Dear colleagues,

We are pleased to announce the fourth v0 5 release of Epoch 2 HST mosaics obtained on the cluster MACSJ0416 1-2403, from the observations of this target from our Frontier Fields program ID 13496 (P I : J Lotz) These mosaics complete the full depth obtained on the second epoch of this cluster, adding a further 22 orbits of WFC3/IR imaging in F105W, F125W, F140W and F160W on the main cluster, along with ACS imaging in F606W and F814W on the parallel field, and completing the total exposure time of 70 orbits on each field for this epoch, and 140 orbits total for this cluster In addition to the standard ACS and WFC3/IR mosaics derived from the default calacs and calwf3 calibration products, we also make available ACS mosaics that include self-calibration to improve low-level noise, and WFC3/IR mosaics that include correction for time-variable sky background All the mosaics are astrometrically aligned, as before, to the mosaics that were obtained during the previous observations of this field We are producing the fully reprocessed v1 0 mosaics during the coming weeks, but are making available these fast-turnaround science-quality v0 5 mosaics at the moment, in order to facilitate immediate science by the community Further details are provided in the readme file, which can be obtained along with all the mosaics at the following location:

• Latest mosaics: http://archive stsci edu/pub/hlsp/frontier/macs0416/images/hst/v0 5-current-epoch2/
• All mosaics: http://archive stsci edu/prepds/frontier/macs0416 html

More general information about the data for this project can be obtained from our Frontier Fields MAST archive website: * http://archive stsci edu/prepds/frontier/ as well as our main Frontier Fields HST project website: * http://www stsci edu/hst/campaigns/frontier-fields/ and our Frontier Fields astronomer's blog and other social media: * https://blogs stsci edu/hstff/ * https://twitter com/MAST_News/ * https://facebook com/MASTArchive/

We hope that these high-level science products are useful for your research, and we welcome any suggestions or questions that you may have about them

Best regards, Anton Koekemoer and the STScI Frontier Fields Team http://archive stsci edu/prepds/frontier/ http://www stsci edu/hst/campaigns/frontier-fields/Contact

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