# Presentation: 313800

## Wide Field Astronomy from Space

- Steven Beckwith
- Space Telescope Science Institute
- January 9, 2002

## Limits:

- Space advantages:
- Low B
- Small  over FOV
- PSF stability
- Photometric stability
- Full sky coverage
- 24 hr operation
- Ground advantages
- Large area telescopes
- Upgradable detectors     (increase/repair FOV)
- High survey speed at BLIP

- D = 6.5 m
-  = 0.3”

- D = 2 m
-  = /D

- 1/9/2002

## ACS Survey Workshop

- Motivation:
- To determine the potential for new surveys with ACS
- To identify areas for teaming on large initiatives
- Discussion findings:
- Obvious synergism between *galaxy formation*, *AGN evolution*, *weak lensing*, and *cosmology* (SN Ia) in need for a ~1 ° HDF-like survey
- Recognition of multiple science potential of deep and wide surveys with HST

- 22-23 March 2001

- 1/9/2002

## GOODs Legacy & Treasury Programs

- Observations
- 300 arcmin2 in two fields: HDF-N, CDF-S
- SIRTF: 3.6-24 μm (IRAC+MIPS), 600 hours
- HST: 4 bands, 500 orbits ACS, near HDF depth
- Chandra: 2x106 sec imaging; XMM: ~5x105 sec imaging

- North

- South

- Science
- Evolution of galaxies, 1 < z < 6
- SN Ia detection via scheduling
- AGN morphologies
- Potential upgrades: wider fields for AGN, weak-lensing, DEEP fields

- 1/9/2002

## All sky surveys

- Space advantages:
- Low B
- Small  over large FOV
- PSF stability
- Photometric stability
- Full sky coverage
- 24 hr operation

- Ground advantages
- Large area telescopes
- Upgradable detectors     (large FOV)
- High survey speed at BLIP

- 1/9/2002

## Ideal limiting magnitudes

- _Space-survey science:_
- Earth-crossing asteroids (sens.)
- Kuiper-belt objects (sens., )
- Transient sources
- Supernovae (e.g. SN Ia) (sens.)
- Micro-lensing sources (# stars)
- Dwarf stars: white, brown (sens.)
- Quantify weak lensing in distant galaxies (small , stable PSF)
- Parallaxes of faint stars (sens.)
- Rare objects (survey to R ~ 27m)
- Eclipses of exo-planets (photometric stability)

- High z SN

- DMT 8.4m

- 1/9/2002

## SN Ia Detection rate

- -40

- 0

- 40

- 80

- 120

- t (days)

- 28

- 27

- 26

- 25

- 24

- 23

- I (mag)

- z = 1.7

- z = 1.4

- z = 1.0

- WFPC2: 2 orbit

- ACS: 2 orbit

- LSST 4

- 1/9/2002

## SN 1998ff

- A. Riess, F. Boffi & SNaZ Team

- 1/9/2002

## HD 209458b: Exoplanet eclipse

- 3 hours

- 1σ ~ 2x10-4

- 5x10-4

- Kepler selected as Discovery-class Mission

-  courtesy Brown *et al*. (2001)

- 1/9/2002

**Notes:**
The light curve in the middle – the U-shaped curve – is an observation of the eclipse of a star by a planet orbiting that star, the first such observation of an extra-solar planet.  The depth of the eclipse confirms that the planet is the same size as Jupiter; it was known to have the same mass as Jupiter from Doppler measurements of the stellar motion.  
Only HST can measure an eclipse with such accuracy.  The depth of the eclipse is 1.5% of the total brightness.  HST can measure the light curve to 1 part in 10,000 accuracy.  It is so accurate that one can now contemplate studying the atmosphere of the extra-solar planet by looking at the rate of dimming and brightening of the star at the ingress and egress of the eclipse.  

## Globular Cluster 47 Tucanae

- Has a metallicity (abundance of elements heavier than helium) about one third that of the sun

- HST/WFPC2

- DSS

- Globular Cluster *47 Tucanae*

- Contains about 106 stars, at ~11 Gyr

- courtesy R. Gilliland *et al*. (2001)

- 1/9/2002

## NEO Hazard

- courtesy DMT consortium
- http://dmtelescope.org/science.html

- 1/9/2002

## Cumulative Distribution of NEAs

- 300m

**4,000 –**
**77,000**

**Follow-up problem ?**

- courtesy DMT consortium
- http://dmtelescope.org/science.html

- 1/9/2002

**Notes:**
Finally, I return to the NASA goal of finding all the 1km or larger asteroids by 2009.  The Top of the Red curve is the Cumulative # of known NEAs greater than or equal to H VS.  H.  Notice the log scale.  The green region represents discoveries by LINEAR.  LINEAR has found close to 1/3 of all known NEA’s in about 1.7 years of operation.

Focus your attention to the hollow dot, which represents the 324 known NEA’s >= 1km.  LINEAR’s task is to add to the green region, so the top of the Red regain (total # of NEA’s) reaches the BLACK or the BLUE dot.  The good news is that recent findings by modellers of NEA populations and other discovery groups indicate that the BLACK dot may be the true population, and that lead by LINEAR, astronomers of the world may meet the 90% NASA goal by 2009.

## Planned surveys with spacecraft

- Galaxy, AGN evolution
- HST/ACS, NGST
- Supernovae, 
- HST/ACS+NICMOS, SNAP
- Eclipsing extra-solar planetary systems
- Kepler
- Astrometric surveys
- Hipparcos, SIM, GAIA

-  ~ /D
- B ~ Zodiacal light
- FOV ~ optics limit

- 1/9/2002