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Science Drivers

HTTP provides a unique multi-band view of the Tarantula Nebula, which is necessary to map the stellar content of the Tarantula Nebula within its main body. HTTP allows us to:  

  • Investigate star formation in an environment that resembles the extreme conditions found in starburst galaxies and the early universe;
  • Reconstruct the temporal and spatial evolution of the stellar skeleton of the Tarantula Nebula over space and time;
  • Test stellar models for very different evolutionary phases and mass regimes;
  • Trace the extent of active star formation within the Nebula
  • Yield the richest and most homogenous sample of metal-poor pre-main sequence stars of different ages and masses
  • Study the properties of dust in metal-poor starbursts 


HTTP was awarded 60 orbits of HST time in Cycle 20 to survey the entire Tarantula Nebula, using both the UVIS and the IR channels of the Wide Field Camera 3 WFC3) and, in parallel, the Wide Field Channel (WFC) of the Advanced Camera for Surveys (ACS). Each of the UVIS orbits consists of one short (14 s) and two long (697 s each) exposures in the filter, F336W, followed by two long exposures (697 and 467 s respectively) in the F275W filter. Each couple of UVIS long exposures was obtained using a two-point dither pattern to enable the rejection of cosmic-rays (CRs) and cover the chip gap. While WFC3 was acquiring the UVIS images, ACS was used to collect one short (13  s) and four long (3x640+1x337 s) exposures in the filter F555W. For the deep F555W exposures, the team used a four-point dither pattern, improving the sampling of the PSF. 

The IR orbits consist of two long (2x799 s) exposures in the F160W filter followed by two long (799 and 499 s respectively) exposures in the F110W filter. At the same time, ACS was used to obtain four long (3x640+1x399s) exposures in the F658N filter. Archival observations in the ACS+WFC3 F775W filters were used to complete wavelength coverage. 

WFC3/UVIS and ACS/WFC images were corrected for the degrading charge transfer efficiency using the pixel-based solution described in Anderson & Bedin (2010). 

Photometric Catalog

The HTTP Photometric Catalog was obtained from the analysis of all the images used in the HTTP program (HST 12939, PI Elena Sabbi + HST 12499, PI Danny Lennon), as defined by Sabbi et al. 2016. The measurements were made using the KS2 (Anderson et al. in prep) PSF astro-photometric package. The photometry was carried out directly on the CTE-corrected FLT images. Zero points were adopted from the STScI Web site

You can download the HTTP photometric catalog here. When using the HTTP catalog, please refer to Sabbi et al. 2016.



These mosaics of 30 Doradus were constructed from all the WFC3/IR observations on this field from the program 12939 (PI: E. Sabbi), consisting of 72 exposures in F110W and another 72 exposures in F160W. You can download the mosaics in FITS format by clicking on the previews above or by visiting the Interactive Display page using the button.
The exposures were all aligned astrometrically to the master reference catalog (Sabbi et al. 2016) using algorithms that make use of the latest drizzlepac/tweakreg scripts, and were combined using astrodrizzle onto an output reference mosaic with the following World Coordinate System (WCS) specifications:
            NAXIS1 =  32000
            NAXIS2 =  29000
            CRPIX1 =  17388.023478781
            CRPIX2 =  13865.850155511
            CRVAL1 =  84.5426015
            CRVAL2 = -69.1394085
            CD1_1   = -9.010672487E-06
            CD1_2   = -6.309340800E-06
            CD2_1   = -6.309340800E-06
            CD2_2   =  9.010672487E-06
The drizzled science mosaics (drz) are all in units of electrons/s, and are accompanied by weight files (wht) that are based on the exposure times of all the input exposures. Please refer to Sabbi et al. (2016) for further details about the observations.


"Hubble Tarantula Treasury Project - VI. Identification of Pre-Main-Sequence Stars using Machine Learning techniques"
Ksoll, V.F., Gouliermis, D. A., Klessen, R.S., Grebel, E.K.; Sabbi, E., Anderson, J., Lennon, D.J., Cignoni, M., de Marchi, G., Smith, L.J., Tosi, M., van der Marel, R.P. 2018, MNRAS, 1265

"Hubble Tarantula Treasury Project V. The star cluster Hodge 301: the old face of 30 Doradus"
Cignoni, M., Sabbi, E., van der Marel, R.P., Lennon, D.J., Tosi, M., Grebel, E.K., Gallagher, J.S., Aloisi, A., de Marchi, G., Gouliermis, D.A., Larsen, S., Panagia, N., Smith, L.J. 2016, ApJ, 833, 154

"Hubble Tarantula Treasury Project. III., Photometric Catalog and Resulting Constraints on the Progression of Star Formation in the 30 Doradus Region"
Sabbi, E., Lennon, D.J., Anderson, J., Cignoni, M., van der Marel, R.P., Zaritsky, D., De Marchi, G., Panagia, N., Gouliermis, D.A., Grebel, E.K., Gallager, J.S., III, Smith, L.J., Sana, H., Aloisi, A., Tosi, M., Evans, C.J., Arab, H., Boyer, M.L., de Mink, S.E., Gordon, K., Koekemoer, A.M., Larsen, S.S., Ryon, J.E., Zeidler, P. 2016, ApJS, 222, 11

"Hubble Tarantula Treasury Project. IV. The Extinction Law"
De Marchi, G., Panagia, N., Sabbi., E., Lennon, D., Anderson, J., van der Marel, R., Cignoni, M., Grebel, E.K., Larsen, S., Zaritsky, D., Zeidler, P., Gouliermis, D., Aloisi, A. 2016, MNRAS, 455, 4373

"Hubble Tarantula Treasury Project. II. The Star-Formation History of the Starburst Region NGC 2070 in 30 Doradus"
Cignoni, M., Sabbi, E., van der Marel, R.P., Tosi, M., Zaritsky, D., Anderson, J., Lennon, D.J., Aloisi, A., de Marchi, G., Gouliermis, D.A., Grebel, E.K., Smith., L.J., Zeidler, P. 2015, ApJ, 811, 76

"Hubble Tarantula Treasury Project: Unraveling Tarantula's Web. I. Observational Overview and First Results"
Sabbi, E., Anderson, J., Lennon, D.J., van der Marel, R.P., Aloisi, A., Boyer M.L., Cignoni, M., de Marchi, G., de Mink, S.E., Evanc C.J., Gallager, J.S., III, Gordon., K., Gouliermims, D.A., Grebel, E.K., Koekemoer, A.M., Larsen, S.S., Panagia, N., Ryon J.E., Smith, L.J., Tosi, M., Zaritsky, D. 2013, AJ, 146, 53

"A Double Cluster at the Core of 30 Doradus"
Sabbi, E., Lennon, D.J., Gieles, M., de Mink, S.E., Walborn, N.R., Anderson, J., Bellini, A., Panagia, N., van der Marel, R., Maiz Apellaniz 2012, ApJ, 754, L37