Quincunx Spotted on the Terminator!
Posted 12 May 2011 - 08:08 PM
At about 9:56 EDT, I noticed an unusual pattern of pinpoint lights at the terminator, north of Copernicus. The floor of Copernicus was still in darkness, but nearly the complete rim was catching the sunlight. There were six sunlit points north of Copernicus. They were in the vicinity of Gay-Lussac and Montes Carpatus. Five points were similiar to the pattern of five pips on the face of a die. A line intersecting the middle pip and two opposite corner pips would be aligned approximately ne-sw. The sixth sunlit point was situated southwest of the five pips.
The six lights together formed the shape of a stubby cross. The pattern lasted from at least 9:56 to around 11:00 EDT, when it began to break up a bit.
This pattern was a very regular, geometric clair obscur, a play of light and shadow. I had never seen it before. I've searched for reports of it in my LOCT* spreadsheet and on the internet at various websites, but could not find it. It was an obvious and striking pattern of lights. I'd be surprised if no one else has seen it and reported their observation.
For now, I'm going to call this apparition the Quincunx, a name so ugly no one will ever steal it. When I was trying to find other reports on this clair obscur, I discovered that the five dots on a die are called a "quincunx." It's an appropriate name because "quincunx" comes from Latin for "five and one!" Well, at least that's what one website says. Others say it's derived from the Latin words for "five twelfths."
* LOCT = Lunar Objects for Common Telescopes
Posted 12 May 2011 - 08:19 PM
Posted 13 May 2011 - 06:34 AM
Hope the below (orientated to suit your view) might be of use – showing your ‘quincunx’ quite nicely in the middle two images. If you want a closer look at the mountains and features producing the six points of light, you might check out LAC 58 (orientation in normal cardinal points) available from LPI. Images below were created using LTVT with LDEM 64.IMG.
In your image, the Longitude reading is showing East 79.681. Presuming you meant an input of West 79.681 for ~ Maryland region into LTVT, all you have do is put a negative (-) sign before the 79.681 when setting up your location next time.
Posted 13 May 2011 - 08:13 AM
Actually, I just Googled my town and got longitude 76.68 W. Maybe I'm becoming dyslexic in my advancing years? Three degrees longitude might not make a big difference, though.
Yes, I see that the bottom of my simulation gives an E longitude, instead of a W. I thought I had entered my location as a West longitude. To me, it does not make sense that I would need to enter a negative (-) sign in LTVT before my longitude when my longitude is W (+). Does LTVT expect all coordinates - even those for terrestrial locations - to be entered in terms of lunar orientation? No sir, that is not intuitively obvious.
I will make these corrections and regenerate the simulation. The two middle images that you posted look the most similar to what I saw. But I remember the middle "pip" being closer to the center of the Quincunx. Also, the six points were much brighter and more obvious than the simulation shows.
Thanks for your help!
Posted 13 May 2011 - 03:45 PM
On the observer’s location stuff. I think the negative sign for any place east of the Greenwich Meridian Line (GML) (Long 0.0) was usually considered (+) until it reached the International Dateline (ID) (Long 180.0), while that to the west of the GML as being (-) until it reached the ID. The same goes for observer’s latitude input, too; north as (+), south as (-). As far I understand, you can also input the E, W, N and S respectively before your Long or Lat into LTVT, and that might work, too (I haven’t tried it, but recall reading it somewhere along my travels). Generally, terrestrial Long and Lat references have the cardinal designation (N, S, E, W) before or after the numbers usually, however, I have come across some references where the (+) and (-) values were used instead – possibly there to avoid the confusion where some softwares can’t handle the letter with the number on either side etc. I don’t think its a very serious point, however, Jim has some additional info here on the observer location stuff for LTVT if it’s of any use to you.
As to the five points etc. They started to ‘stick’ out more and more as the terminator moved across your ‘quincunx’ region, so I was assuming that these were the ones you were talking about. As to the brightness in the simulation, I think that that is just down to the DEM used, which doesn’t take into account the ‘real’ colours, or surface brightness's, reflectance's off features like mountains or terrain etc., of the Moon. So your actual view may indeed have been more brighter, I would imagine.
Whatever, the occasions above, the ‘quincunx’ must have been a nice sight to see. It’s in my diary, so will have to look out for it next apparition time
Posted 13 May 2011 - 05:44 PM
Also, the time of observation has been changed to 2:56 UT because LTVT shows a more complete image of the Quincunx at that time than when the simulation is set for 1:56 UT, as it was originally. I don't really understand this discrepancy, because I believe I saw a complete, fully-formed Quincunx at 1:56 UT (9:56 EDT).
Posted 14 May 2011 - 10:22 AM
Posted 14 May 2011 - 08:32 PM
I do remember seeing some of those bright points next to Copernicus that night, but didn't spend much time. I was focused on those darn Plato craterlets again (which I was treated to one of my top 3 views of, btw).
Will have to check out again in the future thanks to your handy LTVT report (I have to learn how to use that feature). Quincunx in July, maybe? Wonder if it will be dark enough...
Posted 14 May 2011 - 10:48 PM
Thanks. Like I said, I'm surprised I can't find any previous reports on this clair obscure. The Quincunx really was striking and obvious when I first saw it.
An interesting idea to consider is that in Galileo's famous drawing of the Moon, the large crater that is at the terminator may be Copernicus, just as in my simulation. The size of Quincunx is about the same size as Copernicus. Could Galileo have seen the Quincunx through his little telescope on that night long ago?
