- Timestamp:
- Aug 15, 2020, 10:43:08 AM (6 years ago)
- Location:
- trunk/doc/release.2015/ps1.analysis
- Files:
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- 5 edited
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Makefile (modified) (2 diffs)
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analysis.tex (modified) (14 diffs)
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pics/compare.mags.pdf (modified) ( previous)
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pics/petrosians.mags.pdf (modified) ( previous)
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response.txt (modified) (5 diffs)
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trunk/doc/release.2015/ps1.analysis/Makefile
r41324 r41402 4 4 # 5 5 DO_PDFLATEX = 1 6 DO_BIBTEX = 16 DO_BIBTEX = 0 7 7 8 8 help: … … 24 24 PDFPICS = \ 25 25 pics/peaks.pdf \ 26 pics/galplanecut.pdf \27 26 pics/FWHM.smooth.trend.v1.ps1.pdf \ 27 pics/iq.exposures.pdf \ 28 28 pics/radial.profiles.pdf \ 29 29 pics/moment.class.pdf \ 30 pics/mag.resid.psf.pdf \ 31 pics/mag.resid.aper.pdf \ 30 pics/completion.ppsim.pdf \ 31 pics/psphot.complete.pv3.pdf \ 32 pics/mag.resid.psf.v1.pdf \ 33 pics/mag.resid.aper.v1.pdf \ 34 pics/bright.mag.resid.pdf \ 35 pics/zpt.mjd.v0.i.pdf \ 36 pics/zptres.hist.v0.i.pdf \ 37 pics/galplanecut.pdf \ 38 pics/petrosians.mags.pdf \ 32 39 pics/galaxy.exp.complete.pdf \ 33 40 pics/galaxy.dev.complete.pdf \ 34 41 pics/galaxy.exp.params.pdf \ 35 pics/galaxy.dev.params.pdf 42 pics/galaxy.dev.params.pdf \ 43 pics/compare.mags.pdf 36 44 37 45 PNGPICS = \ -
trunk/doc/release.2015/ps1.analysis/analysis.tex
r41347 r41402 29 29 30 30 %\def\picdir{/home/eugene/chipresid.20140404} 31 \def\picdir{pics}32 %\def\picdir{.}31 %\def\picdir{pics} 32 \def\picdir{.} 33 33 34 34 % Pick a terse version of the title here; … … 184 184 the image data products and a hierachical database of measurements 185 185 using a system developed specifically for the Pan-STARRS dataset. 186 Development of this database system swas the product of a186 Development of this database system was the product of a 187 187 collaboration between the Pan-STARRS Project and Alex Szalay's 188 188 database development group at The Johns Hopkins University (JHU) … … 375 375 is performed in parallel on each of the individual CCDs in the 376 376 camera. This so-called \ippstage{chip} stage analysis includes the 377 detrending of CCD image as well as the detection and analysis of377 detrending of CCD image (instrumental signature removal) as well as the detection and analysis of 378 378 sources in the image using the basic version of \ippprog{psphot}. 379 379 The next stage of the analysis, the \ippstage{camera} stage, … … 388 388 a large regular pixel grid is defined, and then subdivided along 389 389 pixel boundaries into smaller units which are well-matched to the 390 memory footprint of our processing compute sr. These smaller images,390 memory footprint of our processing computers. These smaller images, 391 391 called `skycells' are defined with 1 arcminute of overlap with their 392 392 neighbors to that any modest-sized object can be analysed entirely … … 525 525 and astrometry accuracy at the level of our goals, not only must the 526 526 measurement of the astronomical detections be precise, but it is 527 necessary for the detrending (instrumental signature remove)and527 necessary for the detrending and 528 528 calibration processes to correct for a wide variety of systematic 529 529 effects and it is also necessary for the observations to be 530 530 performed in such a way that the data can be calibrated well. These 531 other saspects of the process are discussed in detail elsewhere531 other aspects of the process are discussed in detail elsewhere 532 532 (Papers I, III, V). In the end, the goals were largely achieved for 533 533 the Pan-STARRS\,1 $3\pi$ survey. As reported in Paper V, the … … 1227 1227 classification of the sources. As discussed below, the second 1228 1228 moments are used to select candidate stellar sources to be used in 1229 modeling the PSF and t he exclude`cosmic rays' and extended sources.1229 modeling the PSF and to identify `cosmic rays' and extended sources. 1230 1230 The radial moment is used in the measurement of the Kron magnitudes \citep{1980ApJS...43..305K}. 