HerMES-DR4 - xID24-PACS catalogues July 2016 ================================================================================ Contact: S.Oliver@Sussex.ac.uk Seb Oliver 2016-06-29 Description: This is the README file for the PACS photometry associated with the fourth Hershel-SPIRE/SAG-1/HerMES public data release (DR4). The HerMES program is presented in [1]. These catalogues record 100 and 160 micron photometry at the positions of known sources from “prior” catalogues. The photometric imaging data comes from maps from the Herschel PACS instrument taken as part of the HerMES survey. The map data was reduced using the Unimapper software [2] by Edo Ibar and is described in the PMAP Readme file for HerMES DR4. The known source positions came from Spitzer 24 micron catalogues collated by Mattia Vaccari and Isaac Roseboom, these are identical to those used in the prior based SPIRE photometry in the xID24 products delivered in HerMES DR3 and described in the xID24 Readme. Fluxes are reported with aperture photometry in various apertures and with point response function (PRF) fitting. The shape of the PRF, used in fitting and aperture corrections, was estimated by stacking the PACS maps at the positions of known sources with 24micron fluxes in the range 250muJy < f24 < 1000 muJy. The stacking code was based on that used in [3]. In the absence of clustering the shape of this empirical PRF should be an unbiased estimate of the PRF in the map including all effects from the intrinsic beam, map building, astrometry errors. The normalisation however, needs additional information. We thus normalised the PRF using the MIPS 24 micron photometry to have a peak intensity, P_max: 1./P_max = CONST * mean_24/410.2 Where mean_24 is the mean 24 micron flux of the stacked 24 micron sample in muJy and the CONST was 9361 for the 100 micron data and 164.1 for the 160 micron data. This calibration give photometry consistent with the PEP team's photometry in the COSMOS field [4]. This method avoids the requirement of extensive simulations. However, it introduces an (as yet) unquantified calibration error from the sampling of the distribution of PACS/MIPS galaxy colours. Flux errors are estimated using error propagation and do not take into account correlated errors or calibration errors. If you have any questions, comments or concerns please contact Seb Oliver File names: _PACSxID24_.fits With corresponding to the HerMES field name as used in the PACS maps and described in Table 1 of reference [1]. PRFS the empirical PRFS are also available (normalised as described above) so that a 1Jy point source would be fit with a scaling of the PRF by 1 with the following naming convention “HerMES_PACS_PRFS_V1.0_l””_””_””um_stack.fits” with as 100 or 160 for the green and blue PACS bands. (Note that the PSF files are available alongside the maps). Details about columns: ?IDS? RA DEC F_PACS__Ax : Flux in in mJy in Aperture of x diameter arc seconds Ferr_PACS__Ax : Error in above flux in mJy F_PACS_ : Flux in in mJy using PRF fitting Ferr_PACS_ : Flux in in mJy using PRF fitting F_PACS___SKY : Sky background in mJy/pixel It is recommended to use the aperture fluxes in smaller apertures. Cross matching to xID24 SPIRE: The PACS photometry measurements were linked to the SPIRE photometry. This was done using a positional cross-match based on RA, DEC though this is a unique and unambiguous as both sets of photometry were based on the same prior catalogues. Definition of the fields: The fields released here are: level3_LHN level3_SDP_LHN level3_UDS_HerMES level4_UDS level5_Bootes_HerMES level5_CDFS_SWIRE level5_EGS level5_ELAIS_N1_HerMES level5_Lockman_SWIRE level5_XMM_VIDEO1 level5_XMM_VIDEO2 level5_XMM_VIDEO3 level6_ADFS level6_Bootes_NDWFS level6_ELAIS_N1_SWIRE level6_ELAIS_N2_SWIRE level6_ELAIS_S1_VIDEO level6_FLS level6_XMM_LSS_SWIRE References: [1] Oliver, S.~J., Bock, J., et al. 2012, MNRAS, 424, 1614 [2] Piazzo L et al. MNRAS, 2015, 447, pp. 1471-1483 and http://infocom.uniroma1.it/unimap/ [3] Oliver, S. et al. MNRAS, 2010, 405, 2279 [4] Lutz, D. et al. A&A, 2011, 532, L30 -------------------------------------------------------------------------------- History: July 1st, 2015: Fourth Hermes data release. -------------------------------------------------------------------------------- The research leading to these results has received funding from the Cooperation Programme (Space) of the European Union’s Seventh Framework Programme FP7/2007-2013/ under REA grant agreement n° 607254 ================================================================================ Herschel Extragalactic Legacy Programme (HELP) July, 2016