I had the 90mm Mak out the night I saw the Quincunx. I couldn't see any craterlets in Plato that night, but I didn't push the magnification past 179x. If I'd had the 10" Newt out, I would have gone for them. The funny thing is I believe I saw the rille in Alpine Valley through the 90mm that same night. I suppose that's the difference between linear and point detail. Go figure!
Yep, July 10th 1:08 UT looks like the next opportunity to see the Quincunx for me. I believe that's on a Saturday night, 7/9/2011, 9:08 EDT. As long as it's not cloudy it should be dark enough to see it.
Posted 15 May 2011 - 09:41 AM
I recall reading in the LTVT material sometime (it's in the accompanying user guide), that the dates predicted may not suit everyone as, depending upon the observer’s location, some may not have the Moon above their horizon at the time. For instance, the predictions above are for a geocentric observer as Mike has chosen, however, at his location the ‘quincunx’ on, say, dates 6/6/2011 or 8/8/2011 or 10/6/2011...etc., would not be seen as the Moon wouldn’t be in view. So, if using the LTVT ‘Moon Event Predictor’ button (that is, clicking on the ‘Predict’ button at bottom right of the main LTVT window), be sure to leave the ‘Geocentric Observer’ button unticked if you want those dates for your own location only when you can see the apparition.
Another point also to note in the dates above is in they way that they are out-putted. The predictor window outputs them as Month, Day, Year, however, if you enter these into the main LTVT window afterwards as is, you are actually entering Day, Month, Year, and you won’t get the apparition you are after. The correct input might be fairly obvious when, say, you have dates with the day date above 12 (that is, 13 to 31 days in the month), however, as in the list above, none of the date dates are above 12, so you might end up entering the them in the incorrect way.
Posted 15 May 2011 - 10:02 AM
All good points. Yes, I specifically changed the setting to "geocentric observer" when I generated the prediction list, because I thought that would be better than leaving it set to my specific location. I thought "geocentric observer" would be the best compromise. The user should convert the UT date/time to their own local date/time and use an emphemeris or a planetarium program to see if the Moon would be visible to them during specific apparitions of the Quincunx.
Caveat lector. (...trying to keep in the Latin theme here.)
Posted 15 May 2011 - 12:57 PM
I did some afocal lunar imaging at the Naylor Observatory that night, using a Canon PowerShot SD980 IS camera, an Orion SteadyPix camera mount, a 55mm University Optics Plössl, and the ASH 17" f/15 classical Cassegrain. Although it's hardly the best lunar image that I've ever captured, your quincunx is visible to the upper left of my shot of Copernicus appearing below. Lunar north is up in the photo.
Posted 15 May 2011 - 02:30 PM
Also, did you notice the pattern when you took the picture?
Posted 15 May 2011 - 02:49 PM
While LTVT is simply a superb 'bit-of-kit', one just can't beat an actual, recorded incident of a particular apparition. I'm sure there must be other recordings out there that CN memebers have if they looked up their past photos, however, one thing is for sure, this is the FIRST submitted of the 'quincunx'.
Euge! (...well done)
Posted 15 May 2011 - 03:25 PM
Posted 15 May 2011 - 08:10 PM
I also found this interesting page on Galileo's drawings, Mike. I did not have time to read exhaustively, but seems unclear that the big crater in the drawings was Copernicus. Interesting read for sure. There's some research that attempts to date the different sketches and give the age of the Moon as well at the time it was drawn.
Posted 15 May 2011 - 08:37 PM
I agree that it is unclear exactly which crater is the large one on the terminator in Galileo's drawing. If it is Copernicus, he must have offset it and the terminator somewhat.
Posted 15 May 2011 - 08:57 PM
Great use of the best moon program out there. I see you have the predictions listed for time and date to coincide wit the images you posted. I dont know how to save this though. How did you save the image or text of the preiction info in LTVT. Nice post and again, excellent program.
Posted 15 May 2011 - 09:35 PM
Thanks. I wish that LTVT had a way to print the listing in a hard copy or save to a text file or jpg, but I could not find those functions. So I used an old school trick. First generate the list of predictions. Press PrtScrn (or "Print Screen" on some keyboards). Open MS Paint. Edit-Paste from the menu. Select the list of predictions and then Cut. File-New, then select "No" to "Save changes?" Now Edit-Paste and only the list will be on the screen. You can format and print out the listing or save the file as a jpg to upload to Cloudy Nights.
Posted 16 May 2011 - 02:16 AM
Posted 16 May 2011 - 06:33 AM
(1) Hit Ctrl+A - this selects all the data (or you can drag your mouse cursor over those data that you want only).
(2) Hit Ctrl+C - this copies the data.
(2) Open up your text editor (e.g. Notepad).
(3) Hit Ctrl+V
Done...you can then print it out.
NB. If you are using the WORD text editor instead, you first have to open it, and then
do the steps above.
(1) Hit your PrtScr or Print Screen button.
(2) Open up your image editor (e.g. Paint, Photoshop).
(3) Hit Ctrl+V (in Paint). For Photoshop, just choose New from Clipboard.
You can crop and adjust...etc., accordingly in both afterwards.
Posted 16 May 2011 - 11:30 AM
The Quincunx is much more obvious now in your pics.
Posted 16 May 2011 - 05:45 PM
Over the years I've gotten away from using many of the keystroke shortcuts. The method you give to copy text from a screen and save to file or print is good to remember. (I did use that method many moons ago, but forgot about it.) The second technique is substantially what I suggested in my post, but using a keystroke shortcut instead of menus to paste.