SOFIA: First Light to First Sciencehosting.astro.cornell.edu/academics/courses/astro101/...Right: SOFIA 19.7 m (green) + 37 m (red) image FORCAST First Light to First Science 32 KAO

First Light to First Science 1

SOFIA: First Light to First Science

FORCAST Team members: Terry Herter (Principal Investigator), Joe Adams (Project Scientist), George Gull (Lead Engineer), Justin Schoenwald (Software Engineer), Chuck Henderson (Mechanical Eng), Luke Keller (Ithaca College, Co-I)

Ryan Lau (Grad. Student); Jason Wang & Lea Hirsch (Undergrads); Gordon Stacey (Co-I), Thomas Nikola (Co-I)

Final Exam Reminder

Final Exam: Friday, Dec 7, 2:00 – 4:30 PM

BKL 200: Baker Lab 200

Make-up Final Tuesday, Dec 11, 7:00 – 9:30 PM

105 Space Sciences Building

You must have a valid reason to take the make-up

You must get prior permission and sign up before the end of classes (Friday, Nov 30)

Review Sessions – Malott 251 Monday, Dec. 3 from 6:30 – 8:30 pm

Tuesday, Dec. 4 from 6:30 – 8:30 pm


FORCAST First Light to First Science 3

Outline

The FORCAST Instrument

FORCAST Science

SOFIA and FORCAST Preparation and First light – truly a once in a

lifetime experience

First Light

Observatory Characterization

Science Images & Discussion

Summary

FORCAST Facility Instrument

Built at Cornell

Turn over to NASA this fall

Dual-Channel 256x256 Camera w/ Si BIB arrays 5-25 m with Si:As array (SWC)

25-40 m with Si:Sb array (LWC)

Selectable Filters in 5-40 m range

Field of View 0.75''/pixel giving a 3.2'3.2'

Designed for diffraction-limited imaging for > 15 µm

Able to observe with the SWC and LWC simultaneously But with some penalty in sensitivity in

the LWC



FORCAST Filters

FORCAST filter transmissions (black) overlaid on atmospheric transmission from SOFIA (blue) and from Mauna Kea (red) Roughly 10 m vs. 1 mm precipitable water vapor

Except for very limited bands, transmission for ground based observatories is poor over the 5 – 40 m region


FORCAST Detects “Dirt”

FORCAST is sensitive to emission from dust in the interstellar medium UV and optical photons heat the dust which radiates in the

“thermal” infrared

Dust composition, heating sources, geometry, and optical depth all affect the observed spectrum.

“Large” particles Emitted power in equilibrium with absorbed radiation

Have a well-defined temperature

“Small” particles Temperature significantly affected by single photon

Depends on heat capacity of grain

e.g. PAH’s (Polycyclic Aromatic Hydrocarbons)



Orion: A Different ViewInfrared (IRAS)Visible Light

The IR affords a complementary view of the Universe relative to other wavelengths –The bright extended regions in IRAS view are due to thermal emission from small grains (dust) heated by stellar radiation. Complex molecules emit in the IR and

submillimeter regions of the spectrum


rms ~ 0.49 DN

Nod Subtracted

Mid-infrared Data Acquisition

FORCAST data from OCF#3 on calibration star Alpha Cet at 37.1 micron. The integration time in a single image is 30 seconds. The features in the chop-subtracted image likely dominated by the dewar window but involve all of the optical system on either side of the secondary mirror.

Raw Image

rms ~ 350 DN

Chop-Subtracted

rms ~ 1.4 DN

The thermal emission from the atmosphere and warm optics (telescope, etc.) create a background which we must look through (generating photon noise)



“Original” Team Science Objectives

The Galactic Center region Nature of circumnuclear ring (CNR)

Excitation of “arches”

Star formation Census of “protostars” in nearby molecular clouds

Spiral arms of nearby galaxies

Circumstellar disks Spatially resolve Vega phenomena

Spectral energy distribution of Young Stellar Objects

Start of FORCAST funding: 1997 !


