Changeset 2241 for trunk/doc/design/ippSRS.tex
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trunk/doc/design/ippSRS.tex
r2192 r2241 1 %%% $Id: ippSRS.tex,v 1.1 1 2004-10-22 04:43:35eugene Exp $1 %%% $Id: ippSRS.tex,v 1.12 2004-10-29 22:00:08 eugene Exp $ 2 2 \documentclass[panstarrs,spec]{panstarrs} 3 3 … … 6 6 \subtitle{Software Requirements Specification} 7 7 \shorttitle{IPP SRS} 8 \author{Eugene Magnier, Paul A. Price, Josh Hoblitt}8 \author{Eugene A. Magnier, Paul A. Price, Josh Hoblitt} 9 9 \audience{Pan-STARRS PMO} 10 10 \group{Pan-STARRS Algorithm Group} … … 34 34 \RevisionsStart 35 35 % version Date Description 36 DR.01 & 2003.01.01 & First draft \\ \hline 37 DR.02 & 2003.03.10 & Second draft \\ \hline 38 DR.03 & 2003.04.13 & Most paragraphs fleshed out \\ \hline 39 DR.04 & 2003.04.27 & Basic text frozen for internal review \\ \hline 40 DR.05 & 2003.05.24 & Incorporating comments from internal review \\ \hline 36 DR.01 & 2004.01.01 & First draft \\ \hline 37 DR.02 & 2004.03.10 & Second draft \\ \hline 38 DR.03 & 2004.04.13 & Most paragraphs fleshed out \\ \hline 39 DR.04 & 2004.04.27 & Basic text frozen for internal review \\ \hline 40 DR.05 & 2004.05.24 & Incorporating comments from internal review \\ \hline 41 DR.06 & 2004.08.06 & Revisions in prep of SRR \\ \hline 42 DR.06 & 2004.10.22 & Revisions based on SRR \\ \hline 41 43 \RevisionsEnd 42 44 … … 580 582 \subsubsection{Image Server} 581 583 582 %% IPP Image Server T & F583 584 Image Server tasks and functions:585 586 \begin{itemize}587 588 \item The IPP Image Server stores images on a distributed collection589 of computer disks. Individual instances of a file are only required590 to be stored on a single machine (striping across computers is not a591 requirement).592 593 \item The IPP Image Server attempts to store an image on a specific594 machine if requested by the user.595 596 \item If such a request cannot be honored (ie, the machine is down),597 the IPP Image Server selects an appropriate machine and notifies the598 requesting agent of the new location.599 600 \item The IPP Image Server stores multiple copies of each image upon601 request, the number of copies specified independently for each file602 by the user.603 604 \item The IPP Image Server maintains a record of all image copies605 currently available in the repository. This record includes at606 least the image name, location (which machine), the image size, and607 the state of the image (available, locked,608 deleted).609 610 \item The IPP Image Server locks images in the repository on request.611 Both read (shared) and write (exclusive) locks are provided. A read612 lock prevents write access to the file; a write lock prevents both613 read and write access. Access prevention may be advisory rather614 than rigorously enforced.615 616 \item The IPP Image Server return the image location (the computer or617 computers on which it resides) upon request.618 619 \item The IPP Image Server provides a specified image upon request.620 621 \item The IPP Image Server deletes images in the repository on622 request.623 \end{itemize}624 625 584 %% IPP Image Server Requirements 626 585 627 IPP Image Server requirements:586 IPP Image Server has the following requirements: 628 587 629 588 \begin{enumerate} … … 697 656 \end{center} 698 657 \end{table} 699 700 %% IPP AP DB T & F701 702 The purpose of the AP Database is:703 \begin{itemize}704 \item to enable the photometric calibration of images705 \item to enable the astrometric calibration of images706 \item to enable the construction of flat-field correction frames707 \item to enable the construction of a photometric calibration catalog708 \item to enable the construction of an astrometric calibration catalog709 \item to monitor the system photometry calibration parameters710 \item to monitor the system astrometry calibration parameters711 \item to perform the identification of single-occurance transients712 \end{itemize}713 714 The tasks and functions of the AP Database include:715 716 \begin{itemize}717 \item The AP Database accepts and stores individual detections and718 collections of detections along with information about the image719 which provided the detections.720 721 \item Detections are saved as one of several detection classes (P2,722 P4$\Sigma$, P4$\Delta$, SS) and the AP Database stores the723 appropriate parameters, listed in Table~\ref{APdetections}, for each724 class.725 726 \item The AP Database identifies the image which provided the727 detection, or in the case of external references, an identifier728 specific to the reference source.729 730 \item The