I believe I've completely dealt with the projection issues. There are a lot of new plots available now, pretty much everything for Jun/Jul 05 and July 07. Low on my to-do list is the rest of the pointing model tests. My conclusion now is that I can't match the 3-4" RMS in dAlt and dAz. Even with aggressive sigma-rejection of outliers, I only get down to ~10" RMS (which adds to ~15" RMS). My calculated pointing models differ significantly from Meredith's, but not extremely so for 0707. The code I've used to generate the plots is centroid_plots.pro under plotting/. Using that code, I am able to essentially reproduce each change made in do_the_pointing besides the distortion mapping. Because of the weak dependence of the pointing model on altitude, even errors on the scale of precession won't really hurt the pointing model calculations. The only unanswered question I think may be responsible for some errors - but not enough, I think - is whether eq2hor/hor2eq could be double-correcting for aberration and nutation, but this wouldn't affect the actual data reduction. It WOULD affect my plotting! I think my next test is to try to coadd different epochal data for particular fields, e.g. l001, l033. Not l000 because of the galactic coordinate issue.
Update - Pointing Model
Update - Pointing Model 7/31/08 The pointing model application "works" now, but I have a problem with our model. We don't get down to the <10" RMS offset we're looking for. The mean offsets are all zero, but the spread is more like 20". Example plots on milkyway: [see attached PDFs too]
- ::
- /scratch/adam_work/plots/models_ptgmdl_0506.ps /scratch/adam_work/plots/models_ptgmdl_0707.ps /scratch/adam_work/plots/models_rawcsoptg_0506.ps /scratch/adam_work/plots/models_rawcsoptg_0707.ps
On the left side are plotted "all" of the data points, on the right I've used a two-iteration 3-sigma rejection to eliminate outliers to a small degree.
Top of these plots - as labeled - is altoff vs. alt, bottom is azoff vs. alt.
The red lines are a 2nd order polynomial fit to the data.
The cyan lines are the pointing model corrections calculated by Meredith.
The 'ptgmdl' files have had the pointing model corrections applied. Note that they are centered around offsets of zero.
The 'rawcsoptg' files DO NOT have pointing model corrections applied, and FZAO/FAZO have been REMOVED from the original pointing. Hence, these are RAW CSO TELESCOPE POINTING plots.
Things to note:
- In the 0707 'ptgmdl' set, the az is not quite centered at zero
- the 0506 'ptgmdl' set still has bulk offsets
- the ALTOFF and AZOFF are in delta-coordinate: this means that azoff
should be scaled by dividing by cos(alt) to put the y-axis in consistent units. In most cases, this means that the already large spread at higher altitudes is going to INCREASE. That means the problem is going to get worse... Questions:
- What is the main difference between my plots and Meredith's? i.e. why is my RMS ~an order of magnitude larger?
- Does more outlier rejection make sense? Is there any reason not to trust certain observations if they visible turn out right? PPSes are supposed to be "absolute references" for the 1x1, 3x1 maps OLD PROBLEM: PPS and large maps mapped with same 'pointing model' but ended up with different coordinates
Milkyway /scratch disk usage
-bash-3.00$ du -h --max-depth=1 ../16K ../lost+found80G ../sliced1.3G ../elatov70G ../cleaned58G ../mapped179G ../sliced_polychrome4.0K ../ironsides49G ../coadd_mapped2.1G ../pca_coadd2.8G ../3pca_3iterations11M ../centroid17M ../lost34M ../ptg_maps3.8G ../montage31G ../maps_from_polychrome93M ../ptg_mmd32G ../backup_from_kilauea31G ../sharc1.8M ../distortion6.9G ../fake138G ../adam_work136G ../bgps_dir_from_polychrome815G ../
Galactic vs. RA mapping
They don't match up. This is a serious problem. I think it's only a problem for the GC: ad2xy refuses to map things right around that transition. I think it's OK elsewhere.
Defining Pointing Terminology
There has been a lot of confusion about pointing terminology.
