Hubble Space Telescope will be able to see things that could answer questions about the origins of the universe

1. Hubble Space Telescopewill be able to see things that could answer questions about the origins of the universe

2. HST • Hubble Space Telescopeis an orbiting astronomical observatory operating from the near-infrared into the ultraviolet. • Launched in 1990 and scheduled to operate through 2010 • HST carries and has carried a wide variety of instruments producing imaging, spectrographic, astrometric, and photometric data through both pointed and parallel observing programs.

3. Electromagnetic and sound spectra Wavelengths is a common way of describing light waves.  Wavelength = Speed of light in vacuum / Frequency. The speed of light is the velocity of electromagnetic wave in vacuum, which is 300,000 km/sec.Light travels slower in other media, and different wavelengths travel at different speeds in the same media.

4. HST is able to look deep into space • up to 14 billion light years away! • LY- the distance that light travels in one year. • This means that if you look at something 5 light years away, the light of what you're looking at took 5 years to travel to you. • So when you look at it now, you're actually seeing what it looked like in the past. • The stellar phenomena that Hubble would be studying were so far away that what they would look like to us was what they were like close to the beginning of the universe.

5. Light year: Since light travels at 3.0 x 108 meters per second, then light traveling for one year would travel a total distance of 946.08 x 1013 meters in total. Since that's a really big number, it's easier to call that number one light year.

6. History of the Universe

7. HST observation map (2003)

8. History • Soon after its launch, Hubble was not sending back to Earth the types of images that should have come from such a powerful telescope. • The mirrors on Hubble are 2.4 meters in diameter. • One of the mirrors (known as the primary mirror) had been made too flat on one edge. • The total size of the error amounted to 1/50 of the width of a human hair, but it was still enough to make Hubble's pictures fuzzy. • During a special shuttle mission, the astronauts took the corrective lens (like a pair of glasses) up to space and fitted it on Hubble.

9. Current HST Instruments • ACS: Advanced Camera for Surveys • FGS: The Fine Guidance Sensors • NICMOS: Near Infrared Camera and Multi Object Spectrometer • STIS: Space Telescope Imaging Spectrograph • WFPC2: The Wide Field Planetary Camera 2 • http://www.stsci.edu/hst/HST_overview/instruments Installation of WFPC2

10. Observatory The Observatory Support provide general support of HST. • Maintaining calibration parameters and throughput data for HST and its Science Instruments. • Supporting science through focal plane calibrations, and analysis of telescope pointing. • Updating the SI aperture position files. • Aperture-a device that controls amount of light admitted • Monitoring focus variations and dependencies. • Further related duties include the Data Quality Coordinating Committee, an initiative to increase the scientific productivity of HST users by improving the data assessment, processing, calibration, and archiving functions.

11. Advanced Camera for surveys • The Advanced Camera for Surveys (ACS) is a third-generation Hubble Space Telescope (HST) instrument. • ACS was installed by space shuttle Columbia astronauts Grunsfeld, Currie, Newman, Linnehan and Massimino on STS-109 during HST servicing mission 3B. • The development of ACS is a collaborative effort between: • Johns Hopkins University • Goddard Space Flight Center • Ball Aerospace • Space Telescope Science Institute

12. ACS ACS includes three channels: • Wide Field Channel (WFC), with a field of view of 202x202 square arcsec covering the range from 3700 to 11000 Å and a plate-scale of 0.05 arcsec/pixel; • Angstrom – a unit of length equal to 10 -8 cm (one-hundredth of a millionth of a centimeter). An Angstrom is on the order of the size of an atom • Arcsec- is a wedge of angle, 1/3600th of one degree, in the 360-degree of the sky • High Resolution Channel (HRC), with a field of view of 26x29 square arcsec covering the range from 2000 to 11000 Å and a plate-scale of 0.027 arcsec/pixel; • Solar Blind Channel (SBC), with a field of view of 31x35 square arcsec, spanning the range from 1150 to 1700 Å and a plate-scale of 0.032 arcsec/pixel.

13. Wide Field Planetary Camera 2 • WFPC2 is a two-dimensional imaging photometer which is located at the center of the Hubble Space Telescope (HST) focal plane. • The WFPC2 field-of-view is divided into four cameras by a four-faceted pyramid mirror near the HST focal plane. Each of the four cameras contains an 800x800 pixel Loral CCD detector.