1231 1231 The higher-order moments are provided primarily for image quality … … 1736 1736 radial moment as the major axis size for the Gaussian ($\sigma_a$), retaining 1737 1737 the position angle and axial ratio from the calculation above. We use 1738 these guess parameters for all version of the PSF analytical models,1738 these guess parameters for all versions of the PSF analytical models, 1739 1739 despite the fact that for the versions which are not approximations of 1740 1740 Gaussians these guess values will be systematically incorrect. … … 2146 2146 source model parameters (position in $X$ and $Y$ and flux 2147 2147 normalization) are allowed to vary in the fit. Note that we do {\em 2148 not} allow the local sky to be fitted as a free parameter s. Since2148 not} allow the local sky to be fitted as a free parameter. Since 2149 2149 we have subtracted a model for the background, allowing the sky to 2150 be again at this stage is redundant. In fact, in our testing, we2151 found that allowing the sky to float resulted in higher scatter for2150 be fitted again at this stage is redundant. In fact, in our testing, we 2151 found that allowing the sky background value to float resulted in higher scatter for 2152 2152 the flux normalizations. For the non-linear fitting, 2153 2153 \ippprog{psphot} again uses the Levenberg-Marquardt technique.} The … … 2622 2622 crowding and confusion. Since the injection and recovery analysis of 2623 2623 the fake sources operates on the source-subtracted image and does not 2624 attempt to fully discover ythe sources, this analysis over-estimates2624 attempt to fully discover the sources, this analysis over-estimates 2625 2625 the completeness in crowded fields. To explore the completeness in 2626 2626 crowded field images, we generate a series of simulated images using a … … 3480 3480 least the smallest 4 apertures. Sources for which photometry in these 3481 3481 fixed aperture are calculated have the flag bit 3482 \code{PM_SOURCE_MODE_RADIAL_FLUX} set. \textadd{Although these aperture are3482 \code{PM_SOURCE_MODE_RADIAL_FLUX} set. \textadd{Although these apertures are 3483 3483 chosen to match the SDSS apertures, the SDSS images are measured on 3484 3484 unconvolved images. Since the median seeing for the SDSS images is … … 3769 3769 \includegraphics[width=\hsize,clip]{\picdir/{compare.mags}.pdf} 3770 3770 \caption{\label{fig:compare.mags} Comparison of {\tt psphot} average 3771 chip photometry , average forced-warp photometry, and stack3772 photometry from $3\pi$ Survey data to average forced-warp3771 chip photometry (panel a), average forced-warp photometry (panel b), and stack 3772 photometry (panel c) from $3\pi$ Survey data to average forced-warp 3773 3773 photometry from the Pan-STARRS\,1 Medium-Deep Survey field MD06 3774 3774 At bright magnitudes, average chip photometry is the most … … 3795 3795 Paper V).} 3796 3796 3797 {\TEXTADD As can be clearly seen in the figure, the average from the forced-warp 3798 photometry is slightly worse than the chip photometry, while the stack 3799 PSF photometry is significantly degraded. We attribute the latter 3800 effect to the highly-textured PSF observed in the stack images due to 3801 the combination of variable PSFs in each exposure and significant 3802 masking fraction in the PS1 camera. At the faint end, the chip 3803 photometry is significantly worse that both average warp and stack 3804 photometry. First, in order to have a measurement, a source must be 3805 detected above the detection threshold in at least one of the 3806 exposures, limiting the depth possible of the average chip 3807 photometry. Second, at the faint end, only bright fluctuations will be 3808 detected, resulting in a bright bias. This latter effect is clearly 3809 seen in Figure~\ref{fig:compare.mags} as the average chip magnitudes 3810 diverge from the deeper Medium Deep photometry measurements. As has 3811 been noted elsewhere \citep{2018ApJS..234....1B}, the warp and stack 3812 photometry is also degraded for objects which have significant proper 3813 motion over the course of the $3\pi$ Survey since the position is held 3814 constant for all epochs, while the average chip photometry is 3815 calculated on detections which are cross-matched in the database. 3816 Thus, warp and stack photometry should be avoided for sources with 3817 proper motion greater than roughly 100 milliarcseconds per year.