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Re: (18220) 6286 P-L On 3 Oct
Great!? ?Thanks.? I have one more Astrid location I can plan once I see where you think you'll be.
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FYI, there is another even better one on Oct 12 that has almost the same path, but the star is mag 7.3.? That one is (134421) 1998 QT2.? That one also goes over LA and Greg Lyzenga is planning two stations, I've got two on OW now, with one to be added yet.
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Steve
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(40390) 1999 NR51 on 4 October
To complement the E-W event I just posted on, here's a N-S that is mag 11.6, high
in the S, max duration about 0.5 second. Path is Washington DC to just east of Rochester.? I plan on doing 2 stations. Anyone else able to help? Other than maybe Kevin H, I don't think this gets close to anyone...
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Steve
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Talk about OccultNEUS Efforts at IOTA Meeting
A few of us already kicked this around a bit.? Anyone have any thoughts about doing a brief talk for the IOTA conference on 9/28-29 about our coordination efforts?? Would it be worth a 10 minute talk (I can do this if no one else wants to) just saying what we've been up to?? Or are we better off flying beneath the radar?
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Steve C
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Last Night's 2 Station Attempt
All,
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I tried to do two Astrid stations again on a small asteroid over a bright-ish star (10.1 mag), short (0.3 s), rank 100 event last night.? The two stations were about a km or two apart, both in a park north of me.? My home observatory was way off the path, so I didn't bother collecting data from home.? I left myself an hour and 10 minutes to set both up once I arrived at the park.
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The first station (on the center line) set-up wasn't my finest hour (and it took 55 minutes!).? Focus was way off, so it took a few minutes to find a star bright enough to see the big doughnut and focus it out. This particular C-5 has an especially easy to turn focus knob--so I anticipated this issue.
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The first mistake I made was worrying too much about hiding the equipment in the shadows.? My wrong estimate of where azimuth 108 degree was had me to put the scope in a nicely hidden shadowed area.? I referenced to Polaris (clearly visible) and was "only" about 25 degrees off.? When I ran my prepoint, the 25 degree rotation moved me from a clear line of sight to looking at a tree on the nearby hillside.? Decided to move the system 100 or so feet to make sure this wouldn't recur.
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Second mistake was being lazy and trying to carry the Astrid system powered, resulting of course in unintended power loss when I accidentally pulled the battery connector off.? Luckily, the Astrid did not suffer any issues from the power loss (I had this same unit lose its programming one time when I did something similar).? I had to reconnect and restart it from scratch at its new location.
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Third mistake happened earlier in the day, but I didn't discover it until this point.? For these short events, with very small expected error, the default Astrid recording time is very short (sometimes only 15 seconds or so).? I always want to get the target star recorded when it is in the FOV, which is about 2 minutes for my small C-5's at ~f/4.? So when I load the Astrids off OWC, I manually edit the times to record to record at least 1 minute before and after the event time.? I use the up and down arrows to do this.? Several times now this has resulted in the hour as well as the minute also being adjusted up/down.? Most likely it is user error, but it is strange it has repeated.? This took me at least 5 minutes to straighten out.? BTW--does anyone know if there is a way to tell the Astrid to never record shorter than a certain minimum time?
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When I finally got the first station done, I only had 15 minutes to drive to the next and set-up.? I was able to get there and throw the next Astrid station down.? Two problems there (related)--first was I had "OK" focus out of the box so I didn't take the time to improve it.? This resulted in the second problem, that the last couple of prepoints I did failed to solve--I'm guessing to to a weak field and bad focus.? So I ran out of time and just turned the mount motion knobs to match the last successful solve--crossing my fingers.? Also didn't have time to increase the frame rate from the default 10 Hz to the 30 Hz I wanted.? Hit the autorecord button a few seconds before the recording started.
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Results:? First station on the centerline recorded a perfectly centered, well focused miss.? Second station about halfway from center to north shadow edge has a 2 frame (0.2 s) blink near the field edge at the expected time, well out of focus.? The star basically disappears for two frames, but the noise on the other frames (from defocus and my quick PyMovie analysis) causes PyOTE to reject the solution saying it is roughly 50/50 just a noise related event.? I have to admit I haven't taken the time to learn how to adjust PyMovie to deal with situations like this--anyone have any insight?? I could (I believe) easily do this in Tangra which I've used for years.