AP Database groups detections into objects on the basis of731 positional coincidence and measures average parameters of those732 objects.733 734 \item The AP Database stores parallax and proper motion parameters for735 a subset of the average objects.736 737 \item The AP Database stores image and filter calibration information738 necessary to convert between instrumental magnitudes and calibrated739 magnitudes in standard systems.740 741 \item The AP Database performs at least the follow queries, with742 constraints on the output based on at least time ranges, magnitude743 limits, error limits:744 745 \begin{itemize}746 \item given $(RA,DEC)$ and a Radius, return all objects and/or747 detections in the region.748 749 \item given $(RA,DEC)_0$ to $(RA,DEC)_1$, return all objects and/or750 detections in the region.751 752 \item given $(RA,DEC)$, return closest object.753 754 \item given object ID, return all detections.755 756 \item given detection, return source image data.757 758 \item given detection, return object.759 760 \item given $(RA,DEC)$, return all images overlapping coordinate.761 762 \item given $(RA,DEC)$ and a Radius, return all images overlapping region.763 764 \item given $(RA,DEC)_0$ to $(RA,DEC)_1$, return all images overlapping region.765 766 \item given detection instrumental magnitude, return derived767 magnitudes based on calibration information.768 769 \item given a collection of detections in a filter, determine the770 object average magnitude in that filter.771 772 \item given a collection of objects and detections, determine the773 individual image zero-points.774 775 \item given a region, return all possible combinations of the object776 or detection magnitudes $(M_1 - M_2)$.777 778 \item given a list of $(RA,DEC)$ entries, return all nearest objects.779 780 \item given a filter, telescope, or detector, return all calibration781 terms and history.782 783 \item given a detection, return all non-detections from images which784 overlapped the detection coordinates.785 \end{itemize}786 787 \item The AP Database shall accept detection IDs of moving objects and788 label the detections with the identified object.789 \end{itemize}790 658 791 659 %% IPP AP DB Requirements … … 834 702 \end{table} 835 703 836 %% Metadata DB T & F837 838 The Metadata Database tasks and functions:839 840 \begin{itemize}841 \item The Metadata Database stores the classes of data listed in842 Table~\ref{metadata}. Thus, the Metadata Database stores and serves843 metadata for all raw images, for processed images, for the844 calibration images (both raw and master), for the extracted object845 lists. Metadata describing the environmental conditions at the846 telescope is also stored and provided as needed.847 848 \item The Metadata Database responds to simple queries which return849 the data in the categories listed in Table~\ref{metadata} based on850 the primary data key and with basic constraints of time ranges and851 other simple conditional constraints.852 853 \item The Metadata database stores the configuration information with854 restricted access so that only specific people may change the855 information (eg, science parameters available to the science team;856 software configuration parameters available to the system857 maintainers).858 \end{itemize}859 860 704 %% Metadata DB Requirements 861 705 … … 883 727 \subsubsection{Controller} 884 728 885 %% IPP Controller T & F886 887 IPP Controller tasks and functions:888 889 \begin{itemize}890 891 \item On startup, the IPP Controller attempts to establish892 communication with all of its computers and set their state to be893 {\tt alive} or {\tt dead} based on the success of the894 connection.895 896 \item The IPP Controller detects computers which crash or stop897 responding and set their state to {\tt dead}.898 899 \item The IPP Controller attempts to re-establish communication with900 {\tt dead} computers.901 902 \item The IPP Controller accepts tasks from external users and903 systems, which may specify a desired CPU (node) and priority in904 addition to the task command.905 906 \item The IPP Controller attempts to run pending tasks on the desired907 node, if available (not {\tt dead} or {\tt off}).908 909 \item If the node is unavailable, the IPP Controller attempts to run910 the task on another node.911 912 \item If the node is available, the IPP Controller attempts to run a913 given task only if no higher-priority tasks are available and no914 task is currently being executed.915 916 \item The IPP Controller monitors the output from the task and writes917 it to an associated log destination.918 