NASA Lear JetObservatory

1967

30-cm telescope

NASA Kuiper Airborne Observatory (KAO)

1974

91-cm telescopeNASA/DLR Stratospheric Observatory

for Infrared Astronomy (SOFIA)

2010

2.5-m telescope1975 until 1996 (shut down in

prep for SOFIA)Early 70’s until 1980.

Started operations in 2010

Evolution of Airborne Astronomy

Cornell has been a part of airborne astronomy since its inception (Martin Harwit & Jim Houck)



SOFIA

Instrumentation: wide variety, rapidly interchangeable, state-of-the art – SOFIA is a new observatory every few years

Mobility: anywhere, anytime Deployments to the Southern Hemisphere

and elsewhere

Twenty year design lifetime >120 8-10 hour flights per year

Flight altitude 41,000 – 45,000 ft

Collaboration between NASA and DLR (Germany)


The SOFIA Observatory

open cavity (door not shown)

2.5m telescope

pressure bulkhead

scientific instrument

scientist stations, telescope and instrument control, etc.



Telescope and aperture assembly


Primary Mirror Installed Oct. 8, 2008



FORCAST in the Lab

Extensive testing done in the lab Flight data acquisition simulations

Run two arrays at different rates while synching to a chopping secondary


FORCAST in DAOF lab

From left: FORCAST w/ foreoptics (test equipment), counterweight rack, and PI rack



Installation on the plane

Installing PI rack & getting FORCAST into the plane


Attaching FORCAST

George and Charlie positioning FORCAST

George and Chuck fastening FORCAST to telescope



Cryogen transfers on the plane

George and Luke in their LN2 transfer “costumes”


Example Flight: Galactic Center

Early science flight limited to within 200 miles of NASA Dryden



Flight Log ….Preparation and flights consisted of the following:

LineOps (Line Operations, 19 in total) Park plane on tarmac and look at stars

Allowed end-to-end testing of H/W & S/W

This provided extremely important practice

Observatory characterization flights 25-May-2010, 10-Nov-2010, 18-Nov-2010

Observatory operational and performance checkout

High speed “jitter” measurements of bright stars

Also measured primary-secondary telescope emissivity

Short Science flights 30-Nov-2010, 03-Dec-2010, 07-Dec-2010

Observed Jupiter, Comet Hartley 2, M42, W3, M82 + calibrators

Basic Science flights (support of guest investigations) 10 flights: 05-May through 07-Jun-2011

On the Tarmac for LineOps

Left: Setting up the plane for a “LineOp”(line operation)

Right: Door open, looking at an alignment and calibration star



Preflight Safety Briefing

I don’t think Ryan believes him


TACFL: In flight operations

Holgar, Randy, Andy, and Uli at work

Jim and Joe (foreground),

Alan (background)

TACFL (Telescope Assembly Characterization and First Light) = OCF#1 (Observatory Characterization Flight #1)

First photons ever collected on a SOFIA flight! (May 25, 2010)



It’s the plane that’s moving

Apparent motion of telescope as plane pitches, rolls, and yaws.


TACFL: First “Science” Integration

M82 – first chop-nod sequence: 24 m (left) and 37 m (right)



Example Flight Plan

Sgr A

Ceph

Boo

Lyr

Sgr A

Ceph

Flights are 10 hours long but typically go by very quickly!

NASA Test Pilotquizzing me

Hans Zinneckerquizzing me


FORCAST Science Observations

Sample Science Images Jupiter

Orion and W3 star forming regions

Pistol/Sickle region of Galactic Center Most luminous star in the galaxy?

Circumnuclear disk around Sgr A* Feeding the monster?



Jupiter

Multi-wavelength imaging of Jupiter with FORCAST

Peter Gierasch along with Barney Conrath and Jason Wang (CU undergrad) are analyzing and modeling the data (to look at H2 ortho to para ratio, etc.)

