HQ U.S. Air Force Academy I n t e g r i t y - S e r v i c e - E x c e l l e n c e Slitless Spectroscopy of Geosynchronous Satellites 18 November 2014 Roger Tippets Department of Physics DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -Concerns and Issues- 2 A spectrum produced by a dispersing element (in our case a transmission grating) Spectra of all objects in the FOV are recorded The slit is the zeroth order- resolution depends on focus of zeroth order Order Overlap Stellar confusion A stationary satellite against a moving stellar background (contamination from other objects and overlapping orders occurs often and is essentially unpredictable. 300 g/mm grating F inch telescope Apogee U47 NICRISS (James Webb) Simulated spectra from one of the grisms Galaxy 15 with sidereal track Galaxy 15 track

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -learned mechanics- 3 Steps to extract spectra Place the dispersion orthogonal to the sidereal motion Stellar confusion is easiest to see Mean fee path is ~ 20 seconds Co-add spectra to gain S/R

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -learned mechanics- 4 Use Wolf-Rayet stars to determine plate scale 100 g/mm F inch Library reference Plate scale Calibration

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -learned mechanics- 5 Use Wolf-Rayet stars to determine plate scale 100 g/mm F inch Library reference Plate scale Calibration

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -FTN Systems- 6 All telescope systems have a Richardson 100 g/mm transmission grating in the filter wheel Combining error sources chromatic coma, field curvature and full width at half maximum (Airy disk diameter) spectral resolution goes from 3.3 nm (350 nm) to 4.4 nm (700 nm) R = 103 to 147 Low resolution spectra have 20 times information of Johnson –Cousins broadband filters Spectra can be integrated to obtain Stromgren (intermediate), Johnson-Cousins (broad) bands Experience indicates technique may be automated

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -USAFA Spectroscopy 7 Spectra normalized with a solar analog to remove solar influence (features)

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -simultaneous observations- 8 Sites Colorado (La Junta, Sterling) Penn State Mamalluca, Chile) Terminator on June 21, 2010 at 5:00 am MDT (left panel) and Dec 21, 2010 at 5:00 pm MST (right panel.) Certain times of year support simultaneous obs Much of year near-simultaneous obs

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -simulated simultaneous observations 9 Example of a large communications satellite in the SatMex-6 orbit (29162) that can be seen simultaneously from Colorado (left panel) and Chile (right panel) Simulated photometric light curve (left panel) for a communications cubical satellite (2.75 meters on a side). The blue lighter trace is the signature as observed from Otero Junior College while the thicker green trace is that seen from Las Campanas, Chile. The same signature as a function of phase angle is shown in the right pane

I n t e g r i t y - S e r v i c e - E x c e l l e n c e Distribution C Slitless Spectroscopy of Geosynchronous Satellites -conclusions 10 Develop simultaneous observation techniques (in cooperation with the University of La Serena) Automate reduction process as much as possible Long term simultaneous observations of selected satellites To determine what information can be extracted Results presented are the result of 3 senior Physics/Mathematics capstone projects Currently a paper summarizing these results is being written to be published in a referred journal Future research will involve USAFA cadets Developed observation techniques, calibration procedures for single site slit spectroscopy Spectra taken indicate potential for unique information extraction Future research