4 ms·

I couldn't find an exact exposure time for the Hubble image, the press release by the ESA has this quote though: "This deep field, taken by Webb’s Near-Infrared

I couldn't find an exact exposure time for the Hubble image, the press release by the ESA has this quote though: "This deep field, taken by Webb’s Near-Infrared Camera (NIRCam), is a composite made from images at different wavelengths, totaling 12.5 hours – achieving depths at infrared wavelengths beyond the Hubble Space Telescope’s deepest fields, which took weeks." [1] There is also another comment further down this thread stating Hubble was 140 hours. [2] [1] https://www.esa.int/ESA_Multimedia/Images/2022/07/Webb_s_first_deep_field https://www.esa.int/ESA_Multimedia/Images/2022/07/Webb_s_fir... [2] https://news.ycombinator.com/item?id=32063214 https://news.ycombinator.com/item?id=32063214

perihelions 4y ago
Those exposure times (weeks / 140 hours) are for these images [0,1], Hubble's deep fields. Hubble's photo of this galaxy cluster, the one our root comment shows superimposed over JWST's, took 5 Hubble orbits [2]. I think that's around 2-3 hours of exposure time. [0] https://en.wikipedia.org/wiki/Hubble_Deep_Field https://en.wikipedia.org/wiki/Hubble_Deep_Field [1] https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field [2] https://archive.stsci.edu/prepds/relics/ https://archive.stsci.edu/prepds/relics/ ("For each cluster, the team observed to 5-orbit depth with ACS and WFC3/IR") (If you want to verify [2] is talking about the same photo, you can retrieve it from the "SMACS J0723.3-7327" row, from the "Color Images" column/field).
- lamontcg 4y ago
  LEO should be >= 80 mins so 5 hubble orbits should be >= 400 mins / 6.6 hrs? EDIT: nasa.gov says 95 mins, so ~8 hrs.
  - perihelions 4y ago
    Yes, but Earth obstructs the field of view for about half that time. The way HST refers to an "orbit" for scheduling, only part of the elapsed time is usable observational time, for a single target. https://hst-docs.stsci.edu/hsp/the-hubble-space-telescope-primer-for-cycle-30/hst-primer-orbit-calculation-overview https://hst-docs.stsci.edu/hsp/the-hubble-space-telescope-pr... - "HST GO observing time is counted in terms of orbits. Each 96-minute orbit contains a certain amount of useful time when the target can be observed, called the orbital visibility period..."
    - lamontcg 4y ago
      Ah right, because it is basically in LEO so the Earth is enormous.

perihelions 4y ago

Those exposure times (weeks / 140 hours) are for these images [0,1], Hubble's deep fields. Hubble's photo of this galaxy cluster, the one our root comment shows superimposed over JWST's, took 5 Hubble orbits [2]. I think that's around 2-3 hours of exposure time. [0] https://en.wikipedia.org/wiki/Hubble_Deep_Field https://en.wikipedia.org/wiki/Hubble_Deep_Field [1] https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field https://en.wikipedia.org/wiki/Hubble_Ultra-Deep_Field [2] https://archive.stsci.edu/prepds/relics/ https://archive.stsci.edu/prepds/relics/ ("For each cluster, the team observed to 5-orbit depth with ACS and WFC3/IR") (If you want to verify [2] is talking about the same photo, you can retrieve it from the "SMACS J0723.3-7327" row, from the "Color Images" column/field).

lamontcg 4y ago
LEO should be >= 80 mins so 5 hubble orbits should be >= 400 mins / 6.6 hrs? EDIT: nasa.gov says 95 mins, so ~8 hrs.
- perihelions 4y ago
  Yes, but Earth obstructs the field of view for about half that time. The way HST refers to an "orbit" for scheduling, only part of the elapsed time is usable observational time, for a single target. https://hst-docs.stsci.edu/hsp/the-hubble-space-telescope-primer-for-cycle-30/hst-primer-orbit-calculation-overview https://hst-docs.stsci.edu/hsp/the-hubble-space-telescope-pr... - "HST GO observing time is counted in terms of orbits. Each 96-minute orbit contains a certain amount of useful time when the target can be observed, called the orbital visibility period..."
  - lamontcg 4y ago
    Ah right, because it is basically in LEO so the Earth is enormous.