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Sorry to run long with yet another story of pulling defeat from the jaws of victory...
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Steve?
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Re: Bullwinkle Pulls a Rabbit
Great job, George!??
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Steve C
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Re: Bullwinkle Pulls a Rabbit
Congrats! Your adventures always inspire me. ...Kevin On Tue, Aug 27, 2024 at 5:33?PM George Viscome via <georvisc=[email protected]> wrote:
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Bullwinkle Pulls a Rabbit
Oc-Folks,
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So Steve told his tale of success and woe with (270) Anahita (interesting observing story). I tried for that event but clouds said otherwise. But the next night I had another 10th mag "possibility".... This involved the 6-digit, 6km rock (248227) - with a moderately wide 1-sigma, but at a nice combined mag of 10.7. [This I found on my own Occult4 search - it wasn't listed on my OW Desktop].
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From my Home observatory Occult4 said I had a 44% chance. At the centerline it rose to 59% - not great, but not bad either. As mentioned, the 1-sigma margins were nearly as wide as the path itself. I examined the path on Google Earth (see attached) and my Home observatory was clearly outside the predicted path. But the thought was to setup my QHY174M-GPS in my Home observatory (for the heck of it...) and use the Sequencer function in SharpCap to automate a recording from Home (I wrote a script that will do this). I would then picked a site on the other side of the centerline and "go mobile" to that (using my 12-inch Sky-Watcher 300P and my Astrid). My thought was -- ~maybe~ one of the two sites would capture an event.
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First step... I made up a "timeline" of when things had to be done by (allowing some "fudge factoring" for any "issues").
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Home --?
I used my (absolute favorite!) star chart program Carte du Ciel to generate a pre-point line on a printed chart. I picked a time on the pre-point line (5:45:44UT - about 1:45am) that would be a an hour+ before the time of the event - giving me time to leave and "go mobile". I got the 14.5-inch scope in my Home observatory on the Target Star and found 30fps would easily capture it. I then moved the scope to the point on the pre-point line about 1.4 hours ahead (west) of the event. As the mount is fixed, I only had to move it westward in RA. Since I got on this point on the pre-point line about 10-minutes ""before"" I needed to, I let the drive run, tracking at this point on the pre-point line. At the indicated time on the pre-point line (5:45:44UT), I switched the drive off. But shortly before I was to have left to "go mobile" some rather thick fog rolled in. It was so thick, I somewhat questioned about continuing. Instead, I went back and changed the set exposure from 30fps to 15fps - in case the fog was thick at the time the automatic record kicked in. I then left to "go mobile" about 1 hour before the event time. Event time being 7:07:44UT (~3:08am). ?
Mobile --
Took a 12 minute drive to get to the site. Got set-up and on the Target Star in about 30 minutes (the 12-inch is a GoTo Dob). It was a bit foggy there too (but fortunately the event was 67 degrees Up in the East - out of the horizon murk). I set my Astrid to record at 33fps (which my Astrid will do reliably with 0.00% timestamp error). To my delight, I captured an event! (and it later turned out to be 0.31 seconds duration - the maximum predicted was 0.33!).? ?
Returning Home I checked the observatory (with a heavily dew-covered scope).... Upon playback in SER Player, the Target Star slowly moved toward the center of the FOV, and at nearly the very center of the frame, it briefly winked at me!!! I also captured a Pos from Home!!
[Turns out the duration was 0.13 seconds with 3 very distinct data points in the drop. At least 3 data points are required in most events for PyOTE to be able to "certify" an event is real]. The Target Star was bright(!) in the QHY recording, so it told me that the fog situation wasn't bad at the time the Home recording kicked in. I actually could have left it at 30fps as I originally planned - or maybe even done 50fps. ?
A quick look at the observations (off the plots) shows the 'rough' center-time of the Mobile event to be 7:07:43.590 and the center-time of the Home event to be 7:07:43.760 - just as it should be (as the shadow was moving from south to north). The JPL predicted center-time was, again, 7:07:44UT +/-0 seconds.