919 \item The IPP Controller monitors the execution status of each task920 currently executing on a node and performs the following actions:921 922 \begin{itemize}923 \item identify the task as successful if it has a valid exit status.924 \item identify the task as unsuccessful if it has an error exit status.925 \item identify the task as unattempted if the computer crashed.926 \end{itemize}927 928 \item The IPP Controller accepts and performs the following external929 commands:930 \begin{itemize}931 \item add a task to the pending task list.932 \item delete a specific task from the pending task list.933 \item return the current status of a specific task.934 \item return a list of all pending and non-pending tasks.935 \item set a specified computer state to {\tt off} or {\tt dead}.936 \item restrict a specified CPU to a class of tasks.937 \item halt execution of a specified task.938 \item set the IPP Controller state to {\tt finish}, {\tt abort}, or {\tt stop}.939 \end{itemize}940 \end{itemize}941 942 729 %% IPP Controller Requirements 943 730 … … 963 750 964 751 \subsubsection{Scheduler} 965 966 %% IPP Scheduler T & F967 968 The IPP Scheduler tasks and functions:969 970 \begin{itemize}971 \item The IPP Scheduler sends the analysis tasks which it initiates to972 the IPP Controller.973 974 \item All analysis tasks sent by the IPP Scheduler include a complete975 UNIX command with necessary arguments, the priority of the task, and976 optionally the desired processing node.977 978 \item When the IPP Scheduler is placed in the {\em paused state}, it979 only initiates User-requested tasks.980 981 \item When the IPP Scheduler is placed in the {\em interactive state},982 it initiates User-requested tasks as well as data transfer tasks.983 984 \item When the IPP Scheduler is placed in the {\em automatic state},985 it initiates the most appropriate task based on the inputs and986 dependency rules.987 988 \item The IPP Scheduler sends the exit status of the analysis tasks to989 the appropriate destination as defined by the task dependency table.990 \end{itemize}991 752 992 753 %% IPP Scheduler Requirements … … 1078 839 \subsubsection{Phase 1 : image processing preparation} 1079 840 1080 Phase 1 is the image processing preparation stage. The analysis is 1081 performed on a complete FPA. At the end of this analysis, the FPA is 1082 ready to be analysed in detail in Phase 2. The Phase 1 tasks and 1083 functions are: 1084 1085 \begin{itemize} 1086 1087 \item Extract FPA guide stars to determine astrometry across the full FPA 1088 1089 \item If no guide stars are available, phase 1 must measure the pixel 1090 coordinates of known bright stars expected in the field from the 1091 image data. 1092 1093 \item The total number of stars and size of the bright-star 1094 acquisition box shall be a user-configurable parameter in the range 1095 20 - 250. 1096 1097 \item Calculate the Image cell / Sky cell overlaps for each image. 1098 Sky cells which do not have sufficient science image overlap $< 5\%$ 1099 are excluded from the overlap table. 1100 1101 \end{itemize} 1102 1103 The Phase 1 requirements are: 841 The Phase 1 analysis stage is performed on each science exposure (each 842 complete FPA image) to calculate basic astrometric data needed by the 843 later stages. The Phase 1 requirements are: 1104 844 1105 845 \begin{enumerate} … … 1123 863 %% Phase 2 1124 864 \subsubsection{Phase 2 : image reduction} 1125 865 1126 866 Phase 2 is the detrend stage, in which each detector is separately 1127 867 processed to remove instrumental signatures. The result of Phase 2 is … … 1129 869 collection of objects detected in the image and characterized in a 1130 870 rudimentary way (star / non-stellar), and a measurement of the PSF 1131 across the detector. 1132 1133 The tasks and functions of Phase 2 are as follows: 1134 1135 \begin{itemize} 1136 1137 \item Convolve the flat-field and high-spatial-frequency fringe images 1138 with the OT kernel. 1139 1140 \item Mask ghosts of bright stars which introduce residual feature 1141 more significant than 1\% of the background. 1142 1143 \item Bias subtract the image. 1144 1145 \item Correct each chip independently for non-linearity. 1146 1147 \item Flat-field correct the image. 1148 1149 \item Subtract a fit to the detector-dependent fringing pattern. 1150 1151 \item Subtract a fit to the low-spatial frequency sky background. 1152 1153 \item Identify `cosmic rays' on the basis of morphology. 1154 1155 \item Perform (positive) object detection on the processed images, 1156 down to a user-configured threshold, likely to be $\sim 20\sigma$. 