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NEUS Informal Chat - Wed 6/26
NEUS Folks,
Steve and I are planning an informal chat for this Wed eve 6/26 at 7:30pm (the time is SET). Other NEUS folks are welcome to sit in. I'm setting it up, and for me, part of the reason for the chat is to test out Skype/Meet Now (owned by MicroSoft) as a meeting platform. Skype works very similar to Zoom, is free, and has -NO- time limit. I believe you also don't need to have the Skype/Meet Now app on your computer. I've used Skype often before but not for more than a 2-person chat...? To join-in, send me an email and I will send you the link to get in (this avoids any "gate-crashers" if the link is made public).? To attend, all you have to do is click on the link. My email address is..... [Email address edited off after the chat session was over]. We'll probably cover Astrid, flashers, mobile site selection, recruitment, etc.... George |
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Re: Astrid ?$?
Rick,
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I completely agree with your comment on the Astrid price.? I had thought we were hearing at NEAF that IOTA was going to "buy down" the price and they wanted the cost not to be a big stumbling block for entry into this field.? Not sure why they decided to instead provide it at "near cost".??
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I just received my second Astrid--this one was quite a bit more expensive than my first.? No assembly was required (my first took only an hour or less to put together), and they put a few nice features into it that my first didn't have.? I think the is a huge difference between the $300-400 range and $700 plus shipping.
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Steve C
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Astrid ?$?
Hi,
I plan on buying two Astrids, at least, so I will be able to do multi cords.? I have no problem with the cost. I like the fact that I am making a small contribution to science, and quite frankly, I like the thrill of the hunt. I think Mark should be paid anything he feels is proper to recoup the cost and effort he has invested to Bring Astrid to production. If he¡¯s making money on the product, great. He deserves it. µþ³Ü³Ù¡ I think IOTA may be missing the boat here. $700 is not exactly an incentive to start in the field of occultations. It¡¯s not just the cost of the equipment, it is also the cost of effort, both data acquisition, and then in learning data processing and reporting of the result.? I do astrophotography. It is part of my job at my school. When I take a picture of a deep sky object, I know that object on another level then before I took the picture. I know it¡¯s chemical make up and all sorts of details about that object I did not know before. But I pick and choose the software required to take that image. I don¡¯t like learning new software and new astrophotography processes. It¡¯s a real pain when new software comes out and completely up ends my established procedure. I also do EXO planets, spectroscopy, variable, stars, and more I¡¯m probably forgetting. All take time and have specific software learning curves.? In my view, IOTA should subsidize Astrids. There are many possibilities. A simple one time subsidy or a partial refund after a few occultations reports have been submitted. Whatever form it takes, I think the cost should be half or lower than what is proposed. $299 sounds like a good number. Remember that occultations are not just competing for astronomy funds, it also competes for dark cloudless skies, not to mention time. In our meetings, there are already reports of groups buying $1300 GPS cameras and not using them. Probably because of the complexity of that camera, or whatever. To me, Astrid holds the promise of making asteroid occultations somewhat simpler. That makes it more attractive to a wider audience and our best hope for attracting new members. Astrids and perhaps a low cost IOTA GPS flasher maybe the beginning of a new IOTA era. If anyone in our group is in a position to float the idea of IOTA subsidizing Astrids, I strongly recommend they do so.? Rick Bria? |
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Re: More on Flash Timing - Some testing...
