Dataset Reader Plug-in

This plug-in provides functions that allow reading of individual datasets from Products from the HSA, without the need to read the entire product into memory.

The concrete example for which it was written, are PACS Level 1 Frames products. By not loading the noise cube, for a given amount of memory, one can load products twice as large. This plug-in can be used for any kind of product, but it provides a special function to the PACS Frames, which produces a Frames product that can be reprocessed, but that does not contain the noise cube.

How to use

Products are identified using their URN, which can be retrieved for example as follows, for a PACS Level 1 Frames product:

obs = getObservation(...)
framesRef = obs.refs["level1"].product.refs["HPPAVGR"].product.refs[0]
urn = framesRef.urn

To read a single dataset from a given product:

urn = 'urn:hsa:herschel.pacs.signal.Frames:895939'
dataset = getSingleDatasetFromHSA(urn, 'Signal')

To read several datasets from a given product, the following is faster than repeating the above several times:

map = getDatasetsFromHSA(urn, ['Signal', 'Status'])
signal = map['Signal']
status = map['Status']

Finally, the plug-in provides a dedicated function to reconstruct partial PACS Frames products:

framesPartial = buildSignalOnlyFrames(framesRef)

This product, framesPartial, contains the Signal and Status dataset only. This compares to the "standard way":

framesFull = obs.refs["level1"].product.refs["HPPAVGR"].product.refs[0].product

To read the framesFull product, for this particular observation of about 5 hours, one needs around 8 GB of memory. To create the framesPartial product, 4 GB is enough, and one can use this partial product to make maps, to run the high-pass filter task, and so on.

Installation

To install the plug-in, choose Plug-ins from the Tools menu. Click Install new... and enter the following URL:

http://herschel.esac.esa.int/twiki/pub/Public/DatasetReaderPlugin/datasetReader_1.0.jar

HIPE 9 users, use the following URL: http://herschel.esac.esa.int/twiki/pub/Public/DatasetReaderPlugin/datasetReader_0.2.jar

Limitations

• This plug-in currently only works with products from the HSA.
• Until the resolution of HcssScr:17096, the downloaded FITS file has to be uncompressed as a separate step, which is a little time-consuming.

-- PaulBalm - 05 Nov 2012