7.2 Calibration Target Notes

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 arc minutes in the PSPC bandpass.

HZ 43

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

Crab

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

Vela X

  10,000 year 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 , a black body from the pulsar, and thermal emission from the SNR. The synchrotron nebula has a power-law of also. The column density to the pulsar is very low ( cm ).

Pulsar is 2 UFU with a power-law spectrum. There is a 1' 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 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.

A 2256

  Nearby (z=0.060) cluster of galaxies. X-ray luminosity (2-10 keV)  erg cm  s . Core radius is 0.5 Mpc (5') 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 4' SNR. Spectral variations seen across the remnant. SSS found a complex spectrum dominated by strong lines from He-like ions.

Mkn 421

  BL Lac used a spectral calibration source during its bright state. The assumption of a featureless spectrum, and the 150 counts s 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 [Hasinger et al.1993] and CAL/ROS/93-015 [Hasinger et al.1994]).

CAR, LEO, and Vega

    UV leak tests. These stars are A type which are strong UV emitters, but emit no X-rays.

GD 695, BPM 97895, and EG 187

    Bright hot DA white dwarfs. Bright UV point sources, flux and spectral calibration for WFC\

Dor, Aur, EPS Lyr

     HRI UV leak cal sources.

© X-Ray Group at MPE (group)
last update:2001/09/27 22:35:10, editor of this page:Ortwin Schwentker