by alter-ego » Mon Sep 23, 2013 1:36 am
Ayiomamitis wrote:
...
You write that the view is from the southwest which means that one would then be looking northeast. Since the sun rises as far north as around 57 degrees azimuth (for my geographic location), I am not sure where the problem lies. This particular analemma is for 9:00:00 UT+2 which would place it slightly further south in relation to azimuth.
If there was any possibility of pursuing this exercise and which took three years to complete from the actual grounds, I can assure you I would have done it so as to avoid the digital composite involving the two underlying photos.
Hello Anthony,
First I'd like to commend you on both your effort and image. I enjoy the APOD collection from terrestrial to extra-terrestrial, including artistically creative examples the reflect real or perceived visualizations of astronomical phenomena. I think yours is a quality example, and the time and energy it took you to create the composite (using film no less as one of the components!). I personally don't have a problem with this image. I love analemma shots and their variations, and using an ancient Greek temple in the foreground provides an historically aesthetic perspective. Perfectly fitting the early, astronomy era.
By the way, there are interesting analemma views that I haven't seen yet so there is plenty of room for more creativity
Second, without judgment, I tend to be technical but I'm not a "hit man" searching for errors. With that said, I often do uncover discrepancies but I typically don't bring them up unless there is good reason to do so. I don't like complaining. APOD contributors (and forum members) don't deserve negative input. If and when some technical discussion is appropriate, I try to do so without being judgmental. I thought this was such a case, and I apologize if I upset you.
Your sincere response indicates an interest in any analemma position discrepancy, so I'll try to answer that now.
The sunlit temple didn't seem to fit the location of the analemma. The placement of the Winter Solstice sun is what I first noticed - it looked to be too far north. It was a strong suspicion, but I didn't have enough information to pursue it further. However, your image times provide me enough to be quantitative. I determined that Mt. Geraneia is in the background. I then identified the Winter Solstice sun azimuth ≈ 33°(East = 90°). That is much too far north. Using your exposure times at 9:00am (UT+2), and Corinth's Lat/Long, I simulated the analemma as viewed from the temple. I sampled the sun position every 14 days (26 locations), and I didn't care about daylight saving time as that detail is not warranted here.
It may be difficult to read the simulation's Alt/Az grid, but the analemma varies in azimuth (as viewed from the temple) between ≈90°(due East) and ≈130° (SE). The latter is the azimuth for the Winter Solstice sun. By my simulation, it appears the true position for the entire analemma is outside your field of view. Also, the simulation indicates the analemma is at a lower elevation than your image. I found your image better fit a 10:00am timing, but I'm uncertain about this and don't give that result much credence.
All in all, I'm confident your azimuth placement for the analemma is too far north by at least 90°. Honestly, I would have done exactly what you did with the images. In my mind, any variance from the analemma's true position is not important. You have a great image.
If your have further questions, I'd be happy to discuss them with you via my PM (if you prefer)
[quote="Ayiomamitis"]
...
You write that the view is from the southwest which means that one would then be looking northeast. Since the sun rises as far north as around 57 degrees azimuth (for my geographic location), I am not sure where the problem lies. This particular analemma is for 9:00:00 UT+2 which would place it slightly further south in relation to azimuth.
If there was any possibility of pursuing this exercise and which took three years to complete from the actual grounds, I can assure you I would have done it so as to avoid the digital composite involving the two underlying photos.[/quote]
Hello Anthony,
First I'd like to commend you on both your effort and image. I enjoy the APOD collection from terrestrial to extra-terrestrial, including artistically creative examples the reflect real or perceived visualizations of astronomical phenomena. I think yours is a quality example, and the time and energy it took you to create the composite (using film no less as one of the components!). I personally don't have a problem with this image. I love analemma shots and their variations, and using an ancient Greek temple in the foreground provides an historically aesthetic perspective. Perfectly fitting the early, astronomy era.
By the way, there are interesting analemma views that I haven't seen yet so there is plenty of room for more creativity :)
Second, without judgment, I tend to be technical but I'm not a "hit man" searching for errors. With that said, I often do uncover discrepancies but I typically don't bring them up unless there is good reason to do so. I don't like complaining. APOD contributors (and forum members) don't deserve negative input. If and when some technical discussion is appropriate, I try to do so without being judgmental. I thought this was such a case, and I apologize if I upset you.
Your sincere response indicates an interest in any analemma position discrepancy, so I'll try to answer that now.
The sunlit temple didn't seem to fit the location of the analemma. The placement of the Winter Solstice sun is what I first noticed - it looked to be too far north. It was a strong suspicion, but I didn't have enough information to pursue it further. However, your image times provide me enough to be quantitative. I determined that Mt. Geraneia is in the background. I then identified the Winter Solstice sun azimuth ≈ 33°(East = 90°). That is much too far north. Using your exposure times at 9:00am (UT+2), and Corinth's Lat/Long, I simulated the analemma as viewed from the temple. I sampled the sun position every 14 days (26 locations), and I didn't care about daylight saving time as that detail is not warranted here.
It may be difficult to read the simulation's Alt/Az grid, but the analemma varies in azimuth (as viewed from the temple) between ≈90°(due East) and ≈130° (SE). The latter is the azimuth for the Winter Solstice sun. By my simulation, it appears the true position for the entire analemma is outside your field of view. Also, the simulation indicates the analemma is at a lower elevation than your image. I found your image better fit a 10:00am timing, but I'm uncertain about this and don't give that result much credence.
All in all, I'm confident your azimuth placement for the analemma is too far north by at least 90°. Honestly, I would have done exactly what you did with the images. In my mind, any variance from the analemma's true position is not important. You have a great image.
If your have further questions, I'd be happy to discuss them with you via my PM (if you prefer)
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