This page tracks events in the static sky processing for Large Area Processing for label LAP.ThreePi.20120706

Bill Sweeney

Current Status

Staticsky processing was stopped during the week ending 2012-12-07 to allow the stack construction up to RA 2H to complete. It was restarted on 2012-11-11 with the area with RA < 15 DEC < 10 queued first.

The plot below shows the progress as of 2012-12-13 22:30 UTC

The stripe containing the Kepler field is on the left side of the plot 18 < RA < 20. The current area of interest RA < 15 and DEC < 10 should finish by 14-Dec.

Other areas that have been processed were queued during several changes of direction described below.

Sky calibration status 2012-12-10

The plot below shows the number of detections (matched and real) per skycell (log scale) for the region 267 < RA < 303 DEC > 10.

False Detections from y band stacks

We have noticed that some skycells are getting large numbers of matched (forced photometry) detections. These are caused by false detections in the y band. Recall that forced photometry is performed for all y band sources that are not matched with a detection in another band while detections for the other filters must match 2 other bands before forced photometry is done.

This plot shows the number of matched detetctions in i band verses the number of detected sources in y band.

If we plot the ratio of the number of matched detections to the number of detected sources for each band we can see these outliers. The following plots shows the ratio for the r band versus that in the ratio in i band for each stack. The plot on the left shows the full range including the outliers wile the plot on the right zooms in on the values near zero.

The plots for g and z show the same shape while the y band plot does not show the tail.

We propose re-running psphotStack for these skycells changing the rule that matched detections are created for all unmatched y band detections if some criteria is met. We can get rid of the worst of the outliers with the following cut.

             Nmatched_i / NDetected_i > 0.4 && Nmatched_r /  NDetected_r > 0.6

This effect is seen in 3% of the skycells north of 30 degrees declination.

Archival Notes

The following sections are notes on the early days of static sky processing for LAP 20120706

Beginnings 2012-11-21

It was decided to begin the stack photometry with the region containing the Kepler field (18h30m,+33d45') -> (20h20m,+52d30'). These skycells were queued for staticsky processing on November 21.

After those runs completed a list of projection cells that had completed LAP stacking were queued for processing. These were queued in order of projection cell number. This turns out to be a band at low declinations. These proceeded over the Thanksgiving holiday weekend.

Change of direction 1

After the holiday a change of direction was made. Rather than go in band of declination we went to stripes in RA. The outstanding runs were set to state ='wait' and skycells were queued in the band 9 < RA < 10

Change of direction 2

Due to some mis-communication we decided that it would be better for PSPS to load in decliation bands, so the existing runs were set back to state ='new' and new runs were queued in this region.

Change of direction 3

As a result of further discussions it was determined to go back to processing by RA stripes. The RA band including the Kepler field was made the highest priority. The skycells with centers above declination 10 were completed on 2012-12-04. The plot below shows the completion at that time.

Sky Calibration

The staticsky calibration processing was begun on 2012-12-03. This proceeds at a higher rate then the psphot operations.

For the region of proposed first ingest (270 < RA < 300) there are 55733 skycells to process. 14865 were completed on the first day.

Going Forward

The current plan is to postpone processing of the region near the galactic center (270 < RA < 300, DEC < 10) and proceed with ra stripes at 120 degrees. So far I have left the existing runs in wait state, and change them to run as needed. For simplicity we could drop them and change the label, but so far I've been managing the states. Here are the locations of the "waiting" skycells.

Change in direction 4

It was decided that rather than starting at ra 120 degrees, to instead process southern most part of the sky between 0 and 15 hours and declination < 10 degrees. The goal is to provide potential quasar targets for a KP10 group at MPIA that has observing time at La Silla net month.