Index page for ALMA related results and reports

Results from imaging simulations using SIL


8th November 2000 I've been dealing with the problem of registering images to obtain difference maps for arrays other than A. Registration experiments for the C arrays shows the current state of the art, and proposed future strategy. If people are happy with this, a rash of results will ensue. Also it would be good to have a consensus on a definition of a fractional difference image.
14th September 2000 The first batch of results for the A array images CLEANed to 10,000 iterations have been posted. To aid the organisation of this page, and also reflecting the fact that the CLEAN results are hosted on another site, a single link to a new index page for the CLEAN results is provided below. The old CLEAN results are left here for the time being. The CLEAN parameters used are those of our best consensus, and will be posted soon. The B, C and E arrays are taxing me as to the registration of the convolved downsampled model and the deconvolved subimage for differencing purposes. However the scripts have basically been written, so once this is sorted out the results should follow pronto.
31st August 2000 The A and C arrays' imaging simulations have been redone with the shorter integration times (14 and 60 seconds respectively) and results for the B array (integration time of 29 seconds) are posted for the first time. For the newly posted results, the grey scale plots of the dirty beam are now in the range -3% to +10%, except for the KB???SN+25B7 case where I seem to have lost the image between Linux and Windows. I'll post it later. STOP PRESS 2.15pm 31st August: I have.
22nd August 2000 Since the last upload, it appears that the integration time for the C arrays should be of the order of 60 seconds, and the integration time for the A arrays of the order of 14 seconds. The latter requires more disk space, but I have redone the basic UV and dirty image simulations for the -23 declination, as well as redoing the entire set of declinations for the C arrays. These need to be uploaded, but look pretty much identical to the results posted here at present. Using the new A array results, CLEANing has taken place, and also calculation of difference images. These results are presented in the CLEAN section below.
15th August 2000- The integration time of three minutes (chosen deliberately to keep disk usage sensible) was felt to be too long for the A arrays, so the results so far for the A arrays have been redone with an integration time of 1 minute. This site has been updated with the redone A array results.
11th August 2000- The dirty beam contour plots for the 4 hour tracks are captioned as being to the 10% level- in actual fact they are up to the 5% level, as may be seen by inspection of the list of contours beneath the individual plots. Sorry about that- when I get to 30 MB of errors I'll issue a Sevice Pack for the site.

A array results

Posted 31st August 2000

B array results

Posted 31st August 2000

C array results

Posted 31st August 2000

E array results

Posted 7th August 2000

Index page for the up to date CLEAN results

Old, preliminary, CLEANED images of historical interest

Posted 22nd August 2000 Results posted on 22nd August, below- M51 results are 1000 iterations, MINPATCH 256, PHAT 0.02, BMAJ, BMIN, BPA as indicated on the model images page, one CLEAN covering the whole image, and FACTOR = 0.5; other results are 5000 iterations, MINPATCH 51, other parameters the same.
The 5000 iterations for the four hour tracks took about 3 hours to process, each. An elliptical CLEAN beam was used accidentally due to a (now corrected) bug in my CLEANing script. The models were processed correspondingly however, when convolving prior to calculating the difference images. The actual BMAJ, BMIN values were that of the +25 degree declination for the A array, which is why these models are shown here. Clearly the correct CLEAN beam will have to be employed and these results redone, but they are presented here for consideration.
The results generally suggest more CLEANing is necessary, I believe. The MPD and MAR results are appreiciably poorer than M51, CYG and SDC so other paremater changes may be necessary. This is not a problem- provision for different paramater sets, read from files, for each image/array combination has been made in the automating scripts.

Page updated by Steven Heddle on 8th November 2000