This directory contains Herschel High Level Images (HHLI) obtained
with the PACS and SPIRE instruments. An overview of this project,
along with documentation and links to interactive data access tools,
can be found here.

This browsable directory contains subdirectories that represent
coordinates on the sky: the first two digits represent the right
ascension in hours, and the third character represents the sign (plus
or minus) of the declination. Images are organized within these
subdirectories based on their central positions.

For example, an image with a center at the following coordinates 
 
RA = 00h02m21.3s
Dec = -32:51:00.45

will be found under the subdirectory 00m.

Each positional subdirectory is further divided into subdirectories
based upon the Herschel instrument and mode. The possibilities are:

PacsParallel
PacsPhoto
SpireParallel
SpirePhoto

The PACS images within the PacsParallel and PacsPhoto subdirectories
adhere to the following filename convention:

[ra hours and minutes][sign of dec][dec]_[Herschel obsid]_[observing mode]_[processing level]_[map making method][band]_[SPG version].fits.

"ra hours and minutes" is four characters. The first two are the RA
hours, and the second two are the RA minutes of the image center.

"sign of dec" is p for plus and m for minus.

"Herschel obsid" is the primary Observation ID (obsid) of the image data included this map. Note that data from more than one obsid may be included in a particular HHLI. These are listed in the metadata of the HHLI.

"observing" mode is either PacsParallel or PacsPhoto.

"processing level" is either L20, L25, or L30. These correspond to
Levels 2.0, 2.5, or 3.0, respectively. Please see the Herschel Data
Products Overview for more information:

http://www.cosmos.esa.int/web/herschel/data-products-overview

"map making method" is one of the following: 

    HPPPMAP if the High-Pass Filter (HPF) method (suitable for point sources
    and slightly extended sources) was used for making maps;

    HPPJSMAP if the JScanam map maker (suitable for point and extended
    sources) was used.

"band" refers to the central wavelength of the bandpass of the observation.
For maps processed to Level 2.0, this can be either "R" or "B", reflecting the
fact that PACS users were able to image with a red (160 micron) and a
blue (either 70 or 100 micron) filter simultaneously. For maps further
processed to Level 3, "band" was changed to "G" for images observed
at 100 micron.

"SPG version" stands for Standard Product Generation version and
refers to the processing pipeline used to generate these products.

For example, the blue image (in this case resulting from PACS
observations taken in Parallel mode centered on the coordinates
00h02m32.5s +32d51m52.3s, processed with SPG pipeline version of 14.0,
and mapped with the HPF map maker would have the following file name:

0002m3251_1342220832_PacsParallel_L20_HPPPMAPB_SPG14.0.fits 

In this case, the observer chose the blue band to be at 100 micron.

The SPIRE images within the SpireParallel and SpirePhoto
subdirectories adhere to the following filename convention:

[ra hours and minutes][sign of dec][dec]_[HHLIid]_[observing
mode]_[processing level]_PMP[band]_[SPG version].fits.

All quantities are as above for PACS, except "band" can be either 250,
350, or 500, representing the bandpass central wavelengths of 250, 350,
and 500 microns, respectively.