| | 1 | = Heather's stacking adventures = |
| | 2 | |
| | 3 | This wiki describes my adventures while trying to stack things in both skyprobe and in gpc1. |
| | 4 | |
| | 5 | I am trying to process skyprobe images using ppStack. This has not been done before, but I have a wiki to describe some of my steps (see [wiki:IspSasProcessing]). The stacks look pretty crummy, which led to the following investigations: |
| | 6 | |
| | 7 | 1. why are there big chunks missing |
| | 8 | 2. why did it take 10k seconds? |
| | 9 | 3. why are the edges nan'd off |
| | 10 | |
| | 11 | These are stacks of roughly 100-200 skyprobe warps (in a special skyprobe tessalation where the pixel size is the size of a skyprobe pixel, and the 'skycell' is the size of a projection cell. The first investigation (why are there big chunks missing) I answered by writing a tool (in ipptrunk/tools/heather/stack_inspector.pl) - give it a stack_id, it will make binned fits of the stack and the input warps. You can easily open up the stack and all the inputs, which I did with skycell 1315 (g band). What I found out is that everything is covered multiple times. The skycell should be completely filled with pixels. |
| | 12 | |
| | 13 | At this point, I committed a sin: I downloaded IRAF to see if it could stack better. I did the dumbest stack possible (I fed it 200 images and said, go make a stack). IRAF complied and gave me a stack ~ 1 minute later, completely filled, very deep, very nice: |
| | 14 | |
| | 15 | [[Image(stuff.png)]] |
| | 16 | |
| | 17 | Next was to play with gpc1 images with IRAF for SAS. I downloaded a random g band skycell ( skycell.1495.014 ), grabbed the inputs, and stacked. I discovered 2 things: |
| | 18 | |
| | 19 | 1. Iraf doesn't like compressed files |
| | 20 | 2. Iraf doesn't like different bzero and bscale. |
| | 21 | |
| | 22 | Ken played with IRAF, and got a better IRAF stack: |
| | 23 | {{{ |
| | 24 | Apr 1 12:15: IMCOMBINE |
| | 25 | combine = median, scale = none, zero = none, weight = none |
| | 26 | reject = avsigclip, mclip = yes, nkeep = 1 |
| | 27 | lsigma = 3., hsigma = 2.5 |
| | 28 | lthreshold = -1000., hthreshold = 1000. |
| | 29 | blank = 0. |
| | 30 | Images |
| | 31 | /home/heather/sas_v8_stacks/o5745g0409o.356779.wrp.453852.skycell.1495.014.fun.fits |
| | 32 | /home/heather/sas_v8_stacks/o5745g0421o.356794.wrp.453876.skycell.1495.014.fun.fits |
| | 33 | /home/heather/sas_v8_stacks/o5745g0432o.356807.wrp.453888.skycell.1495.014.fun.fits |
| | 34 | /home/heather/sas_v8_stacks/o5745g0442o.356814.wrp.453903.skycell.1495.014.fun.fits |
| | 35 | /home/heather/sas_v8_stacks/o5746g0418o.357453.wrp.453912.skycell.1495.014.fun.fits |
| | 36 | /home/heather/sas_v8_stacks/o5746g0428o.357464.wrp.453927.skycell.1495.014.fun.fits |
| | 37 | /home/heather/sas_v8_stacks/o5746g0441o.357477.wrp.453937.skycell.1495.014.fun.fits |
| | 38 | /home/heather/sas_v8_stacks/o5746g0450o.357486.wrp.453947.skycell.1495.014.fun.fits |
| | 39 | /home/heather/sas_v8_stacks/o5748g0357o.358780.wrp.453989.skycell.1495.014.fun.fits |
| | 40 | /home/heather/sas_v8_stacks/o5748g0368o.358778.wrp.454010.skycell.1495.014.fun.fits |
| | 41 | /home/heather/sas_v8_stacks/o5748g0379o.358756.wrp.453971.skycell.1495.014.fun.fits |
| | 42 | /home/heather/sas_v8_stacks/o5748g0389o.358765.wrp.453992.skycell.1495.014.fun.fits |
| | 43 | |
| | 44 | Output image = sastestkenmed2, ncombine = 12 |
| | 45 | }}} |
| | 46 | |
| | 47 | Here is a comparison of IRAF to IPP for gpc1 |
| | 48 | |
| | 49 | [[Image(stuff.png)]] |
| | 50 | |
