June 14th twilight to moonrise
June 14-17, 2025 All Sky Airglow
June 14
Brightness: 2.5/10 - Slight naked eye visibility and SQM degradation 0.15 or less
Structure: 2.5/10 Noise (Noise, Amorphous, Ripples, Blotches, Walls, Cross-hatch ripples, Streaks)
Flow Direction: NE to SW
Tonight we had an hour between twilight and moonrise. Geomagnetic activity was low. The sky was clear and I had the scope set up and was also looking forward to taking photos to see the conditions in the night sky. Twilight is almost as late as it gets with astronomical twilight not until after 10:30 pm.
As twilight darkened into night, I started to pick out the local light domes from Montrose, Delta, Grand Junction, and the Mine. I snapped a few photos and did not see much in the way of glow or structure. Maybe it was just a normal night. As it got darker still, I took some Sky Quality Measuring readings on my Unihedron SQM-L. It was an average of 21.44 mpsas pointed at the zenith near Corona Borealis. Seemed a little bright. The Milky Way seemed a little faded, hazy rather than crisp. It improved as it rose higher. Maybe some haze on the horizon. I remember nights getting g to 21.65 or darker on the SQM meter. Why not tonight? It was crystal clear all day. Was it some haze in the air column, or was it from space like airglow?
I noticed that the Grand Junction glow seemed brighter than normal, so I pointed the camera over to the west northwest. Sure enough there was some green glow and structure. This is when I decided to affix the fisheye all-sky lens and walk up the road to the meadow for some all sky shots.
As seen in the gif, there was some faint wisps of green glow floating over the zenith and accumulating towards the horizons, mainly towards the west . It looks like it is flowing from east to west, but very quickly. Almost looks like white noise.
To rate the brightness on scales from 1-10, with 1 weak and 10 strong, maybe like a 2 or 3.
There was some visual confirmation with the unaided eye. It seemed brighter towards the west-northwest.
There was some degradation of sky quality, like 0.10-0.15 mpsas brighter. Say a normal night would be 21.60 pointing at the zentih toward Corona Borealis. This needs to be confirmed.
To rate the structure and flow, also probably 2-3 for both. There was some rippling but almost looked like noise rather than a perturbation or flow.
So overall ratings:
Brightness: 2.5/10
Structure: 2.5/10 Noise (Noise, Amorphous, Ripples, Walls, Cross-hatch ripples, Streaks)
Flow: 2.5/10
June 15th
Brightness 3.5/10
Structure: 3/10 Blotches
Flow Directiom : NE to SW
More glowy ripples. I could see it faintly in the viewfinder so set up the timelapse. SQM was 21.51 around 11pm, then dipped to 21.40 an hour later. Was the decreased darkness due to Milky Way, moonlight, airglow blotches, or something else? I could see it brightened a bit in the sky, it looked like an icy gray haze way up high, like very faint high clouds. The Milky Way is much brighter and the dark rift and bright starfields are much brighter than the glow. I’d be hard pressed to say I could see the movement with my unaided eye, but I could definitely detect the hazy quality as it rolled in from the north.
June 17th, 2025 All Sky Airglow
June 17th
Ratings:
Brightness = 3/10. Not visible unaided. Faint green seen in the viewfinder. Strong green in post-processing. Mpsas = 21.55 so 0.10 reduction in darkness. Settings = 20 sec iso6400 f3.5.
MPSAS = 21.55 at 10:50 pm near CrB. Readings stayed the same but became more sporadic as it got later. I wonder if the airglow ripples can be seen in SQM data?
Structure = Ripples. More fine ripples to the east, more amorphous to the west.
Direction of flow: Southeast to Northwest.
After a cloudy night on June 16th, tonight the sky was crystal clear. Moonset was about 1 am, so I had a good window of time to be out in the starry night. I set up the 10” astrograph and the 12” dobsonian and started observing. I like to let it get nice and dark and try to see the local glows of light. What does skyglow from the surrounding cities look like. How about skyglow from the mine? I started seeing what looked like faint clouds floating by. They looked a bit whiteish but also dark. Like how clouds during the day are fluffy and white but also dark underneath. But then again, were they even clouds at all?
Upon examination, it appears as though the flow has shifted directions. The past two entries show a flow from northeast to southwest. This night it was from southeast to northwest. All nights have the East to West component, but this night the flow is now from south to north.