Night Sky Quality Monitoring Report

 

 

Denali NP&P

Moose Rut Pullout

14-Sep-2010

To effectively manage any resource, we need to know what we have and what we've lost. Light pollution, the brightness in the nighttime sky due to artificial light, effectively masks natural sources of light at night such  as the stars and the Milky Way. The NPS has developed a system for measuring sky brightness to quantifthe source and severity of light pollution. This system, developed with assistance from professional astronomers and the International DarkSky Association, uses a researchgrade digital camera to capture the entire sky with a series of images. Data clearly show that almost every park, even remote national parks, are not immune from stray artificial light. Sky brightness is measured in astronomical magnitudes in the visual band or Vband, abbreviated as "mags". The Vband measures mostly green light, omitting purple through ultraviolet and orange through infrared. The magnitude scale is a logarithmic scale. A difference of 5 magnitudes corresponds to a 100x difference in brightness. Lower values (smaller or more negative) are brighter. Further information on astronomical magnitudes can be found on this Sky and Telescope webpage. Data images are shown in false color, with yellow, red, and white corresponding to brighter sky and blue, purple and black corresponding to darker sky.

 

A more detailed explanation is available.

 

 

Data Set Attributes and Visual Indicators

 

Category

Details

Observed and Estimated Artificial Sky Brightness Mosaics

Park:

Denali NP&P

Click on either image for a high resolution view --THESE ARE LARGE FILES

Site Name:

Moose Rut Pullout


Longitude:

-149.19

Latitude:

63.71

Elevation (m):

917

Date (LMT):

14-Sep-2010

Time (LMT Hours):

21.55

Camera:

SBIG 1

Lens:

Nikon 1.8


Observers:

D Duriscoe

Air temp. C):

5.1

R. H. (%):

57.0

Wind Speed (mph):

2

Extinction Coeff. (mag/airmass):

0.16

 

NELM:

7.1

Bortle Class:

1

Synthetic SQM:

21.34

SQI All- sky:

97.8

SQI to Z.A. 70°:

97.3

Number of stars visible:

5090

NARRATIVE:  Moose Rut sign on Park road, 1 mile east of Savage River C.G.  Very bright aurora to east, extending to 40 degrees above the horizon, unfortunately, will prevent accurate sky quality measurements, accompanied by very bright airglow throughout the sky.  Nevertheless, a fantastic night, extremely clear and steady .  ZLM 7.1. Bortle 1 or 2.  No artificial sky glow detected anywhere in this, admittedly blocked horizon, sky.

 

 

 

 

Photometric Indicators

 

Indicator

Observed

Estimated Artificial

Light Pollution Ratio (Artificial/Natural)

Sky Luminance Measures

 

mag/ arscec2

μcd/ m2

mag/ arscec2

μcd/ m2

 

Zenith

21.51

270

24.21

22

0.13

Mean all-sky

20.88

482

24.96

11

0.04

Brightest

20.57

635

22.58

99

0.58

Darkest

21.77

209

> 24.5

< 17

< 0.10

Median

21.41

292

> 25.1

< 10

< 0.03

Illuminance Measures

 

mags

milli-lux

mags

milli-lux

 

Horizontal

-6.71

1.23

-2.81

0.03

0.04

Max Vertical

-6.64

1.15

> -1.0

< 0.01

< 0.025