1157 The detection threshold may optionally be a function of the average 1158 background flux or the local noise level. 1159 1160 \item Measure the following object parameters: 1161 1162 \begin{itemize} 1163 \item object centroid and position errors. 1164 \item an extended object position ($x_g, y_g$). 1165 \item instrumental PSF magnitude and error. 1166 \item local background level and error. 1167 \item second moments ($\sigma_{\rm min}, \sigma_{maj}$) of the object 1168 and their covariance matrix. 1169 \end{itemize} 1170 1171 \item Perform minimal object classification to distinguish objects 1172 which are consistent with a single PSF, objects which are 1173 inconsistently large, objects which are inconsistently small, and 1174 objects which are saturated. 1175 1176 \item Match the detected objects with known astrometric reference 1177 objects, including proper-motion compensation. 1178 1179 \item Fit the reference and detected object coordinates to determine 1180 astrometric parameters for the individual OTAs, including 1181 polynomials of the coordinates up to 3rd order (user-specified 1182 parameter). The Cell astrometric parameters are not allowed to vary 1183 in the fit, which uses outlier rejection to determine a robust 1184 solution. 1185 1186 \item Extract subrasters (`postage stamps') surrounding a 1187 user-specified list of coordinates from the flattened 1188 images, to be saved in the IPP Image Server. 1189 1190 \item measure the PSF variation as a function of detector position. 1191 1192 \end{itemize} 1193 1194 The Phase 2 requirements are: 871 across the detector. The Phase 2 requirements are: 1195 872 1196 873 \begin{enumerate} … … 1238 915 reference catalogs to determine improved photometric and astrometric 1239 916 calibrations for the FPA as a whole, and to improve the measurement of 1240 the PSF and sky variations across the field. The Phase 3 tasks and 1241 functions are as follows: 1242 1243 \begin{itemize} 1244 1245 \item Phase 3 uses the objects detected in Phase 2, matched with a 1246 user-specified reference photometry catalog, to determine the image 1247 photometric zero point and zero-point variations across the field. 1248 1249 \item If zero-point variations are significant ($> 0.01$ mag 1250 peak-to-peak), the zero-point variations are modeled with a 1251 polynomial correction of order 3 or less. 1252 1253 \item The photometric nature of the FPA image is categorized on the 1254 basis of the zero-point consistency, the transparency compared with 1255 recent long-term measurements in the filter, and the external 1256 indicators of photometricity. 1257 1258 \item Phase 3 uses the objects detected in Phase 2, matched with an 1259 appropriate astrometric reference catalog, to improve the distortion 1260 model used for the image. The resulting astrometric accuracy is 1261 consistent across the field to 30 mas, and is limited by the 1262 astrometric reference catalog, (eg, 100 - 250 mas for 1263 USNO-B1.0). 1264 1265 \item The Phase 3 analysis modifies the background correction of Phase 1266 2 based on the full-field statistics to achieve an accuracy of 1\% 1267 of the background. 1268 1269 \end{itemize} 1270 1271 The Phase 3 requirements are: 917 the PSF and sky variations across the field. The Phase 3 requirements 918 are: 1272 919 1273 920 \begin{enumerate} … … 1310 957 Phase 4 is the image combination stage, in which multiple images of 1311 958 the same portion of the sky are merged and confronted with the static 1312 sky image. The Phase 4 tasks and functions are as follows: 1313 1314 \begin{itemize} 1315 1316 \item The Phase 4 analysis determines the corresponding set of image 1317 pixels for a given sky cell. 1318 1319 \item These pixels are extracted from the input images, using the 1320 astrometric information for each OTA and Cell to determine the exact 1321 overlaps. 1322 1323 \item The Phase 4 analysis skips any sky cells with fewer than 5\% of 1324 their pixels overlapping the input images. 1325 1326 \item Pixels which have been extracted from the input images are 1327 geometrically warped to match the corresponding pixels in the sky 1328 image. This transformation is based on the measured astrometric 1329 solution for the input images relative to the reference catalog used 1330 to generate the static sky image. The warping may use a 1331 locally-linear astrometric solution to speed the processing. 1332 1333 \item Phase 4 determines the appropriate photometry scaling factors 1334 needed to combine the images photometrically. 