CSO pointing model: the telescope pointing model used and written as a black box
- has already been corrected for aberration/nutation
- is in current epoch coordinates (e.g. J2007.34)
Instrument-specific correction to pointing model
- ??? also referred to as 't terms'
- is offset between CSO pointing model and real locations
- should be a function of alt (and maybe az)
- is recorded in "RPC" files
- is in units of distance on the sky: delta-RA and delta-DEC, or delta-ALT and delta-AZ will be in the same units, while if they were in coordinate units delta-RA and delta-AZ would have to be scaled by 1/cos(DEC) or 1/cos(ALT) respectively
FAZO and FZAO: Fixed Azimuth Offset and Fixed Zenith Angle Offset
- these are ambiguously defined in the pipeline code
- ???? FAZO/FZAO include both the functional instrument specific pointing offset and any manual changes made at the telescope [manual only relevant to 2007 observations]
- ???? or are these JUST fixed offsets, and the instrument specific corrections are not included? Either way, how can I separate out manually-applied fixed offsets from fitted-model offsets?
New Pipeline to CVS
Open topic - what needs to be done to put the new pipeline on the CVS?
- Under the assumption that it will be used by others, the documentation needs to be complete.
- Needs to be compatible with current pipeline (no name overlap)
- Have to fix / update some Goddard astrolib routines that have short integer for loops and need long integer for loops Which ones?
- Probably need to add instrument specific pointing model corrections for non-BGPS observations
BOLOCAM PIPELINE BLOG
Guy pointed out in the CU meeting today that we need a better way to keep track of changes / problems / etc. The wiki's kind of a pain, and this will serve as something of a replacement for the e-mail-only conversations that have been going on with the Software Power Team.
Galactic Center Photo Contest
The Galactic Center and the surrounding Central Molecular Zone comprise the most active star formation region in the Milky Way. This 2 x 1 degree field was imaged at 20 cm (purple) with the NRAO Very Large Array, tracing H II regions that are illuminated by hot, massive stars, supernova remnants, and synchrotron emission. Emission at 1.1 mm (orange) was observed with the Caltech Submillimeter Observatory and highlights cold (20-30 K) dust associated with molecular gas. Some of this material will form stars within in the next few million years; the remainder will be blown away. The diffuse cyan and colored star images are from the Spitzer Space Observatory's Infrared Array Camera. The cyan is primarily emission from stars, the point sources, and from polycyclic aromatic hydrocarbons (PAHs), the diffuse component.
My view of the Galactic Center is the winner of this year's NRAO photo contest. It displays a multiwavelength view of the galactic center. The caption at the NRAO photo contest (reproduced above) describes it well, but I will go into further depth here.
The 'arches' are the large purple filamentary structures seen near the brightest point in the map, Sgr A*, the center of our galaxy. They are thought to be large scale magnetic fields possibly generated by winds from hot stars. Farhad Yusef-Zadeh, my collaborator on the photo, leads the study of radio emission from the Galactic Center. The orange color is 1.1mm emission, which means that we're seeing something completely different. This light actually comes from dust. We usually see dust in absorption because in the optical, it blocks light. There is so much dust between us and the Galactic Center that we can't see it at all at optical wavelengths.
Sagittarius B2 is the bright blob just to the left of center. It is the most massive collection of gas and dust in our galaxy. It is full of different types of molecules including complex organic molecules. A new generation of massive stars is thought to be forming there. Spitzer's 8 micron view is presented in cyan. Mostly this comes from PAH, Polycyclic Aromatic Hydrocarbon, emission. PAHs are big molecules with lots of Carbon and Hydrogen chained together. Stars are visible at these wavelengths because the dust isn't as effective at blocking out infrared light - but look closely at the orange regions on the right side of the image. You might notice that not only is there dust there, but there's also less PAH emission visible. This is because on the right side of the Galactic Center, the spiral arm is behind the dust, and on the left side it is in front. When dust blocks out infrared light, the object we see is called an 'infrared dark cloud'. These clouds are usually places where star formation has not yet started, but will soon. This image was created using GIMP, the Gnu Image Manipulation Program, using a variety of layers, opacities, etc.
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