We present the first results from the Off-plane Grating Rocket for Extended Source Spectroscopy (OGRESS) sounding rocket payload based at the University of Iowa. OGRESS is designed to perform moderate resolution (R~10- 40) spectroscopy of diffuse celestial x-ray sources between 0.3 – 1.2 keV. A wire grid focuser constrains light from diffuse sources into a converging beam that feeds an array of off-plane diffraction gratings. The spectrum is focused onto Gaseous Electron Multiplier (GEM) detectors. OGRESS launched on the morning of May 2, 2015 and collected data for ~5 minutes before returning via parachute. OGRESS observed the Cygnus Loop supernova remnant with the goal of obtaining the most accurate physical diagnostics thus far recorded. During the flight, OGRESS had an unexpectedly high count rate which manifested as a highly uniform signal across the active area of the detector, swamping the expected spectrum from Cygnus. Efforts are still in progress to identify the source of this uniform signal and to discover if a usable spectrum can be extracted from the raw flight data.
The Off-plane Grating Rocket Experiment (OGRE) is a high resolution soft X-ray spectrometer sub-orbital rocket payload designed as a technology development platform for three low Technology Readiness Level (TRL) components. The incident photons will be focused using a light-weight, high resolution, single-crystal silicon optic. They are then dispersed conically according to wavelength by an array of off-plane gratings before being detected in a focal plane camera comprised of four Electron Multiplying Charge-Coupled Devices (EM-CCDs). While CCDs have been extensively used in space applications; EM-CCDs are seldom used in this environment and even more rarely for X-ray photon counting applications, making them a potential technology risk for larger scale X-ray observatories. This paper will discuss the reasons behind choosing EM-CCDs for the focal plane detector and the developments that have been recently made in the prototype camera electronics and thermal control system.
Photon counting detector systems on sounding rocket payloads often require interfacing asynchronous outputs with a synchronously clocked telemetry stream. Though this can be handled with an on-board computer, there are several low cost alternatives including custom hardware, microcontrollers, and Field-Programmable Gate Arrays (FPGAs). This paper outlines how a telemetry interface for detectors on a sounding rocket with asynchronous parallel digital output can be implemented using low cost FPGAs and minimal custom hardware. It also discusses how this system can be tested with a simulated telemetry chain in the small laboratory setting.
The Off-plane Grating Rocket Experiment (OGRE) is a sub-orbital rocket payload designed to advance the development of several emerging technologies for use on space missions. The payload consists of a high resolution soft X-ray spectrometer based around an optic made from precision cut and ground, single crystal silicon mirrors, a module of off-plane gratings and a camera array based around Electron Multiplying CCD (EM-CCD) technology. This paper gives an overview of OGRE with emphasis on the detector array; specifically this paper will address the reasons that EM-CCDs are the detector of choice and the advantages and disadvantages that this technology offers.
A novel design of X-ray optical system - concentrator for astrophysical rocket experiment is investigated. The proposed system is
based on four modules with Kirkpatrick-Baez (KB) configuration allowing usage of multi-foil mirrors arranged to parabolic profile.
The KB modules are supplemented by rotationally symmetrical parabolic segments. This X-ray optical system effectively uses
a circular aperture. The KB modules are placed in four quadrants while the segments are set into a Cartesian cross between
the KB modules. Studied optical system is under consideration for the student rocket experiment of University of Colorado that
should verify function of NIST’s energy-dispersive detector based on Transition Edge Sensors (TES microcalorimeters).
We present an overview of the Off-plane Grating Rocket for Extended Source Spectroscopy (OGRESS)
sounding rocket payload based at the University of Iowa. OGRESS is designed to perform moderate resolution (R~10-
40) spectroscopy of diffuse celestial X-ray sources between 0.3 – 1.2 keV. A wire grid focuser constrains light from
diffuse sources into a converging beam that feeds an array of diffraction gratings in the extreme off-plane mount. The
spectrum is focused onto Gaseous Electron Multiplier (GEM) detectors. Scheduled to launch in 2014, OGRESS will
obtain accurate physical diagnostics of the Cygnus Loop supernova remnant and will increase the technical readiness
level of GEMs. OGRESS is the fourth-generation of similar payloads from the partnership between the University of
Iowa and the University of Colorado, with higher throughput, and improved noise characteristics over its predecessors.
In this work, we investigate a novel design of optical system for astrophysics. In addition, a new testing method in the X-ray laboratory was verified. The proposed optical system is composed of modules with Kirkpatrick-Baez configuration allowing usage of multi-foil mirrors arranged to parabolic profile. This system effectively uses a circular aperture, which is divided into petals. Individual petals consist of diagonally oriented KB cells with common focus. The hybrid optical system includes a set of rotationally symmetrical parabolic mirrors to achieve higher reflection efficiency of harder X-rays. New results are presented.
In this work, we investigate a novel design of optical system for astrophysics. In addition, a new
testing method in the X-ray laboratory was verified. The proposed optical system is composed of modules with
Kirkpatrick-Baez configuration allowing usage of multi-foil mirrors arranged along a parabolic profile. This
system effectively uses a circular aperture, which is divided into petals. Individual petals consist of diagonally
oriented KB cells with a common focus. This optical system can be improved by a set of nested rotationally
symmetric X-ray mirrors in order to achieve higher reflection efficiency in harder part of considered spectrum.
We present the CODEX sounding rocket payload, a soft x-ray (0.1-1.0 keV) spectrometer designed to
observe diffuse high-surface brightness astronomical sources. The payload is composed of two modules, each with
a 3.25° x 3.25° field of view defined by a stack of wire grids that block light not coming to a 3.0 m focus and admit
only nearly-collimated light onto an array of 67 diffraction gratings in an off-plane mount. After a 2.0 m throw, the
spectrum is detected by offset large-format gaseous electron multiplier (GEM) detectors. CODEX will target the
Vela supernova remnant later this year to measure the temperature and abundances and to determine the
contributions of various soft x-ray emission mechanisms to the remnant's energy budget; resulting spectra will have
resolution (E/▵E) ranging from 50 to 100 across the band. CODEX is the third-generation of similar payloads from
the University of Colorado, with an increased bandpass, higher throughput, and a more robust mechanical structure
than its predecessors.
CODEX is a sounding rocket payload designed to operate in the soft x-ray (0.1-1.0 kV) regime. The instrument has a
3.25 degree square field of view that uses a one meter long wire grid collimator to create a beam that converges to a line
in the focal plane. Wire grid collimator performance is directly correlated to the geometric accuracy of actual grid
features and their relative locations. Utilizing a strategic combination of manufacturing and assembly techniques, this
design is engineered for precision within the confines of a typical rocket budget. Expected resilience of the collimator
under flight conditions is predicted by mechanical analysis.