1335 1336 \item When multiple images are combined, the group of input pixels 1337 which contribute to an output pixel are examined and pixels from the 1338 group of images which are inconsistent with the ensemble (by an 1339 amount defined by the user-configurable parameters) are identified 1340 and flagged, though this outlier rejection shall be performed 1341 optionally. 1342 1343 \item The resulting collection of pixels is used to construct a single 1344 output image, cleaned of the outliers. 1345 1346 \item The cleaned, combined image is PSF matched with the static sky 1347 image. 1348 1349 \item The static sky image is subtracted from the stacked, cleaned 1350 image, resulting in the difference image (P4$\Delta$ image) 1351 1352 \item The Phase 4 analysis performs object detection on the difference 1353 images. All objects in the difference image above a user-configured 1354 signficance threshold are detected, including both positive and 1355 negative flux objects. The detection threshold may optionally be a 1356 function of the average background flux or the local noise 1357 level. The likely significance threshold is $\sim 3\sigma$. 1358 1359 \item P4$\Delta$ objects have the following object parameters 1360 measured: 1361 \begin{itemize} 1362 \item object centroid and position errors. 1363 \item instrumental PSF magnitude and error. 1364 \item local background level and error. 1365 \item streak L, $\phi$, $\sigma_L$, $\sigma_\phi$. 1366 \item second moments ($\sigma_{\rm min}, \sigma_{maj}$) and their covariance matrix. 1367 \end{itemize} 1368 1369 \item Minimal object classification is performed to distinguish 1370 objects which are consistent with a single PSF, objects which are 1371 inconsistent, and objects which are saturated. 1372 1373 \item The pixels belonging to variable sources are masked in the 1374 input image. 1375 1376 \item A new, cleaned image is constructed from the masked input images 1377 (P4$\Sigma$ image) 1378 1379 \item Object detection is performed on the cleaned, summed image to a 1380 user-configured significance threshold ($\sim 7\sigma$). Only 1381 positive flux object are considered. The detection threshold may 1382 optionally be a function of the average background flux or the local 1383 noise level. 1384 1385 \item P4$\Sigma$ objects have the following object parameters 1386 measured: 1387 \begin{itemize} 1388 \item object centroid and position errors. 1389 \item an extended object position ($x_g, y_g$). 1390 \item instrumental PSF magnitude and error. 1391 \item local background level and error. 1392 \item second moments ($\sigma_{\rm min}, \sigma_{maj}$) and their 1393 covariance matrix. 1394 \item the Petrosian radius, magnitude, axis ratio, and angle. 1395 \item the S\'ersic radius, magnitude, axis ratio, angle, and parameter $\nu$. 1396 \end{itemize} 1397 1398 \item Minimal object classification is performed to distinguish 1399 objects which are consistent with a single PSF, objects which are 1400 inconsistent, and objects which are saturated. 1401 1402 \item Before the image is added to the static sky, it must pass Q/A 1403 tests: 1404 \begin{itemize} 1405 \item the measured photometry scatter for the image must be less 1406 than \tbr{1\%}. 1407 1408 \item the measured astrometry scatter for the image must be less 1409 than \tbr{30 mas}. 1410 \end{itemize} 1411 1412 \item The final, cleaned input image is added to the static sky so 1413 that an incrementally-deeper static sky image may be 1414 made. 1415 \end{itemize} 1416 1417 The Phase 4 requirements are: 959 sky image. The Phase 4 requirements are: 1418 960 1419 961 \begin{enumerate} … … 1433 975 time. \VER{TEST}{TLR:17} 1434 976 1435 \item completeness?1436 1437 \item contamination?977 \item \tbd{completeness} 978 979 \item \tbd{contamination} 1438 980 1439 981 \end{enumerate} … … 1458 1000 \end{enumerate} 1459 1001 1460 \subsubsection{Bias Image Creation} 1461 1462 The Bias calibration stage constructs a master bias image from a 1463 collection of raw bias images. The tasks and functions include: 1002 The calibrations consist of the following types of data: 1464 1003 1465 1004 \begin{itemize} 1466 1467 \item The Bias calibration stage corrects the input images based on 1468 the overscan region, determined from either the header or from 1469 metadata. 1470 1471 \item The Bias calibration stage combines the input images using the 1472 statistic specified by the user, selected from one of the following: 1473 sample mean, median, and mode, robust mean, median, and mode, and 1474 the clipped mean and median. 1475 1476 \item The Bias calibration stage construct residual images, in which 1477 the master bias is applied to the input images. 