under the Executive Committee, that concern astronomers across a wide range of scientific sub-disciplines and provide interactions with scientists in a wider community, including governmental organizations, outside the IAU.

We have constructed a detailed model for the infrared (IR) point source sky that comprises geometrically and physically realistic representations of the galactic disk, bulge, stellar halo, spiral arms (including the “local arm”), molecular ring, and the extragalactic sky. We represent each of the distinct galactic components by up to 87 types of galactic source, each fully characterized by scale heights, space densities, and absolute magnitudes at BVJHK, 12, and 25 μm, and a spectrum from the IRAS Low Resolution Spectrometer (LRS). Our model has been guided by a parallel Monte Carlo simulation of the Galaxy at 12 μm. The content of our galactic source table constitutes an excellent match to the 12 μm luminosity function in the simulation, as well as to the luminosity functions at V and K. We are able to predict differential and cumulative IR source counts for any bandpass lying fully within the IRAS LRS range (7.7–22.7 μm) as well as for the IRAS 12 and 25 μm bands. These source counts match the IRAS observations extremely well. The model can be used to predict the character of the point source sky expected for observations from future IR space experiments (e.g., ISO, SIRTF, LDR).