This is a high value event that just appeared on my predictions. Remember the LUCY Mission will be arriving at the Jupiter Trojan asteroids later this year. We as yet have no close up photos of any Trojan asteroid and so their origin and evoluton are a matter of theory and conjecture. Getting a clearer outline of Deiphobus and possibly discovering a moonlet would be of great value. It's a LuckyStar event so results should be sent to LuckyStar (see the OWc page).
My plan is to try this from the SC Mtns, probably Pine Ridge, to get the darkest skies possible for best S/N, with the 8SE scope. I may also, instead try to get the 12" at Cabrillo Observatory to get it, but will have to have a firm bail-out time to instead drive to dark skies to get it, if the 12" fails. And if I feel I can spare the time needed to do this. There are about a half dozen observers on the path map at the moment. The path looks to be coastal California and Oregon, mostly.
Alt=63, Az=282 in Andromeda. I used Alpheratz and Pollux as align stars. The GoTo worked well.
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Jordan's unable to join, and so, In pursuit of the darkest skies, I will be driving up to Pine Ridge cul-de-sac tonight, again, for this occultation I'll use whatever integration will bring out the star decently. Probably 32x, but I'll go 64x if necessary. The duration of 8 or 9 seconds should still make this do-able.
We had a good turnout and perfect weather, and solid occultation recordings from Kirk, Karl, me, and other NorCal locals.
Jordan had a soccor competition that would not let out till too late, so the Observatory attempt did not happen. Instead, I focused on getting to dry dark skies to maximize S/N. I chose last night's destination - Pine Ridge Rd in Bonny Doon at 1800 ft elevation. Weather was dry, calm, still, and cloud free. Seeing was excellent. The target was high in the sky, and permitted relatively short integrations of 16x or 32x. I could see the target without doubt at 16x, but the light seemed focused on just one or maybe 2 pixels, and sometimes disappeared from live view. So, I recorded at 32x. I set the recording brightness level and contrast to bring the sky to just below detection level, and maximum ability to see the target above sky. I tried playing with gamma, lowering it below the usual 1.0, but that did not help detection and instead raised sky noise. Lowering gamma makes the background sky brighter and so for Startech recordings, I've yet to find any advantage to playing with gamma. I left it at 1.0, sharpness at 4 as is default, Gain=41, integration=32x. The target was easily seen on every integration.
I recorded also with the Canon camcorder, to get audio for possible posting to YouTube later. 30 minutes after the event, I did a dark video using my jacket over the corrector plate, for 20s long.
Conditions were perfect. Dry, no wind, calm. No clouds or evidence of aerosols. No moon. seeing was excellent.
Manual Time Stamps for use in PyOTE. Times are the time stamp for the first field in the 2-field pair which constitute the frame.
* frame=967 at 5:23:55.5383
* frame=1967 at 5:24:35.5381
* frame=4217 = 5:26:05.5376
First soln: do not use the ref star. I want to see how it changes the timings...
magDrop report: percentDrop: 95.1 magDrop: 3.267 +/- 0.726 (0.95 ci)
DNR: 4.83
D time: [05:25:02.8929]
D: 0.6800 containment intervals: {+/- 0.0911} seconds
D: 0.9500 containment intervals: {+/- 0.2238} seconds
D: 0.9973 containment intervals: {+/- 0.4535} seconds
R time: [05:25:13.1102]
R: 0.6800 containment intervals: {+/- 0.0911} seconds
R: 0.9500 containment intervals: {+/- 0.2238} seconds
R: 0.9973 containment intervals: {+/- 0.4535} seconds
Duration (R - D): 10.2174 seconds
Duration: 0.6800 containment intervals: {+/- 0.1334} seconds
Duration: 0.9500 containment intervals: {+/- 0.2960} seconds
Duration: 0.9973 containment intervals: {+/- 0.5286} seconds
Second solution: Use the ref star.
All statistics got just a little bit better using the ref star, even though sky variance seemed minimal. Better: timing accuracies, DNR, NIE test. These are the results I will be using for the IOTA report.
