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ROSAT Guest Observer Facility

Calibration Targets


(Notes on some calibration targets:)

N132D
Brightest X-ray SNR in the LMC. Emission-line dominated X-ray spectrum with strong O lines at 573 and 652 eV. Constant spectrum. Source has an extent of a few arcminutes in the PSPC bandpass.

HZ43
Bright DA white dwarf with T_e ~ 55,000 K, nearly pure H atmosphere and very low N_H. Commonly used for calibration the soft X-ray response.

Crab
Power-law emission spectrum due to synchrotron radiation. Size is approximately 1.25 arcmin x 1.75 arcmin. Embedded 33 ms pulsar produces ~10 percent of X-ray flux. Source is bright enough to use as a rate-gain calibration for the PSPC.

Vela
10,000 yr old remnant of size approximately 6 degrees diameter. Several hundred counts/sec in PSPC and KT ~ 0.13 keV. Contains an X-ray pulsar embedded in an extended synchrotron nebula. X-ray pulsations are found only in the lowest PSPC channels (below 0.85 keV). The spectrum of the pulsar is complex, with an underlying power-law of Gamma ~2., a black body from the pulsar, and thermal emission from the SNR.The synchrotron nebula has a power-law of Gamma ~2 also. The column density to the pulsar is very low (~10^{19} cm^{-2}).

Pulsar is ~2 UFU with a power-law spectrum. There is a one arcminute nebula surrounding the pulsar.

Meaty
White dwarf discovered by WFC team and thereafter used a soft calibration source.

AR LAC
Eclipsing RS CVn. Two temperature spectrum with very low $N_H$ value. Bright, unabsorbed point source used for detector point spread function calibrations.

CYG X-2
LMXB, shallow X-ray dips seen at optical period (9.8 days). Shows oxygen edge at 0.533 keV. Dust halo makes this an extended X-ray source at soft X-ray energies.

CYG X-3
LMXB with high and low states. Partial eclipses observed. Heavily obscured at low energies. Smooth, quasi-sinusoidal modulation suggests the observed X-rays are scattered from an accretion disk corona.

A2256
Nearby (z=0.060) cluster of galaxies. X-ray luminosity (2-10 keV) ~3 times 10^{44} erg \ cm^{-2} \ s^{-1}. Core radius is 0.5 MPC (5 arcmin) and the distribution is smooth. No cooling flow.

LMC X-1
Black hole candidate, soft X-ray spectrum. Embedded in optical nebula. Soft X-ray halo.

LMC X-3
BV3 star and black hole candidate. 1.7 day optical period but no X-ray eclipses seen. Soft X-ray spectrum. Boresight target.

CAS A
Diameter four arcmin SNR. Spectral variations seen across the remnant. SSS found a complex spectrum dominated by strong lines from He-like ions.

MKN421
BL Lac used a spectral calibration source during its bright state. The assumption of a featureless spectrum, and the 150 ct/sec brightness were the reasons it was used for recalibration of the matrix. Unfortunately this source was affected by the rate-gain and this was not known at the time of recalibration.

Also used to test the tail of the PSPC point spread function to high S/N, after these tests the Lorentzian tail of the psf was eventually rescaled (CAL/ROS/92-001a and CAL/ROS/93-015).

BETA CAR, BETA LEO and Vega
UV leak tests. These stars are A type which are strong UV emitters, but emit no X-rays.

GD695, BPM97895, and EG 187
Bright hot DA white dwarfs. Bright UV point sources, flux and spectral calibration for WFC

Delta Dor, BETA Aur, EPS Lyr
HRI UV leak cal sources.


Next Calibration Tasks

ROSAT GOF Return to the ROSAT GOF Last Update: Jan 11, 1995 Curator: Michael Arida (SP Sys); arida@milkyway.gsfc.nasa.gov
HEASARC Guest Observer Facility


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This file was last modified on Monday, 13-Sep-1999 15:47:28 EDT

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