Relative alignment was performed by finding the peak of the cross-correlation between images and a pointing master selected from the epoch with the best-constrained pointing model for that field. Each observation was initially mapped individually, then all observations of a given field were cross-correlated with a selected master image of that field. The cross-correlation peak was fit with a gaussian and the difference between the gaussian peak and the image center was used as the pixel offset. The offsets were recorded and written to the timestreams. Finally, all observations of a field were merged into a single timestream with pointing offsets applied to create the field mosaic.
Articles by Adam (adam.g.ginsburg@gmail.com)
a bunch of plots
I wasted a lot of time making these so I figured I might as well waste a little space showing them.
A new series of problems
- There are severe (~5 pixel) pointing offsets in the MOSAICs. They are caused by IRAF and I can't figure out exactly why.
- Deconvolution has created more artifacts at l=54, 70, 357. I don't know how to fix them.
- Either my earlier time estimates were way off, or the mapping has gotten slower. It now takes ~120 computer hours (72 real hours) where before it was taking closer to 48.
Return to Deconvolution
I ran the v0.7 reductions with deconvolution on for 50 iterations. I had cut out deconvolution originally because of the funky noise maps, but that was partly an error on my part. There is also an issue with bright sources being largely left over in the noise maps. The deconvolver does MUCH better at filtering out the fuzzy atmospheric emission, so I want to use it. It leaves some flux from bright point sources behind, though, so I decided to try to make the deconvolution kernel smaller to see if that recovers more of the pointlike flux.
planet fluxes
; ephemerides from the JCMT ; MARS: ; June 30 2005: 730.14 Jy UT:53551 ; July 15 2005: 872.83 Jy UT:53566 ; Sept 10 2005: 1941.72 Jy UT:53623 ; June 5 2006: 553.13 Jy UT:53891 ; June 23 2006: 674.14 Jy UT:53544 ; Sept 10 2006: 135.79 Jy UT:53896 ; July 20 2007: 381.18 Jy UT:54301 ; Sept 10 2007: 597.87 Jy UT:54353 ; ; URANUS: ; June 30 2005: 43.43 Jy UT:53551 ; July 15 2005: 44.35 Jy UT:53566 ; Sept 10 2005: 45.78 Jy UT:53623 ; June 5 2006: 41.71 Jy UT:53891 ; June 23 2006: 42.96 Jy UT:53544 ; Sept 10 2006: 41.62 Jy UT:53896 ; July 20 2007: 43.90 Jy UT:54301 ; Sept 10 2007: 45.57 Jy UT:54353 ; ; NEPTUNE: ; June 30 2005: 17.42 Jy UT:53551 ; July 15 2005: 17.58 Jy UT:53566 ; Sept 10 2005: 17.50 Jy UT:53623 ; June 5 2006: 17.04 Jy UT:53891 ; June 23 2006: 17.33 Jy UT:53544 ; Sept 10 2006: 17.09 Jy UT:53896 ; July 20 2007: 17.59 Jy UT:54301 ; Sept 10 2007: 17.56 Jy UT:54353
Rant: calc_beam_locations
It took me a few days to figure this out, but "calc_beam_locations" is about 800 lines of wasted space. It does nothing substantive until line 335. Everything to that point is parameter parsing. But there doesn't need to be any of that crap, really, and it should have been outsourced to functions to begin with. NCDF files are read to get the rotation angle - JUST as an error check! There is no a priori reason to include it. All that the code does is read in a centroid file (a list of x,y offsets), rotate them, and output them as r,theta,error. Sure, there's a bunch of automated outlier rejection etc, but... seriously?! We don't have enough observations to hold up the statistics necessary for that to begin with! NO ONE would if each observation takes an hour. It's absurd. Odd as it is coming from me, manual rejection makes a lot more sense in this case. Now, I still have to understand WHY the beam locations are rotated by the fiducial array angle.
distortion mapping done?