Steve (and Rick):
Thx for the thoughts. As for "next steps"... I think I'm done with flasher 'testing' for now.? I have more magnitude tests waiting to process - magnitude depth vs exposure for several scopes. It's a very good thing to know... how deep you can reach with a certain scope given a certain exposure. Seeing as I have 3 cameras and 8 scopes (20, 14.5, 12, 8, 6, 4.5, 3, 135mm) and my list includes about 25 different exposure settings.... Ouch!? I'm about half way done with that. But as far as general testing for someone who gets a flash timer and already has a "pretty-picture camera" (that is video capable)... There are a number of folks near me that have such cameras and I have hoped that someday they might consider getting a flash timer and try an occasional occultation. [After all, astronomy is a SCIENCE, not an ART FORM]. In which case I could test their flasher against perhaps my Astrid - and at least "certify" that their flasher is up to spec. But as for an individual's camera system.... that would probably remain a wild card. It's possible (tho somewhat difficult) to test that, but so far I haven't needed to go that route..... Since they are still stubbornly ignorant of doing any real science and too wound-up doing their "astro-art".? 'Guess that may be their "plateau". As for some other questions......... * In my test videos, could I see a slope? Attached are typical sample light curves for two of the tests presented in the prior post (tests 5 & 9). In each image the top plot just shows the Target Star and its simulated occultation. As you can see, the simulation is very much what you would see in a real event (with a quick deep drop - and recovery). Any fading is VERY minimal. The bottom plot shows both the Target and the "Flash Sense" (a Static PyMovie aperture with the "white aperture" chosen).? What's interesting to note in these plots is the variation in light intensity of the "Flash Sense" aperture - especially in test 9! You will note that one video has almost a "square-wave" variation in its "baseline" for the "Flash Sense". This is caused by an automatic gain stage kicking in and out in the actual sensor chip of the Astrid. I sometimes also see this with my RunCams. The actual sensors in both the Astrid and RunCams have this "build-in automatic gain switching" and it is NOT something that can be disabled in any camera control software. It's simply how the sensor works. Sometimes this can be seen visually on a monitor. At times it "behaves itself" and the automatic gain switching is minimal, but it seems if the light on the sensor is near a certain "threshold", it can cause the sensor's gain to continually jump between two different settings. Note that you only see this "jumping" in the PyMovie aperture that is set to sense the flash (a Static white aperture). You will note that in the light of the Target Star, the gain jumping is "absent". This is because in PyMovie for each individual frame of video of the Target Star, PyMovie calculates, then subtracts-out the background level. This effectively "removes" the gain jump. For the white aperture which senses the flash, no background level is subtracted out (so as the gain jumps up, so does the background level!). But even with the "gain jumping" in the "Flash Sense" white aperture, PyOTE can still accurately determine the leading edge of the flash. You asked... * "What happens to one of Aart's flashers if they have dicey GPS reception? ?I think he logs such things, but is a new user going to understand they have to check the log..." In the log my flasher creates it logs the number of GPS satellites used. I just looked at the log for the 12 tests I presented above and at a minimum I see "Sats: 12" and at a maximum I see "Sats: 18". So yes.... a flash user (if they want to do things right) should consult their log files. I believe 4 or 5 satellites for most GPS time devices is satisfactory. A dozen or more is almost overkill. You asked... * "Do you know what GPS receiver is on your Adafruit shield board?" No. If I get the opportunity to check I'll let you know. You asked... * Any idea what testing Aart has done? I just know that Aart and John Moore have done extensive testing. Some time last year I presented them with my test results and the reply I got was...... "Yeah, we know that... We've already done it". SEXTA.... Thanks, but I'm done with flash testing on my unit. It's "proven". Need to run mag tests next and get those videos off my hard drive (all these tests are taking up a serious percentage of the space on my hard drive!!). You asked... * "Are you planning to present your results at the IOTA meeting in September?" Not unless I feel like punishing myself. I'm sure there would be a few hard-line 'denouncers' of using flash timing (irregardless of any situation) and I'd get their wrath. Which leads me to saying (/repeat)........... I ALWAYS would advocate that folks use per frame GPS timestamping as the proper way to time, but... I DO feel using flash timers "have their place" in our 'sport'....... * First, as Rick mentioned, it can be an inexpensive way for folks to get started in occultations. With flashers, the cost to get started in occultations apparently may be under $100 (if they already own a video-capable "pretty-picture camera"). ...and as Steve mentioned, it seems very soon (if not now) assembled Astrids will be available. Right now, they seem to be the cheapest "occultation-ready" camera that can be bought --- but the cost is $700+ with shipping(!). I know of some observers who - without question - won't spring for that to start out. ...And now let's discuss another