<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">                         HerMES-DR4 - SPIRE Maps (SMAP)                July 2016
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Contact: smap@astro.caltech.edu
A. Conley, G. Marsden, M. Zemcov, M. Viero
2015-05-12

Description:

  This is the README file for the SPIRE map files associated with the fourth
  Hershel-SPIRE/SAG-1/HerMES public data release (DR4), known as version 6.  The
  HerMES program is presented in [1].

  The primary changes in this release relative to previous releases are
  low-level reprocessing and calibration updates, and the fact that all of the
  HerMES data is now included.  In addition, we no longer provide maps
  constructed from observations of individual AORs when nested data are
  available.  Instead, only the full nest is provided.  Thus, for example, there
  is no longer an individual map for the UDS field because it is part of
  XMM-NEST.  We only provide on nested fields some shallow maps for people
  needing homogeneous noise properties over large areas.  Also, point source
  filtered maps are no longer provided.  More details are provided below.

  If you have any questions, comments or concerns please contact the SMAP team
  at smap@astro.caltech.edu


File names:

  The file names indicate the field, image type, band, and version number:

  &lt;field&gt;_&lt;type&gt;_&lt;band&gt;_SMAP_&lt;version&gt;.fits

  For instance, Bootes-HerMES-NEST_image_250_SMAP_v6.0.fits is the DR4 (SMAP
  version 6) image map at 250 Âµm of the BoÃ¶tes field, including all nested data.

File content:

  Each fits file in this data release contains 4 extensions:

  1 - signal map [Jy / beam]
  2 - error map, based on propagation of time-stream weights [Jy / beam]
  3 - exposure map [sec]
  4 - mask map with the following values:
          0: no mask (ie good data)
          1: regions with low depth relative to the rest of the map


Definition of the fields
------------------------

The fields released here are:

Clusters:
Abell-370
Abell-1689
Abell-1835
Abell-2218
Abell-2219
Abell-2390
Cl0024+16
MS0451.6-0305
MS1054.4-0321
MS1358+62
RXJ0152.7-1357
RXJ13475-1145

Blank fields:
ADFS
Bootes-HerMES-NEST (observations of Bootes with a deeper central region)
Bootes-HerMES  (like Bootes-HerMES-NEST but without the deeper observations
                in the central region - shallow map)
COSMOS-NEST
CDFS-SWIRE-NEST (includes deeper data in GOODS-S and ECDFS)
CDFS-SWIRE (the same as CDFS-SWIRE-NEST but without the GOODS-S and ECDFS data
            - shallow map)
EGS-NEST (observations of the EGS-SCUBA field with deeper observations in
          the Extended Groth Strip)
EGS-HerMES (like EGS-NEST but without the deeper Extended Groth Strip data
            - shallow map)
ELAIS-N1-NEST
ELAIS-N2
ELAIS-S1-NEST (observations of Elais-S1 with deeper observations in the S1-VIDEO
               subfield)
GOODS-N-NEST (includes data from HerMES and the Goods-Herschel project)
FLS
Lockman-NEST (observations of the Lockman field with deeper observations in
              Lockman-North, Lockman-East-ROSAT, and the Global-Epicentre-1
              fields)
Lockman (like Lockman-NEST but without the deeper sub-fields - shallow map)
SA13
XMM-LSS-NEST (maps of the XMM-region with deeper data in the UDS and VVDS regions)
XMM-LSS (like XMM-LSS-NEST but without the deeper UDS, VVDS data - shallow map)
XMM13hr

The fields with additional data not included in previous releases are:

Abell-370 includes new wider but shallower data
EGS-NEST and EGS-HerMES include new wide area data
FLS includes small area, slightly deeper observations -near the z=6.3 source FLS3
Lockman-NEST and Lockman include new wide area shallow data
RXJ13475-1145 includes new wider but shallower data
SA13 is a new field
XMM13hr is a new field

In addition, only Bootes-HerMES-NEST was available in previous releases;
Bootes-HerMES is new.

The exact list of Herschel/SPIRE OBSIDs used in each map are provided in the
headers of each file.

Additional new composite field Hers/HeLMS/XMM-LSS
-------------------------------------------------

As a contribution to the Herschel Extragalactic Legacy Project (HELP,
herschel.sussex.ac.uk) we also provide a new map that combines the HerMES HELMS
field, the Herschel Strip 82 Survey (Viero et al. 2014 [5] and the HerMES
XMM-LSS-NEST field).  This field is the largest contiguous extra-galactic field
observed by Herschel covering 385 deg^2 and roughly 50 deg tip-to-tip.  The
overlap between HerS and HeLMS where the map is more sensitive and has been
nicknamed Helmâ€™s Deep after the valley in middle earth from Tolkienâ€™s Lord of
the Rings trilogy.


Complementary maps *** (not available for all fields) ***
---------------------------------------------------------

ang1:   sub-map made from all scans in one orientation on sky (eg
        horizontal)
ang2:   sub-map made from all scans in other orientation on sky (eg
        vertical)
bolo1:  sub-map half of detectors in focal plane
bolo2:  sub-map other half of detectors in focal plane
half1:  sub-map made from first half (in time) of data
half2:  sub-map made from second half (in time) of data
subfield: e.g., UDS for XMM-LSS-NEST.  Only contains data for
        a particular AOR set.

In some fields, there is more than one set of rotation angles. Here, we provide,
e.g., ang1a/ang2a and ang1b/ang2b jack-knife maps where possible.

The complementary maps are not iterated, but simply use the offset and weights
solution calculated for the full "image" map, as well as the cosmic ray
information.

Details of the Map Making process
---------------------------------

HerMES maps are created by the SMAP pipeline. The SMAP map-maker iteratively
removes a low-order polynomial baseline from each scan. At each iteration
i a polynomial is fit to the time-stream residual R_i = S - M_{i-1}, where S is
the time stream and M_{i-1} is the predicted time stream given the map
calculated on the previous iteration. Additionally, each scan is given a weight
based on the inverse variance of the time-stream residual. The order or the
polynomial baseline varies from 0 to 9, depending on the scan length, with
longer scans requiring higher order polynomials. The polynomial order is chosen
using an automated algorithm which is only a function of the scan length. These
maps are made with 20 iterations, which appears to provide sufficient
convergence. The mapping algorithm is described in [3] and [4].

Additional Notes
-----------------

Changes to the SMAP algorithm as described in [3] and [4] compared with the
DR1 release:

* The algorithm for the temperature-correlation removal has been modified
  slightly to use more robust fitting.

* One must use a full implementation of the WCS specification to use the
  astrometry for these (and all previous) SMAP maps. In particular, for far
  northern or southern fields, LATPOLE and LONPOLE do not have their standard
  values to reduce field distortion. Currently, this only affects the GOODS-N
  and MS1358 fields.

References
----------

[1] Oliver, S.~J., Bock, J., et al. 2012, MNRAS, 424, 1614
[2] Chapin, E.L., et al. 2011, MNRAS, 411, 505
[3] Levenson, L., Marsden, G., Zemcov, M., et al. 2010, MNRAS, 409, 83
[4] Viero, M., et al. 2013, ApJ, 772, 77
[5] Viero, M., et al. 2014, ApJS, 210, 22

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History:

 July 1st, 2015: Fourth Hermes data release.

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The research leading to these results has received funding from the Cooperation
Programme (Space) of the European Unionâ€™s Seventh Framework Programme
FP7/2007-2013/ under REA grant agreement nÂ° 607254

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Herschel Extragalactic Legacy Programme (HELP)                        July, 2016
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