Created 'beam_locations_0707.txt' from uranus_070702_o42 with a few contributions from g34.3_070630_o34. The rest were created by averaging over all of the beam location files
0707 distortion maps
They're consistent but not very close to each other.
beam locations & peak fluxes
The results of my distortion mapping work below. Note that, especially for 06, there are a LOT of cases where no beam locations correction (noBL) had a higher peak than the distortion corrected map. I have no explanation for this yet. More work to come...
PEAK COMPARISON BL: 5.95824 noBL: 3.09836 uranus_050619_o23 PEAK COMPARISON BL: 3.93725 noBL: 2.85479 uranus_050619_o24 PEAK COMPARISON BL: 15.5613 noBL: 523.035 neptune_050626_o19 PEAK COMPARISON BL: 16.4601 noBL: 16.0038 neptune_050626_o20 PEAK COMPARISON BL: 426.671 noBL: 375.174 mars_050627_o31 PEAK COMPARISON BL: 415.968 noBL: 413.327 mars_050627_o32 PEAK COMPARISON BL: 15.2464 noBL: 33.8593 uranus_050628_o33 PEAK COMPARISON BL: 34.6631 noBL: 35.5086 uranus_050628_o34 PEAK COMPARISON BL: 164.832 noBL: 403.189 uranus_050904_o31 PEAK COMPARISON BL: 216.820 noBL: 425.613 uranus_050904_o32 PEAK COMPARISON BL: 134.972 noBL: 156.196 uranus_050911_ob8 PEAK COMPARISON BL: 11.0957 noBL: 11.1993 neptune_060602_o30 PEAK COMPARISON BL: 12.0000 noBL: 11.0947 neptune_060602_o31 PEAK COMPARISON BL: 2478.20 noBL: 2365.17 mars_060605_ob1 PEAK COMPARISON BL: 2144.68 noBL: 2147.18 mars_060605_ob2 PEAK COMPARISON BL: 17.7354 noBL: 25.7041 uranus_060621_o29 PEAK COMPARISON BL: 18.7889 noBL: 25.6599 uranus_060621_o30 PEAK COMPARISON BL: 28.1957 noBL: 31.1013 uranus_060625_o46 PEAK COMPARISON BL: 23.0236 noBL: 27.8556 uranus_060905_ob6 PEAK COMPARISON BL: 18.8731 noBL: 28.4964 uranus_060906_o12 PEAK COMPARISON BL: 23.3481 noBL: 29.8294 uranus_060908_o13 PEAK COMPARISON BL: 20.6238 noBL: 26.9424 uranus_060909_o12 PEAK COMPARISON BL: 21.1049 noBL: 28.8533 uranus_060910_o12 PEAK COMPARISON BL: 24.0231 noBL: 32.0877 uranus_060914_o10 PEAK COMPARISON BL: 23.2590 noBL: 33.3496 uranus_060914_o11 PEAK COMPARISON BL: 24.0538 noBL: 30.0552 uranus_060919_ob9 PEAK COMPARISON BL: 355.467 noBL: 669.416 g34.3_070630_o34 PEAK COMPARISON BL: 246.803 noBL: 296.252 g34.3_070630_o35 PEAK COMPARISON BL: 724.874 noBL: 807.152 uranus_070702_o42 PEAK COMPARISON BL: 7.60370 noBL: 9.02960 uranus_070912_o27 PEAK COMPARISON BL: 98.8058 noBL: 88.9957 mars_070913_o22 PEAK COMPARISON BL: 82.2708 noBL: 89.3476 mars_070913_o23
sign errors
pinned down the problem. Was a minor sign error in the offsets. Why is it that simple sign errors are ALWAYS the hardest things to track down? Now, open question: should x,y scaling be free parameters or not? What I mean is, when I measure the positions of bolometers on the array using the planet map, should I allow the X and Y stretch (the bolometer spacing) to change? Should it be a uniform stretch in X and Y or should it be allowed to 'distort' too? My opinion is, none of the above: I'm measuring their actual positions (in terms of a fixed spacing) and therefore stretching or distorting to match the nominal positions is not necessary.