aspect... HOW GOOD IS GOOD ENOUGH? Do we always record our occultation videos at 30fps? Answer - NO. Sometimes the Target Star is quite faint and we may need to record at 4fps. So in that case, even if someone uses a flasher which references NTP, and which has an inherent [tested] "inaccuracy" of 0.01 seconds, that "inaccuracy" is still 1/25th of the frame rate that is being recorded(!). ...and yes, remember PyMovie can do timing to sub-frame accuracy (to some extent). So in such a case, I'd say that even flash timing based on NTP might be quite valid for a camera recording at 4fps. So... In short...? I feel that the timing method really needs to be selected/evaluated based on each individual occultation event. Also.......... Consider the case where an experienced observer sets out to record an event (perhaps using an Astrid - ie, timestamps). But... He knows another observer who mainly does "astro-art" (they are intent on taking the 40 millionth picture of M13), and he [----!!somehow!!----] persuades them to set aside their "astro-art" for a moment...... and use a GPS-based flash timer to also time the event (some distance away). Consider... Without the additional flash timing, the experienced observer would only get ONE CHORD on the asteroid. But if the 2nd observer (flash timer) also gets a chord, and both observers report their events, now you [potentially] have TWO CHORDS on the same event. Which brings up an important point.......... When an occultation gets reported, one of the things that gets asked on the report form is... "What was your timing source?" So the experienced observer reports that he used his Astrid (which has GPS-based timestamps on every frame of video). The inexperienced observer reports that he used a GPS-based flash timer. [And the experienced observer does the analysis of his video]. It's very important that the timing device be clearly noted in EVERY report. There should be the choice in our report forms which includes flash timing, and the sub-categories of... * Flash Timing - GPS based * Flash Timing - NTP based So when it comes to determining the "chords" for the asteroid, much more "weight" could (should?) be given to the chord obtained via the Astrid, vs the chord obtained via the Flash Timer. If there's a large discrepancy --- Simply throw out the chord obtained by the flash timer.? But... If they "fit", now you have a much more valuable observation -- you now how TWO CHORDS where there may have been just ONE! So what was gained by using a Flash Timer?.... A SECOND CHORD! Sorry for the novel. George |
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Re: A Tale of Three Stations
Steve:
Triple Congrats on the multi-station deploy! ...and great that you got Hits at all stations! Thanks for the story too... Fun reading about such efforts.? Looks like Tom should have been in the shadow too - hope it worked out for him. I like the last hour "creative solution" aspect (using the finderscope at your observatory). Likewise, I've had to Gerry-rig many last minute solutions in the field. BTW I have a nice shot at (1852) Carpenter on the 16th. I'll be going mobile to put myself right on the centerline. The shadow runs from me to right over Buffalo to Cleveland (a bit west of you - but maybe possible for Tom?). Mag 11.9 for 1.65 sec. I'm considering trying a 2nd station. Anyway...... Thanks for the story and Congrats! ? ?-G |
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A Tale of Three Stations
For last night's 2000 AP126 event, I got aggressive and tried 3 stations.? BLUF:? with a lot of luck, I managed to get 3 positives:
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Bobcat Observatory (home):? +31 km, 32%--had a ~0.3 second positive-->used a Watec 910/VTI on the finder scope of my C-14 (prepoint)
Grand Canyon Airport:? +28 km, 74%--had a ~0.5 second positive-->used an Astrid on a C-5 (prepoint)
Cherry Spring State Park:? +9 km, 100%--had a ~1.2 second positive-->used a QHY 174GPS on a 66 mm refractor (tracked), this is where I was in person
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Tom at Martz Observatory:? +4 km, 100%--might also have usable data
It didn't start well--I wondered into the observatory about an hour before I had to get in the car to work the remote stations with no clue how I was going to do this.? Normally, unattended I get the C-14 on field with a go-to and just let it track.? But this time I had to set up 2.5 hours before event time, the target was so low at this time I couldn't acquire it--plus the event time was right around a meridian flip.? I thought about a C-14 prepoint but didn't like the odds with the small FOV.? Then it occurred to me that my finder (80 mm) would be fine given the star was 8.5 mag (even at 17 degrees elevation)--I've never tried this before.? The f/4 finder would have 4x the FOV.? So I mounted the Watec to the finder, and quickly found the c-mount to 1.25" adapters I had were all too long to come to focus.? After a half hour hunting for a shorter one, I fired up the bandsaw and cut a quarter inch of the length of on of the adapters I did have (I'll clean it up in the lathe eventually--looks pretty ugly right now, and yes I still have all my fingers, but my father would have yelled at me about safety if he saw how I did it!).? Dropped that in, and was able to focus--nice images, good enough limiting magnitude.? Used the mount to prepoint at general field, locked down and verified the prepoint by looking at the star field go by and comparing the what TSX showed--then doing the math.? In the end, this worked perfect--the blink happened when the star was near center.