“Raw” 11.1 m Jupiter images – right image has been rescaled to show Callisto and Io (and noise level)

11.1 m

5.4 11.1 19.7 24.2 31.5 37.1


Orion Nebula

Orion Nebula at the Sword of Orion is the closest region to the earth of Massive Star Formation Distance = 415 pc

Both Optical stars (Trapezium), embedded star formation (OMC 1/BNKL and OMC2)

Observed at 6.4 (PAH), 6.6, 7.7 (PAH), 11.3 (PAH), 19.7, 31.4, and 37.1 m

Science Objectives: Determine luminosity and spectral energy distribution (SED)

of sources in the BNKL region (De Buizer et al. 2012, ApJL)

Measure SED of Orion proplyds to look at disk termination (Shuping et al. 2012, ApJL)

SED and properties of OMC2 embedded stars with disks (Adams et al. 2012,ApJL)


SOFIA: Orion Image

Left: Visible (HST, O’Dell and Wong),

Middle: Near-IR (McCaughrean),

Right: SOFIA 19.7 m (green) + 37 m (red) image


KAO 38 um

(Stacey et al. 1995)

BN/KL RegionBlue=19um Green=31um Red=37um

De Buizer et al. (2012)

SOFIA

Background Image:Spitzer

BN

IRc3

IRc4

IRc2

Source I


W3: from previous to the present

Above left: Spitzer composite image at 3.6, 4.5, and 8.0 m of W3 (Ruch et al. 2007). Middle: 20 m image from Wynn-Williams, et al. 1972 and FIR images from Werner et al. 1980. Right: Images from SOFIA

20 m (Mt Wilson)

30 m (KAO)

50 m (KAO)

19.7 m

31.5 m

37.1 m


GC Science

Pistol Nebula & Quintuplet Cluster Pistol star may be the most luminous star in our galaxy (Teff

~ 14,000 K) Nebula is a result of mass loss from the star

Ryan Lau working on paper discussing morphology and dynamics of the nebula What is source of heating of the dust?

What are the dynamics of the stellar winds in the region?

Circumnuclear ring Almost perfect r ~ 1.5pc ring around the 4x106 Msun BH

Thickness/Diameter ~ only 1/10; inclination to galaxy ~18°

Clear color gradient seen across the ring: internally heated

Probably by young stars interior to the ring

Interesting structure on fine scales


The Galactic Center

At right are mulitcolor infrared images of two regions of the center of the Milky Way made from SOFIA.

SOFIA/FORCAST images at 19.7 (blue), 31.5 (green), 37.1 (red) m

Radio image of Sgr A, pistol, sickle, filaments and arches

120 lightyears

Sgr A - CND

Mulitcolor image of circumnuclear disk (CND) in the Galactic Center.

Scaling varies from left (scaled to central brightness) to right(scaled to emphasize ring)

19.7 (blue), 31.5 (green), 37.1 (red)



Experiences flying on SOFIA

It has been both challenging and rewarding We are part of a making a highly complex system

work

But, of course, that is the point (to push new boundaries)

At every stage things have worked better than (I personally) expected

Observatory performance is quite good Would like continued image quality improvement

Great team effort by everyone


Summary

Science flights have been highly successful. 3 Short Science and 10 Basic Science have lots of

publishable results

Science breadth Wide range of programs covering planetary

science, star formation, stellar evolution, the interstellar medium, and others.

FORCAST niche will be Spatial resolution & wavelength coverage

(Grism) spectroscopy (to be commissioned the next time FORCAST flies)



What should you remember?

Interstellar dust Emits primarily in the infrared (IR)

“Thermal” IR wavelengths: ~ 2 m to ~ 200 m

Atmospheric transmission Generally poor in the infrared

Must get above (most of) the atmosphere to look at the sky

Infrared emission Important for studying star forming regions

Can see through dust to see newly born stars

Questions?

Documents

SOFIA: First Light to First Sciencehosting.astro.cornell.edu/academics/courses/astro101/...Right: SOFIA 19.7 m (green) + 37 m (red) image FORCAST First Light to First Science 32 KAO