} 3797 {\TEXTADD As can be clearly seen in the figure, the average from the 3798 forced-warp photometry is slightly worse than the chip photometry, 3799 while the stack PSF photometry is significantly degraded. We 3800 attribute the latter effect to the highly-textured PSF observed in 3801 the stack images due to the combination of variable PSFs in each 3802 exposure and significant masking fraction in the PS1 camera. At the 3803 faint end, the chip photometry is significantly worse that both 3804 average warp and stack photometry. First, in order to have a 3805 measurement, a source must be detected above the detection threshold 3806 in at least one of the exposures, limiting the depth possible of the 3807 average chip photometry. Second, at the faint end, only bright 3808 fluctuations will be detected, resulting in a bright bias, a form of 3809 Eddington bias \citep{1913MNRAS..73..359E}. This latter effect is 3810 clearly seen in Figure~\ref{fig:compare.mags} as the average chip 3811 magnitudes diverge from the deeper Medium Deep photometry 3812 measurements. As has been noted elsewhere 3813 \citep{2018ApJS..234....1B}, the warp and stack photometry is also 3814 degraded for objects which have significant proper motion over the 3815 course of the $3\pi$ Survey since the position is held constant for 3816 all epochs, while the average chip photometry is calculated on 3817 detections which are cross-matched in the database. Thus, warp and 3818 stack photometry should be avoided for sources with proper motion 3819 greater than roughly 100 milliarcseconds per year.} 3818 3820 3819 3821 \subsection{Forced Galaxy Models} … … 4089 4091 \cite{2008ApJ...677..808Y}. The analysis of the sources detected in 4090 4092 these difference images uses a portion of the \ippprog{psphot} code 4091 embedded in the program, \ippprog{ppSub}, which generates those image .4093 embedded in the program, \ippprog{ppSub}, which generates those images. 4092 4094 Difference images are generated from three different possible image 4093 4095 combinations: 1) pairs of individual exposures are differenced using … … 4287 4289 4288 4290 \bibliographystyle{apj} 4289 \bibliography{lib}{}4290 %\input{analysis.bbl}4291 %\bibliography{lib}{} 4292 \input{analysis.bbl} 4291 4293 4292 4294 \end{document} -
trunk/doc/release.2015/ps1.analysis/response.txt
r41347 r41402 1 2 We thank the referee for the many detailed suggestions. We have 3 incorportated these in almost all cases into the article. The 4 result is greatly improved in terms of clarity and context. Below are 5 our specific responses the the suggestions of the referee. 6 7 (Our responses to the comments start with "**" and are indented). 1 8 2 9 Referee Report … … 67 74 mask values appear in the DR1 and DR2 data releases. For example, 68 75 Tables 1-4 must refer to some named quantities in the data releases. 69 This paper should also clearly indicate which quantities are recommended70 to be most reliable for point source astrometry, fluxes and colors. 71 (My guess would be the astrometry from the stacked images in Sec 4.7, since 72 those aren't recomputed; fluxes from the averaged forced photometry 73 in Sec 6; and colors from either aperture photometry on the stacked 74 images or from the averaged forced photometry, and the authors must 75 know which is demonstrated to be more reliable). The paper should 76 state the same for galaxy astrometry, fluxes and colors.76 This paper should also clearly indicate which quantities are 77 recommended to be most reliable for point source astrometry, fluxes 78 and colors. (My guess would be the astrometry from the stacked images 79 in Sec 4.7, since those aren't recomputed; fluxes from the averaged 80 forced photometry in Sec 6; and colors from either aperture photometry 81 on the stacked images or from the averaged forced photometry, and the 82 authors must know which is demonstrated to be more reliable). The 83 paper should state the same for galaxy astrometry, fluxes and colors. 77 84 78 85 ** for each section, we have added a summary of where the values may … … 97 104 that the photometric goals are achieved 98 105 99 ** added comparion discussion of chip, warp, stack photometry at the end of Sec 6.1 106 ** added comparion discussion of chip, warp, stack photometry at the 107 end of Sec 6.1 100 108 101 109 - Sec 7, where the image differencing detections and photometry is used … … 643 651 are completely constrained. 644 652 645 We have renamed Section 6 as Forced Warp Analysis and split out the646 PSF vs extended source analysis sections as recommended. We added647 some explanation at the end of the section to explain what we mean by 648 'forced'.653 ** We have renamed Section 6 as Forced Warp Analysis and split out the 654 PSF vs extended source analysis sections as recommended. We added 655 some explanation at the end of the section to explain what we mean 656 by 'forced'. 649 657 650 658 - The general description of the section should end with "variant of psphot", … … 665 673 - The terms "skycell" and "warp image" are first used here without 666 674 definition. Are warp images the same as CAMERA and CHIP? 675 667 676 ** Updated Section 2 to outline the relevant processing stages and 668 677 define 'warp', 'skycell', and 'stack' more cleanly.
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