From the two observations, it rather clearly defines where the path actually went (it shifted a tad west). ?
Overall, technically, everything went as planned - no equipment / time issues.
When I finish and submit the reports on this event I'll now have __25__ Positive events awaiting review by the IOTA review folks.?
....And I have TWO nice events (mags 9.5 & 9.6!) tonight... but it will probably be cloudy - Sigh. ?
Nice having luck on your side once in a while. Hope some might have enjoyed this saga.?
So this time.... Bullwinkle pulled a rabbit. ?
G
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Re: 270 Anahita Last Night
Steve:
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Congrats.
I tried and got "skunked" -- well, totally clouded out anyway. It was supposed to be clear (OW said 0% clouds, and Astrospheric hinted at that too). Instead it was thick overcast. But I did do the 50-minute drive, got to the site (and never had to bother setting up). A bit prior to the event I gave up - no chance of clearing.
But I have another 10th mag event tonight!, and as the attached says..........
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270 Anahita Last Night
I ended up with one of everything last night--a miss, a hit, and a no-observation.
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The miss was expected from the prediction from my home observatory (C-14 on a SB MX+ mount), but still should provide a meaningful constraint on the profile.? Since there was no meridian flip required, and (thanks to recent tree removals) I was able to get on the target 2.5 hours before the event, the mount was able to easily track the target through event time.? The only "prepoint" I had to do was the observatory dome--which I can't trust to track the telescope due to a few dead spots in its drive.? All worked as expected.
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The 4.2 second hit was from Cherry Springs State Park (PA's dark sky astronomy park)--one of my usual locations when an event crosses west of me.? This one actually cost me my no-obs, as everything there took more time than it should have.? First, I hadn't been up there since they started major construction.? Finding my way around the driveways, parking, and the effectively new observing field location in the dark was a challenge.? Hindsight says I should have taken the time for a daylight survey, but the 45 minute drive each way discouraged me from doing that.? The second problem was I chose to set-up on the other side of a treeline from the parking area, but was in plain sight of cars driving in to the park.? I was really not expecting people arriving at the park at 2:30 AM, with a 3rd quarter moon well up in the sky, on a work night.? But several did.? I was hesitant to leave my equipment unattended with people just having seen me set-up as they were driving in.? I also have to implement Mark's fix to turn most of the Astrid lights off for next time.
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By the time I got by these problems, it was too late for me to drive to Patterson State Park and set-up a station there.? Too bad, would have had another positive chord.
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My positive did show a dip after the occultation that looked contrail-like.? My initially chosen reference stars did not show this.? But once I used stars on the same rough declination, leading and trailing the target and ran them long enough, they all showed similar (but evolving) features at a believable offset in time.? The dip also happened for each at a different location on the imaging plane, so not caused by contamination on the CMOS surface or optical path.? In the attached plot, the blue star was leading, target star (red) between, and green star was trailing.? Both the green and red go off the field prior to the end--hence they drop to zero.? I haven't had one of these in a few years, and they seem to come up on the main IOTA message board once a year or so when someone thinks they might have a real strange result.
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John Barton also had a positive on this event.
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Steve C
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Re: (270) Anahita Early Monday AM
Hope to try but no guarantees. Quite the drive for me but I'll do it if the weather seems promising.
Attached is a more "local" path plot.
A prospective "new" observer - Paul Walker in VT - is in the path... But he's just learning his Astrid. I'll mention it to him.
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(270) Anahita Early Monday AM
Right now we have 7 stations signed up for this one tomorrow night, hopefully the weather cooperates.? It is "bright" at 11.1 with a 1.4 mag drop, long at 5.2 seconds and high in the ESE at 49 degrees elevation.? Other than the 3 AM time, what's not to like?? Anyone else able to try it?
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Steve C
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Re: Impact review
Lawrence:
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Well, good that you try. ...And good that you video record the effort. Video lends itself to just "so much more" credibility in a report.
I was interested in your project but that clear night - Aug 11th UT - I had to go mobile and got a Pos asteroid occultation.
Hope that you can try for some upcoming asteroid occultations in the future. I know the "lone wolf" feeling sometimes...
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George |
Steve C
Kevin Hartnett
George Viscome