Note on the Screen Capture of PyMovie that the target star was in a dark band, which at 32x integration, becomes visible on my recordings, but not so at shorter integrations. The ref star was slightly below this dark band. The target star remained inside this dark band during the entire recording. Tracking was excellent. This aspect does not look to have affected the results. There were no other secondary apparent events, nor duplicity in the target star. The magnitude drop was deeper than expected, at 3.3 magnitudes. Perhaps due to a color difference between star and asteroid vs. bandpass for the Watec.
I used the median horizontal and vertical filtering option in PyMovie. It's PyMovie's way of trying to do flat fielding.
I also took a dark frame video for 20s right after the event. Temperature of the ambient air was 55F. A day later, I took a twilight flat field video. But to avoid saturation and to be able to see the dust motes clearly, I had to dial the recording brightness down to just above 1 even after using the 1/100,000th second integration. I exposed for about 40s. All 3 videos are deposited with LuckyStar, along with the PyOTE and PyMovie files and forms. On Jan 17.
magDrop report: percentDrop: 95.1 magDrop: 3.269 +/- 0.726 (0.95 ci)
DNR: 4.90
D time: [05:25:02.8936]
D: 0.6800 containment intervals: {+/- 0.0903} seconds
D: 0.9500 containment intervals: {+/- 0.2236} seconds
D: 0.9973 containment intervals: {+/- 0.4605} seconds
R time: [05:25:13.1116]
R: 0.6800 containment intervals: {+/- 0.0903} seconds
R: 0.9500 containment intervals: {+/- 0.2236} seconds
R: 0.9973 containment intervals: {+/- 0.4605} seconds
Duration (R - D): 10.2179 seconds
Duration: 0.6800 containment intervals: {+/- 0.1311} seconds
Duration: 0.9500 containment intervals: {+/- 0.2922} seconds
Duration: 0.9973 containment intervals: {+/- 0.5237} seconds
The 32x integration shows banding in the background. However, during the processing I used both horizontal and vertical median filtering in PyMovie. The target star, unknown to me during recording, was sitting very close to a horizontal discontinuity in sensitivity, but remained beneath this line during the entire recording. |
The top two stars were used for tracking only, and had significant saturated pixels. Neither the ref star used, nor the target - at same brightness - had saturated pixels. |
PyMovie raw recording. |
PyOTE reductions. Event happened perfectly on time. But longer than predicted duration. |
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THE NIE signal was remarkably strong for a 14.4 magnitude object; at 46 sigma. |
Got a long positive at the Eco Reserve.
It was clear but seeing wasn't great, there was some jiggling in the stars at low integration. I'll send my report to IOTA and Lucky Star shortly.
magDrop report: percentDrop: 75.5 magDrop: 1.528 +/- 0.303 (0.95 ci)
DNR: 4.26
D time: [05:25:02.3733]
D: 0.6800 containment intervals: {+/- 0.1291} seconds
D: 0.9500 containment intervals: {+/- 0.3204} seconds
D: 0.9973 containment intervals: {+/- 0.6479} seconds
R time: [05:25:12.8060]
R: 0.6800 containment intervals: {+/- 0.1291} seconds
R: 0.9500 containment intervals: {+/- 0.3204} seconds
R: 0.9973 containment intervals: {+/- 0.6479} seconds
Duration (R - D): 10.4327 seconds
Duration: 0.6800 containment intervals: {+/- 0.1958} seconds
Duration: 0.9500 containment intervals: {+/- 0.4454} seconds
Duration: 0.9973 containment intervals: {+/- 0.8669} seconds
Got an ~8s event at home, at 32x. Notes: Jan 15 9:25:07 (1867) Deiphobus from S of Rock. Clear, dark, mediocre seeing, no breeze, used 32X . Tracking kept slowly drifting up and down in alt for about 20 minutes - became fairly steady by occ time. Saw about 8 sec event starting a couple seconds early. Need to do dark and Flat frames
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