1478 1479 \item Outlier residual images, those for which the residual bias and 1480 variance in the bias image are excessive, are excluded from the 1481 input image stack and the bias image reconstructed. 1005 \item Mask 1006 \item Bias 1007 \item Dark 1008 \item Flat-field 1009 \item Fringe Pattern 1010 \item Low-spatial-frequency sky model 1011 \item Flat-field correction image 1012 \item Non-linearity correction 1013 \item Telescope astrometry model 1014 \item Zero-point corrections 1482 1015 \end{itemize} 1483 1484 \subsubsection{Dark Image Creation}1485 1486 The Dark calibration stage shall construct a master dark image from a1487 collection of raw dark images. The tasks and functions include:1488 1489 \begin{itemize}1490 1491 \item The Dark calibration stage raises an error if the input images1492 have exposure times which deviate by more than 2\%.1493 1494 \item The Dark calibration stage corrects the input dark images for1495 the bias.1496 1497 \item The Dark calibration stage combines the input images using the1498 statistic specified by the user, selected from one of the following:1499 sample mean, median, and mode, robust mean, median, and mode, and1500 the clipped mean and median.1501 1502 \item The Dark calibration stage constructs residual images, in which1503 the master dark is applied to the input images.1504 1505 \item Outlier residual images, those for which the residual level and1506 variance are excessive, are excluded from the input image stack and1507 the dark image reconstructed.1508 \end{itemize}1509 1510 \subsubsection{Flat-field Image Creation}1511 1512 The Flat-field calibration stage constructs a master flat-field image1513 from a collection of raw flat-field images. The tasks and functions1514 include:1515 1516 \begin{itemize}1517 1518 \item The Flat-field calibration stage accepts a group of images from1519 one of the following flat-field sources: dome, twilight,1520 night-sky.1521 1522 \item The flat-field calibration stage raises an error if the1523 input images in a single stack used more than one of the above1524 flat-field sources or multiple filters.1525 1526 \item The Flat-field calibration stage corrects the input flat-field1527 images for the bias and dark.1528 1529 \item The Flat-field calibration stage combines the input images using1530 the statistic specified by the user, selected from one of the1531 following: sample mean, median, and mode, robust mean, median, and1532 mode, and the clipped mean and median.1533 1534 \item The Flat-field calibration stage constructs residual images, in1535 which the master flat-field is applied to the input images.1536 1537 \item Outlier residual images, those for which the residual level and1538 variance are excessive ($> 0.1$\%, or 1.02 times the Poisson limit1539 of the flat-field image), are excluded from the input image stack1540 and the flat-field image reconstructed.1541 \end{itemize}1542 1543 \subsubsection{Mask Image Creation}1544 1545 The Mask calibration stage constructs a bad-pixel mask from a stack of1546 raw flat-field images and a master flat-field image. The tasks and1547 functions include:1548 1549 \begin{itemize}1550 1551 \item The Mask calibration stage masks the pixels which are1552 inconsistent in the input flats by more than 1\%, given sufficient1553 signal-to-noise in the input flats.1554 1555 \item The Mask calibration stage mask the pixels which are1556 consistently low or high in the input flats by more than a factor of1557 3 beyond the typical pixel.1558 1559 \item The Mask calibration stage masks the pixels identified in a1560 table of bad pixels generated externally to the calibration stage.1561 1562 \item The Mask calibration stage uses multiple bit values to identify1563 the different types of masked pixels.1564 1565 \item The Mask calibration stage raises an error if the input images1566 generate too many bad pixels in the mask.1567 \end{itemize}1568 1569 \subsubsection{Fringe-frame Creation}1570 1571 The Fringe-frame Creation calibration stage constructs a master fringe1572 frame from a stack of raw night-time sky images or from a stack of1573 dome fringe frames. The tasks and functions include:1574 1575 \begin{itemize}1576 1577 \item The Fringe-frame Creation calibration stage raises an error if1578 the input stack consists is images generated with more than one type1579 of fringe source or with multiple filters.1580 1581 \item The Fringe-frame Creation calibration stage flattens the input1582 images to remove the pixel-to-pixel sensitivity variations of the1583 detector.1584 1585 \item The Fringe-frame Creation