Night Sky Quality Monitoring Report
Great Basin NP, Nevada
Mt. Washington, October 7, 2005
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, can be seen from almost every park. The NPS has developed a system for measuring sky brightness to quantify the source and severity of light pollution. This system, developed with the assistance from professional astronomers and the International Dark-sky Association, utilizes a research-grade digital camera to capture the entire sky with a series of images. Data clearly shows that even remote national parks are not immune from stray artificial light. Sky brightness is measured in astronomical magnitudes in the V-band, abbreviated as "mags". The V-band 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.
| Category | Details | Image |
|---|---|---|
| Park | GRBA |
 Narrative: Summit of Mt. Washington, 1/4 mile walk from end of road. Spectacular site but very exposed, cold, windy. Excellent sites for public or telescope near end of road but difficult 4WD access. Very transparent, seeing fair, breezy, exceptionally dry at 5% R.H. Airglow has distinct blue green color, gegenschein easily seen but not the entire zodiacal band. Detail in the Milky Way in Cassiopeia substantial, M33 easy naked eye object, seen with direct vision. Light domes of Las Vegas and Salt Lake City are apparent but not brighter than Mars. Would be Bortle class 1 or 2 if not on high mountaintop. Lack of oxygen may be a handicap for visual observing.
|
| Site Name | Mt. Washington | |
| Longitude | -114.30922 | |
| Latitude | 38.91464 | |
| Elevation (m) | 3558 | |
| Date (UT) | October 7, 2005 | |
| Time Start (UT) | 3:26:53 | |
| Data Quality | Excellent | |
| Equipment | SBIG 50mm f/2 6048 | |
| Observers | D.Duriscoe, B. Roberts | |
| Air Temp (°F) | 39.7 | |
| Rel Humid (%) | 5 | |
| Wind Sp (mph) | 10 | |
| CCD Temp (°C) | -20 | |
| Exp (seconds) | 12 | |
| Bortle Class | 3 | |
| ZLM | 7.2 |
| Data Set Number | Time (UT) | Extinction Coefficient (mag/air-mass) |
Std Err Y Extinction Stars (mags) |
Zenith (mag/sq arc-sec) |
Whole Sky (mags) |
Sky Above 20° Altitude (mags) |
Brightest (mag/sq arc-sec) |
Darkest (mag/sq arc-sec) |
Links to Sky Maps |
|---|---|---|---|---|---|---|---|---|---|
| 1-Start End |
3:26:53 3:45:37 |
0.114 |
0.046 |
21.42 21.31 |
-7.37 |
-6.76 |
20.08 |
21.68 |
PAN HEMI |
| 2-Start End |
4:24:31 4:43:08 |
0.108 |
0.043 |
21.43 21.54 |
-7.40 |
-6.77 |
20.01 |
21.71 |
PAN HEMI |
| 3-Start End |
5:22:01 5:40:44 |
0.116 |
0.034 |
21.57 21.61 |
-7.39 |
-6.75 |
20.21 |
21.72 |
PAN HEMI |
| 4-Start End |
6:19:37 6:38:16 |
0.113 |
0.040 |
21.70 21.69 |
-7.35 |
-6.71 |
20.24 |
21.75 |
PAN HEMI |
| 5-Start End |
7:17:10 7:35:51 |
0.101 |
0.042 |
21.69 21.65 |
-7.31 |
-6.69 |
20.32 |
21.74 |
PAN HEMI |
| City | Distance (km) |
Azimuth | 1st Data Set Brightness (mags) |
Image |
|---|---|---|---|---|
| Las Vegas, NV | 311 | 195.3 | -0.50 |
 |
| Salt Lake City, UT | 290 | 43.8 | -0.41 | |
| Total | -2.21 |