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The second station at the airport was no drama--the Astrid had me in and out of there in less than 15 minutes.
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The last station at Cherry Spring State Park (our PA darksky observing park) had only minor issues.? I had the NextStar mount set-up and aligned very quickly.? Took me a bit of time to convince myself I was on the right field (too many stars!).? QHY's GPS wouldn't do anything but say "Bad Data" initially, but once I cycled SharpCap off/on it came up fine.? Unfortunately, right before event time it indicated "Partial Data" and continued to produce times without location.? Hopefully that won't impact the timing data (my hand calcs show the three stations roughly align in time as you expect with their distances along the path).? My last problem there was as I was packing up a car pulls into the (quite large and almost empty) parking lot, goes all the way around, and parks right next to me.? The guy get out, and wants me to explain to him what you can do where in the park--a potentially long discussion.? It is 2:45 AM!? Hopefully I wasn't too rude to him...
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Anyway, my first triple deployment worked out great.? I would even out the spacing more if I was doing it again, but some of that is hindsight.
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Tonight I'll be trying (14965) Bonk.? Weather looks 50/50.
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Steve
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Re: More on Flash Timing - Some testing...
Good stuff, George.
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My comments:
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Steve C
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Re: More on Flash Timing - Some testing...
Great news!
I hope IOTA is developing GPS flashers for sale. I think it will be a great way to get new members in at low cost, if they already have a CCD camera.? I tried the phone app flasher, and had issues with recommending the phone app flasher for new users, but a GPS based flasher should be a good way to attract new members. Rick Bria? |
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Re: More on Flash Timing - Some testing...
NEUS Folks:
An overabundance of cloudy, rainy skies lately so I thought I'd complete the analysis/tests I started a little while ago using my "Aart's Flasher".? Why am I dong these tests?.... I've heard/read several discussions about timing with flashers - with some folks liking the devices and some folks being critical of them. But in all discussions, I can't recall anyone who has ever backed up their statements with actual test results. Well, here's some test results... Mainly I'm doing this to satisfy my own curiosity, ....and sharing the results. Purpose of the Test: To compare D & R times obtained first by using (GPS-based) Timestamps (on every frame of video) as the reference source, and then comparing the D & R times obtained by using two (GPS-based) "Bookend" Flashes as the reference source -- using the same .CSV file. Conditions: As with all flasher tests I've done the "bookend" flashes were put on a video that also contained GPS timestamps (on every video frame). A single .CSV file was generated and that file was used to measure a "simulated occultation" -- first by using the timestamps, and then by using the two flasher "bookends". The tests were conducted under "real sky" (outdoor) conditions by very quickly waving a piece of cardboard in front of the telescope (the simulated occultations probably averaged about 3/4 of a second in duration). The simulated occultation was near the mid-point between the two flashes. A typical time between the 1st flash and the simulated occultation was 45 seconds, and also 45 seconds between the simulated occultation and the 2nd flash. The D & R of the simulated occultation was measured using PyMovie/PyOTE. PyOTE reported a GPS Timestamp error of 0.00% for every test. For the 12 tests listed here, I used my Astrid camera -- so the flash-derived times are a comparison against Astrid's GPS timestamps. The flasher used was a unit made for me and based on Aart Olsen's Arduino-based design. Summary of some numbers for this series of tests (GPS-based flasher against GPS-based timestamps).... * The Average difference between the calculated D & Rs - between timestamps vs flasher was 0.0015 seconds ? (about 1/666th of a second). * The Minimum difference was 0.0001 seconds * The Maximum difference was 0.0034 seconds (1/294th of a second) * In 11 out of 12 tests, the flasher yielded D/R times a minuscule fraction of a second before times via timestamps. I'm attaching scans of the 12 test results. The important number are in the yellow boxes. Conclusions: With these results (and many earlier ones), I would feel confident to record an occultation solely based on _MY_ flasher unit -- as I consider it "proven". I also know how my cameras (RunCam, QHY, Astrid) perform, and they nearly always produced 