Fortunately, the sky stayed fairly clear every time I checked while I was home, so I set up the lawn chair outside with the little table next to it, and I started getting ready for a meteor watching session. I had the charts outside, the little red light that I’d doctored up last night, and a mechanical pencil, before 3:30 AM. This is when I planned to start my session.
Just a minute or two after 3:30 AM, however, I was startled by a very strange sound that seemed to be coming from the easement or maybe the very back part of our backyard, or my neighbors' backyard to the north. It sounded like a cross between power equipment revving up and a nasty animal growl! I also thought that I heard peeping sounds as the louder sound kept going on and on. This was honestly like nothing that I've ever heard before! I wondered if a pit bull or stray dog was attacking something nearby. I went back in the house to grab the big halogen flashlight and I shone it around the back yard for five minutes, but saw nothing. The sound was gone. I was nervous about going back out not knowing what animal had made that noise, but I kept the flashlight with me on my lap in case I heard it again. I was also annoyed that now I had less time to do the meteor watching I wanted to do! I started back up at 3:45 AM and I was outside for the next hour and 25 minutes until dawn was getting too bright at 5:10 AM.
It was chilly enough for me to be wearing a sweatshirt and long pants. It was also dewy, and the lawn chair was a little bit wet. The dampness made it feel even chillier than it should have, and the back of my head was wet throughout the watch. The sky was clear but a little hazy due to light fog in the air. The wind stayed calm the whole time. Besides that unexplained noise that I heard when I tried to start observing I could hear some Crickets chirping and some whirring sounds from Long-Horned Grasshoppers, some local car traffic every now and then and some neighborhood dogs occasionally, and the hum of traffic a mile away on I-65 which picked up all night. Local traffic sounds also picked up as it got closer to dawn, and I heard birds singing a little after 5:00 AM. Trees were dripping dew and I could hear water drops falling now and then like very scattered and very light rain on the foliage. Between 4:50 AM through the end of the session there were a lot of low jet aircraft flying overhead from west to east. This was also a little distracting. I had no problems at all with mosquitoes, and fireflies were very few and far between tonight.
One other negative thing about this night was that my neighbor two houses down to the south had his floodlight on the whole time! I was fortunate that my lawn chair was low enough to the ground so that I didn't have this light in my eyes directly, but it was still a distraction because it was lighting up some of the trees to my south. I’m sure that it affected my night vision a little even though the wooden privacy fence on the south part of the patio blocked most of it.
By 4:45 AM through the end of the session the Pleiades were visible over the roof of our house, from my vantage point on the lawn chair, even though I was lying very low to the ground.
I started to see a hint of dawn in the Northeast part of the sky just after 5:02 AM. By 5:10 AM it was noticeable enough for me to cut my meteor watching short (the limiting magnitude had dropped below 5.0.) By the time I ended I could see the entire “pentagon” of Auriga over the roof of the house and the Hyades were also well above the roof and trees, all from the edge of the patio. By 5:20 AM it was getting bright enough that stars of 4th magnitude were very difficult to see, and by 5:30 AM only stars brighter than 2nd magnitude could be seen with some 3rd magnitude stars still visible close to zenith. I think the limit of any telescope observing this time of year would have to be about 5:15 AM - 5:20 AM and meteor watching was pretty much useless by 5:10 AM. To sum it all up!
Conditions at 4:00 AM - Temperature = 60°F, Dew Point = 54°F, Humidity = 80%, Wind = Calm, Pressure = 30.06”.
Conditions at 5:00 AM - Temperature = 59°F, Dew Point = 52°F, Humidity = 78%, Wind = Calm, Pressure = 30.07”.
SESSION - 3:45 AM - 5:10 AM (7:45 - 9:10 UT July 25)
Effective Observing Time = 77 minutes (1.2833 hours)
Center of Gaze = 00:00 +25 (Great Square of Pegasus and close to Alpha Andromedae.)
Cloud Cover Obscuration = High clouds covered the north between 3:45 AM - 4:00 AM and obscured about 20% of the sky. For the other 1 hour and 10 minutes of observing the sky remained clear.
Tree / Other Obscuration = 10% (Approximately. (1.275 for the tree cover for all of this session minus 0.0353 = 1.2397)
Visual Limiting Magnitude = 5.05 = 5 to 6 stars in Area 6 (Pegasus) (5.08 mag.), 6 stars in Area 7 (Cepheus) (5.12 mag.), 7 stars in Area 14 (Cygnus) (4.94 mag.).
3 Meteors Seen During This Session:
Meteor #1 - 4:05 AM (8:05 UT July 25). Anthelion (ANT). 4.0 magnitude. Speed = 3 (Average). No wake or train visible. This was a faint one that passed from between the “head” and “forelegs” of Pegasus into the Great Square. While I was outside I decided that this could well be an Anthelion, and the plot that I made for it (on Page 6 of the BRNO Atlas) also seems to bear this out, since it could have come from the Eastern Aquila part of that big spread-out radiant.
Meteor #2 - 4:17 AM (8:17 UT July 25). Sporadic (SPO). +1.0 magnitude. Speed = 4 (Swift). No wake or train seen. This was a nice bright meteor that blazed out of the corner of my eye from between Deneb and Cepheus through Cepheus, near Alpha Cephei and Beta Cephei. I plotted it on Page 1 of the BRNO Atlas. When I did this and extended the trail back, I realized that it could have been an Anthelion or one of the Capricornus-radiant showers, but the thing is, my view of it was so rough that I don’t trust the plot so much, especially extended back to another chart. For this reason I’m going to call it a Sporadic to be on the safe side.
Meteor #3 - 4:24 AM (8:24 UT July 25). July Pegasid (JPE). -2.0 magnitude or brighter. Speed = 4 (Swift). Had a train that glowed along the path for one or two seconds! This meteor sailed from between Triangulum and Perseus through Perseus. Unfortunately, I didn't see where it ended, since it went behind the roof of our house from where I was sitting! It was almost fireball level! When I plotted this meteor on Page 1 of the BRNO Atlas, I decided that the evidence was very good for it being a member of the July Pegasid shower, even though that shower peaked on July 10 and this was the last date that the AMS web page lists for that shower to be happening (July 25). The speed and direction and path length that I saw all seem to match up well. I’m at least 80% sure of it.
1 Notable Satellite Seen During This Session:
Satellite #1 - 5:02 AM (9:02 UT July 25). Bright and steady in brightness, about +1.5 magnitude (a little fainter than Deneb). This went right through the “forelegs” and “neck” of Pegasus heading north to south. I plotted the path of this one on Page 6 of the BRNO Atlas.
The diagrams below show the meteor positions plotted tonight along with a plot of the path of the satellite that I noted, done on the BRNO Atlas.
No comments:
Post a Comment