calibration stage measures the fringe1586 amplitude on the input fringe images.1587 1588 \item The Fringe-frame Creation calibration stage scales the input1589 fringe images based on the fringe amplitude.1590 1591 \item The Fringe-frame Creation calibration stage combines the scaled1592 input images using the statistic specified by the user, selected1593 from one of the following: sample mean, median, and mode, robust1594 mean, median, and mode, and the clipped mean and median.1595 1596 \item The Fringe-frame Creation calibration stage constructs residual1597 images, in which the master fringe image is applied to the input1598 images, along with all necessary preceding calibration images.1599 1600 \item The Fringe-frame Creation calibration stage measures the1601 residual fringe amplitude on the residual images.1602 \end{itemize}1603 1604 \subsubsection{Low-spatial-frequency Sky Models}1605 1606 The Sky Model calibration stage constructs a sky model image set from1607 a stack of raw night-time sky images.1608 1609 \subsubsection{Flat-field correction Frame Creation}1610 1611 The Flat-field correction calibration stage constructs a flat-field1612 correction image from dithered observations of a stellar field. The1613 tasks and functions include:1614 1615 \begin{itemize}1616 1617 \item The Flat-field correction calibration stage constructs a1618 flat-field correction image from dithered observations of a stellar1619 field.1620 1621 \item The Flat-field correction calibration stage constructs a1622 flat-field correction image for each filter and camera1623 independently.1624 1625 \item The Flat-field correction calibration stage constructs a1626 correction image which makes the photometry of multiple observations1627 of the same stellar source consistent at different locations in the1628 focal plane.1629 1630 \item The Flat-field correction calibration stage constructs corrected1631 flat-field images using the measured correction.1632 1633 \item The Flat-field correction calibration stage determines the1634 consistency of the corrected flat-field images using the dithered1635 stellar field observations flattened with the corrected flat-field1636 image.1637 \end{itemize}1638 1639 \subsubsection{Non-linearity correction}1640 1641 The Non-linear correction calibration stage constructs a correction1642 model for low-level non-linearity effects in the detector. The tasks1643 and functions include:1644 1645 \begin{itemize}1646 1647 \item The Non-linear correction calibration stage constructs a1648 non-linear correction from a collection of images of a constant1649 source with varying exposure times.1650 1651 \item The Non-linear correction calibration stage construct a1652 non-linear correction which linearizes the detector fluxes1653 $<0.5\%$.1654 1655 \item The Non-linear correction calibration stage determines the1656 saturation regime, in which the non-linear correction is no longer1657 consistent to $<0.5\%$.1658 \end{itemize}1659 1660 \subsubsection{Telescope Astrometry Parameters}1661 1662 \begin{itemize}1663 \item The IPP Calibration system constructs static models of the1664 telescope astrometry parameters (e.g., distortion, detector warps)1665 once per week.1666 1667 \item The IPP Calibration system constructs static models of the1668 telescope astrometry parameters (e.g., distortion, detector warps)1669 with an accuracy to produce astrometry consistent to 301670 milliarcsec.1671 1672 \item The IPP Calibration system monitors changes in the telescope1673 astrometry parameters and issue a warning if the parameters change1674 by more than 2\%.1675 \end{itemize}1676 1677 \subsubsection{Zero-Point Monitoring}1678 1679 The IPP Calibration system determines telescope filter and camera1680 zero-points on a nightly basis with an accuracy sufficient to1681 determine photometry in the native filter systems to 5 millimags.1682 1016 1683 1017 \subsection{Modules} … … 1794 1128 1795 1129 \item IPP Controller - Analysis Tasks. The IPP Controller shall 1796 initiate the Analysis Tasks and monitor their output and exit1130 initiate the Analysis Tasks and monitor their output and exit 1797 1131 status.\TASK 1798 1132 … … 1835 1169 1836 1170 The report, `The Pan-STARRS Image Processing Pipeline Computational 1837 Chall ange' (PSDC-4xx-xx) discusses the assumptions and measurements1171 Challenge' (PSDC-400-006) discusses the assumptions and measurements 1838 1172 made to determine the IPP computing requirements, for both the PS-1 1839 1173 configuration and the PS-4 configuration, under multiple assumptions
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