14. CCD detector • Charge Coupled Device: one of the two main types of image sensors used in digital cameras. • When a picture is taken, the CCD is struck by light coming through the camera's lens. • Each of the thousands or millions of tiny pixels that make up the CCD converts this light into electrons. • The number of electrons, usually described as the pixel's accumulated charge, is measured, and then converted to a digital value.

15. Charge Coupled Device - CCD • were invented in 1969 by Bell Labs • lightweight, low-powered, extremely sensitive image sensors, and they are about 15 times more sensitive to light than regular photographic film. • The surface of a CCD is covered with a rectangular grid of microscopic light-sensitive elements. • An image is created by a CCD when light falls on individual sensors creating an electrical charge proportional to the light intensity.

16. CCDs • do have some disadvantages. • they photograph a much smaller area than other image sensors, and they do not photograph in color. • The images, however, can be colorized later by combining images taken through different mono-chromatic filters. • CCD's can photograph items as small as grapefruits from a low Earth orbit.

17. CCD noise • Noise on the image itself ("shot noise") • The detection of photons by the CCD is a statistical process. • We cannot be sure that the intensity of a particular image represents the "true" intensity as we know that this value will deviate from the average. • This deviation which is considered to be the noise associated with the image. • The deviation is known to follow a Poisson distribution, we know that the likely deviation will be plus or minus the square root of the signal intensity measured.

18. CCD noise Thermal Noise • Additional electrons will be generated within the CCD not by the absorption of photons (i.e the signal) but by physical processes within the CCD itself. • The number of electrons generated in a second depends on the operating temperature of the CCD and hence this noise is known as thermal noise (sometimes also known as dark noise).  • As with the detection of the signal, the same number of electrons will not be generated in equivalent periods of time as the thermal noise will also have a Poisson distribution.

19. Dark current • Dark current Even in the absence of light, thermally generated electrons will be collected in the CCD and will contribute to the overall signal measured

20. Sources of CCD noise: Readout noise • The readout noise is the noise of the on-chip amplifier which converts the charge (i.e the electrons) into a change in analogue voltage. The amplifier has an associated noise which is typically 1/f at low sampling frequencies and a white noise at higher sampling frequencies. . • White Noise: random noise, providing constant energy at all frequencies. • The sampling frequency corresponds to the rate at which each pixel is read by the CCD.

21. WFPC2 Field-of-View Projected on the Sky. The readout direction is marked with arrows near the start of the first row in each CCD. The X-Y coordinate directions are for POS-TARG commands. The position angle of V3 varies with pointing direction and observation epoch.

22. Tracking Data Relay Satellite (TDRS):the Internal computer • Hubble uses TDRS to send the data back to Earth for scientists to analyze. • The information goes to a station in White Sands, New Mexico where it can be distributed to scientists who need it. • The ground station can also send instructions to Hubble's instruments via the TDRS system.

23. Internal computer • Any instruction that the ground station sends to Hubble is translated into a series of commands to be sent to the onboard computers • These commands are then uplinked several times a day to keep the telescope operating efficiently. • Up to 24 hours of commands can be stored in the onboard computers of Hubble. • Data collected can be broadcast from Hubble to the ground stations immediately or stored and downlinked later.

24. But not all of its time is spent observing. Each orbit of the earth lasts about 95 minutes, with the time divided between housekeeping functions and observation. Housekeeping functions include turning the telescope towards a new target, or away from the Sun or Moon, switching communications antennas and data transmission modes, receiving command loads and downlinking data, calibrating, and similar activities. …operations never stop

25. Hubble reveals Galactic drama in the ultra deep field Galaxies engaged in boxing matches with galactic neighbors

26. The galaxies were plucked from a harvest of nearly 10,000 galaxies in the Ultra Deep Field (UDF), the deepest visible-light image of the cosmos. • UDF, taken by the ACS, represent a narrow, "deep" view of the cosmos. Peering into the Ultra Deep Field is like looking through an eight-foot-long soda straw. • In ground-based images, the patch of sky in which the galaxies reside (just one-tenth the diameter of the full Moon) is largely empty. Located in the constellation Fornax, the region is so empty that only a handful of stars within the Milky Way galaxy can be seen in the image.

27. HST Data Reduction & Analysis • Hubble Space Telescope (HST) science data are stored in the HST Archive in FITS format: Flexible Image Transport System http://archive.stsci.edu/hst/analysis.html • The Space Telescope Science Institute (STScI) supports dedicated software, the Space Telescope Science Analysis System (STSDAS), for reducing and analyzing HST data. • This software works within the Image Reduction and Analysis Facility (IRAF).