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btieman
sage
Reged: 07/24/08
Posts: 481
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First off...this is all in good fun! Groz and I have had many off forum discussions about precision photometry as well as other topics. I think we've learned a lot from each other--well, I've learned a *lot* from him! I know I would not have gotten to this level of precision without some of the discussion we've had as well as the great information and discussions with folks in this forum. Thank you all for helping me approach my goal 
Pleasentries out of the way, after Groz's post of his great Tres-1b transit and how it was his "best ever" I have to push back and try and raise the bar higher 
Below is my measurement of Hat-P-1 from 10/4/2009 where I acheived a model fit sigma of 4.0--with the full moon 30 degrees away! When I started measureing transits, sigmas of 6-7 were more commonplace--it's been a lot of work to lose 2-3mmag of variance! My goal is 2.5 sigma. It's going to take a *lot* more work to get there--if it's even possible with my equipment from my location...
The large 50 minute gap is bizarre. I was not monitoring the acqusition during that period so I don't know what happened. CCDsoft was taking 60s exposures and everything was running smoothly. Then it looks like CCDsoft took a 50 minute coffee break! There are no missing frames in the sequence. Timestamps and fits header information agree, the time between frame 90 and 91 was ~50 minutes. I can't explain why CCDsoft stopped taking images, but it recovered on it's own and collected 6 more hours of frames without a hitch. It's quite a shame as this is otherwise the best quality data I've yet acquired.
So, come on everyone! Step up to the plate and show us what you've got! I need some proof that it's possible to do better than this!
Brian
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CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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groz
Pooh-Bah
Reged: 03/14/07
Posts: 1071
Loc: Duncan, BC
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It's good to see the bar headed higher.
it does remain to be seen if we are at the limits of our equipment, or, if it's the limits of our analysis techniques. Like you, I'm still expecting we can get some incremental improvements on the analysis front, but it's a lot of work to get there, and I'm hoping to do so without taking the 'throw more money at it' approach.
At tresca, my Tres-1b shows a model sigma fit of 4.5, you've got this one down to 4.0, a decent improvement. This is somewhat different than the number you and I have focussed on in the past, the standard deviation on the check1-check2 line.
There's still a lot to learn, and a lot of questions to be answered regarding the final analysis, but it's good to see the bar headed up...
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btieman
sage
Reged: 07/24/08
Posts: 481
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Quote:
At tresca, my Tres-1b shows a model sigma fit of 4.5, you've got this one down to 4.0, a decent improvement. This is somewhat different than the number you and I have focussed on in the past, the standard deviation on the check1-check2 line.
True, we've been focusing on STD of C2-C1. To be consistant with that, I've included the check plot below. The STD for C2 (labeled C4 on the plot!) - C1 over the entire data set is 5.5mmag. If I take the best 60 minutes from the end, STD is 3.4mmag. C4 was very close to the non-linear portion of my chip which may account for the slight variability early on.
I switched to the sigma on the fit for this post because it's a published value. Go to TRESCA and it's there--not just for you and I, but for all TRESCA entered transits. You can even get this value from the AXA data by cutting and pasting the raw data into a file and feeding it back through the modeling routines. I'm not sure how good of a comparison number it really is. After the original post, I poked through some more of my transits and found one of my Wasp-3 transits that had a sigma of 3.6mmag--so I guess this one isn't my best yet  And I did see one that was a detrended average of several comparison stars that was 1.5mmag--I'd like to know what it was before the averaging! Anyway, the point is to start getting some reality checks on what is *possible* verses that we are *achieving*
Yes, it's good to see we're still improving a bit...I'd like to see a few others playing along too, though 
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CPC 1100
Orion 120st
Milburn Wedge
QSI 520i
Meade DSI Pro
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