0.00% timestamp errors. That said, I do feel that any flasher unit must first be tested (numerous times) against timestamped video before any assumed accuracy should be inferred. The camera & recording system used should be proven to not be susceptible to dropped or duplicate frames. Of course, I would always prefer using a system that placed GPS timestamps on EVERY frame of video, and would only resort to using "flash timing" as a last resort (or perhaps for unmannned stations). Just a word of note for anyone attempting their own tests.... Keep the simulated occultation short in duration (1 second or under). Since you will be very briefly covering the entire front of the telescope, ALL stars in the FOV will be gone during the simulated event. Thus you can't use a "Tracking Star" to keep the PyMovie aperture locked on the Target Star during the "occultation". In using a simulated occultation of 1 second or under, the PyMovie aperture will not have time to wander off the Target Star. (And even if it did, it often won't matter since you will be using the same .CSV file in measuring times via both Flasher vs Timestamps. In a worse case, any "wander" may simply introduce an unwanted "fade" in the "R"). Maybe this is of interest... maybe not. George |
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Re: Astrids
Ted reports the current Astrids are completely assembled and have all the parts (except for a power supply and tablet or notebook PC of course!).
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Steve
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Astrids
All,
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Is anyone on this waiting on an Astrid?? I just paid for my second, sounds like it is ready to ship.? The IOTA price, which is I believe "all inclusive" (completely assembled, and I'm assuming includes qualified USB stick, feather for switching modes, GPS antenna) is $695 plus shipping.
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Steve
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Re: (15532) 2000 AP126 Thursday Morning
Tom,
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Great--can you mark you location on Occult Watcher?? Or I can do it for you.
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Steve C
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(15532) 2000 AP126 Thursday Morning
I don't think anyone is anywhere close to this one, but just throwing it out there.? Low in the south at 17 degrees, but rank 100, modestly wide path (60 km) and mag 8.5 with 8.7 drop.? Also 1.6 second max duration.
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Path crosses:
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?Steve C
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Re: Flasher Box Status
George,
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The box design came from John Moore, who is a much better 3D print designer than me.? It looks nice, and fits the board perfectly
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Power connections are on the opposite end from the LED and GPS antenna connectors.? 2 choices for which to use (both available by default) (1) a typical 2.1 x 5.5 mm male cable input with 6 to 12 vdc center positive or (2) a USB-B (old boxy style for most Arduinos, some now have USB-C inputs).? Aart tells me he just uses the USB, so if you have a USB battery, that should work fine.
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The LED uses the typical audio jack (mono), so you can vary the cable length or leave the LEDs on various telescopes.
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Prices look like:
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Steve
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Re: (5361) Goncharov Campaign
Steve:
Re: (5361) I'd thought about it, but like you, it's also about a 4 hour drive for me. If I need to accomplish something else by doing such a drive I'd consider it, but right now... probably not. I wonder if anyone had thought of checking to see if there were a nice event going on while Stellafane was happening this year? If there were that might have been a good opportunity to promo occultations. I'll find this year's Stellafane dates and try to see if a nice event is planned for their Springfield VT location. George |
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Re: Flasher Box Status
Steve:
Nice. Looks like you used an off-the-shelf "project box". Looking at it I see the GPS connection and what looks like a plug for the LED flasher, but I don't see any power connection. What voltage does it use and how are you getting power to it? Did you indeed make it so the lead to the LED flasher can be unplugged from the box (seems like a good thing to do)? I know of a friend in VT who might be interested -- maybe. For a "trustworthy" unit (with a quality Arduino board), what would be a rough price -- the $80 you mentioned (plus shipping)? What would the user need to buy... the GPS antenna?, Micro-SD card (of what capacity)? George |
George Viscome
Steve C
rickbria22
